Moving soil on slopes. Construction machines and equipment. Development of frozen soils

Part 1

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

Construction of embankments carried out in two ways: by transverse passages from the reserve (Fig. 137, I) and longitudinal one-way movements of the machine (Fig. 137, II).

Rice. 137. Basic excavation bulldozer work

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 fed to the center of the embankment, the subsequent ones - closer to its edges.

The drawing prisms are placed in a clamped position. The rise of the embankment slopes along which soil is supplied should not exceed 30%. With large elevations of the embankment, the work is ineffective.

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

Development of excavations produced by longitudinal double-sided passes (Fig. 137, III) and transverse passages (Fig. 137, IV). The longitudinal two-way method provides greater productivity of bulldozers. It is used for short excavations and in cases where the soil removed from the excavation is completely placed in adjacent embankments. The transverse excavation method is used when excess soil is placed in cavaliers along the future road surface.

Excavation of canals, irrigation structures, trenches, pits produced by transverse moves of the bulldozer with a gradual displacement of the machine along the structures (Fig. 137, V). The soil is placed in cavaliers along the entire length of the canals, creating earth banks on both sides. The soil is excavated in parallel trenches with a depth no greater than the overall height of the machine. The distance between the trenches is up to 0.4...0.6 m. After the passage, the intertrench jumper is destroyed. In this case, group operation of machines with paired parallel moves is effective.

Planning work carried out on a flat surface, cutting off small mounds and filling in depressions, holes, and ravines. Large depressions are filled up from neighboring slopes with longitudinal passages (Fig. 137, VI). The last passes are made offset by 3/4 of the blade width to prevent the appearance of side rollers. After a rough front layout (see Fig. 130, G) it is advisable to finish the surface while moving the bulldozer in reverse (see Fig. 130, V) and the “floating” position of the blade. For greater accuracy, it is advisable to use mutually perpendicular passages of bulldozers.

Rice. 130. Main types of work performed by bulldozers: A- development of trenches, pits, channels with soil filling into cavaliers, embankments, b- cutting of slopes and filling of excavations, V- removal of fertile layer or waste rock, G- forward layout, d- forward leveling, e- rearward planning, and- backfilling of trenches, h- pushing scrapers when filling the bucket with soil, And- loading soil into vehicles from the overpass, To- loading materials into transport from a tray, l- felling trees, m- uprooting stumps, n- cutting of bushes and small forests, O- snow removal works; 1 - initial position of the bulldozer, 2 - cutting and transporting soil, 3 - bulldozer on an embankment, 4 - embankment or cavalier, 5 - trench, 6 - slope, 7 - excavation, 8 - fertile layer or waste rock, 9 - minerals and building materials, 10 - scraper, 11 - overpass, 12 - vehicles, 13 - loading chute

Punching terraces and shelves on slopes carried out by bulldozers with fixed and rotary blades. The most effective and safe way to move soil from a slope to a half-embankment is by transverse passes of the machine downhill (Fig. 138, I). It is used on gentle slopes. For large angles of inclination of slopes, the longitudinal method is used (Fig. 138, II). In this case, the bulldozer blade, installed at an angle, first breaks through passage 1, then 2, 3, 4 and 5. Working with longitudinal passes is more productive, but special care must be taken, since the machine may slide laterally or tip over on a slope. Therefore, for the safety of work, the lateral stability of the bulldozer is taken into account.

Rice. 138. Development of slopes with a bulldozer

Backfilling of trenches produced by bulldozers with a non-rotating (Fig. 139, A) or a rotary blade (Fig. 139, b). This operation is performed with straight passes perpendicular to the axis of the trench, or with oblique movements at a certain angle to it.

Rice. 139. Filling trenches with bulldozers: A- with a fixed blade, b- with a rotary blade; 1 - soil embankment, 2 - trench

A bulldozer with a fixed blade grabs some of the soil from the embankment and moves it into the trench. If the depth of the trench is 1.5 m or more, then the soil is poured through one or two prisms to prevent the walls of the trench from collapsing and the bulldozer from sliding into it. After the first pass, the bulldozer moves in reverse and the operation is repeated.

For a bulldozer with a rotating (wider) blade, it is installed at an angle to the right to the longitudinal axis of the machine and with oblique moves at an angle of 30...40° they push the soil into the trench. The use of bulldozers with a rotary blade is more effective for this work, since the soil is partially shifted to the side when colliding.

Pushing scrapers(see Fig. 130, h) are carried out by bulldozers when collecting soil and exiting a loaded scraper from a face with a large slope of access roads.

Loading soil into vehicles from an overpass(see Fig. 130, And) are produced primarily in sand quarries. The overpass is built in a trench dug by a bulldozer. Using longitudinal moves, the bulldozer moves the material to the overpass bunker and loads the dump trucks. The bulldozer works through one or two prisms so as not to cause the overpass to collapse. Loading soil into vehicles from a tray is shown in Fig. 130, To.

Felling trees(see Fig. 130, l) is carried out by focusing the maximum raised blade into the barrel.

Uprooting stumps(see Fig. 130, m) can be done with a straight blade or a skewed blade. First, with the deepest depth of the blade, the roots of the stump are cut off with middle or corner knives and rocked by repeatedly engaging the clutch. Then, by simultaneous forward movement of the machine and lifting of the working equipment, the stump is uprooted. Large stones and boulders that are partially on the surface are removed from the ground in a similar manner.

Cutting shrubs and small forests(see Fig. 130, n) is produced with a straight blade lowered into the ground to a depth of 10...20 cm, with the entire bulldozer moving forward. As heaps of bushes, roots, and small trees accumulate, they are moved with a turning movement away from the cleared route.

Snow removal(see Fig. 130, O) perform for maintenance highways in a good condition. The most effective in this case is a bulldozer with a rotating blade with an oblique working body.

General provisions. The construction of roadbeds for highways in mountainous areas is complicated, as a rule, by the fact that in the places where the route is laid there are steep slopes with intense manifestation of exogenous processes (landslides, avalanches, fallouts, screes) in a certain short section. In connection with this, it is recommended when drawing up a project execution of work (PPR) take into account the engineering and geological features of a site or group of sites that differ in the specified characteristics. It is recommended to assign a technology for the construction of the roadbed, 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.

The PPR must provide for a set of technological measures to ensure the stability of natural slopes and excavation slopes during the construction and subsequent operation of the road.

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

Availabilitycracks in igneous rocks, it reduces the stability of slopes and slopes of excavations. The incidence of cracks at an angle of more than 35° towards the road contributes to the occurrence of landslides, landslides, and fallouts already during the work process. It is safe for cracks to fall towards the massif.

Layering leads to weakening of the massif on slopes and slopes, especially when they are trimmed or worked.

With an increase in the angle at which the strike of the layering meets the longitudinal axis of the road, the stability of the slopes and slopes increases sharply. The most stable position of the bedding meeting angle relative to the road axis will be 90°. When the azimuth of the bedding strike coincides with the direction of the road axis, the undercut or undermined slopes and excavation slopes are destroyed only along the bedding planes.

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

If the working area is inaccessible for direct operation of machines, the first stage of construction should include laying a pioneer road along the designed route. If laying a pioneer road along the designed route is impossible, it is built as close to it as possible with approaches to the work area of individual structures. In this case, a walking trail is laid along the highway itself.

Loosening and development of rocks belonging to group V and higher in terms of development difficulty is carried out using the explosive method. The explosive method is also recommended to be used for the formation of deep excavations by mass ejection explosions or targeted explosions for the construction of embankments in hard-to-reach areas of mountainous terrain.

At all stages of work, measures must be constantly taken on slopes and slopes to prevent geodynamic phenomena (landslides, screes, avalanches, etc.), which may pose a danger to working people, equipment, and structures. For these purposes, before the start of work, as well as during the development of mountain slopes, constant monitoring of the stability of both individual rock fragments and the entire slope from the upstream side should be organized. If signs of instability are detected, safety measures must be taken immediately, such as blasting and removing overhanging rocks. In the presence of active landslides, intense landslides, large fallouts, drilling and blasting operations are carried out only for loosening with small-hole charges.

Work on the construction of roadbed on slopes, stable and landslide slopes includes: a preparatory complex associated with marking work, removal of plant soil; arrangement of construction drainage, parking for equipment, special landslide protection structures; the main work on the construction of a roadbed located on various elements of the slope relief or in its environment and a set of landslide prevention measures.

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

Construction of embankments and excavations. The construction of a roadbed in mountainous areas includes the installation of the following structures, depending on the conditions of the route in a particular region and area of the mountainous area, their hypsometric, geomorphological and engineering-geological features: roadbed in a shelf, half-embankment-half-excavation, excavation in a rock mass, embankment from rocky or coarse soils.

The choice of technology for developing excavations and constructing embankments is determined by the design features of the roadbed, the category of rocks according to the difficulty of their development, and the sources of obtaining rocky or coarse soil for the roadbed of embankments.

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

Construction of embankments and excavations on slopes a slope of 1:3 or more is performed by sequentially cutting shelves for recesses or half-recesses or ledges at the base of the embankment. Cutting ledges (shelves) is carried out, as a rule, starting from the top tier. If the stability of the slope is ensured and it is necessary to create a passage for drilling operations, the first flange is excavated at the level of the lower edge of the excavation (flange).

Development of excavations in rocks carried out immediately with a little overkill in order to avoid subsequent difficult and expensive work on removing the under-removed thin layer of rocky soil. Level the roadbed to the design marks with small torn stones and crushed stone.

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 placement and safe work excavator, the soil is developed from top to bottom and moved by powerful bulldozers of the 250-300 tf class. With the help of an excavator, the soil is subsequently processed and loaded into vehicles with movement to the embankment construction sites.

To form smooth surfaces of slopes when constructing excavations and half-excavations in favorable engineering-geological conditions (weak fracture resistance of rocks, separation into rectangular sections with a vertical direction of the separation planes, the ability of rocks to be brittle, etc.), contour blasting is used.

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

Before drilling and blasting operations are carried out, vegetation cover, fertile soil layer and overburden are removed and removed. When the thickness of overburden rocks is no more than 1/3 of the excavation depth, loosening of rocky soil is allowed without removing them.

Drilling and blasting operations and loading of loose rock with excavators can be carried out in parallel. In this case, the first work must be completed ahead of schedule. If the method of blasthole charges is used for loosening in excavations or ledges up to 5 m deep, drilling and blasting operations should be carried out ahead of time, ensuring no less than a replaceable supply of blasted rock. In this case, the minimum advance distance must be maintained in accordance with the Unified Safety Rules for Blasting Operations (M.: Nedra, 1985).

Before the excavator starts working, oversized materials located in the upper layer of blasted soil are crushed by additional explosions. During the development of the excavation, oversized rocks are rolled aside and then also crushed by explosions, moving the blasted rock with a bulldozer to the excavator face.

When developing half-recesses on rocky slopes, first a shelf for a working passage with a width of 3.5 m is installed, allowing the passage of the main machines (drilling rigs, excavators, bulldozers, dump trucks, etc.). Then the shelf is widened, bringing the roadbed to the design outline.

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

With explosive mining and loosening methods, shortfalls at the base of excavations are not allowed. Shortfalls on the slope surface should not exceed 0.2 m, provided their stability is ensured. The amount of overhaul after final cleaning of the bottom and slopes of the excavations should not exceed the values indicated in the table. 1.

When reworking excavations in rocky soils after ejection explosions, the following work procedure should be followed:

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

leveling piles of loosened soil with a bulldozer;

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

removal of non-hanging stones and peaks using an excavator and small explosions;

completion of the excavation to the design outline by explosions; leveling the main site.

Table 1

Note. During drilling operations underwater and in offshore waters and roadsteads, the size of the overhaul is established by the construction organization project.

When developing excavations in layers, each tier must be completed to the design contour and cleaned before work begins on the next tier.

When constructing embankments from coarse soils, being a product of loosening or weathering of rocks, the maximum particle size of the block fraction should be determined depending on the thickness of the compacted layer, the type and technical parameters of the compacting agents and the physical and mechanical characteristics of the soil, but should not exceed 2/3 of the thickness of the compacted layer.

Oversized debris, the dimensions of which do not meet the specified requirements, may be placed 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 at the base of the embankment, to avoid 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 installed.

Filling of the embankment from coarse-grained soils is carried out using a bulldozer using the push-pull method so that the largest fragments are located in the lower parts of the embankment. The most rational use of a bulldozer with a universal blade, which allows, during the distribution process, to reject oversized items and then place them in the side of the embankment.

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

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

It is rational to use specially equipped dumps with a mixed sorting device similar to a ripper to reject oversized items.

Before compaction, the side parts of the embankment, including oversize slopes, are leveled with soil of finer fractions. When constructing a subgrade on slopes with a steepness of more than 1:3, it is advisable to arrange the leveling from soils with sand filler using the declinging method.

It is advisable to develop coarse-grained soils after blasting operations using an excavator with a bucket capacity of 0.65-1 m 3 and 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.

In case of layered occurrence of easily weathered softened rocks interspersed with layers of clayey soils, development is carried out to the full thickness of the face, taking into account that the developed soils contain 30-40% (by weight) of clayey fine earth. Otherwise, development is carried out in separate layers.

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

Compaction of coarse soils, the strength of which is less than 5.0 MPa (50 kg/cm2), should be carried out in two stages: in the first - with lattice rollers; on the second - rollers on pneumatic tires weighing at least 25-30 tons. When using softened coarse soils, work should be carried out in dry weather with minimal time gaps between individual technological operations.

Methods and technical means for compacting easily weathered, non-waterproof coarse soils are prescribed to ensure the destruction of aggregates before filling the pores with fine earth. To increase the efficiency of destruction of aggregates, they are periodically moistened.

Good results are achieved by a technological compaction scheme in two stages: in the first (immediately after leveling and moistening) - with lattice rollers, which additionally crush the soil, in the second - with 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 soils of low strength, compaction by ramming is effective.

If it is impossible to ensure the destruction of aggregates of non-waterproof rocks, they should be protected in the embankment from the effects of weather and climatic factors. When constructing protective layers of clay or loamy soils, the latter are added to a given thickness layer by layer level with the layer of clastic soil and compacted together with it.

When constructing a protective layer 15-20 cm thick from soils strengthened with organic binders, the soil is pre-mixed with binding materials in stationary or mobile installations and transported by dump trucks to the installation site. To distribute the mixture on the surface of the slopes, bulldozers or leveling excavators are recommended. As compacting means, platform vibrators or vibrating screeds can be used, moving along the slope from top to bottom or from bottom to top.

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

Organization of work on the construction of highways in the presence of landslides, it includes two independent issues: the construction of the roadbed and the construction of a complex of landslide-proof structures installed 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 landslide protection structures and must be specified in the design and calculation documentation. In practice, there are several options for organizing the sequence of excavation work and the installation of landslide-proof structures: construction of a complex of landslide-proof structures before the construction of the roadbed; implementation of landslide protection structures during its construction; construction of anti-landslide structures after the construction of embankments or the development of excavations.

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

Of course, the variety of complex conditions for the construction of highways in landslide or potential landslide areas requires the creative application of these schemes with the subsequent development of specific technological and organizational solutions in work projects. This section only covers general issues organization of construction in landslide areas and does not cover the specifics of the construction of specific types of landslide structures, which are reflected in other chapters.

In addition to the features associated with the sequence of excavation work and the construction of landslide protection structures, it should be noted that the technology of excavation work largely depends on the design principles (in relation to the relief) of highways. The following types of individual technological schemes for organizing excavation work are distinguished: development of deep excavations and construction of high embankments; construction of embankments on slopes crossing landslide areas; arrangement of subgrade in the shelves. One of the most difficult cases of work is carrying out work at emergency sites, when landslides have destroyed sections of operated roads.

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

Technological factors in this case include: the method and time of excavation or construction of embankments, the method and time of construction of landslide protection 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 impacts on the stability of the subgrade slopes and adjacent slopes, especially landslide ones.

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

An unsuccessfully chosen direction of work when developing deep excavations can lead to the development of landslides on slopes. The intensity of excavation work affects the stability parameters of slopes during construction. So, with a short work front and high speed When excavating excavations in the slopes (at the working depth of development), deformations leading to landslides do not have time to occur, which makes it possible to give steeper angles to the slopes of the working tiers. The construction of high embankments and embankments on slopes (including landslide ones), on the contrary, requires a slower mode of soil filling, 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 the implementation of their design configuration have a significant influence on the development of landslides on slopes and slopes. The most common mistake in this regard is associated with the installation of berms, tiers, drainage structures and strengthening work on slopes not during the development of excavations and construction of embankments, but after their completion. Of particular importance is the technological sequence of construction of embankments on slopes. Work plans must include a principle of work that would guarantee the stability of the inclined foundation during the construction of the roadbed. In particular, for example, in many cases, the stability of embankments on slopes was violated due to the incorrect method of work: instead of sequential construction of the embankment on the downstream side of the slope, work was carried out on the upside, which led to the development of uncompacted zones in the slope parts, overstressing of the slope base, the development of landslides both on slopes and on embankment slopes.

Become very important technological factors when carrying out excavation work on landslide slopes or in their environment. The correct placement of earthmoving and transport equipment, determining the required pace, maintaining the required development depth or slope steepness ensure not only the possibility of implementing design decisions, but also their further reliability during operation of the road section, as well as the degree of preservation of the landslide slope itself in a stable state.

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

Construction of embankments carried out in two ways: transverse passages from the reserve and 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 applied to the center of the embankment, the subsequent ones - closer to its edges.

Rice. 137. Basic excavation bulldozer work.

See also:

Development of excavations produced by longitudinal bilateral passes and transverse passes . The longitudinal two-way method provides greater productivity of bulldozers. It is used for short excavations and in cases where the soil removed from the excavation is completely laid in adjacent embankments. The transverse excavation method is used when excess soil is placed in cavaliers along the future road surface.

Excavation of canals, irrigation structures, trenches, pits produced by transverse moves of a bulldozer with a gradual displacement of the machine along the structures . The soil is placed in cavaliers along the entire length of the canals, creating earth banks on both sides. The soil is excavated in parallel trenches with a depth no greater than the overall height of the machine. The distance between the trenches is up to 0.4...0.6 m. After the separation, the intertrench jumper is destroyed. In this case, group operation of machines with paired parallel moves is effective.

Planning work carried out on a flat surface, cutting off small mounds and filling in depressions, holes, and ravines. Large depressions are filled up from neighboring slopes with longitudinal passages . The last passes are made with an offset of V4 of the blade width to prevent the appearance of side rollers. After rough front leveling, it is advisable to finish the surface with the bulldozer moving in reverse and the blade in a “floating” position. For greater accuracy, it is advisable to use mutually perpendicular passages of bulldozers.

Punching terraces and shelves on slopes carried out by bulldozers with fixed and rotary blades. The most effective and safe way to move soil from a slope to a half-embankment is by transverse passes of the machine downhill. It is used on gentle slopes. For large angles of inclination of slopes, the longitudinal method is used . In this case, the bulldozer blade, installed at an angle, first breaks through passage 1, then 2, 3, 4 and 5. Working with longitudinal passes is more productive, but special care must be taken, since the machine may slide laterally or tip over on a 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-circular, b - spiral, c - shuttle with displacement, d - longitudinal-transverse.

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

When loosening category IV soils and hard rocks, it is advisable to organize the operation of machines according to longitudinal-ring and spiral patterns, since they provide the greatest productivity of the machine. Shuttle and longitudinal-transverse schemes are used when 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 soil are developed layer by layer to the maximum possible depth.

With a freezing depth of rocks of 50...70 cm, you can loosen the massif with three teeth. If the depth of rock development is greater, then use 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 chassis to the ground.

Soils are loosened in the working gear of the tractor at a speed of 0.9...2.7 km/h. At the end of the working cycle, deepen the ripper and check for the presence of a removable tip. If you lose the tip, you can damage the toe of the stand and it will not hold the tip. In this case, the rack is replaced.

Rice. 141. Methods for developing soils and extracting minerals:

A-trench with feeding into vehicles by a loader, b - downhill with loading from a stack into vehicles with an excavator, c - two bulldozers-rippers with backfill and from the dump into vehicles with a loader;

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

Loosened soils and rocks are removed by earthmoving and transport machines. The most effective way to develop hard, frozen rocks and minerals is with a bulldozer-ripper.

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

When developing a massif using the trench method, bulldozer-ripper 1 loosens the rock layer-by-layer at the bottom of the trench. Then, using bulldozer equipment with the ripper raised, the rock is moved into the stack using shuttle movements of the machine. From the stack, a single-bucket loader 2 loads the crushed material into vehicles 3 and transports it to the place of storage or processing.

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

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

In open-pit mining, a complex squad 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 shift the loosened waste rock 4 into a stack, from which the excavator 1 loads it into vehicles 4 and transports it to the dump. After removing waste rock, minerals are developed in a similar way.

Rice. 142. Open-pit mining of minerals with preliminary loosening:

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

Construction of subgrades in very rugged and mountainous terrain

Experimental work on the comprehensive mechanization of roadbed construction was carried out by DORNII not only in flat and slightly rugged areas, but also in mountainous and highly rugged terrain.

The terrain where the work was carried out is typically mountainous, since the roads there are designed mainly along steep slopes and ravines with serpentines, partly with retaining walls and with the use of drilling and blasting operations in some places.

Ground conditions in this area are characterized by a predominance of highly crushed soils of categories III and IV, interspersed with individual areas of rock (limestone). The conditions for mechanization of earthworks in this area differ sharply from the usual conditions of flat and less rugged terrain; the use of grader-elevators in these conditions is completely excluded, and the use of graders and motor graders is possible only to a very limited extent for finishing works. The main machines suitable for working in mountain conditions are: an excavator working with a straight shovel without transport, a bulldozer and a scraper. The main type of roadbed in mountainous areas is a semi-embankment-floor with an excavation on slopes, often cut by ravines, in which artificial structures (pipes) are located with approaches in the form of relatively high and short-length embankments. Thus, the entire complex of work on constructing a subgrade under these conditions consists of:
a) development of relatively flat slopes into a gulun embankment-half-cut,
b) development of steep slopes,
c) construction of embankments in ravines for approaches to artificial structures.

In the construction area, this complex of work was complicated by the fact that all the slopes were covered with dense deciduous forest.

Rice. 25. Scheme of felling forest with uprooting using a tension cable: 1 - tractor, 2 - cable Felling forest from below

The use of excavators and bulldozers for slope work allows in many cases to get rid of some of the most difficult preparatory work - uprooting stumps and combing out the root system from the upper layers of soil of the road strip. Mandatory in all cases of construction of a road in mountainous terrain in the presence of forests is the work of felling the forest and clearing the strip of bushes. Forest felling can be done simultaneously with uprooting, which is quite cost-effective in mountain conditions. Relief conditions with slopes of 35° and higher often do not allow mechanization equipment to be delivered directly to the route of the road under construction and force them to be located below or above the road route on existing temporary roads.

Let's look at these cases.

When the temporary road is located below the main road (Fig. 25), it is advantageous to fell the forest together with uprooting, grabbing 10-15 trees at the same time with the uprooting cable, as shown in Fig. 26. In this case, after felling the forest from the roots, no more preparatory work will be needed, since the branches of the felled trees are removed from the road strip in one step with felling and uprooting. When the access temporary road is located above the highway (Fig. 26), felling the forest with a straight upward pull of the cable is impractical and very difficult. In such cases, the use of a block and an anchor stump located below the route is required, as shown in Fig. 26. As in the first case, uprooting with simultaneous felling of the forest is more profitable here, since it only requires a tractor and a cable. Separate felling of forests with electric saws, obviously, in these cases will be unprofitable from an organizational point of view, since it will require, on the one hand, the delivery of a power plant and saws to the work site, and on the other hand, it will cause the need for an unnecessary operation to remove felled trees from the road strip, which in conditions mountainous areas will create additional organizational difficulties. For gentle slopes, you can also use the above method of simultaneous felling and uprooting of forest. Separate felling of forests with saws can be profitable only when the growing forest consists of such large and thick trees that uprooting them with a tractor will present significant difficulties.

Rice. 26. Scheme of felling forest with uprooting using a tension cable:
1 - tractor; 2 - cable, 3 - block, 4 - anchor Forest felling from above

After removing the felled tree trunks from the work area, you can begin to carry out the main excavation work. The development of gentle slopes with a steepness of up to 20° should be carried out mainly by bulldozers, since the use of excavators for it is unprofitable, because the latter will have to work mainly in low-height faces, which will reduce their output. The development of gentle slopes in the presence of rotary bulldozers can be carried out according to two fundamentally different basic work schemes.

The first scheme can be used with rotary bulldozers D-161 or D-149. It consists of preliminary development of a slope layer by layer with gradual movement of soil from the excavation to the embankment.

Subsequent passes are used to cut with the right edge of the knife 30-50 cm from the line of each previous cut. After 3-4 cuttings, a mass of soil is formed, sufficient for a full passage to move the soil into the embankment without cutting. When developing each cutting layer, the first pass is usually not completely complete.

The length of the processed area should be as large as possible in order to reduce the number of knife rearrangements during the reverse stroke. On average, about 1 minute is spent on each permutation.

This scheme has a number of significant disadvantages, which are as follows.
1. The scheme can only be implemented with rotary bulldozers. Conventional bulldozers cannot work according to this scheme.
2. The scheme requires repeated movement of the soil before placing it in place in several passes. As a result of this scheme, each soil particle moves not only in the transverse, but also in the longitudinal direction. Therefore, the design features of bulldozers are not used appropriately and their productivity is reduced.
3. At the beginning of work, the rotary bulldozer must operate with a relatively large distortion in relation to its longitudinal axis.

If the slope is more than 12-15%, such a distortion can cause the tractor tracks to come off. With a slope of 18%, working with a slope becomes completely impossible due to the frequent derailment of the tractor from the tracks.

Rice. 27. Scheme for developing a slope with a slope of 20° in a half-embankment-half-cut

4. The scheme requires frequent rearrangements of the blade grip angle (with each turn of the machine), which also negatively affects the rational use of machines.

All these negative aspects of this scheme of work allow us to consider it inappropriate for widespread use in production, despite the fact that it is recommended by some authors.

The second scheme is applicable when developing slopes with a steep slope of up to 20 and even 25° (with an experienced operator) and consists in the fact that the development of the slope is carried out from the very first pass by transversely moving the soil with a bulldozer. The procedure for developing a slope according to this scheme is shown in a specific example.

Having placed the bulldozer perpendicular to the axis of the road, so that its blade is located 5 m from the point of transition of the half-cut into the half-embankment, we will make the first cut. Having moved the bulldozer another 5 m, we will make a second cut, which, together with the first one in this case, will cover the entire surface of the slope to be developed into a half-excavation.

We will make the next (3,4 and 5) cuts in the same order. Obviously, the cutting marked in Fig. 27 No. 6, cannot be done with a bulldozer, since a steep step has formed between the surface of the slope outside the half-excavation and the soil surface in the half-excavation after the first cuts were made. Therefore, soil cutting in sections 6, 8, 10, etc. will have to be done with a grip angle of 67° with the left end of the knife or a motor grader. Thus, the final development of the slope for the side ditch can be done with working together bulldozer and only partially rotary bulldozer and motor grader; The construction of the ditch is carried out by a series of additional passes of the motor grader in the process of finishing the already rough subgrade. This scheme is devoid of most of the disadvantages of the first scheme and can be recommended for widespread use.

If the balance of earth masses allows for the development of a slope with a more gentle half-excavation slope (up to 25°), the scheme can be significantly simplified and all the main work can be done with a bulldozer without the participation of more complex machines such as D-149 or D-161.

In many cases, the development of reserves for constructing approaches to artificial structures on sloped sections of the Road where it intersects with ravines is difficult, and there is a need to prepare reserves in the process of developing slopes. As a particular solution to this problem, a method for developing a slope with a wide ditch, used as a reserve for backfilling pipes in ravines, can be proposed.

On slopes overgrown with forest, the first passes of the bulldozer near the felling of the forest are made specifically for the purpose of uprooting the remaining stumps and removing the top vegetation cover. Thus, when developing flat slopes, a complex of machines should be used, consisting of tractors for uprooting, bulldozers, a scraper, a D-162 ripper (for loosening dense soils before scraping work) and a motor grader for finishing work.

The development of steep slopes cannot be done with bulldozers alone, since bulldozers cannot work on large slopes either in the direction of the slope, much less in the direction along the slope due to the inevitable derailment of tractors from the tracks.

Of the available machines, the most suitable for developing steep slopes are excavators working with a straight shovel with a bucket capacity of 0.5 to 1.0 m3. During experimental work in 1948, the development of steep slopes was carried out mainly by excavators with a bucket capacity of 0.5 m3. Excavators with a bucket capacity of 1 m3 can work not only in soils of III, IV and V categories, but also in pre-loosened soils of the highest category. The productivity of these excavators is almost twice that of excavators with a bucket capacity of 0.5 m3, but their mobility is less construction site, and when transferred from object to object, it greatly reduces the effectiveness of their use in linear road works.

The development of steep slopes cannot be completed with excavators. In the best case, only 50-60% of the volume of earthwork on a slope is put into place by an excavator, the rest of the work should be carried out by bulldozers or their varieties (D-149 and D-161), and partly by other machines. Thus, when developing steep slopes, even more than in other relief conditions, it is required complex work a number of machines that make up a mechanized link. The development of the slope begins with the preparation of the site from which the pioneer trench begins, which is necessary for the excavator to enter the level of the future roadbed (Fig. 28).

Rice. 28. Beginning of development of a pioneer trench with an excavator with a bucket with a capacity of 0.5 m3

The pioneer trench is usually passed with a rise of up to 10-12%; it is developed with a straight shovel to the width required for the excavator to pass, i.e., 2.5-3.5 m. After the excavator reaches the level of the roadbed, it must begin developing the main trench, depositing soil from the downstream side of the slope. The width of the trench being developed should not exceed 4.5-5 m in order to increase the output of the excavator along the length of the road. During experimental work in 1948, in some cases, Stakhanovite excavator operators (Comrades Efimenko and Gavryushin) achieved output up to 100 linear meters. m per working day with a productivity of up to 500 m3 per shift, which was about 200% of the norm. After the excavator, the development of the shaft filled with it was carried out by bulldozers, and the latter’s output in leveling the shaft and expanding the trench made by the excavator was several times higher than in linear meters. m excavator output. Thus, in order to more uniformly load the machines participating in the slope development team, one should strive to reduce the width of the trench developed by the excavator in order to increase its output along the length of the road and at the same time to load the bulldozers more. Experience has shown that one bulldozer can easily handle the work of 2-3 excavators, even with some time to spare. independent work for the development of less steep sections of the slope.

With a slope of less than 30°, development of a slope using the specified method is possible with the construction of a subgrade in a half-embankment-half-cut without a retaining wall, but with the obligatory arrangement of at least one ledge to support the soil of the half-embankment. During the experimental work in 1948, the ledges were built manually, which, of course, with the comprehensive mechanization of work should not be allowed in the future. It must be kept in mind that benches can also be made mechanized using small excavators with a bucket capacity of 0.25 m3. In Fig. Figure 29 shows the location of the ledges: the main one - for the road surface and the auxiliary one, produced by a small excavator - to stop the embankment slope.

With slopes steeper than 33°, the construction of a half-embankment-half-cut without retaining walls is impossible if it is necessary to withstand the one-and-a-half slope of the half-embankment.

If the construction of a retaining wall, according to calculations, turns out to be uneconomical, and if we take into account that when determining the technical and economic indicators of the construction of a retaining wall, it is necessary to take into account the decrease in the degree of mechanization and output per worker in in physical terms, then the development of the slope should be carried out without a half-embankment, so that the entire shelf of the roadbed is located on the mainland in the excavation (Fig. 30). In this case, all the soil excavated by the excavator and then by the bulldozer will go down the slope of the slope to be thrown away without registering it as a cavalier.

Rice. 29. Layout of ledges for ground support during slope work

It is necessary to make a reservation that when building roads in mountains made of massive rocks, in many cases the installation of retaining walls can be much more profitable than expanding excavations, since work in dense rocky soils requires a significant amount of relatively expensive and labor-intensive drilling and blasting work. Behind last years in the practice of the Ministry of Railways and other departments, massive explosions began to be used to eject excavations and half-excavations. Since these works are of a specific nature and in road conditions require special equipment, specialists, explosive materials, etc., this issue is not discussed in this work, especially since a fairly extensive literature is devoted to drilling and blasting operations in the construction of railways.

Rice. thirty. Cross profile roads on a slope in a recess

Rice. 31. Development of a trench for lowering an excavator into a ravine

Let us now turn to the issue of arranging passages through ravines on a mountain road routed along the slopes of steep slopes. It has already been mentioned that in many cases the laying of special reserves for the construction of these embankments is made difficult by local conditions. In particular, the impossibility of laying individual reserves occurred at almost all intersections of ravines along the mountain road that was built in 1948.

The development of slopes at the approaches of the road route to the ravine can be organized in such a way as to create a reserve of soil on the road route itself so that in the future it can be fed into the embankment using scrapers with a longitudinal carriage. This can be achieved by developing a slope at the approach to the ravine at elevations higher than for the designed road surface.

Having determined in advance, by means of appropriate calculations, the volume of soil required for the formation of an embankment, the development of the slope when approaching the ravine should be carried out from a certain location above the design level until the descent into the ravine. Approaching the descent, you should develop a pioneer trench for lowering the excavator into the ravine and crossing through it at the bottom (Fig. 31). On the other side of the ravine, the development of the slope also begins from a higher elevation. In diameter, the ratio of the design diameter of the road and that actually developed by the excavator when approaching the ravine is shown in Fig. 32.

Rice. 32. Diagram of the relationship between the design diameter of the road and the diameter actually developed by the excavator when approaching the ravine: 1 - a shaft of soil excavated by a bulldozer down a slope, 2 - a full embankment, 3 - a reserve for a scraper, h - the height of the trench, I - the slope of the excavator trench

All the soil that is not collected by the excavator in height with this method of developing a slope is easily fed into the embankment with a bulldozer and scraper (Fig. 33). The bulldozer feeds the shaft of soil developed by the excavator down the ravine and softens the descent to the limits at which the scraper can be put into operation.

The work of bulldozers when developing steep slopes is carried out according to schemes slightly different from those used in flat and slightly rugged areas. It consists of leveling relatively high banks of soil previously developed by an excavator, preparing the work front for scrapers and, where possible, sites for installing excavators in the face.

The most common operation carried out by bulldozers when developing steep slopes is moving downhill and leveling the shafts of soil poured by an excavator to expand the excavated shelf to the width of the roadway required by the project.

Rice. 33. Development of soil shafts filled with an excavator with a scraper

From this table it can be seen that with a slope of up to 12°, the excavator places in place only about 10% of the soil it excavates. Thus, with slopes with a small slope, up to 90% of the excavator's output requires recycling, which indicates the obvious unprofitability of using excavators when developing gentle slopes.

With slope slopes of 24° and higher, the excavator puts in place about 30-35% of the soil it has excavated. The cross-sectional area of the trench he develops, depending on the steepness of the slope, ranges from 8.5 to more than 20 m2, and the dimensions of the shaft to be further processed by a bulldozer reach 17 m3 per linear meter. m of road. To complete the work done by an excavator in 1 hour, it is necessary to spend from 0.17 to 0.27 machine-hours of bulldozer operation.

Therefore, on average, one bulldozer can handle the work of 4 excavators. Obviously, when the capacity of an excavator bucket increases to 1 m3, the number of excavators serviced by one bulldozer decreases to an average of 2. In addition, these data also indicate that reducing the cross-section of the trench excavated by the excavator will increase the speed of construction of the roadbed in linear terms. m and will load bulldozers more fully.

The development of shafts poured by an excavator can be done with bulldozers D-157 or D-161. The operation of a rotary bulldozer is more efficient and more convenient in production conditions, since its operations require a smaller trench width (for the D-157 bulldozer to operate, it is necessary to ensure a trench width of about 6 m, and for the D-161, 4.5 m is sufficient). The bulldozer begins development with the knife raised and pushes the soil forward (Fig. 34). At this moment, the soil located above the bulldozer blade is poured down. It turns out that the shaft is being mined. The bulldozer blade is lowered onto the soil that has poured down. In one or two passes, the soil falls down the slope, and the trench developed by the excavator expands. From the table 18 shows how high the productivity of bulldozers is in this work. To develop a shaft with a volume of 57.4 m3 in a loose body (with an average loosening coefficient of 1.3) only 0.23 machine-hours are required. work of a bulldozer, i.e. the productivity of the bulldozer is about 140 m3 per hour of pure work, and for the development of a shaft with a volume of 50.6 m3 - 0.2 machine-hours, i.e. the productivity in this case will be 115 m3/hour. On average, the productivity of bulldozers D-157 and D-161 when processing shafts downhill will be about 1200 m3 per shift.

In cases where it is necessary to dump a shaft not down a slope, but to move it along a slope to fill up any depression, the development of the shaft should be carried out in two steps: in the first step, the bulldozer, rising from the end side to the crest of the shaft, slightly smoothes and expands the upper part shaft so that a tractor with a scraper can subsequently climb onto it for further longitudinal transportation of soil.

Therefore, the task of the bulldozer operator is not only to smooth the crest of the shaft with its expansion at the top to at least 3 m, but also to position the entrance and exit from the shaft to create a convenient work front for the scraper.

In cases where the length of the longitudinal movement of the soil is small, the bulldozer can independently carry out the work of moving the soil into place. With high and relatively narrow shafts, this work is carried out by digging with the installation of a knife during the first pass approximately in the middle of the height of the shaft - to shed the soil, and then the knife is buried in the soil by half or a third of its length, to the entire height of the dump and moves with the soil along the axis of the road .

Rice. 34. Movement of shafts filled with an excavator or bulldozers

The productivity of the bulldozer with such shaft development is also very high and, with moving distances of 30-40 m, ranges from 800 to 1000 m3 per shift.

Thus, the composition of the detachment for the construction of roads in mountainous areas was determined: the main machine of this detachment is an excavator. When working on steep slopes, it is better to work with one excavator with a bucket capacity of 1 m3 on the main shelf and one small excavator with a bucket capacity of 0.25 m3 included in the squad specifically for constructing benches.

To service such a small detachment, only one bulldozer needs to be assigned, but it will not be fully loaded.

Therefore, it is advisable to form a detachment of two excavator units (4 excavators), served by one bulldozer and one scraper.

Such a detachment should include a D-162 ripper (to ensure the operation of scrapers in heavy rocky soils) and a supply of cable for felling forests.

The work front of such a detachment should be at least 1-1.5 km, and the excavator units should work with a gap of at least 1 km between themselves in order to avoid frequent transfers of these heavy machines.

TO category: - Mechanization of earthworks

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