Before starting work on the device subgrade from the surface of the future bases of the embankment and excavations, cavaliers, ditch-reserves, soil quarries, temporary warehouses for the storage of road materials, the soil and vegetation layer is removed. The breakdown of work on the removal and storage of this layer consists in setting out the boundaries of the cut and the contours of the shafts for temporary storage of the soil. To break down the boundaries of the cut, poles 1.0 ... 1.5 m high are used, which are installed after 20 ... 25 m.
Shafts of vegetable soil, depending on the terrain, can be arranged on one or both sides of the subgrade. Their volume is determined by the need for fertile soil for plating (application) on the bottom, slopes of reserves and slopes of the subgrade on each side. Shafts of soil and vegetable soil must be protected from water and wind erosion, as well as from oil pollution. The soil stored in them, as necessary, is used for the reclamation of the territory of soil reserves and quarries, as well as all lands disturbed during road construction.
The fertile soil layer to the thickness provided by the project is usually removed with an auto-fader or bulldozer. Before starting work, the cutoff boundaries on the ground are marked with furrows, which are carried out with a plow or an autofader blade.
When laying a road through forests and valuable lands, land acquisition for temporary storage of soil and vegetable soil is impractical, so it is immersed in vehicles and transported to special sites. These sites are located on low-value land.
In the case when the soil-vegetable soil has high density or roots remain in it after uprooting the stumps, before cutting, it is loosened. The scheme of operation of a bulldozer or motor grader depends on the width of the grip, on which the soil is removed and moved. If it does not exceed 25 m, then a one-sided transverse method is used (Fig. 3.37). When erecting high embankments or lateral ditch-reserves, as well as when developing deep excavations, cutting and moving the soil should be done first from one half of the strip, and then from the other. In this case, the road strip has a width of 30 ... 40 m and the cutting of the soil with rectangular chips begins from the axis of the future road.
The productivity of the bulldozer Pb when cutting and moving the soil and vegetable soil is determined by the formula
where Tcm is the duration of the shift; V is the volume of soil moved in one cycle, m3; Kp - coefficient taking into account the loss of soil during its movement; Ki - coefficient taking into account the slope of the terrain; Kv - coefficient of working time utilization; tc - time spent on one cycle, h; Kp - soil loosening coefficient.
The volume of soil, m, moved in one cycle, is determined by the formula
where l is the length of the bulldozer blade, m; H is the height of the bulldozer blade, m; K - coefficient characterizing the properties of the soil.
Before the start of work on the construction of embankments and the development of excavations, upland ditches and fencing shafts are arranged for drainage surface water. Ditches are dug, starting from the downstream side, with a total slope of at least 5%, with the provision of water discharge into a natural channel, thalweg, ravine or reservoir. When constructing upland ditches on slopes, the excavated soil is laid in the form of a prism (banquet), only from the downstream side.
One of the services offered by the SMGroup company is the cutting of the vegetative soil layer and the removal of the fertile soil layer in Moscow. This is important for maintaining soil fertility and subsequent reclamation. The process is carried out before construction work.
The need to cut the vegetative soil layer and remove the fertile soil layer
Fertile soil is upper part ground cover that has properties that are favorable for plant growth. After cutting, a layer of vegetable soil is stored for preservation. To do this, use one of the following processes:
- the removed land must be stored in a separate dump if the cutting of the vegetation layer of the soil is carried out on the road;
- during the construction of structures, it is immersed in piles near the construction site;
- can be transported by trucks.
The removal of the fertile layer is carried out subject to certain rules. The thickness depends on the characteristics of cutting the vegetative part of the soil and should be determined in project documentation. Too dense earth with plant roots must first be loosened or plowed with multi-body plows.
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Cutting and removing the vegetative and fertile layer -
Cutting and removing the vegetative and fertile layer
Cutting and removing the vegetative and fertile layer -
Cutting and removing the vegetative and fertile layer
Cutting and removing the vegetative and fertile layer
Features of cutting the vegetative layer of soil
It is important that during the removal of the fertile soil layer it does not erode, become polluted and does not mix with the underlying mineral deposits. If the storage time exceeds one year, it is strengthened by sowing grass or other means. However, the land cannot be used. According to the norms, the removal of the fertile soil layer may not be carried out in the following cases:
- if the thickness of the plant part is less than 10 cm;
- in swamps, as well as non-wetlands;
- if trenches are dug, the width of which in the upper part does not exceed 1 meter;
- on soils with low fertility.
Soil cutting by a bulldozer and its movement are carried out in accordance with various schemes. They depend on the size of the area from which the removal is made, as well as on what kind of embankment can be formed under existing conditions. This is a time-consuming and difficult process that requires professional knowledge. Initially, it is required to carefully mark the site and determine the thickness of the cut of the plant layer. Then it is necessary to determine where and in accordance with what schemes the land will move. After that, you will need equipment for cutting and transporting the soil.
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Cutting and removing the vegetative and fertile layer
Cutting and removing the vegetative and fertile layer -
Cutting and removing the vegetative and fertile layer
Cutting and removing the vegetative and fertile layer -
Cutting and removing the vegetative and fertile layer
Cutting and removing the vegetative and fertile layer
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Removal of plant soil. The fertile soil layer, including the sod-vegetation layer, must be removed over the entire area occupied by embankments, excavations, reserves, quarries and other structures of the road complex. The boundaries in the plan, the thickness of the removal and the places of storage of soils of the fertile soil layer are determined by the project. Qualitative indicators and norms for removing the fertile soil layer are established by GOST 17.5.3.06-85.
The breakdown of soil removal works consists in setting out the boundaries of cutting and the contours of storage stacks. To break down the boundaries of the cut, poles 1.0-1.5 m high are used, installed every 20-25 m. The contours of the storage shafts are marked with stakes; cutting border before the start of work - a furrow (plow or ripper).
In order to prevent breakage or backfilling, the previously installed signs of project removal to the area should be protected with fences of three rails, fastened with the upper ends “into a tent”, or marked with special poles. After the completion of the removal of the fertile soil layer, the breakdown established for this work is removed.
If the layer to be removed has a high density or roots remain in it after the removal of the forest, the layer is loosened before cutting or plowed with multi-furrow plows.
The fertile soil layer is removed, as a rule, in a thawed state. In case of difficult terrain of machines, it is allowed to remove the soil in the spring when the soil thaws to the appropriate depth.
The fertile soil layer is cut off and moved to storage sites by bulldozers or motor graders, using the following work schemes:
when erecting embankments from imported soil, when the width of the strip from which the soil layer is to be cut does not exceed 25 m, use shuttlescheme transverse movement of soil in relation to the axis of the road;
when erecting embankments from lateral reserves or high embankments, as well as when developing deep cuts, when the road lane has a width of 30-40 m or more, cutting and moving the soil should be done first from one half of the lane, starting cutting from the axis, and then from it the other half, according to the so-called transverse or cross-sectional traffic pattern;
with large volumes of work to remove the soil layer (thick layer, large width of the road strip), the soil is first cut with a motor grader or bulldozer with a rotary blade into longitudinal shafts, from which the soil is later moved by bulldozers outside the road strip. At the same time, the transverse movement of the soil at half the width of the road strip is carried out by oblique passages of the bulldozer (at an angle to the longitudinal axis of the road), so that at each pass the bulldozer is fully loaded, corresponding to its power. Such a scheme is called longitudinal-transverse.
When removing soil from areas of large width, a scheme is used with the formation of shaft-stacks in the contour of the structure. Prior to the start of the next type of work, the soil soil must be removed to the storage sites specified by the project by road with loading by loaders.
In the case of vertical planning of areas and strips with a grass cover wider than 50 m, it is allowed to collect soil into transverse shafts within the contour, followed by distribution over a planned area.
Soil stacks are placed taking into account the terrain and other local conditions with a strip width of up to 25 m, as a rule, on one side; with a larger width - on both sides with gaps for travel construction machines, surface water runoff. In forest areas, on arable lands and other valuable lands, soil storage is carried out on areas specially allocated for these purposes.
When removing, storing the fertile soil layer, measures must be taken to prevent its loss (washout, swelling), as well as a decrease in its quality (mixing with underlying layers, roots, forest waste, pollution, etc.). With a storage period of more than a year, the surface of the soil shafts is strengthened by sowing grasses or by other methods provided for by the project.
The main activities for the preparation of the base of the subgrade. Prior to embankment construction, the prepared base surface must be leveled by a bulldozer. Pits, trenches, pits and other local recesses in which water can stagnate are filled in layers with compaction to the required density for the base (SNiP 2.05.02-85, table. 22). To ensure drainage in horizontal sections, a transverse slope from the axis is given not less than the coating established for the surface.
When using highly compressible non-draining soils (peat, silt, clays of low density, etc.) as a base, and draining soils in an embankment, when leveling, a construction rise should be created in the middle part, the value of which should be greater than the calculated settlement of the base provided for by the project .
Seal ground base low embankments and soil layers under the bottom of the working layer of pavement in recesses and zero places is carried out in cases provided for by SNiP 2.05.02-85 and SNiP 3.06.03-85. The base soils are compacted immediately before the filling of the overlying layers of soil or layers of pavement (airfield pavement).
If the required compaction depth exceeds the thickness of the layer effectively compacted by the means used, the excess soil layer should be removed with a bulldozer and compaction of the underlying layer should be carried out. After compaction and leveling of the lower layer, the removed soil is returned and compacted to the required density.
During the reconstruction of roads using the existing embankment, the vegetative soil from the roadsides and slopes of the reconstructed embankment is removed and moved to the edge of the right of way for subsequent reclamation. If it is impossible to use its biological properties, it is distributed at the base of the additional part. Before filling additional layers, the surface of the old embankment should be loosened to a depth of 10-15 cm with compaction together with the next layer. The need for disassembly and removal of layers of old pavement is established by the project.
Prior to the commencement of work on the construction of the embankment, culverts and communication pipes, as a rule, must be completely completed and backfilled on both sides to a width of at least 4 m on each side, from above - with a layer of a thickness not less than specified in the project, with layer-by-layer compaction to the required density . In this case, the movement and leveling of the soil, as well as compaction with rollers, is carried out by machine passages longitudinal in relation to the pipe, while building up the embankment on both sides. It is necessary to constantly monitor the approach of the machine to the pipe wall in order to avoid its displacement or possible destruction. The thickness of the soil layer on top of the pipe, at which it is possible to compact the backfill soil and let machines and vehicles through, must be indicated in the pipe design, but not less than that provided for by current standards.
The boundaries in the plan, the thickness of the removal and the places of storage of soils of the fertile soil layer are determined by the project. Before removing the soil layer, it is necessary to perform a breakdown, which consists in setting out the cutting and contours of the storage shafts.
To remove and move the fertile soil layer, a special unit is organized, equipped with a bulldozer on a tractor with a traction class of 100 kN, an excavator with a bucket with a volume of 0.5-1.25 m 3, a loader with a carrying capacity of 2 tons and dump trucks with a carrying capacity of at least 7 tons. depends on the distance that the soil is moved to the place of use.
The thickness of the layer to be removed in the Central region of the EChS is approximately 8-12 cm in soddy areas, 15-18 cm in arable areas, 15-20 cm in forested areas, less often 25 cm. Additionally, the thickness of the layer to be removed is specified directly at the work site.
There are the following schemes for cutting and moving the fertile soil layer: a) shuttle with shafts of cut soil arranged in a checkerboard pattern; b) transverse with shafts on both sides of the subgrade; c) cross-sectional; d) longitudinal-transverse.
The first scheme is used for one-sided cutting of the fertile layer on a strip up to 25 m wide. The cut soil is laid in the form of longitudinal shafts at a distance from the bottom of the embankment (when it is erected from imported soils), which ensures the passage of road vehicles and trucks. Bulldozer slaughtered fertile layer from one edge of the cutting strip and move to the opposite edge, where the soil is laid in the longitudinal shafts. The speed of the bulldozer in the opposite direction is 1.5 times greater than when cutting. To increase the productivity of the bulldozer, the soil should be cut down a slope.
The length of the longitudinal shaft is calculated based on its volume and the need for soil to strengthen one half of the subgrade. Excess soil is laid on opposite side, the deficiency is compensated by imported peat or silt.
The second scheme, i.e. transverse with shafts located on both sides of the subgrade along its entire length, is applicable if the cutting width is more than 25 m. Unlike the first scheme, the fertile soil layer is cut off and moved by a bulldozer only from the street axis, first to one and then the other way.
Rice. 8.1. Cross-sectional diagram of the removal of the fertile soil layer by a bulldozer with a fixed blade during the construction of deep excavations or high embankments n is the thickness of the fertile soil layer being removed; A - shafts fertile soil on both sides of the street axis; m - lane for the passage of earth-moving machines and construction vehicles; L - bulldozer blade width; 1-26 - bulldozer passes 
Rice. 8.2. Longitudinal-transverse scheme of removing the fertile soil layer using bulldozers with a universal and conventional blade B - a roller of cut soil; c - bulldozer with a universal blade; g - the same, with the usual; The rest of the designations are the same as in Fig. 8.1
The third, cross-sectional scheme (Fig. 8.1), is used with a cutting width of up to 40 m or a significant thickness of the cut fertile layer. The soil is cut and moved along the length of the transverse cutting strip in 3-4 steps.
The fourth, longitudinal-transverse scheme is appropriate for strips with a width of more than 44 m, a significant thickness of the fertile layer and the presence of a universal bulldozer. Longitudinal passages of a bulldozer with a blade set at an angle to the axis of the street cut off the fertile layer along the entire length of the grip; intermediate soil rollers are formed (Fig. 8.2). In the future, it is also possible to use a conventional bulldozer, which will move the soil perpendicular to the axis of the street outside the cutoff strip. If the volume of soil within the transverse lane exceeds the volume taken by the bulldozer in one pass, then the direction of its movement is changed: the soil is moved at an angle to the road axis of more than 45 °, taking it as much as the bulldozer is able to move.
The length of the capture depends on the power of the bulldozer blade, the thickness of the cut fertile layer, its moisture content and density, as well as on the daily output, which does not allow overdried soil to be laid in the shafts. The cutting area is determined by the thickness of the cut layer and the volume of soil moved by the bulldozer in one pass. With a well-turfed surface, the volume of soil taken by a heavy bulldozer reaches 4 m 3 (in a loose state). If humus soil is cut, for example rich black soil with a size of soil particles less than 25-30 mm, then the volume is reduced to 3 m 3 .
With a lack of soil for finishing and strengthening works, peat is added to the shafts and mineral fertilizers to get compost High Quality. The costs associated with its preparation are always paid off; at the same time, the layer of subgrade cladding can be successfully reduced by 20-30% compared to current standards.
The working cycle of the bulldozer is considered to be the cutting of the fertile layer across the design cleared strip to the total width of the dump and the additional width of the strip (0.5-0.6 m), on which the remaining soil is cut with simultaneous stripping and selection.
Reducing the loss of soil when moving a bulldozer and thereby increasing the Kp coefficient is achieved by using a blade with openings and a visor, as well as by performing work according to a trench scheme (see Chapter 12).
Using the calculated performance values when clearing a strip for the construction of a carriageway and sidewalks, a line graph is compiled for each specific section of the street (city road).
Clearing the territory of a construction site is a set of activities that includes cutting down trees and shrubs, uprooting stumps and removing stones, preserving the fertile soil layer, demolishing buildings, engineering networks and communications, backfilling of pits, pits and trenches, cleaning and planning of the territory and other types of work.
The clearing of the territory and cutting of the vegetable soil is carried out in accordance with the project for the production of works, which indicates: the thickness of the cut layer of the vegetable soil, the places of cutting, collection and embankment of the vegetable soil; methods of protection against damage or transplantation of trees and plants used in the future; areas for storage of vegetable soil cut from the construction site, suitable for use in landscaping and gardening; methods and procedure for soil reclamation.
The boundaries of the areas to be cleared must be fixed with clearly visible milestones, signs, benchmarks.
Cutting down or replanting forests and shrubs on the territory of the construction site is carried out only upon agreement with local authorities and State bodies technical supervision and obtaining a logging ticket strictly within the boundaries established by the project. Green spaces that are not subject to felling must be marked with signs or fenced and transferred to the safety of the construction organization according to the act, with a diagram of their location on the ground attached.
Tree clearing can be performed with on-site cutting of trees and subsequent removal of logs or cutting of fallen trees outside the construction site.
Root residues are removed from the vegetation layer immediately after the area is cleared of stumps and logs. Seized roots and bushes are removed from the cleared area to specially designated areas for subsequent removal.
Vegetative soil to be removed from the built-up areas must be cut, moved to specially designated places on the construction site or outside it and laid in dumps for further use in the reclamation of disturbed lands or for other needs in accordance with the project.
Prior to the start of work on cutting the soil of the vegetative layer, the following work must be performed:
- the axes are taken out and the boundaries of the site (route) of the work are marked;
- the places of dumping of dumps of vegetable soil are indicated;
- a working layout of the site was made with the fixing of markers;
- familiar with the technology and organization of work and trained safe methods labor workers and engineering and technical workers.
When working with vegetable soil, it should not be mixed with the underlying non-vegetative soil, as well as polluted with waste, construction debris.
Reclamation of disturbed lands is a complex of engineering measures for technical training lands for subsequent targeted use and biological development of lands to restore their fertility.
All lands disturbed by construction, in which changes have occurred, expressed in violation of the soil cover, in the formation of new forms of relief, changes in the hydrogeological regime of the territory (drying, flooding), as well as adjacent lands, on which there has been a decrease in productivity as a result of construction, are subject to reclamation.
Reclamation is carried out in two stages - technical and biological.
The technical stage provides for the implementation of measures to prepare the lands vacated after the development of the deposit for subsequent intended use in national economy. These include: rough and fine planning of the surface of disturbed lands; flattening and (or) terracing of slopes of dumps and sides of quarry excavations; preparation of sites (cutting down forests, bushes, cleaning stones, etc.); selective removal, transportation, storage (if necessary) and application of potentially fertile rocks and fertile soil layer to recultivated lands; liquidation of the consequences of sedimentation of dumps of open-cast mining and anti-erosion measures; backfilling with rock or filling with water of residual quarry cuts; a set of reclamation measures aimed at improving the chemical and physical properties dump soils, constituting surface layer recultivated lands (if necessary); construction of roads and hydraulic structures, etc.
The biological stage of reclamation includes measures to restore the fertility of reclaimed lands. These include: planting trees and shrubs, sowing perennial herbs, carrying out agrotechnical measures, phytomeliorative and other works aimed at restoring flora and fauna.
