Movement of soil on slopes. Construction of subgrade in highly rugged and mountainous terrain. Soil excavation by earth-moving machines

The soil can be developed in three main ways: cutting- earth-moving (single-bucket excavator with replaceable equipment "forward" and "reverse" shovels and multi-bucket rotary or chain excavator) and earth-moving (scraper, bulldozer, grader) machines; hydromechanical- with the help of hydraulic monitors and suction dredgers in the presence of powerful sources of water supply, while soil erosion and its supply to the laying site occur due to the kinetic energy of the water jet; explosion using various explosives. In addition to the above, there are special methods of soil destruction - ultrasound, high-frequency currents, thermal installations, combined methods.

Soil excavation by cutting

Soil excavation by earthmoving mechanisms (single and multi-bucket excavators). Excavators are single-bucket cyclic action on pneumatic or caterpillar tracks and multi-bucket continuous action. Single-bucket excavators are equipped with various interchangeable equipment (Fig. 1.7).

slaughter called workplace excavator, including the place of its standing and soil sampling. A penetration is a recess formed by one stroke of an excavator. Passages are: frontal(end), in which development is carried out on steep slopes along the axis of the excavation and ahead of itself and on both sides of the axis, and lateral, in which the development of the soil occurs on one side in the direction of travel. Excavations of considerable depth are developed by tiers-ledges arranged in different levels. Vehicles are located on the same level with the excavator or above its level. Schemes of frontal penetrations of an excavator with "direct" and "reverse" shovels are shown in fig. 1.8: longitudinal symmetrical, longitudinal with transverse movement, zigzag.

Rice. 1.7. Types of construction excavators with various interchangeable equipment: a - straight shovel; b - backhoe; in - grab; Mr. dragline; d- pile driver; e, and - crane for installation and loading operations; to - diesel hammer for loosening frozen soil; and - stump puller

The development of dense soils in the face plane is carried out in a checkerboard pattern, i.e. offset from the previous cutting strip by a value less than the width of the bucket. When the boom is rotated in the opposite direction, strips of uncut soil are removed, which ensures that the bucket is quickly filled with soil, since the lateral cutting resistance is reduced. Sandy soils are developed in successive strips (chips) with a slight overlap of the previous strips.

Bucket excavators are divided according to the type of main working equipment into chain used in the development of soft soils of 1-3 categories at a depth of less than 4 m, and rotary used for soils of increased strength, including frozen ones, at a depth of less than 2.5 m. The development of soil by rotary and chain excavators in cohesive soils (clays, loams) is carried out to a depth of 3 m without additional fastening.

Rice. 1.8. Soil excavation with single-bucket excavators when excavating pits: a - frontal driving of an excavator equipped with a front shovel, with one-sided loading into a transport vehicle; b - the same, with double-sided loading; in - broadened frontal penetration with zigzag movement of the excavator; g - the same with moving the excavator across the pit; d - side penetration of an excavator equipped with a straight shovel; e, f, h - face driving along the pit with an excavator equipped with a backhoe; and, to - the same, when driving across the pit; l- side penetration; m- cross-shuttle penetration

dragline excavator

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Soil excavation by earth-moving machines. Depending on the type of relationship between the working equipment and the tractor, trailed, semi-trailed and self-propelled scrapers are used. Scrapers are used in the planning of the area and the construction of linearly extended earthworks (Fig. 1.9).

The possibility and conditions for excavating the soil with a scraper are determined by the consistency of the soil (B): B= (IV- H / p) / (IV, - SCH,), where IV- natural soil moisture, %; SCH,- soil moisture at the border of rolling, %; IV,- soil moisture at the yield point, %. For hard ground (B 0) and semi-solid ( B= 0-0.25) the soil should be loosened beforehand. With a hard-plastic consistency (AT- 0.25-0.5) and soft-plastic consistency (5= 0.5-0.75) soil can be developed without loosening. With ductile ( AT- 0.75-1) and viscous (?>1) consistency scrapers cannot be used.

Rice. 1.9. Subsequence technological operations performed by the scraper: a - loading the bucket with soil with a pusher;

b - unloading the soil from the bucket

A complete excavation work cycle includes: cutting and filling the bucket, moving, dumping, laying in an even layer and compacting with the scraper wheels. The filling of the bucket occurs during the movement of the scraper with the knife lowered. Cutting can be performed on the following profiles: with even chips (Fig. 1.10, c) (used for planning work); chips of variable cross section from 20 to 36 mm with a comb profile (Fig. 1.10, b); wedge profile (Fig. 1.10, a).

Rice. 1.10. Soil cutting profiles with a scraper: a - wedge-shaped chips; b - comb shavings; in- thin chips of constant size

Depending on the direction of the soil intake in relation to the axis of the working, a transverse or longitudinal scheme for transporting the soil can be selected. transverse the carriage scheme is adopted with a close relative position of the excavation and embankment. With this scheme, it is necessary to arrange entrances to the embankment and exits from it. At longitudinal In the haulage scheme, loaded scrapers move along the backfilled embankment, which has two end ramps. The main part of the working cycle of the scraper is its movement to the place of unloading and back. The most common scraper movement patterns are: ellipse used in the planning of sites and backfilling of embankments from reserves with a limited number of grips (Fig. 1.11 , a); eight - with a scope of work that allows, during the cycle, to take soil twice in the reserve and unload it into the embankment (Fig. 1.11, b); in a spiral at low embankments, if large volumes of work are not required for the arrangement of ramps (Fig. 1.11, d); along the zigzag during column development of soil in reserves of great length (Fig. 1.11, c) transverse shuttle - with concentrated movement of soil masses and a large distance from each other (Fig. 1.11.5); longitudinal shuttle(Fig. 1.11, c); at one end of the embankment and alternating embankments(Fig. 1.11 , f, h).

Technological schemes for the development of soil by a bulldozer. Bulldozers are used to develop shallow excavations up to 2 m or embankments with a height of less than 1.5 m with the movement of soil into the dump at a distance of up to 200 m; for rough site planning; backfilling of trenches, sinuses of pits; soil hilling in the area of ​​work of loaders, as well as an additional tractor when excavating soil with scrapers. The maximum cutting depth is 20-60 cm. The working body of the bulldozer is a straight mounted blade, rigidly fixed and rotated in the vertical (90-54°) and horizontal planes (3-8°).

Bulldozer cutting profiles are similar to scraper cutting profiles. The most rational are the wedge-shaped and comb cutting patterns. When developing soil in wide excavations and on sites, several technological schemes(Fig. 1.12), providing the highest productivity: transverse with longline trench development; trench according to the shuttle scheme (during the development of pits); continuous layer; stepped-tiered; stripes; trench-strip, etc. With the trench method of excavating the soil between parallel penetrations of the bulldozer, untouched soil shafts are left, bordering the trenches and preventing soil losses.

Shafts are cut off by a bulldozer last. When moving over a distance of more than 40 m, the development method with an intermediate shaft or the paired operation of bulldozers moving side by side at the same speed at a distance of 0.5 m from one another is used. With a shuttle scheme (in small and wide recesses) in the pit, they cut off and move the soil along the axis of the pit, starting from the middle,

both ends. First, a pit is developed on the first grip to a depth of 1 m, and then on the second to the same depth, etc. Between adjacent trenches, bridges of untouched soil and shafts 0.5-1.2 m wide are left, which are cut off after several trenches have been developed. When constructing linear structures of small width, the soil is developed according to the scheme ellipse or eight.

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soil set soil unloading

direction of the scraper

Rice. 1.11. Scheme of soil development with scrapers: a - along an ellipse; b - eight; in - along the zigzag; g - in a spiral; d- transverse shuttle; e- longitudinal shuttle; g - when reserves or excavations are located at one end of the embankment; h - under development

cuts alternating with embankments

yut for the construction of a subgrade trough; layouts of soil poured into an embankment with a height of not more than 1.2 m; cutting and planning slopes of cuts and embankments; profiling the earthen trough of the sandy layer; leveling the crushed stone base; mixing road building materials with binders; devices for diversion ditches and upland ditches up to 0.7 m deep. The main body of the grader is a blade with a knife for cutting and moving soil and an auxiliary scarifier used to remove small stumps, roots, loosen soils and road surfaces (Fig. 1.13).

Design surface

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Rice. 1.12. Methods and schemes for excavating soil with bulldozers: a - paired work; b- shuttle scheme; c - layered development;

g - layered dumping; d, e- piles without layer-by-layer compaction; g - development of soil "from the head"; 1-7 - bulldozer movement sequence; 8- soil moved by a single bulldozer;

9- additional volume of soil moved by two bulldozers; I-VII- the sequence of soil development during planning

Rice. 1.13. The position of the motor grader blade: a - transport; b - installation of the blade at an angle (3; c, g - the same from different angles

to the horizontal plane

The development of soil by a motor grader is carried out by removing rectangular and triangular chips, which depends on the adopted scheme of work in reserve. During the construction of the embankment, the most rational is the layer-by-layer cutting of the soil of rectangular chips, and when developing the soil from the outer edge of the reserve to the inner, cutting is performed by removing the triangular-shaped chips. When operating motor graders use various ways laying the soil - pressing, half-rigging, staggered, in a layer with a given slope, etc. (Fig. 1.14). Ground laying hold on produced by rollers pressed against each other without a gap (with an embankment up to 0.7 m high).

With the method half-press the soil is poured into shafts with partial pressing against the previously laid, overlapping its base by "/ 4 widths (with an embankment up to 0.5 m high). With the method scatter the soil is poured with shafts that are in contact only with the base (with an embankment up to 0.25 m high). When conducting profiling work, laying the soil is carried out layers 10-15 cm thick, and soil dumping is carried out from the curb to the axis of the road with a given transverse slope. The shortage of soil in 5-7 cm to the design mark in the pits and trenches is cleaned manually. Sometimes, instead of manual methods, soil compaction by mechanical vibrotamping is used.

Backfilling of the sinuses of trenches with soil is carried out by bulldozers according to the shuttle or cross-shuttle scheme, as well as manually. Backfilling of the sinuses is necessarily accompanied by soil compaction, which is carried out in layers. The thickness of the first layer compaction is 1 m, and the subsequent layers are 0.4-0.6 m. If it is impossible for a worker to access a narrow bosom (laid collector), the soil is leveled with a micro-bulldozer, and then with a small-sized bulldozer, compacted with a self-moving rammer. The soil in the sinuses of the collector is compacted by parallel passages of a small-sized vibrotamper-

coy. Backfilling is carried out immediately after laying the pipes in order to avoid collapse of the trench walls from precipitation, overdrying or moistening of the soil in the dumps.

Rice. 1.14. Ways of laying the soil into the body of the embankment with a grader (dimensions in m): a - press; b- half-press; in - scatter; g-layers; d- diagram of the operation of a motor grader column during layer-by-layer leveling of soil in an embankment; e- layout of the slopes of the embankment with a steepness of 1: 3 by a motor grader; 1 - the first pass for cutting roller No. 1; 2- passages for moving roller No. 1 to the place of laying; 3 - the second pass for cutting roller No. 2; 4 - passages for moving roller No. 2 to the place of laying;

C - the length of the working grip; / 1 - reserve width; / 2 - the width of the embankment;

/ 3 - subgrade width

Bulldozers perform operations as follows. Layer-by-layer development and movement of materials produced at a transportation distance of 50 ... 150 m. Large travel distances are economically beneficial for heavy bulldozers. In the surface development of soils and minerals, the shuttle movements of the machine are characteristic, alternating the working stroke and the departure back empty. It is advisable to collect and transport the soil in one pass with the formation of side rollers, in a trench way, in paired operation of bulldozers, and in the formation of several prisms. In light soil conditions, additional interchangeable bulldozer equipment (openers, expanders, extensions) is used.

Elevation of embankments carried out in two ways: by transverse passages from the reserve and by longitudinal one-way movements of the machine.

When transversely moving soil from reserves, it is advisable to use the trench method of developing materials and the paired operation of several machines. The first prisms are given to the center of the embankment, the subsequent ones are closer to its edges.

Drawing prisms are placed in a clamp. The slopes of the embankment, along which the soil is supplied, should not exceed 30%. With large elevations of the embankment, the work is inefficient.

Rice. 137. Basic excavation bulldozer work.

See also:

By longitudinal movements of the bulldozer in the direction of the longitudinal axis of the embankment, it is advisable to feed the soil down the slope. The height of the embankment in this case can be up to 4 ... 5 m.

Development of recesses produced by longitudinal double-sided passages and transverse passages . The longitudinal double-sided method provides greater productivity for bulldozers. It is used for small excavations and in cases where the soil excavated from the excavation is completely laid in adjacent embankments. The transverse excavation method is used when excess soil is laid in cavaliers along the future roadbed.

Extraction of canals, irrigation facilities, trenches, pits produced by transverse strokes of the bulldozer with a gradual displacement of the machine along the structures . The soil is laid in cavaliers along the entire length of the channels, creating earth ramparts on both sides. Soil is developed in parallel trenches with a depth not exceeding the overall height of the machine. The distance between the trenches is up to 0.4 ... 0.6 m. After the separation, the inter-trench bridge is destroyed. In this case, the group operation of machines with paired parallel moves is effective.

planning work carried out on a flat surface, cutting off small bumps and filling up depressions, pits, ravines. Large depressions fall asleep from neighboring slopes with longitudinal passages . The last passes are made with an offset of V4 of the blade width in order to exclude the appearance of side ridges. After a rough front layout, it is expedient to carry out surface finishing with the rear of the bulldozer and the "floating" position of the blade. For greater accuracy, it is advisable to use mutually perpendicular passages of bulldozers.

Punching of terraces and shelves on slopes carried out by bulldozers with fixed and rotary blades. The most efficient and safest way is to move soil from a slope to a semi-mound with the transverse passages of the machine down the slope. It is used on gentle slopes of slopes. At large angles of inclination of slopes, a longitudinal method is used . In this case, the bulldozer blade, installed with a skew, punches first passage 1, then 2, 3, 4 and 5. Working with longitudinal passages is more productive, but special care must be taken, as it is possible to cross-slide or tip the machine down the slope . Therefore, for the safety of work, the transverse stability of the bulldozer is taken into account.

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Rice. 140. Soil loosening schemes:

a- longitudinal-annular, b - spiral, c - shuttle-night with offset, d - longitudinal-transverse.

The choice of loosening scheme depends on the strength and nature of the rocks being developed.

When loosening soils of category IV and strong rocks, it is advisable to organize the operation of machines according to longitudinal-ring and spiral schemes, since they provide the highest productivity of the machine. Shuttle and longitudinal-transverse schemes are used for loosening rocks and permafrost soils. The latter scheme is used when it is necessary to obtain loosened rock of smaller sizes. It is additionally crushed by tractor tracks.

Areas of frozen soils are developed in layers to the maximum possible depth.

With a depth of freezing of rocks of 50 ... 70 cm, it is possible to loosen the array with three teeth. If the depth of the development of rocks is greater, then with one tooth in two or three passes with a loosening depth of 30 ... 40 cm for each cycle. When working on frozen rocks, the traction force of the machine is reduced by 35 ... 45% due to a decrease in the coefficient of adhesion of the undercarriage to the ground.

Soils are loosened on the working gear of the tractor at a speed of 0.9 ... 2.7 km / h. At the end of the working cycle, the ripper is dug out and the presence of a removable tip is checked. If the tip is lost, the toe of the rack can be damaged and it will not hold the tip. In this case, the rack is replaced.

Rice. 141. Methods for the development of soils and the extraction of minerals:

a-trench with feed into vehicles by a loader, b - downhill with loading from a stack into transport by an excavator, with - two bulldozers-rippers with backfilling and from the dump into vehicles by a loader;

1 - bull-dozer-ripper; 2 - loader, 3 - vehicles, 4 - excavator.

Loose soils and rocks are removed by earth-moving vehicles. The most effective development of strong, frozen rocks and minerals is by a bulldozer-ripper.

There are several rational schemes for organizing the work of a bulldozer-ripper in combination with loaders and excavators.

When developing an array in a trench way, the bulldozer-ripper 1 loosens the rock in layers at the bottom of the trench. Then, with bulldozer equipment, with the ripper raised, the rock is moved into the stack by shuttle movements of the machine. From the stack with a single-bucket loader 2, the crushed material is loaded into vehicles 3 and transported to the place of storage or processing.

A more rational scheme for loosening and cleaning rocks with a bulldozer downhill. A stack of material is formed at the bottom of the slope. From the pile, an excavator or loader loads the rock into vehicles. The performance of the unit in this case is higher.

To coordinate the performance of the loading equipment, sometimes two bulldozers-rippers are used, which first loosen the bottom of the trench with longitudinal-transverse strokes, and then one bulldozer delivers the material to the storage site, and the other pushes it into the pile, from which the loader picks up breed and fills vehicles.

In open-pit mining, a complex detachment of machines is used, which includes 3 ... 5 bulldozers, rippers, an excavator or loader, and several dump trucks. To avoid downtime, one bulldozer-ripper 3 only loosens the site. Several bulldozers 2 in parallel move the loosened waste rock 4 into a pile, from which the excavator 1 loads it into vehicles 4 and transports it to the dump. After harvesting the waste rock, minerals are developed in a similar way.

Rice. 142. Open pit mining with preliminary loosening:

1 - excavator or loader, 2 - bulldozers, 3 - bulldozer-ripper, 4 - waste rock, 5 - vehicles, 6 - minerals.

General provisions. Road bed construction highways in highlands is complicated, as a rule, by the fact that in the places where the route is laid, there are steep slopes with an intensive manifestation of exogenous processes (landslides, landslides, falls, screes) in a certain area of ​​​​short length. geological features of a site or group of sites that differ in the specified characteristics. It is recommended to assign the technology for the construction of the subgrade, taking into account the design features of the embankment or excavation, the construction region as a whole, the structure of the slope (slope) and the properties of the constituent rocks.

It is necessary to provide for a set of technological measures in the WEP to ensure the stability of natural slopes and slopes of excavations during the construction and subsequent operation of the road.

When developing a PPR, choosing a technology, machines and method of drilling and blasting, the presence of cracks in the developed massif and the nature of the layering of sedimentary rocks are taken into account.

Availabilitycracks in rocky igneous rocks reduces the stability of slopes and slopes of excavations. The fall of cracks at an angle of more than 35° towards the road contributes to the occurrence of landslides, collapses, falls already in the process of work. Safe is the fall of cracks in the direction of the array.

Layering leads to a weakening of the array in the slopes and slopes, especially when they are pruned or undermined.

With an increase in the angle of meeting of the strike of the layering with the longitudinal axis of the road, the stability of slopes and slopes increases sharply. The most stable position of the bedding meeting angle with respect to the road axis will be 90°. If the azimuth of the strike of the layering coincides with the direction of the axis of the road, the cut or undermined slopes and slopes of the cuts are destroyed only along the bedding planes.

During the construction of roads in mountainous conditions, the main difficulties are associated with the development of rocks, a reduction in the scope of work, and limited transport accessibility. working area, moving, leveling, compaction of coarse soils, finishing works.

If the working area is not available for the direct operation of machines, the first stage of construction should include the laying of a pioneer road along the planned route. If the laying of a pioneer road along the planned route is impossible, it is arranged as close as possible to it with approaches to the work area of ​​individual structures. In this case, a hiking trail is laid along the route itself.

Loosening and development of rock, belonging to the difficulty of development to group V and above, is carried out by the explosive method. The explosive method is also recommended for the formation of deep cuts by mass ejection explosions or targeted explosions for the construction of embankments in hard-to-reach places in the mountainous terrain.

At all stages of work, measures must be constantly taken on slopes and slopes to prevent geodynamic phenomena (landslides, scree, avalanches, etc.) that may pose a danger to working people, equipment, structures. To this end, prior to the start of work, as well as in the process of developing mountain slopes, constant monitoring of the stability of both individual rock fragments and the entire slope from the upper side should be organized. If signs of instability are found, safety measures must be taken immediately, such as undermining and removing overhanging boulders. In the presence of active landslides, intense landslides, large falls, drilling and blasting operations are carried out only for loosening with small-hole charges.

Works on the construction of a subgrade on slopes, stable and landslide slopes include: a preparatory complex associated with marking work, removing vegetation; arrangement of a construction drainage system, parking lots for equipment placement, special anti-landslide structures; the main work on the construction of a subgrade located on various elements of the slope relief or in its environment and a set of anti-landslide measures.

It should be borne in mind that the choice of technology is also associated with the need to develop deluvial, rocky or semi-rocky rocks, as well as their use in the form of coarse soils for filling embankments. The latter depends on the passage of the route in conditions of rugged terrain.

Construction of embankments and excavations. The construction of a subgrade in a mountainous area includes the installation of the following structures, depending on the conditions for laying the route in a particular region and region of a mountainous area, their hypsometric, geomorphological and engineering-geological features: a subgrade in a ledge, a half-fill-half-cut, a cut in a rock mass, an embankment of rocky or coarse soils.

The choice of technology for the development of excavations and the construction of embankments is determined design features subgrade, category of rocks according to the difficulty of their development, sources of obtaining rocky or coarse-grained soil for the subgrade of embankments.

Construction of subgrade in shelves in pressure areas with a slope steepness of more than 1:3 in rocks, they are carried out by blasting, followed by excavation of the blasted mass, its transportation to the areas of the embankment. If there are deluvial deposits on the slopes, the subgrade in the shelf is developed by initially cutting the slope with powerful bulldozers of the 250-300 tf class, followed by refinement by excavators and transportation of coarse soils by dump trucks.

Construction of embankments and excavations on slopes with a steepness of 1:3 or more is carried out by the method of successive cutting of shelves for recesses or half-pits or ledges at the base of the embankment. Cutting ledges (shelves) is performed, as a rule, starting from the upper tier. With the provided stability of the slope and the need to create a passage for drilling operations, the first shelf is produced at the level of the lower edge of the excavation (shelf).

Development of excavations in rocks are carried out immediately with a small enumeration in order to avoid subsequent difficult and costly work to remove an under-selected thin layer of rocky soils. The subgrade is leveled to the design marks with small torn stone and rubble.

The development of excavations in deluvial soils, softened and highly weathered collapsible, fractured rocks is recommended to be carried out according to the “sliding shelf” scheme, when, after the implementation of the pioneer trench-face necessary for the placement and safe operation of the excavator, the soil is developed from top to bottom and moved by powerful bulldozers of the class 250-300 tf. With the help of an excavator, the subsequent refinement of the soil and its loading into vehicles with movement to the construction sites of embankments takes place.

To form smooth surfaces of slopes during the construction of cuts and half-cuts in favorable engineering and geological conditions (poor crack resistance of rocks, separation into rectangular parts with a vertical direction of the interface planes, the ability of rocks to brittle chipping, etc.), contour blasting is used.

The choice of the method and parameters of loosening rocky and coarse-grained soil should be carried out in accordance with the soil group according to the difficulty of development, with the area and conditions of its application. If the calculated number of oversized items in the loosened soil and their maximum size are exceeded, it is necessary to make appropriate changes to the loosening scheme and parameters.

Prior to drilling and blasting, the vegetation cover, topsoil and overburden are removed and removed. When the thickness of overburden is not more than 1/3 of the working depth, loosening of rocky soil is allowed without their removal.

Drilling and blasting and loading of loose rock by excavators can be carried out in parallel. In this case, the first work must be carried out ahead of time. If the method of blasthole charges is used for loosening in recesses or ledges up to 5 m deep, drilling and blasting operations should be carried out ahead of time, providing at least a replaceable supply of blasted rock. In this case, the minimum lead distance must be maintained in accordance with the Uniform Safety Rules for Explosive Operations (M.: Nedra, 1985).

Before the start of the excavator, oversized items located in the upper layer of the blasted soil are crushed by additional explosions. In the process of excavation development, oversized pieces are rolled off to the side and then also crushed by explosions, moving the exploded rock with a bulldozer to the excavator face.

When developing half-holes on rocky slopes, they first arrange a shelf for a working passage 3.5 m wide, which makes it possible for the main machines (drilling rigs, excavators, bulldozers, dump trucks, etc.) to pass. Then the shelf is widened, bringing the subgrade to the design outline.

When developing excavations loosening of rocks to the required particle size must be ensured by the proper drilling and blasting technology and proceed from the required compaction conditions provided for by SNiP 2.05.02-85. Crushing of large oversized fragments is carried out by overhead charges. This method is used with limited compressor capacity or in the absence of drill hammers and a small amount of oversized. The ledges of rocky soil remaining on the slopes and the main excavation site are also crushed.

With explosive methods of development and loosening, shortfalls at the base of the excavations are not allowed. Shortfalls on the surface of the slopes should not exceed 0.2 m, provided that their stability is ensured. The value of the searches after the final cleaning of the bottom and slopes of the excavations should not exceed the values ​​\u200b\u200bspecified in Table. one.

When finalizing excavations in rocky soils after explosions for ejection, the following work procedure should be observed:

crushing of oversized objects located on the surface, formed during the explosion of the trench;

leveling loosened soil heaps with a bulldozer;

removal of blasted soil from slopes by an excavator (slope trimming);

removal of non-hanging stones and visors with an excavator and small explosions;

finalization of the excavation to the design outline by explosions; leveling of the main platform.

Table 1

Note. During drilling operations under water and in offshore areas and roadsteads, the size of the searches is established by the construction organization project.

In the case of tiered excavation, each tier must be completed to the design contour and cleaned before work begins on the next tier.

When constructing embankments from coarse-grained soils, which are the product of loosening or weathering of rocks, the maximum particle size of the blocky fraction should be assigned depending on the thickness of the compacted layer, type and technical parameters sealing agents and physical and mechanical characteristics of the soil, but should not exceed 2/3 of the thickness of the compacted layer.

Oversized fragments, the dimensions of which do not meet the specified requirements, are allowed to be laid in the side (slope) parts and in the lower layer of the embankment in one row so that they do not fall into the working layer of the embankment.

When laying oversized debris in the base of the embankment, in order to exclude uneven settlement due to spillage of fine-grained aggregate from the overlying layers into the underlying layers, interrupting layers of crushed stone (pebble), sandy or clayey soils should be arranged.

The filling of the embankment from coarse-grained soils is carried out by a bulldozer using the “push” method in such a way that the largest fragments are located in the lower parts of the embankment. The most rational is the use of a bulldozer with a universal blade, which allows during the distribution process to produce a rejection of oversized items with their subsequent placement in the side of the embankment.

There are two patterns of distribution of coarse-grained soil: longitudinal and diagonal. Depending on the method of filling the soil, the longitudinal and diagonal distribution patterns can be one-sided or two-sided.

For axial dumping, a two-sided distribution scheme is used, for lateral dumping - one-sided.

It is rational to use specially equipped dumps with a mixed sorting device according to the type of ripper for rejecting oversized items.

Before compaction, the side parts of the embankment, including slopes made of oversized, are leveled with soil of smaller fractions. When arranging a subgrade on slopes with a steepness of more than 1: 3, it is advisable to arrange alignment from soils with sandy filler according to the wedging method.

The development of coarse-grained soils after blasting should be carried out with an excavator with a bucket capacity of 0.65-1 m 3 with loading into vehicles. If it is necessary to hill up the soil of an oversized dump on horizontal surfaces and slopes with a steepness of up to 1: 3, bulldozers are used.

With a layered occurrence of easily weathered softening rocks, interspersed with layers of clay soils, the development is carried out for the entire thickness of the face, taking into account that the developed soils contain 30-40% (by weight) of clayey fine earth. Otherwise, the development is carried out in separate layers.

Layingand compaction of coarse soils. Coarse-grained soils of frame and imperfect-frame structure from durable water-resistant rocks should be compacted, as a rule, by vibration. Coarse clastic soils containing more than 30% clay aggregate are compacted at a moisture content not exceeding the allowable values ​​for heavy sandy loams and light loams, and with a clay aggregate content of less than 30% - at a moisture content not exceeding the allowable values ​​for light and silty sandy loams.

Compaction of coarse soils, the strength of which is less than 5.0 MPa (50 kg / cm 2), should be carried out in two stages: at the first - with lattice rollers; on the second - rollers on pneumatic tires weighing at least 25-30 tons. When using softened coarse-grained soils, work should be carried out in dry weather with minimal time gaps between individual technological operations.

Ways and technical means compaction of easily weathered non-water-resistant coarse-grained soils is prescribed from the condition of ensuring the destruction of aggregates until the pores are filled with fine earth. To improve the efficiency of the destruction of aggregates, they are periodically moistened.

Good results are obtained by the technological scheme of compaction in two stages: at the first (immediately after leveling and moistening) - by lattice rollers, which carry out additional crushing of the soil, at the second - by heavy rollers on pneumatic tires. The required degree of soil compaction is achieved after 10-12 passes along one track of rollers on pneumatic tires weighing 25-30 tons. For coarse-grained soils of low strength, compaction by tamping is effective.

If it is impossible to ensure the destruction of aggregates of non-water-resistant rocks, their protection in the embankment from the effects of weather and climatic factors should be provided. When constructing protective layers from clay or loamy soils, the latter are filled up to a given thickness in layers, level with a layer of clastic soil and compacted together with it.

When constructing a protective layer with a thickness of 15-20 cm from soils reinforced with organic binders, the soil is pre-mixed with binders in stationary or mobile units and transported by dump trucks to the place of laying. Bulldozers or leveling excavators are recommended for spreading the mixture on slope surfaces. Site vibrators or vibrating slats moving along the slope from top to bottom or from bottom to top can be used as sealing means.

Quality control of work when constructing a subgrade on slopes, stable and landslide slopes, in addition to general requirements, provided for by SNiP 3.06.03-85, includes: control over the restoration, fixing and breakdown of the subgrade on the marked relief elements; quality control of ledge cutting (in compliance with the design geometric parameters), compliance with the technology for developing slopes and slopes when constructing a subgrade in a shelf and the sequence of a set of anti-landslide measures (drainage, drainage and retaining structures).

Organization of work on the construction of roads in the presence of landslides, it includes two independent issues: the construction of a subgrade and the construction of a complex of anti-landslide structures established by the project. The sequence of these works is determined by the specific conditions of the territory, the location of the subgrade, the composition and types of anti-landslide structures and should be specified in the design and calculation documentation. In practice, there are several options for organizing the sequence of earthworks and the installation of anti-landslide structures: the construction of a complex of anti-landslide structures before the construction of the subgrade; implementation of anti-landslide structures in the process of its construction; construction of anti-landslide structures after the construction of embankments or excavation.

As a rule, the first scheme is the most appropriate for the construction of a road on landslide slopes, when the construction of the subgrade is possible only under the direct protection of supporting structures or after measures have been taken to regulate surface and underground runoff. The second scheme is used when the subgrade is located in deep excavations and high embankments. For example, as each tier is developed, excavations strengthen slopes and construct drainage structures. The third scheme is used in many cases in the construction of roads in mountainous conditions, when, in particular, after the construction of the subgrade in the shelf, upper retaining walls or anchor structures are constructed.

Undoubtedly, the variety of complex conditions for the construction of roads in landslide or potentially landslide areas requires the creative application of these schemes with subsequent development to specific technological and organizational solutions in work projects. This section only deals with general issues organization of construction in landslide areas and does not cover the specifics of construction specific types anti-landslide structures, which is reflected in other chapters.

In addition to the features associated with the sequence of earthworks and the construction of anti-landslide structures, it should be noted that the technology of earthworks largely depends on the design principles (in relation to the relief) of roads. There are the following types of individual technological schemes for organizing earthworks: the development of deep excavations and the construction of high embankments; construction of embankments on slopes with crossing of landslide areas; arrangement of subgrade in the shelves. One of the most difficult cases of work performance is their implementation at emergency facilities, when sections of operated roads are destroyed by landslides.

The fact established by repeated surveys of the violation of the stability of natural slopes and slopes of the subgrade during the construction of roads in various regions of our country convincingly shows that the influence of technological factors can be significant, and in some cases prevailing.

In this case, technological factors include: the method and time of excavation or construction of embankments, the method and time of construction of anti-landslide structures. These factors can be combined into a general technological system for the construction of individual subgrade structures, which, during its implementation, will have certain effects on the stability of the slopes of the subgrade and the slopes adjacent to it, especially landslides.

An analysis of the construction of roads in landslide areas showed that the impact technological system on the stability of slopes and slopes is manifested in the following.

An unsuccessfully chosen direction of work in the development of deep excavations can lead to the development of landslides in the slopes. The degree of intensity of earthworks affects the stability parameters of slopes during the construction process. So with a short front of work and high speed excavation in slopes (at the working depth of development) does not have time to develop deformations leading to landslides, which allows you to give the slopes of the working tiers steeper angles. The construction of high embankments and embankments on slopes (including landslides), on the contrary, requires a slower soil dumping mode, due to the need for thorough compaction of the soil, as well as the gradual transfer of the load from the weight of the embankment to the slope base, which ensures its stability and further stability.

The order and timing of their design configuration have a significant impact on the development of landslides in slopes and slopes. The most common mistake in this regard is associated with the installation of berms, tiers, drainage structures and strengthening works on slopes not during the development of excavations and the construction of embankments, but after their completion. Of particular importance is the technological sequence of the construction of embankments on the slopes. In the projects for the production of work, such a principle of conducting work should be laid down, which would guarantee the stability of the inclined base during the construction of the subgrade. In particular, for example, in many cases, the stability of embankments on slopes has been compromised due to the wrong way works: instead of the consistent construction of the embankment from the downstream side of the slope, the work was carried out from the upstream side, which led to the development of uncompacted zones in the slope parts, overstressing the slope base, and the development of landslides both in the slopes and in the slopes of the embankments.

Technological factors become very important in earthworks on landslide slopes or in their environment. Proper placement of earth-moving equipment, determination of the required pace, maintaining the required depth of development or steepness of the slope provide not only the possibility of implementing design solutions, but also their further reliability during the operation of the road section, as well as the degree of preservation of the landslide slope itself in a stable state.