Drainage project

Calculation and design

In order for the drainage, equipped on the land plot, to function correctly, to have the necessary throughput, before starting work, it is necessary to draw up a draft of the drainage system.

This is technical documentation, which is compiled taking into account generally accepted requirements and norms of SNiP.

The design begins with hydraulic drainage calculations. They will help determine the amount of material required for the work, as well as its characteristics.

In the course of calculations, you need to determine:

• the degree of permeability of all rocks that make up the soil on the site, as well as the tendency of hard rocks available in this area to crack;
• indicators of resistance of rocks to leaching of mineral particles, which can provoke soil salinization;
• the presence of tectonic disturbances on the site, the quality of the rocks on it;
• the average amount of precipitation falling in a given climatic zone for a certain period of time;
• the level and composition of groundwater at the site;
• features of the location and activity of groundwater sources.

Hydraulic calculation of drainage

Of course, if we are talking about a private plot, then the drainage project in such cases is not always done, usually the standard system scheme is taken as the basis.

But, if special climatic or geological conditions are observed here, the project is still needed.

Site drainage scheme

In addition to the above calculations, it is imperative to investigate the relief of the site. Determine the place where the largest amount of water accumulates after rain or snow melt. This will help to correctly determine the slope of the elements of the drainage system, to make it more efficient.

Now you can begin to make a project for the drainage system of the site.

It will include:

Site drainage project

• a schematic sketch of the laying of drainage pipes for the arrangement of deep and surface communications;
• design indicators of drainage pipes: length, cross-sectional diameter, slope, laying depth, as well as the distance between several drains;
• dimensions and location of other elements of the drainage system: connecting nodes, wells, water receivers;
• a list of materials that will be required in order to be able to create an effective drainage system.

Having a project in hand, it will be easier to determine the required amount of material, as well as perform installation work.

What rules and regulations are regulated by SNiP

To equip the drainage system of a land plot, you will need to carefully study the norms of SNiP 2.06.15-85 and 2.04.03-85.

It contains all the information you need to successfully complete the job.

First of all, study the rules that govern the SNiP drainage device.

They are as follows:

SNiP norms for drainage

• to create a drainage system, moisture-resistant pipes should be used, preferably ceramic, asbestos-cement or plastic;
• observe the slope of the pipes to the place of collection of water. It should be 0.5-0.7%;
• be sure to equip revision wells - elements that allow you to control the operation of the drainage system, flush and clean it;
• in front of the wall of the basement, vertical drainage must be made to allow water to be diverted from the building into the drainage system;
• place pipes along the walls of the building. If the foundation has an irregular shape, drains can be laid at an increased distance from it;
• lay pipes so that the bottom of the products is located below the edge of the base of the foundation by 20 cm or more. The top edge of the pipes should not protrude beyond the bottom of the foundation base;
• wall drainage should be equipped around the entire perimeter of the building.

The next step is the preparation of technical documentation. First, a site drainage project.

When compiling it, you will need the following data:

Project according to the norms of SNiP

• trench dimensions - for open drainage, the depth should be 50 cm, and the width 40 cm, for deep drainage, the depth of the ditch is 70-150 cm, the width is 40-50 cm;
• drainage pipe slope indicators (SNiP) - 2 cm per meter of pipe with clay soil and 3 cm per meter of product with sandy soil;
• pipe diameter - drainage pipes with a diameter of 110-160 mm are usually taken;
• sand cushion height 10 cm;
• the thickness of the gravel layer is from 20 to 40 cm.

Estimate of landscape works

Now an estimate is being drawn up, which will include the calculation of the volume of drainage, the length of the pipes, the amount of geotextiles.

How to calculate drainage? For example, there is a house whose walls are 10 x 10 meters long.

The foundation is laid in the ground at 1.2 meters.

The depth of soil freezing is 0.8 m.

Foundation wall drainage

Now consider an example of wall drainage of the foundation, SNiP norms are taken into account here.

First, determine the number of drainage wells. The length of one drainage pipe, given the indentation of 3 meters from the foundation, will be 16 m.

The total length of the drains along the perimeter will be 64 m. If the flow is organized along two parallel drains into one well, then we will get a length of 32 meters.

The top point will be the corner opposite in its placement to the well.

Considering a slope of 1 cm per meter, we get a difference in the height of the collection and drainage points of 32 cm.

If you install two wells on opposite sides of the house, then the length of each section of drains can be reduced to 16 m, respectively, the difference will be 16 cm, so it turns out to reduce the cost of installation work.

Foundation wall drainage

Given that the depth of soil freezing is 0.8 m, and the thickness of the drainage layer itself is 0.5 m, we will need to dig a trench 1.3 meters deep.

Project example

To understand how much it will cost to equip a drainage system on a site, consider an example of a project offered by specialized companies.

This includes:

• site drainage;
• arrangement of a trench with an average depth of 1 meter;
• laying a pipe with a diameter of 110 mm;
• winding the pipe with geofabric;
• laying a layer of sand about 15 cm high;
• crushed stone layer 40 cm;
• backfilling with gravel pipes in geotextiles;
• backfilling with soil.

Drainage calculation project

So, one meter of such a system will cost about 1550 rubles.

If you need to equip the drainage of the site, for example, 15 acres, you will need 200 running meters of drainage. The total price will be about 295,000 rubles.

This includes the design of drainage according to SNiP standards, materials and work.

Site drainage

If you do the work yourself, you will only have to pay for the materials.

The calculation of the drainage system will include:

• pipe with a diameter of 110 mm - 80 rubles per bay (50 meters);
• drainage well with a diameter of 355 mm - 1609 rubles per meter;
• hatch for a well - 754 rubles;
• bottom cover for a well - 555 rubles;
• quarry sand - 250 rubles per cubic meter;
• crushed stone with a fraction of 20-40 mm - 950 rubles per cubic meter;
• geotextiles - 35 rubles per square meter;
• plastic well with a diameter of 1100 mm - 17240 rubles per meter.

Design of drainage systems on the site

Of course, by designing drainage systems on the site, and arranging them with your own hands, you can save money.

But you can do this work yourself only if you have special knowledge and skills.

First, you will need to perform all the necessary measurements and calculations to determine the required amount of materials, and, accordingly, their cost.

In this case, you will not have to pay for the work.

Video

THE GOVERNMENT OF MOSCOW
MOSCOWARCHITECTURE

MANAGEMENT
for the design of drainage of buildings and structures

1. DEVELOPED by OJSC “Mosproekt” (engineer Kiskin L.K., Chernyshev E.N., Kovylyaev V.M.).

2. Prepared for publication by the Department of Advanced Design and Standards of the Moscow Committee for Architecture (Eng. Ionin V.A., Schipanov Yu.B.).

3. APPROVED AND PUT INTO EFFECT by the indication of the Moscow Architecture Committee of November 20, 2000 N 48

Introduction

Introduction

Until now, design organizations that design drainage systems (hereinafter referred to as drains) in Moscow are guided by the “Temporary guidelines for the design of drainage in Moscow (NM-15-69)”, developed in 1969 by “Mosproekt-1” and "Mosinzhproekt".

During the practical use of the "Temporary Directives", new drainage designs have appeared based on the use of modern materials, both positive and negative experience in the design and construction of drainage has been accumulated, which necessitates the development of a new regulatory document.

Application area

The "Guide" is intended for use in the design and construction of drainage of buildings, structures and underground utility channels located in residential areas, as well as for stand-alone buildings and structures.

The ”Guidelines” do not apply to the design of shallow road drainages, transport and other special-purpose structures, as well as to temporary dewatering during construction work.

a common part

To protect the buried parts of buildings (basements, technical undergrounds, pits, etc.), intra-quarter collectors, communication channels from flooding with groundwater, drainage should be provided. Drainage structures and waterproofing of the underground parts of buildings and structures should be carried out in accordance with SNiP 2.06.15-85, SNiP 2.02.01-83*, MGSN 2.07-97, “Recommendations for the design of waterproofing of underground parts of buildings and structures”, developed by TsNIIPpromzdanii in 1996, and the requirements of this “Manual”.

Drainage design should be carried out on the basis of specific data on the hydrogeological conditions of the facility construction site, the degree of groundwater aggressiveness to building structures, space-planning and design solutions for protected buildings and structures, as well as the functional purpose of these premises.

Anti-capillary waterproofing in the walls and coating or painting insulation of the vertical surfaces of the walls in contact with the ground must be provided in all cases, regardless of the drainage arrangement.

The device of drainages is obligatory in cases of location:

basement floors, technical undergrounds, intra-quarter collectors, communication channels, etc. below the calculated groundwater level or if the excess of floors above the calculated groundwater level is less than 50 cm;

floors of operated basements, intra-quarter collectors, communication channels in clay and loamy soils, regardless of the presence of groundwater;

basement floors located in the zone of capillary moisture, when dampness is not allowed in the basement;

floors of technical undergrounds in clay and loamy soils when they are buried more than 1.3 m from the planning surface of the earth, regardless of the presence of groundwater;

floors of technical subfields in clay and loamy soils when they are buried less than 1.3 m from the planning surface of the earth when the floor is located on the foundation slab, as well as in cases where sand lenses approach the building from the upland side or a thalweg is located from the upland side of the building.

In order to exclude watering of the soils of the territories and the flow of water to buildings and structures, in addition to drainage, it is necessary to provide for:

normative soil compaction when backfilling pits and trenches;

as a rule, closed outlets of drains from the roof of buildings;

drainage open trays with a section of 15x15 cm with a longitudinal slope of 1% with open outlets of the drain;

installation of a blind area for buildings 100 cm wide with an active transverse slope from buildings of 2% to roads or trays;

hermetic sealing of openings in external walls and foundations at the inlets and outlets of engineering networks;

organized surface runoff from the territory of the facility being designed, which does not impair the removal of rain and melt water from the adjacent territory.

In cases where, due to the low elevations of the existing surface of the earth, it is not possible to ensure the drainage of surface water or achieve the required lowering of groundwater, the area should be backfilled to the required elevations. If gravity drainage of drainage waters from individual buildings and structures or a group of buildings is not possible, provision should be made for the installation of pumping stations for pumping drainage waters.

The design of drainages of new facilities should be carried out taking into account existing or previously designed drainages of adjacent territories.

With a general decrease in the level of groundwater in the territory of the microdistrict, the marks of the lowered level of groundwater should be assigned 0.5 m below the floors of basements, technical undergrounds, communication channels and other structures. In case of impossibility or inexpediency of a general lowering of the groundwater level, local drainage should be provided for individual buildings and structures (or groups of buildings).

Local drainage, as a rule, should be arranged in cases of significant deepening of the underground floors of individual buildings when gravity removal of drainage water is impossible.

Types of drains

Depending on the location of the drainage in relation to the aquiclude, the drainages can be of a perfect or imperfect type.

Drainage of the perfect type is laid on the aquiclude. Groundwater enters the drainage from above and from the sides. In accordance with these conditions, a drainage of a perfect type must have a draining coating on top and sides (see Fig. 1).

Drainage of an imperfect type is laid above the aquiclude. Groundwater enters the drains from all sides, so the drainage sprinkling must be closed on all sides (see Fig. 2).

Initial data for drainage design

To draw up a drainage project, the following data and materials are required:

technical opinion on the hydrogeological conditions of construction;

a plan of the territory on a scale of 1:500 with existing and planned buildings and underground structures;

relief organization project;

plans and marks of floors of basements and subfloors of buildings;

plans, sections and developments of building foundations;

plans, longitudinal profiles and sections of underground channels.

In the technical report on the hydrogeological conditions of construction, the characteristics of groundwater, the geological and lithological structure of the site and the physical and mechanical properties of soils should be given.

In the groundwater characteristics section, the following should be indicated:

reasons for the formation and sources of groundwater supply;

groundwater regime and marks of the appeared, established and calculated levels of groundwater, and, if necessary, the height of the zone of capillary moistening of the soil;

chemical analysis data and a conclusion on the aggressiveness of groundwater in relation to concrete and mortar.

The geological and lithological section provides a general description of the structure of the site.

In the characteristics of the physical and mechanical properties of soils, the following should be indicated:

granulometric composition of sandy soils;

filtration coefficients of sandy soils and sandy loams;

porosity and water loss coefficients;

angle of repose and soil bearing capacity.

The conclusion should be accompanied by the main geological sections and "columns" of soils from boreholes, necessary for compiling geological sections along drainage routes.

If necessary, in complex hydrogeological conditions for drainage projects for blocks and microdistricts, a map of hydroisogypsum and a map of soil distribution should be attached to the technical report.

In the case of special requirements for the drainage device, caused by the specific operating conditions of the protected premises and structures, these requirements must be stated by the customer as additional source materials for the design of drainage.

General conditions for choosing a drainage system

The drainage system is selected depending on the nature of the protected object and hydrogeological conditions.

When designing new quarters and microdistricts in areas with a high level of groundwater, a general drainage scheme should be developed.

The drainage scheme includes drainage systems that provide a general decrease in the level of groundwater in the territory of a quarter (microdistrict), and local drainages to protect individual structures from flooding by groundwater.

Drainages that provide a general lowering of the groundwater level include drainages:

head or coastal;

systematic.

Local drainages include drainages:

annular;

wall-mounted;

reservoir.

Local drainage also includes drainage designed to protect individual structures:

drainage of underground channels;

pit drainage;

road drainage;

drainage of filled rivers, streams, ravines and ravines;

slope and wall drainage;

drainage of underground parts of existing buildings.

Under favorable conditions (in sandy soils, as well as in sandy interlayers with a large area of ​​​​their distribution), local drainage can simultaneously contribute to a general decrease in the level of groundwater.

In areas where groundwater occurs in sandy soils, drainage systems should be used to ensure a general decrease in the level of groundwater.

In this case, local drainages should be used to protect certain especially buried structures from flooding by groundwater.

In areas where groundwater occurs in clayey, loamy and other soils with low water loss, it is necessary to arrange local drainage.

Local “preventive” drainages should also be arranged in the absence of observed groundwater to protect underground structures located in clay and loamy soils.

In areas with a layered structure of the aquifer, both general drainage systems and local drainage should be arranged.

General drainage systems should be arranged to drain flooded sand layers through which water enters the drained area. In this system, individual local drainages can also be used, in which the radius of the depression curve captures a significant area of ​​the territory. Local drainage must be arranged for underground structures laid in areas where the aquifer is not completely drained by the general drainage system, as well as in places where perched water may appear.

In built-up areas, during the construction of individual buildings and structures that need protection from groundwater flooding, local drainage should be arranged. When designing and constructing these drains, consideration must be given to their impact on adjacent existing structures.

head drainage

To drain the territories flooded by the flow of groundwater with a supply area located outside this territory, head drainage should be arranged (see Fig. 3).

Head drainage should be laid along the upper, in relation to the underground flow, boundary of the drained area. The drainage route is assigned taking into account the location of the building and is carried out, if possible, in places with higher elevations of the aquiclude.

The head drainage should, as a rule, cross the groundwater flow along its entire width.

If the length of the head drainage is less than the width of the underground flow, additional drains should be installed along the lateral boundaries of the drained area in order to intercept groundwater entering from the side.

When the aquiclude is shallow, the head drainage should be laid on the surface of the aquiclude (with some penetration into it) in order to completely intercept groundwater, as a drainage of a perfect type.

In cases where it is not possible to lay drainage on the aquiclude, and according to the conditions of drainage, it is required to completely intercept the flow of groundwater, a screen from a waterproof sheet pile is arranged below the drainage, which must be lowered below the aquiclude marks.

When the aquiclude is deep, the head drainage is laid above the aquiclude, as an imperfect type of drainage. In this case, it is necessary to calculate the depression curve. If the device of one line of the main drainage does not achieve a decrease in the level of groundwater to the specified levels, a second drainage line should be laid parallel to the head drainage. The distance between the drains is determined by calculation.

If the part of the aquifer located above the drainage consists of sandy soils with a filtration coefficient of less than 5 m/day, the lower part of the drainage trench should be backfilled with sand with a filtration coefficient of at least 5 m/day (see Fig. 4).

The height of backfilling with sand is 0.6-0.7H, where: H is the height from the bottom of the drainage trench to the unreduced calculated groundwater level.

With a layered structure of a part of the aquifer located above the drainage, with alternating layers of sand and loam, the backfilling of the drainage trench with sand with a filtration coefficient of at least 5 m / day should be carried out 30 cm above the unlowered calculated groundwater level.

Backfilling with sand can be carried out over the entire width of the trench with a vertical or inclined prism, at least 30 cm thick. water).

If the head drainage is laid in the thickness of relatively weakly permeable soils underlain by well permeable soils, a combined drainage should be arranged, consisting of a horizontal drain and vertical self-flowing wells (see Fig. 5).

Vertical wells must communicate with their base with permeable soils of the aquifer, and the upper part with the inner layer of horizontal drain sprinkling.

To drain coastal areas flooded due to the backwater of the water horizon in rivers and reservoirs, coastal drainage should be arranged (see Fig. 6), where the designations are: MG - low-water horizon of the reservoir, GWL - horizon of backed waters of the reservoir.

Coastal drainage is laid parallel to the shore of the reservoir and is laid below the normally supported horizon (NPH) of the reservoir by a value determined by the calculation.

If necessary, head and bank drainage can be used in combination with other drainage systems.

Systematic drainage

In areas where groundwater does not have a clearly defined flow direction, and the aquifer is composed of sandy soils or has a layered structure with open sandy interlayers, systematic drainage should be arranged (see Fig. 7).

The distance between the drainage drains of systematic drainage and the depth of their laying are determined by calculation.

In urban areas, systematic drainage can be arranged in combination with local drainages. In this case, when designing individual drains, one should consider the possibility of their simultaneous use as a local drainage protecting individual structures and as elements of a systematic drainage providing a general decrease in the groundwater level in the drained area.

When laying drains of systematic drainage in the thickness of soil with low water permeability, underlain by well-permeable soils, combined drainage should be used, consisting of horizontal drains with vertical, self-flowing wells (see Fig. 5).

In territories flooded by the flow of groundwater, the supply area of ​​\u200b\u200bwhich also captures the drained territory, head and systematic drainage should be used together.

ring drainage

To protect basements and subfloors of detached buildings or a group of buildings from flooding by groundwater, when they are laid in water-bearing sandy soils, circular drainages should be arranged (see Fig. 8).

Circular drainages should also be arranged to protect especially ruined basements in new quarters and microdistricts with an insufficient depth of lowering the groundwater level by the general drainage system of the territory.
After payment is confirmed, the page will

Low filtration of soils lying under the soil is the cause of excess water in the area. It slowly goes into the lower layers or does not seep at all. Cultivated plants grow poorly here or do not take root at all, the territory becomes swampy, slush is felt. In such cases, a drainage system is needed, which should be properly organized.

We will explain in detail how to make a site drainage project. A system arranged according to our advice will perfectly cope with its duties. Acquaintance with the proposed information will be useful for both independent owners and customers of landscape arrangement in a specialized company.

We have presented practical schemes for the construction of drainage systems for suburban areas. The article describes in detail the factors that need to be taken into account in the design and construction of drainage. The information proposed for consideration is illustrated with photographs, diagrams, and videos.

Land reclamation measures, in accordance with the norms (SNiP 2.06.15), are carried out in forest and agricultural lands so that the soil becomes as suitable as possible for growing fruit trees, cereals and vegetables.

For this, an extensive system of open ditches or closed pipelines is formed, the main purpose of which is to drain overly wet areas.

The ultimate goal of collecting water through branches and sleeves of various types is artificial or natural reservoirs (if conditions permit), special drainage ditches, or storage tanks from which water is pumped out for irrigation and maintenance of the territory.

Often, pipes buried in the ground, if the relief allows, are replaced by external structures - ditches and trenches. These are open-type drainage elements, through which water moves by gravity.

According to the same principle, a pipeline network is designed for a summer cottage, regardless of its area - 6 or 26 acres. If the area suffers from frequent flooding after rain or spring floods, the construction of catchment facilities is mandatory.

Accumulation of excess moisture is facilitated by clay soils: sandy loam and loam, because they do not pass or very weakly pass water into the underlying layers.

Another factor that encourages thinking about a drainage project is the increased level of groundwater, the presence of which can be found out even without special geological surveys.

Image Gallery

Excess moisture in the soil is always a danger to the integrity of the foundation of construction projects: houses, baths, garages, outbuildings

Elements of the drainage structure

What is a drainage system? This is a network consisting of various components, the main purpose of which is the removal and collection of capillary water contained in the pores of non-cohesive soils and cracks in cohesive rocks.

Image Gallery

System of regional regulatory documents
urban planning activities in St. Petersburg

REGIONAL GUIDANCE DOCUMENTS

DRAINAGES IN BUILDING DESIGN
AND FACILITIES

RMD 50-06-2009 St. Petersburg

Government of St. Petersburg
Saint Petersburg
2009

Foreword

1 DESIGNEDResearch and Design Institute for Housing and Civil Engineering (JSC "LENNIIPROEKT") and St. Petersburg State University of Architecture and Civil Engineering (SPb GASU)

2 INTRODUCEDConstruction Committee of the Government of St. Petersburg

4 APPROVEDfor use in work by order of the State Construction Supervision and Expertise Service of St. Petersburg dated November 26, 2009 No. 105p.

5 AGREEDwith the Committee for State Control, Use and Protection of Historical and Cultural Monuments, with the Committee for Energy and Engineering Equipment, with the State Construction Supervision and Expertise Service of St. Petersburg.

6 PREPARED FOR EDITION CJSC "Engineering Association" Lenstroyingservice "

7 DESIGNED FOR THE FIRST TIME

Introduction

This regional methodological document has been developed in order to provide an effective system of groundwater protection for buildings and structures being built and reconstructed on the territory of St. Petersburg.

The document takes into account the features of hydrogeological conditions and the location of modern construction sites:

High level of groundwater of man-caused and natural origin, the presence of pressure water with the formation of springs; regional distribution of groundwater in the territory of the city with violation of the natural regime in its island part;

The presence of a heterogeneous upper stratum of weakly permeable soils, alluvial and bulk territories along the banks of rivers and the bay, peaty soils and buried layers of peat; formation of technogenic layers by soil dumps, ash, urban and construction waste;

Filled with technogenic soils and canalized natural water bodies; waterlogging, soil suffusion, quicksand phenomena associated with the impact of surface and groundwater;

Placement of construction sites near operated buildings, structures, engineering and transport communications, including near buildings with defects caused by uneven precipitation.

The methodological document takes into account the possibilities of modern technologies in the field of construction, safety and environmental requirements in the design, construction and operation of water protection systems for facilities:

Preservation of the draining function of canalized or filled water natural objects;

Ensuring safety, which excludes a negative change in the properties of the soils of the base of the protected object, operated by neighboring ones, as well as engineering infrastructure structures;

The use of water protection system designs that allow the least possible impact on the natural regime of groundwater;

A comprehensive solution to the issues of organizing surface and underground runoff, devices for waterproofing the building.

The document eliminates inconsistencies that impede the adoption of an effective solution, which so far exist in various reference literature on the design and installation of drainage.

This methodological document contains requirements for source materials, the composition and content of design documentation for drainage, the necessary terms, recommendations for choosing types, systems, schemes and designs of drainage, performing preliminary and filtration calculations.

In compiling this methodological document, the experience of design, surveys and surveys accumulated at the institutes LenNIIproekt, LenzhilNIIproekt, PI-1, St. Petersburg State Agrarian University of Architecture, Spetsproektrestavratsiya, Trust GRII, LenTISIZ, NPO Georeconstruction - Fundament-project and other organizations was used.

The following people took part in the development: from SPb GASU, Ph.D., Professor G.I. Kliorina (theme leader), engineer I.S. Nefedov; from JSC "LENNIIPROEKT" engineers T.L. Sokolova, T.A. Gribanova, V.V. Tkachuk.

REGIONAL GUIDANCE DOCUMENT

DRAINAGES IN DESIGN OF BUILDINGS AND STRUCTURES

1 area of ​​use

This methodological document applies to the design and installation of drainage of buildings and structures during their design, construction and reconstruction on the territory of St. Petersburg.

The document does not apply to drainages for special purposes - landslide slopes, subsiding soils and peat, retaining walls and shallow drainage for roads.

2 Normative references

This document uses references to the following normative documents:

SNiP 2.04.03-85Sewerage. Outdoor networks and facilities

SNiP 2.06.14-85Protection of mine workings from underground and surface waters

SNiP 2.06.15-85Engineering protection of territories from flooding and flooding

Reference manual to SNiP 2.06.15-85 Flooding forecasts and calculation of drainage systems in built-up and built-up areas

SNiP 2.07.01-89*Urban planning. Planning and development of urban and rural settlements

SNiP II-89-80Master plans for industrial enterprises

SNiP 12-03-2001Occupational safety in construction, Part 1. General requirements

SNiP 12-04-2002Labor safety in construction. Part 2. Construction production

SNiP 22-02-2003Engineering protection of territories, buildings and structures from hazardous geological processes. Basic provisions

TSN 50-302-2004Saint Petersburg. Design of foundations for buildings and structures in St. Petersburg

TSN 30-305-2002Saint Petersburg. Urban planning, reconstruction and development of non-central districts of St. Petersburg

TSN 30-306-2002Saint Petersburg. Reconstruction and development of historically established districts of St. Petersburg

PUE- 7 edition. Rules for the installation of electrical installations.

3 Terms and definitions

The following terms and their respective definitions are used in this document:

Coastal drainage - a linear drainage system to intercept the flow of groundwater from the side of the river.

head drainage- a linear drainage system to intercept the flow of groundwater from a higher area.

Geocomposites- combinations of a geofilter and polymeric moisture conductors in the form of porous, perforated or profiled plates and sheets.

Geotextiles - (geotextiles) - filtering membranes (geofilters), used independently and in various composites.

Geofilters- permeable synthetic fabrics that perform the functions of separation and filtration in the drainage structure.

Geotechnical drainage - a set of measures to organize the relief, surface and underground runoff, developed to protect the underground volumes of the building and its location.

Building waterproofing system - a set of elements that protect a building or structure from the effects of water and moisture.

risk zone- the area around the source of adverse impact on neighboring buildings due to dewatering during construction and reconstruction, where negative changes in the properties of the soil massif and / or structures of existing buildings and structures are possible.

contour drainage - near the foundation or ring, have a closed or not closed contour in terms of plan.

ring drainage - contour drainage used to protect a building or several buildings, laid at some distance from the wall of the protected objects.

Linear drainage- head, coastal or a combination of them.

Dehumidification rate- the smallest depth of the maximum predicted groundwater level from the floor mark of the basement of the building or the design surface mark, which ensures normal operating conditions for buildings and the territory.

imperfect drainage - a tubular drain is laid in the water-containing soil layer above the aquiclude.

Foundation drainage - a contour, linear or combined system with a vertical filter layer on the outside of the protected buried part of the object and a horizontal drain laid under the basement floor or along the outer wall, at a distance sufficient to accommodate manholes.

Reservoir drainage - a filter bed at the base of the building made of large-pore soil material or geocomposite.

Plastic drainage - a geocomposite of a three-dimensional drainage plastic base and a filtering membrane (geofilter). It is a two-layer structure made of high-strength polyethylene fabric with molded rounded spikes and a polypropylene filtering geotextile membrane []. Orderly arranged rounded spikes create the thickness of the material and form drain channels between themselves, through which water enters the near-foundation drainage and is discharged from the protected object. The geotextile membrane protects the canvas from mechanical influences, filtration of small soil particles and prevents silting of plastic drainage.

Drainage type- perfect or imperfect, depending on the position of the drains in relation to the water-resistant layer.

Perfect drainage - a tubular drain is laid on a water-resistant layer.

Drainage systems- 1 - contour, linear, combined; 2 - diagrams of the placement of drains in the plan in relation to the protected object; 3 - local, general, depending on the created effect of water protection, respectively, for the object, site.

Geotechnical drainage systems - drainage and rainwater networks on the building site, external (or internal) drains of the building with diverters.

4 Abbreviations

GWL - groundwater level

GW - groundwater

PV - groundwater

PP - polypropylene

HDPE - low pressure polyethylene

PVC - polyvinylchloride

NDPE - high density polyethylene

5 Fundamentals

5.1 Drainage design is carried out taking into account the requirements of reliability, efficiency and economic feasibility, as well as safety, which excludes the negative impact of dewatering on neighboring buildings and preserved structures of the reconstruction object, taking into account the assessment of the geotechnical situation for the protected and existing neighboring buildings, structures in accordance with TSN 50-302-2004 Saint Petersburg, TSN 30-306-2002 Saint Petersburg, TSN 30-305-2002 Petersburg, as well as forecasts for the development of negative hydrogeological processes in the selection and installation of a particular drainage system in accordance with the recommendations of the reference allowances for SNiP 2.06.15 .

5.2 The drainage project should solve the following main tasks:

Ensuring the required dehumidification rate by regulating the GWL and the sewage runoff at the site of the building, excluding the flow of pollutants into underground and buried rooms and the contact of pollutants with the external surface of the structure;

Prevention of watering of soils and increased filtration, which can cause negative changes in soil properties, the emergence or activation of dangerous geological processes;

Ensuring the required sanitary conditions at the construction site and maintaining environmental safety.

The dehumidification rate for buildings with basements and technical undergrounds should be taken as 0.30 m, calculated from the floor mark of these premises and undergrounds.

5.3 Drainage for the protection of buildings is arranged when the floors of basements and technical undergrounds are located:

At elevations below the calculated groundwater level and when they are exceeded relative to the calculated level by less than 30 cm;

In the zone of capillary moistening, when dampness is not allowed in the basements;

In clay and loamy soils, when they are buried more than 1.3 m from the planning surface of the earth, regardless of the presence of groundwater;

In clay and loamy soils, when they are buried less than 1.3 m from the planning surface of the earth;

When the floor is located on the foundation slab, when infiltration in the upper layer of natural or technogenic soil layers is possible from the upland side of the building, and also when the building is located in close proximity to the thalweg, into which groundwater is discharged.

5.4 Drainage should be arranged in cases where the features of the hydrogeological conditions of the construction site adversely affect the strength properties of soils and the bearing capacity of the foundations and can cause buildings to settle.

5.5 The protection of the building from the negative effects of water and moisture is carried out using a set of geotechnical drainage measures, which are performed for the buried part of the building and at the site of its placement.

If possible, preference should be given to drainage systems that simultaneously protect the site and the building located on it from flooding.

Drainage should be designed in conjunction with the organization of the relief, taking into account the water-protective role of the waterproofing of the buried structures of the building.

5.6 The choice of drainage schemes for the object should be carried out taking into account the peculiarities of the hydrogeological conditions of the territory of St. Petersburg, the data of engineering and geological surveys, the configuration, dimensions and design of the foundation of the protected object, the deepening of basements, the presence of closely spaced exploited engineering structures, buildings, their geotechnical category, characteristics designs, requirements.

6 Initial data

6.1 The design is carried out on the basis of the initial data on the engineering and geological conditions of the construction site, the protected object, as well as information about the buildings and structures in operation located nearby.

6.2. The volume of surveys and surveys in order to obtain the necessary initial data depends on the geotechnical category of the object, the design stage, the category of complexity of the natural conditions of the construction site.

The composition and volume of these materials for the purposes of reconstruction and construction in urban areas should be determined in accordance with the requirements TSN 50-302-2004 Saint Petersburg.

6.3. To develop a drainage project, the following materials are needed:

- technical report on the engineering and geological conditions of the construction site;

Conclusion on the hydrogeological conditions of the construction site (if necessary);

Materials of engineering surveys and surveys of past years;

Territory plan with existing and planned buildings and underground structures, elevations;

Plan for organizing the relief of the building site;

Plans and marks of the floor of the basements and subfields of neighboring objects and the designed (protected) building, as well as its first floor;

Plans and sections of the foundations of buildings, elements attached to the outer facade (stairs, ramps, pits, etc.);

Plans, longitudinal profiles and sections of underground channels;

Pit plan and sections (objects of reconstruction or subject to restoration).

6.4 Groundwater protection of palace and park ensembles and historical buildings should be developed in conjunction with measures to strengthen the foundations and foundations of historical buildings, the vertical layout of the site and the water protection of park areas.

The composition of additional source materials is determined by specific conditions (the condition of underground structures and waterproofing, historical drainage and waste systems, near-surface infrastructure, the presence of valuable green spaces, the use of the ensemble, etc.) based on a specially designed research program.

7 Drainage design

7.1 Drainage design includes the selection of its system and design, determining the position in the plan and depth, the method of draining drainage water, as well as making the necessary calculations, including preliminary ones.

7.2 Drainage project should contain the following materials: drainage plan, list of main works on drainage arrangement, drain designs.

If the construction site provides for backfilling of water bodies or sewerage of their sections, then design proposals should be developed for:

Preservation of the draining function of the covered objects;

Measures that compensate for the discharge of natural drainage;

Arrangement of natural springs.

The construction of longitudinal profiles of local drainage is performed by:

If there are special requirements of departmental services;

In difficult conditions (during reconstruction, developed existing engineering networks, etc.).

In the explanatory note, as part of the design documentation, the decisions made are justified and the estimated costs of drainage water are given. When developing working documentation, they are limited to brief information of a similar content in the explanations in the drawings.

7.3 For water protection projects of palace and park ensembles and historical buildings, the composition of graphic and text materials is determined taking into account this document, the task of KGIOP, as well as the requirements TSN 30-306-2002 Saint Petersburg.

7.4 Preliminary verification calculations determine:

The safe distance of the drain from the outer walls of the designed (or existing) building, structure, engineering networks, if their bases are buried above the drainage pipe tray.

For calculation use the formula

Where

b- broadening of the foundation, m;

IN- width of the drainage trench, m;

H- depth of the drain, m;

h- foundation laying depth, m;

a- angle of internal friction of the soil, deg.

The ordinates of the depression curve are the position of the reduced groundwater level as a result of the action of drainage, if there are buildings, structures, utilities, valuable green spaces in the vicinity of the protected object. The purpose of the calculation is to determine the risk zone to exclude negative impacts on existing buildings, engineering and near-surface infrastructure. In the event of an undesirable decrease in GWL in the area of ​​the existing building, the drainage route is corrected.

7.5. If there is a drainage network serving other buildings or structures in the immediate vicinity of the facility under construction, it is necessary to calculate the ordinates of the depression curve of the operated network. The purpose of such a calculation is to determine the position of the depression curve of the operated drainage and evaluate its capabilities in relation to the effect of water protection for a new object. If the reduced GWL, established as a result of the operation of the drainage, does not exceed the dewatering rate, the drainage device for the new facility can be abandoned or its planned position can be changed.

7.6 The calculation of the ordinates of the depression curve is performed in accordance with the methodology described in section 12 of this document.

8 Systems and types of drainage

8.1 There are two type of drainage: perfect and imperfect. The latter does not completely cut through the aquifer, in contrast to the perfect type of drainage, the base of which reaches the aquifer.

Preference should be given to drainages of the perfect type, if the water-resistant layer is located at an insignificant depth from the planning surface and does not require unjustified (taking into account the drainage rate) deepening of the drainage pipes.

8.2 According to the configuration in the plan, one should distinguish between contour, linear and combined systems (schemes), according to the created water protection effect - general systems (protection of the site and the building located on it) and local systems (protection of the building).

8.3 When choosing systems and, the nature of flooding should be taken into account depending on the position of the unloading site, groundwater recharge sources:

Above - infiltration feeding by storm and melt waters;

Below - capillary and underground waters with a free surface during periods of seasonal and annual increases in their level, as well as local pressure waters; the latter are fixed, as a rule, in drilling surveys when passing sandy lenses in poorly permeable soils;

On the side - groundwater flowing from elevated sections of the slopes, and water filtering from reservoirs;

Mixed nutrition - a combination of the various options listed above for feeding GV.

8.4 Depending on the geological structure of the construction site, sources of groundwater supply, purpose and location of protection objects, the following drainage systems should be used:

Linear (head, coastal);

Contour (near foundation, ring);

Reservoir drainages (areal and linear);

Combined from linear, contour, reservoir.

For construction sites composed of poorly permeable layered soils with atmospheric HW supply, as a rule, a foundation drainage device is required for the buried premises of the building and an effective solution for vertical planning.

8.5 Single-line systems in the form of cut-off head drainage are used with a power source “from the side”, when the ground flow coming from the overlying territory is clearly expressed.

Drainage is laid along the upper boundary of the protected area from the side of the inflow of the ground flow. The route is laid taking into account the location of the building, if possible, in places with higher elevations of the aquiclude.

8.6 Two-line systems are designed when the device of one head drainage line does not provide the required decrease in GWL. The second drainage line is laid parallel to the head drainage. The distance between the two designed lines is determined by calculation, based on their joint work, and the calculated position of the reduced GWL is compared with the dehumidification rate.

A two-line drainage system is necessary if the protected area is located between the groundwater recharge zones and their discharge by the local hydrographic network.

It should be borne in mind that when using two-line systems (head and bank drainage), a high drainage effect is achieved only in areas composed of well-permeable soils. In this case, the formation of wide depression funnels is possible as a result of the joint work of the head and coastal drainages.

In areas composed of poorly permeable soils, especially of a layered structure, a two-line combination will not provide the desired reduction in GWL. In this case, it is necessary to consider the following options for protecting the site from groundwater:

Buried parts of the building - local contour drainage system;

Elements of improvement and underground communications - associated drainage;

Plot - proper vertical planning and organization of surface runoff, which reduces the infiltration of precipitation into the ground.

8.7 In coastal areas, in order to lower the GWL caused by the backwater of the water horizon in the river, one-line bank drainage should be arranged. It is laid parallel to the coastline and laid below the horizon of the high waters of the river.

The feasibility of constructing coastal drainage should be justified by the significance of the protected area, since the costs of construction and operation of coastal drainages, especially when pumping large drainage water flows, are quite high.

8.8 When protecting small areas from flooding, the following options are primarily considered:

Local increase in planning marks of the surface;

Protection of a building with a buried basement using local contour and linear systems, as well as waterproofing.

Along with this, it is advisable to use planning opportunities, for example, it is possible to “plant” a building at higher elevations in order to reduce the cost of measures to protect against HP.

8.9. With a lateral source of power supply, combined with atmospheric precipitation infiltration, drainage is performed along the entire contour of the protected building. Depending on the engineering and geological conditions of the building site, wall (foundation) or ring contour systems are used.

When the flooding of the basements is due to a clearly pronounced one-sided inflow of hot water (supply from the side), the drainage is designed in the form of an open loop system.

8.10 Annular drainage protects the basements of the building with mixed groundwater supply and the laying of these premises in water-bearing sandy soils.

When groundwater is fed from above in conditions of a homogeneous structure of the aquifer, perfect annular drainage is also effective for a group of buildings. In the latter case, even when the drains are located above the aquiclude, the GWL is set at levels close to the water level in the drains.

Annular drainage is also used if there is no supply from above, and an increase in GWL is due to the flow of water from below. In the latter case, the dimensions of the drainage circuit should be smaller than with a similar solution in terms of groundwater sources from above.

When the deepening of the drains is not enough due to the amount of uplift, then intermediate drains - “cuts” should be arranged.

8.11 Near-foundation (wall) drainage is used to protect basements and subfields laid in clayey, loamy soils and with a layered structure of a weakly permeable stratum:

As a preventive measure in the absence of HB;

In the presence of a mixed power source HW.

The foundation drainage system, in contrast to the ring one, should be as close as possible to the protected object at a distance that is regulated by the foundation design, the possibility of placing manholes, the conditions for the production of work, as well as the requirements.

With large sizes of the protected object, in order to achieve the effect of water protection over the entire basement area, imperfect contour drains are supplemented with underground lines or areal reservoir drainage is used.

8.12 When protecting several buildings with one circuit, as well as with a width of the protected building of more than 20 m, the depth of imperfect drains should be justified by calculation (see ) taking into account the position of the depression curve inside the circuit.

8.13 If the drainage is laid below the base of the foundation of the protected and neighboring buildings (structures), it is necessary to calculate the safe distance from the drains to the walls of the building in order to exclude the removal, weakening and settlement of the soil under its foundation (see).

8.14 Reservoir drainage should be arranged in combination with contour and linear systems in the following cases:

With insufficient efficiency of contour and linear drains;

In the conditions of the complex structure of the aquifer with a change in its composition and permeability;

With a preventive purpose in clay and loamy soils;

In aquifers of high thickness, with their layered structure, the presence of pressure water sources.

8.15 When constructing reservoir drainage, the following requirements must be taken into account:

Reservoir drainage should be combined with the sprinkling of tubular drains, ensure the necessary conditions for removing moisture so that the filter bed does not become an accumulating reservoir for groundwater; if reservoir drainage is laid below the foundation drainage (for objective reasons of a different nature), the filter bed should be led into the foundation drainage trench in order to ensure the discharge of GW into the trench;

If the tubular drainage is laid along the inner contour of the building (under the basement floor), the layered structure must be made in the form of filling the sinuses of the excavation along the outer walls of the building and “connect” the layered structure of the sinuses with the filling of the underground drainage, tilting its base towards the tubular drains (Fig.);

With different depths of the protected basement, the layered structure for the deepest basements should be matched with a similar design for the basement floor with less depth; the choice of a rational solution of interface nodes depends on the location of especially deep volumes in the spot of the protected circuit, the difference in floor elevations of unevenly buried rooms and the height position of tubular drains.

Rice. 1 . The scheme of backfilling the sinuses of the pit

8.16 Reservoir drainage as an independent dewatering system should be used for the period of construction if it is necessary to drain the pit for a large building. In this case, the bottom of the reservoir drainage filter bed should not be lower than the level of the tubular drain tray laid for the removal of HW.

The reservoir drainage filter bed is used during the construction and operation of the building. Tubular drains draining groundwater collected by a filter bed cannot always be stored in a drainage system designed to protect basements during the life of the building.

9 Drainage schemes, longitudinal profile, structures on the network

9.1 Drainage schemes of the object are formed on the basis of standard systems, taking into account the hydrogeological conditions of the construction site, the characteristics of the protected object, as well as the requirements of this document.

The drainage scheme of the protected object may consist of one or more systems (simple and complex). In some cases, the scheme is limited to only one system, in others it requires a combination of several systems.

9.2 The choice of scheme depends on:

From the hydrogeological conditions of the construction site and the deepening of the basement;

foundation structures;

Location and depth of the storm network that receives the drainage runoff;

Deepening and foundation structures of protruding volumes along the perimeter of the building;

Planning marks along the perimeter of the building;

The presence of neighboring operated buildings and structures;

Dimensions and configuration of the protected premises.

9.3 The drainage scheme of modern civil buildings, especially with a large area of ​​the protected basement floor and a complex configuration of the object, are combinations of various complicated drainage systems.

9.4 Single line head system. The optimal drainage scheme is the intersection of the groundwater flow along the width of the route and the deepening of the drains into the water-resistant layer (Fig. ).

Rice. 2 . Scheme of a single-line drainage system of the perfect type:

a - plan; b - section; 1 - building with a basement;
2 - drainage route; 3 - the direction of the slope of the drains;
4 - site boundary; 5 - inspection wells;
6 - drainage outlets

Therefore, the linear head system is effective in narrow, elongated areas, especially in such hydrogeological conditions, where a perfect type of drainage can be applied.

When the length of the linear drainage is less than the width of the underground flow, additional lines are arranged along the lateral boundaries of the protected area. In this way, the interception of groundwater entering from the side is achieved.

With a deep aquiclude, drains are laid in the water-containing layer, arranging imperfect drainage. In this case, the filtration capacity of the permeable layer is of great practical importance, since it affects the position of the reduced GWL in the protected area. To determine the position of the reduced GWL, a depression curve is calculated (see).

9.5 Traditional (typical) schemes of annular drainage - contour and contour-linear with external spurs. Tubular drains are laid at a distance from the walls of the building, taking into account hydrogeological conditions of the territory, safety requirements and work performance. If the building has a complex facade configuration or basements of different depths, the drainage may have external transverse branches - spurs (Fig.).

Legend:

Rice. 3 . Scheme of contour drainage with transverse spurs

9.6 Traditional wall drainage schemes for typical buildings of small width (up to 20 m) and simple configuration (see):

Linear;

Contour with drains external (along the facade) or internal (under the basement floor), closed or open (contour scheme);

Combined in the form of linear or contour with reservoir drainage.

The most commonly used scheme is with a closed loop due to the predominance of mixed groundwater recharge. If there are restrictions on the construction site, it is possible to lay an open loop. Such restrictions arise in most cases during the reconstruction of objects, the restoration and reconstruction of historical buildings, as well as the cramped conditions of the construction site [, , ].

9.7 The foundation drainage route is tied to the protected building. The distance between the drainage and the wall is determined by the protruding structural elements of the building foundation and the diameter of the manholes. It also depends on the depth of the drains.

Wall (contour) and underground (including reservoir) drains are linked to each other in height in such a way as to ensure effective removal of water from under the protected premises (see).

9.8 Groundwater protection of large basements is carried out according to the following main schemes: contour-linear, contour-area, combined (see).

Contour-linear scheme - a drainage system with a contour network (actually near-foundation drainage) and linear underground (tubular or reservoir) lines.

Contour-areal scheme - a drainage system with a contour network and a reservoir areal filter bed.

The combined scheme combines elements of both of the above schemes.

The contour-linear scheme is used when arranging imperfect drainage without any restrictions for objects with a pile foundation. With a strip foundation design, the distance of tubular drains from the walls should be calculated if they are buried below the foundation foot mark.

If the foundation of the building is arranged in the form of a monolithic reinforced concrete slab, only a tubular structure of underground drains or a contour-areal scheme is used.

Underground drains are usually routed along the short axis of the basement and connected to the foundation drainage.

The position of the drains is determined by the features of the design solution of the foundation. The distance between the underground drains is chosen in such a way as to remove the uplift of the depression curve inside the protected circuit.

With a developed system of underground lines, it will be necessary to deepen wall drains so that the depth of their laying ensures gravity removal of the costs of an extensive network of underground drains, therefore, drainage water is often required to be pumped out from wall drains.

The contour-areal scheme is characterized by the presence of reservoir areal and near-foundation drainage. The latter is often laid along the outer (outer) contour of the basement. Such a scheme is used when arranging perfect and imperfect wall drainage. It has no restrictions associated with the design of the foundation of the building and is widely used in case of insufficient efficiency of imperfect wall drainage of buildings, the foundation of which is made in the form of a monolithic reinforced concrete slab.

In cramped conditions, the contour-areal scheme can be made only with the help of internal underground drains or their combination with external wall drains, when the foundation of the building is of a pile or tape type.

9.9 Drainage of large area objects, especially in difficult hydrogeological conditions, is effective only due to the joint operation of near-wall and underground drainage devices, the design of which is adopted taking into account the specific conditions of construction (reconstruction).

9.10 Wall and underground (including formation) drains should be subordinated to each other in height in such a way as to ensure effective removal of water from under the protected premises and outside the building.

9.11 Drainages are designed taking into account the general requirements for the placement of underground networks, ensuring safe construction conditions (in accordance with SNiP 12-03, SNiP 12-04), work efficiency and serviceability dewatering facilities (in accordance with SNiP 2.06.15, SNiP 22-02).

The horizontal distance (in the light) between the drainage and utilities, is taken in accordance with regulatory requirements ( SNiP 2.07.01, PUE-7).

In the vertical plane, the position of drains relative to other engineering networks is taken taking into account their purpose, methods of performing work on the drainage device and its normal operation in accordance with SNiP II-89.

9.12 When designing a drainage, one should consider the option of laying it together with a drain - above it or in parallel, preferably in one trench.

It is preferable to lay drainage and drain in the same vertical plane. In this case, the drainage is laid over the drain and drainage water outlets are arranged in each inspection well of the drain. This option is convenient from the point of view of removing drainage costs, however, it is not always possible due to the deepening of the drainage below the drain or insufficient distance between them.

The minimum distance between the drain and the drainage laid above it must be at least 5 cm.

9.13 The connection of drainage lines in the plan should be carried out at an angle of at least 90°; in the vertical plane, tubular drainage branches can be connected with and without a drop device with the installation of manholes along SNiP 2.06.15 5.28. The presence of drops may be due to different depths of drains, as well as the connection of more than three lines in one node.

9.14 Drainages are laid with slopes that ensure the gravity flow of water at speeds that exclude silting of pipes and soil erosion, and also taking into account the water content of the drained horizon.

The minimum slope of tubular drainage is taken:

In sandy soils - 0.003;

In clayey - 0.002.

It is advisable to arrange drains with minimal longitudinal slopes, since an increase in the slope of drains leads to an increase in the amount of work.

The minimum slope of reservoir drainage laid in the base of the protected building should be taken as 0.005 - 0.01, the slope of the accompanying reservoir drainages may coincide with the slope along the route of the protected engineering networks, pavement base, etc.

The maximum drainage slope is regulated by the maximum allowable water flow rate of 1 m / s and is determined on the basis of a hydraulic calculation according to the method described in the literature.

9.15 The depth of the drainage should provide the required rate of drainage (according to , ), protection of the drainage structure from destruction by temporary and permanent loads, as well as from freezing. If the deepening of the drainage below the freezing depth is impossible or impractical, special measures are taken to protect the network at low temperatures.

9.16 The longitudinal profile of the drainage lines should be formed taking into account the drainage pattern of the facility, the position and number of outlets, the elevations of the receiving network and the floor of the basements, the method of draining drainage water, ensuring the reliability of the system in normal and emergency mode, as well as uniform loading of pumps to remove drainage expenses.

9.17 On objects of a large area, when constructing a longitudinal drainage profile, the following should be taken into account:

Significant length of underground linear and area of ​​reservoir underground drains;

The need to pump water from wall drains;

The feasibility of gravity discharge of water from underground systems to contour wall systems.

9.18 The choice of the optimal longitudinal profile of underground linear drains is determined by their length, the allowable range of deepening of the receiving contour drainage lines, the conditions for the production of work, the ratio of the dimensions (length and width) of the basement, the position of the latter in the “building spot”, the difference in planning marks along the building facade, the presence of the perimeter of the object of attached volumes.

9.19 The optimal longitudinal profile of wall drains along the facade of the building with a difference in elevation of the planning surface is formed due to additional outlets or an increase in the depth of the drainage.

With a significant difference in planning marks along the facade of the protected building and a large basement area, when forming a longitudinal profile, one should proceed from the allowable minimum and maximum depth of drains.

With a constant mark of the basement floor, it is advisable to increase the number of outlets in order to avoid a large deepening of the drainage, if the differences in marks along its route are limited only by the drainage rate or the methods of work.

For basements with different depths, as well as with their large area, laying drainage with a difference in elevations across sections will also require an increase in the number of outlets, which will make it possible to eliminate backwater in the drainage system in emergency situations.

9.20 Inspection (inspection) wells for monitoring the operation of the system are installed in places where the route turns and changes in drain slopes, at drops - in pipe junctions with different tray marks, as well as in straight drainage sections (Fig. ).

Rice. 4 . Layout of drainage wells:

a - turns of the route, differences in elevations of drainage pipes; b - ledges of the building;
c - starting sections, d - with a pump in the transit section of the drainage; 1 - building;
2 - drainage; 3 - wells; 4 - the same differential; 5 - the same with the settling part;
6 - plugs; 7 - release (transit drainage); 8 - well with a pump;
9 - pressure section of transit drainage;
10 - well pressure absorber; 11 - storm sewer manhole

Drainage manholes (with a drain diameter of up to 300 mm) are arranged at least every 50 m according to SNiP 2.06.15(see 5.28), according to the operating conditions of the drainage network, the optimal limit distance is according to - 40 m.

At turns, it is not necessary to arrange drainage inspection wells at the ledges of buildings if the distance from the turn to the nearest well does not exceed 20 m. When the drainage makes several turns in the area between the wells, inspection wells are installed through one turn. Starting sections of the drainage network up to 20 m long can be performed without the first manhole. In this case, it is necessary to provide a plug for the drain pipe.

9.21 Arrangement of releases. The release of water from tubular drains is carried out into drains or reservoirs. In some cases, the discharge is carried out into the general sewer network, ditches and specially arranged containers. In the final drainage manholes, before water is discharged into the public sewerage system, a control manhole with a “slam” valve is provided (according to the terms of connection of SUE “Vodokanal”).

The discharge of water from the drainage tubular network is carried out using transit drainage from pipes without perforation and sprinkling. Drainage flows are diverted by gravity or by pumping with pumping units or submersible pumps. Then the transit section of the drainage to the damper well is arranged in the form of a pressure network.

Transit drainage and pumping equipment are designed in accordance with the requirements for a rainwater drainage network ( SNiP 2.04.03).

9.22 In areas of the urbanized landscape of palace and park ensembles and historical buildings, in the absence of places for receiving drainage water (sewer networks) or the impossibility of discharging drainage water into water bodies in appropriate hydrogeological conditions, absorbing wells (wells) should be used, the design of which should be taken in accordance with the Reference Manual To SNiP 2.06.15, SNiP 2.04.03, as well as to carry out other activities of geotechnical drainage in accordance with the requirements.

9.23. For reliable operation of the drainage system, mandatory regular cleaning of drainage wells is required in order to prevent silting of drainage pipes, therefore, the need for such operational measures should be indicated in the text and graphic part of the project.

10 Drain design

10.1 To protect the buried parts of buildings, traditional and modern horizontal drainage designs should be used:

With filtering sprinkling of pipes (or filling of closed drainage) from loose sorted material (sand, gravel, crushed stone);

With a filter made of geosynthetic (or natural) materials in combination with sand and gravel;

With compositions of drainage materials based on plastics (geocomposites);

With and without geotextile (or natural) pipe wraps.

Geotextiles in drainage construction should be used as:

Filtration membranes for separating the backfill from the backfill of tubular drainage, the filter layers of the latter;

Pipe wraps.

Geocomposites should be used to increase the efficiency of the drainage network and reduce the volume of filtering soil materials.

10.2 The choice of geotextile membranes and geocomposites should be carried out taking into account their operating conditions, engineering and geological conditions of the construction and reconstruction site, technical characteristics of materials [, , , ].

The geotextile filter must allow water to pass through and screen out the soil, not unnecessarily deform and not restrict the access of moisture to the drainage structure, have bio- and chemical resistance, and maintain working condition throughout the entire life of the drainage.

Geocomposites must meet wear resistance requirements; bio- and chemical resistance; safety in working order during the entire service life and have high filtration properties.

Preference should be given to:

Filtering non-woven geotextile membranes made of endless PP yarns, needle-punched;

Three-dimensional geocomposites of a drainage plastic (PP) base and a filter membrane, which are called plastic drainages. The task of the membrane in plastic drainage is to pass water into the moisture conductor (base) and retain particles of the drained soil. The task of the plastic base is to transport water to the foundation system of horizontal drains.

For certain types of plastic drainage, there is a design option with a special sinus (channel) for the drainage pipe.

10.3 Filtering soil fillings, depending on the composition of the soil to be drained, should be arranged in single or double layers. Along with this, it is planned to backfill part of the trench with sandy soil (Fig.). When constructing a sloping trench, such backfilling is done in the form of prisms for reasons of material savings.

Rice. 5 . Sprinkling device scheme:

a - rectangular; b - in the form of a trapezoid;
1 - drainage pipe; 2 - crushed stone; 3 - sand with coefficient
filtration not less than 5 m/day; 4 - local soil

The purpose of the prism is to receive water flowing from the sides. The smallest height of the sand prism is 0.6 - 0.7 of the excess of the calculated groundwater level relative to the bottom of the drainage trench, the maximum is 30 cm higher than the calculated groundwater level; the optimal one is determined by the specific conditions of construction.

10.4 Single-layer filter media are acceptable in gravelly and coarse sands, as well as in medium-sized sands with an average particle diameter of 0.3 - 0.4 mm and larger.

Two-layer backfill should be arranged in sandy loam, fine silty and medium-grained sands with an average particle diameter less than the specified one, as well as in the layered structure of the aquifer.

Soil materials used for backfilling must meet the requirements for materials for hydraulic structures and comply with applicable state standards.

The composition of the filter cakes should be selected to exclude suffusion and clogging of the system, the thickness of one layer sprinkling must be at least 150 mm.

For the inner layer of sprinkling, crushed stone M1000 - 1200 with a particle size of 3 - 10 mm (depending on the size of the pipe cuts) is used, the outer layer and sandy prisms - sand with a filtration coefficient of at least 5 m / day.

Sprinkling is given a rectangular or trapezoidal shape, more complex configurations require special inventory shields. Sprinkling of trapezoidal shape is performed with slopes of a stable shape, rectangular - with the help of shields.

10.5 The choice of tubular drainage design depends on the hydrogeological conditions of the construction site, the characteristics of the protected object, the type and system of drainage, the depth of the basement and its purpose (Fig. ).

10.6 Formation drainage to protect the buried parts of the building should be performed in the form of a continuous sand and gravel layer (areal), in the form of prisms (linear) and sloping towards the tubular drain, as well as using geotextile membranes and high-strength geocomposites.

The formation drainage design may consist of one or two layers, depending on the nature of the underlying soil, the width of the protected structure and the water inflow.

Single-layer reservoir drainage is made of crushed stone (gravel), two-layer drainage is made of crushed stone and sand. The sand layer can be replaced with an appropriate geotextile membrane. In reservoir drainage, crushed stone with a particle size of 3–20 mm (heterogeneity coefficient is not more than 5), as well as medium-grained sand, is used. The requirements for the soil filtering bed of the drainage are similar to the requirements for the soil filtering of the tubular drainage.

Area reservoir drainage with a single-layer crushed stone bed should have a thickness of at least 300 mm. A two-layer drainage bed is structurally solved from a crushed stone layer with a minimum thickness of 150 mm, and a sandy one - 100 mm.

To reduce the amount of crushed stone, the areal reservoir drainage of a buried building can be structurally solved in the form of a layer of sand cut in the transverse direction by crushed stone prisms.

The thickness of the linear reservoir drainage with a single-layer gravel bed should be at least 200 mm. The required number of drains (prisms) is determined taking into account hydrogeological conditions, and their position in the plan depends on the design of the foundation of the protected object.

a - imperfect type

b - perfect type

c - perfect type on conditional aquiclude with linear reservoir drainage

g - with drainage-insulating geocomposite

e - with a geotextile layer in the sprinkling of drains and a geocomposite

g - with a geotextile layer in the drain sprinkling without geocomposite

Rice. 6 . Wall drainage design schemes

The reservoir drainage filter bed must be mated with the drainage pipe backfill in accordance with the requirements. During the production process, reservoir drainage is protected from clogging. Examples of the construction of reservoir drainage of buildings are shown in the figure.

10.7 When choosing the design of underground drainage lines, special attention should be paid to its reliability.

When internal drainage lines are laid under the basement floor slab, the possibility of access to them is excluded, therefore, the installation of drainage crushed stone prisms (with optimal routing and appropriate design parameters) has certain advantages over tubular structures.

10.8 Drainage pipes are selected and designed in accordance with the requirements:

Sufficient culvert capacity;

Strength when exposed to backfill soil and dynamic loads;

Resistance to aggressive ground water;

Convenience of the device and operation of drainage.

To the greatest extent, these requirements are met by single-layer and double-layer plastic pipes made of low-pressure polyethylene (HDPE), polyvinyl chloride (PVC), as well as polypropylene (PP) and high-density polyethylene (HDPE). Depending on the material and design, they belong to different stiffness classes.

10.9 The choice of the design of the drain pipe is determined by the conditions of use and the requirements of operation.

Knot I

Rice. 7 . Reservoir drainage design scheme:

A - buildings; a - two-layer of sand and gravel layers;
b - the same with a geotextile filtering membrane; in - the same single-layer of crushed stone;
1 - filter bed; 2 - drainage perforated pipe; 3 - gravel filter;
4 - sand filter; 5 - backfill; 6 - bypass pipe without perforation;
7 - waterproofing membrane; 8 - concrete preparation;
9 - geotextile filtering membrane; 10 - local soil

The dimensions of the water intake openings of the drainage pipes should be selected taking into account the granulometric composition of the drained soil [, ,]. This requirement should be taken into account when choosing pipes presented on the modern construction market with various options for drainage slots.

Traditional designs are single-layer pipes with a smooth or (more often) corrugated surface, which increases the strength of the pipe, maintains its flexibility and increases the water-holding area of ​​the drainage holes. Modern designs are two-layer and even multi-layer pipes. The latter are effective at high dynamic loads and depths of the protected object.

In two-layer pipes, the inner wall is smooth, and the outer shell is corrugated, securely fastened to the inner layer. Thanks to the smooth inner wall, the speed of the water flow increases and the conductivity of the pipe increases. The presence of an external corrugated shell makes the pipe structure resistant to impact deformation, which is especially important when transporting and installing pipes in winter conditions. Such pipes are distinguished by a high water-draining and self-cleaning capacity, they usually “keep” a small predetermined slope of the drainage route well.

The permissible maximum depth of single-layer plastic drains depends on the pipe material, the smallest depth of pipe laying is determined by the requirements for their protection from dynamic loads and freezing.

In weak soils with insufficient bearing capacity, the drainage pipe should be laid on an artificial base.

10.10 Manholes. Traditional well designs should be made of reinforced concrete rings with an internal diameter of 1000 mm, wells with pumps - 1500 mm.

Modern compact manhole designs are made of plastic with a minimum diameter of 315 mm. The latter are manufactured at the factory and delivered ready-made to the construction site or assembled on site from the appropriate elements.

Transit drainage pipes are made without perforation and arranged without filtering sanding. In terms of design and technical characteristics, they are similar to gravity storm sewer pipes.

Preference should be given to plastic manholes made of prefabricated elements assembled on site. It is advisable to use wells and plastic pipes of the same system, since in this case all the necessary components are available: for connecting pipes to each other, pipes and manholes, antifreeze devices, etc.

Such a drainage system is the most efficient in terms of operation and durability.

10.11 The design of the prefabricated well consists of three main parts: bottom, vertical and cover or hatch (Fig. ). Pipes are either cut in place into the lower part of the vertical structure, or there are factory bends in it. As a rule, the option of tapping pipes in place is preferable. The structural elements of wells are made of various materials based on the conditions of their work. The upper part - the hatch, depending on the purpose of the territory and the expected loads, is performed in various versions. The vertical part of the well can be a single-layer corrugated or two-layer pipe made of various materials (PVC, HDPE, PP), the bottom of the well is made of PP.

10.12 Wells made of plastic products are arranged with a settling part (sand trap) with a depth of at least 0.5 m and are cleaned using mechanization.

In traditional reinforced concrete wells, a sedimentary part with a depth of at least 0.5 m is required in the last manhole of the network at the starting section of the transit drainage, in overflow wells, as well as in manholes along the drainage route after 40 - 50 m.

If there are requirements of special organizations, constructions on the transit drainage network should be carried out in accordance with these requirements.

Rice. 8 . Well design schemes:

a - plastic, assembled on site with a conical concrete neck;
b - the same with a cast-iron hatch and a skirt; c - the same with an embedded drainage pipe;
1 - well corrugated pipe; 2 - PVC skirt; 3 - bottom made of propylene;
4 - conical concrete neck; 5 - rubber ring; 6 - cover.

11 Drainage calculation

11.1 In the process of calculating horizontal drainages, two stages should be distinguished:

1) Hydrogeological calculations, which determine the flow rate of drains and the position of depression surfaces of groundwater in the protected area.

2) Hydraulic calculations that determine the required throughput capacity of the selected parameters of drains at admissible flow rates of water in them and the corresponding filling.

Hydraulic drainage calculations are traditionally performed by the selection method. At present, the solution of this problem is facilitated by the use of special schedules, which, as a rule, are contained in the methodological recommendations of modern drainage pipe suppliers.

Hydrogeological (filtration) calculations are performed on the basis of special (calculation) schemes to display the main hydrogeological characteristics of the construction site and the operating conditions of drains.

11.2 When choosing design schemes, the specific conditions of the construction site are taken into account:

Drainage system and groundwater sources;

Type of drainage (perfect or imperfect);

The structure of the drained massif (the degree of uniformity of rocks in terms of water permeability) and the filtration properties of its layers;

Hydraulic state of the aquifer (pressure or non-pressure water);

Groundwater flow characteristics (direction, thickness, slopes).

The boundaries between the individual layers are schematically represented as horizontal planes passing through the middle marks of the contacting layers. Inclined planes in the section under consideration are replaced by horizontal ones, which is permissible with slopes of not more than 0.01 [].

The hydraulic state of the aquifer determines the operation of drainage systems in pressure or non-pressure water conditions. In the first case, drainage solves the problem of removing the piezometric pressure (full or partial) in the aquifer. In the second case, the aquifer is drained with the help of drainage.

11.3 Variants of calculation schemes:

Single-line (single) horizontal drain (shore, head) with one-sided or two-sided inflow of groundwater from the overlying territory and / or from the side of the reservoir;

Two-line horizontal drainage (a combination of coastal and head drains) with a two-way inflow of groundwater from the overlying territory and from the side of the reservoir;

Horizontal contour system (annular or near-foundation drainage) when groundwater is fed, flowing mainly within the area lying outside the drained contour;

Horizontal drains located on the site at conditionally equal distances (systematic drainage *) and usually operating under ground (or similar) water flow conditions when fed from above and / or below;

Filtration bed at the base of the protected object (reservoir drainage) when groundwater enters from the side and / or from below.

_____________

* The system is used, as a rule, only for general dewatering.

11.4 Calculation of horizontal tubular and reservoir drainage devices operating under conditions of steady-state filtration, free-flowing waters and a homogeneous medium should be made according to the calculation formulas below.

The calculated level of groundwater should be taken on the basis of the predicted values ​​of the long-term average annual level of GW at the construction site.

When draining buildings by local systems in combination with the formation flow, which is diverted by transit drainage, is determined only by the flow rate of tubular drainage drains.

11.5 To calculate drains operating under pressure, as well as plastic drains, it is necessary to use additional information available in reference materials [, , , ].

11.6 In the formulas and the calculation schemes shown below in the figures, the following designations are accepted:

H- height of unreduced GWL above the aquiclude, m;

h- depth of drain immersion under non-lowered GWL, m;

T- excess of imperfect drain over aquiclude, m;

H X - excess of the reduced groundwater level above the water level in imperfect and perfect drains at a distance X from them, m;

h y - excess of the reduced groundwater level relative to the drain in the center of the contour drainage, m;

H max - the maximum height of the lowered GWL above the aquiclude in the interdrainage space of systematic drainage, m;

h high - seepage height - the gap between the water level in the drain and at the contact of the drainage sprinkle with the soil, m;

R- depression radius, m;

r 0 - reduced contour radius, m;

r g - drain radius, m;

a - half the distance between drains of systematic drainage, m;

Q- estimated consumption, m 3 / day;

Q o - specific consumption, m/day per 1 linear meter m;

W- intensity of atmospheric precipitation seepage, m/day.

11.7 The calculation is made based on the hydrogeological conditions of the construction site, the actual design position of the drainage, its system (local or general) and type (perfect or imperfect).

Filtration coefficient TO drained soils in the absence of experimental data are taken on the basis of reference materials and taking into account local construction experience. The latter is especially important, since the reference sources do not always give the same ranges of values ​​for the filtration coefficients of the same soil. This is due to the characteristics of the studied breeds.

With a heterogeneous structure of the water-bearing stratum, the weighted average value K cf, calculated by the formula

Where K 1 + K 2 + ... + K n- filtration coefficient of individual drained soil layers, m/day; T 1 + T 2 + ... + T n - the thickness of the corresponding layers, m, which is taken on the basis of the initial data and the calculated drainage scheme.

The area of ​​​​use of the formula () is limited by the ratio of the filtration coefficient of different layers not more than 1:20:

K n: K n +1 < 20

11.8 The intensity of precipitation infiltration is determined taking into account the nature of the soil, the amount of precipitation and the degree of improvement of the building site.

For the territory of St. Petersburg, the approximate values ​​of the seepage intensity, according to , should be taken for areas of new development 0.00129 m/day, old - 0.00246 m/day.

11.9 Single line and double line drains. Drainage water flow rates and depression curves of single-line drainages (local and general) are calculated using the formulas below.

For committed drainage, the design scheme of which is shown in the figure, and the specific flow rate is determined by the formula () for a two-sided inflow of groundwater and by the formula () - for a one-sided inflow:

Where R- drainage depression radius, m, which is calculated by the formula () or determined from the figure:

Drainage water consumption for a drainage line with a total length L determined by the formula

Drainage systems in summer cottages and house adjoining areas are often designed "by eye". This is not eaten properly and often leads to flooding and other problems. In order to make the drainage system correctly, it is necessary to be guided by the requirements of regulatory documents.

The basic document is SP 104.13330.2012 - this is an updated version of SNiP 2.06.15-85 "Engineering protection of the territory from flooding and flooding". Unfortunately, it contains little useful information for drainage systems used to protect low-rise buildings.

There is another document - "Guidelines for the design of drainage of buildings and structures" from the Moscow Committee for Architecture, published in 2000 (hereinafter referred to as the "Guidelines"). It contains a lot of useful information, but, like any other piece of legislation, the manual is difficult to read and redundant in places. Therefore, the site brings to your attention a summary, which outlines all the most important things from this document.

When is it permissible to arrange an open drainage system?

According to SNIP, an open drainage system of horizontal ditches can be used to drain territories with one and two-story buildings of low density, as well as to protect roads and other communications from flooding (p. 5.25). At the same time, concrete or reinforced concrete slabs or rockfill should be used to strengthen the slopes of the channels.

Obviously, this item is related to the general drainage systems of settlements or microdistricts. With regard to a specific private house on its own land plot, the creation of an open drainage system cannot be considered appropriate, since the ditch on the site takes up space and poses a potential hazard.

What materials can be used as a filter and filter bed in closed drainage systems?

As a filter and filter dressing in drainage systems, you can use:

• sand and gravel mixture;
• slag;
• expanded clay;
• polymeric materials;
• Other materials.

What pipes can be used to create drainage systems?

According to SNIP, to create drainage systems it is allowed to use:

• ceramic pipes;
• polymer pipes;
• concrete, asbestos-cement, reinforced concrete pipes and pipe filters made of porous cement can be used in soils and water that are non-aggressive to concrete;

How to determine the maximum depth of pipes in closed drainage systems?

The depth of pipes in closed drainage systems depends on their material and diameter. Data on the maximum depth of laying pipes are presented in the table.

How to determine the depth of porous concrete pipe filters?

The maximum laying depth of pipe filters made of porous concrete is determined in accordance with VSN 13-77 "Drainage pipes made of large-pore filtration concrete on dense aggregates."

How to determine the size of the hole in the drainage pipes and the distance between them?

The size of the holes in the drainage pipes and the distance between them is determined by calculation.

How to determine the thickness of the filter around the pipes of the drainage system?

The filter around the pipes of the drainage system should be in the form of sand and gravel fill or wraps or polymeric permeable materials. The thickness of the filter and the composition of the coating is determined by calculation in accordance with the requirements of SNiP 2.06.14-85. "PROTECTION OF MINING WORKINGS FROM UNDERGROUND AND SURFACE WATER".

Can drainage water be discharged into storm sewers?

SNiP allows the discharge of drainage water into storm sewers, provided that the storm sewer is designed for such a load. At the same time, the backwater of the drainage system to the point of discharge into the storm sewer is not allowed.

How to determine the maximum distance between the manholes of the drainage system?

The maximum distance between the wells of the drainage system in straight sections is 50 meters. In addition, wells should be located at the points of turns, changes in angles and intersections of drainage pipes.

What should the manhole of the drainage system be made of?

According to SNiP, manholes must be prefabricated from reinforced concrete rings. They must be equipped with settling tanks with reinforced concrete bottom. Settling tank depth - not less than 50 cm

What data is needed to create a drainage system project?

To design a drainage system, you need:

• technical opinion on the hydrogeological conditions of construction (in everyday life "hydrogeology");
• plan of the territory with existing and planned buildings and structures. The scale of the plan is not less than 1:500;
• plan with floor marks in the basements and undergrounds of buildings;
• developments, plans and sections of the foundations of all buildings located on the territory;
• plans and profile sections of underground utilities;

What should a hydrogeological report include?

The hydrogeological conclusion consists of several sections:

The section "Characteristics of groundwater" includes the following information:

• groundwater sources;
• reasons for the formation of groundwater;
• groundwater regime;
• mark of the estimated level of groundwater;
• mark of the established level of groundwater;
• the height of the zone of capillary moistening of the soil (if dampness in the basement is unacceptable);
• results of chemical analysis and a conclusion on the aggressiveness of groundwater in relation to building structures.

The geological and lithological section includes general information about the land plot.

Soil characteristics include:

• geological sections and columns of soils from boreholes;
• bearing capacity of soils;
• granulometric composition of sandy soils;
• filtration coefficient of sandy and sandy soils;
• coefficients of water loss and porosity;
• angles of natural repose of soils.

Is foundation waterproofing necessary if there is a drainage system?

The “Guideline” of the Moskomproekt unambiguously requires the use of coating or paint waterproofing of vertical wall surfaces in contact with the ground, regardless of the presence of a drainage system.

Are there other ways to protect buildings from flooding and flooding areas (besides creating drainage systems)?

Such methods exist. The Moskoproekt Guidelines for Designing Drainage Systems also recommends:

• soil compaction during the construction of pits and trenches;
• the use of closed outlet drainage systems that collect water from the roofs of buildings;
• the use of open drainage trays with open outlets of drainage systems. The size of the trays is not less than 15*15 cm, the longitudinal slope is not less than 1%;
• blind area around the perimeter of buildings. The width of the blind area is at least 1 m, the slope away from the building is at least 2%;
• sealing of all openings located in the outer walls and foundations with the conclusions of engineering systems. Simply put, if you run a sewer pipe through a foundation or wall, the holes must be sealed;
• creation of a system of surface runoff from the territory.