What is the length of the hole usually. What is a pit and a well. Planned and high-altitude survey of underground utilities

Parameters and methods of driving pits. By depth, exploration pits are divided into shallow - up to 5 m, medium depth - from 5 to 10 m, deep - more than 10 m. In some cases, the depth of the pits reaches 40 m (cuts are usually made from deep pits). The depth of the pits is determined not only by geological conditions, but also by the stage of exploration - shallow pits pass during prospecting; deep pits are most typical for detailed exploration.
More than half of the pits during exploration work are up to 10 m deep. With an increase in the depth of the passable pits, the process of sinking becomes more complicated, the costs of funds, time and energy for lifting, ventilation, drainage and even fastening increase. In connection with the possible increase in the strength of rocks at great depths, the breaking operation is also complicated. Therefore, when driving deep pits, it is necessary to pay special attention to the issues of improving technology and mechanization of work.
Pit holes pass rectangular or round cross-sectional shape; the choice of the shape of the cross section of the pit is made taking into account the physical and mechanical properties of the rocks, the method of penetration and the design of the support.
The most common are pits with a rectangular cross-sectional shape; recommended typical sections of rectangular exploration pits are shown in fig. 134. In pits with a cross-sectional area in the penetration of 2 m2 or more, two departments are usually arranged - lifting and stair. The cross-sectional area of ​​the pit in the penetration is chosen mainly depending on the projected working depth; for pits of greater depth, a larger cross-sectional area in the penetration is taken. In general cases, between these values, the following relationship can be traced (within the depth change from 5 to 20 m):

where Sp is the area of ​​the cross section of the pit in the penetration, m2;
Hpr - design depth of the pit, m.
The cross-sectional areas of the pits, from which the cuts pass, are taken somewhat large, providing a sufficiently productive lift.
The round shape of the cross section of the pits is chosen in the following cases: when driving in fairly stable rocks of shallow pits without markings (sometimes called "pipes"); when driving pits in loose loose rocks using frame-lowering lining; when driving pits by drilling.

At round shape the cross-sectional area of ​​​​the pit is used (due to the absence of corners) more fully, and the construction of the support, the main elements of which are made of materials stronger than wood (for example, metal), is compact. Therefore, with a round shape, the cross-sectional dimensions of the pit can be taken smaller than with a rectangular shape.
Round pits often pass with a diameter of 0.7-1.35 m, respectively, with which their cross-sectional area in the penetration is from 0.4 to 1.5 m2.
With a round section, the pit can have not only a cylindrical, but also a “stepped” shape - the working is traversed by ledges of different diameters. The diameter of each successive ledge is less than the diameter of the previous (upper) one. The stepped shape of the pits is necessary for the installation of a special type of lining - "frame-window". The relationship between the cross-sectional area in the penetration of a cylindrical pit Sn and its depth Hpr can be expressed by the following formula:

When driving round stepped pits, the relationship between the average, maximum and minimum cross-sectional area of ​​the working is expressed by the formula

The dependence of Scp on Hpr can approximately be expressed by the formula

Among the methods of driving exploration pits, it seems appropriate to single out the following: with manual breaking of rocks, with thawing and freezing of rocks, with the use of drilling and blasting and drilling method. Such a division of pit sinking methods makes it possible to characterize them not only in relation to the means of performing the main production operation (destruction of rocks), but also determines, to a certain extent, the significance and technology of other basic operations of the tunneling cycle. So, for example, the driving of pits with manual breaking, carried out in loose or loose-cohesive rocks, requires special attention to the fastening operation, while ventilation of the workings loses its importance to a certain extent. Sinking is relatively often carried out with a low degree of mechanization.
A very specific method of driving pits with thawing of frozen or freezing of thawed watered rocks, including operations to change the thermal regime of rocks in order to change their mining properties.
The method of driving pits with drilling and blasting, used in rocks of various strengths, is characterized by a multi-operational driving cycle and usually a higher degree of mechanization. And, finally, the drilling method, which is currently gaining popularity when driving exploratory pits in weak rocks, is characterized by complex mechanization of tunneling operations and the peculiarity of working out fixing.
Penetration of pits with manual breaking of rocks. Manual breaking is typical for driving pits in soft and loose rocks; this operation is simple and usually not very time consuming. Breaking is carried out mainly with shovels and sometimes picks; in some cases, the rock is first loosened with picks, crowbars, or even jackhammers. The complexity and laboriousness of other operations of the tunneling cycle depend not only on the properties of the rocks, but to a large extent also on the depth of the pits being passed.
Pit-holes with manual breaking go to various depths, however, the largest volume of tunneling work falls on shallow pits.
When driving pits up to 2.5 m deep, the operations of loading and lifting the rock are excluded from the tunneling cycle - in this case, the rock is thrown out of the working to the surface.
Fastening of small pits, passable in soft rocks, is often not performed; ventilation is carried out by natural diffusion.
When driving pits to great depths, the driving cycle includes the operations of raising the rock and fixing the working, the latter having a particularly significant impact on the technology of driving in loose (loose) rocks.
Drilling pits in soft rocks. TO preparatory work include the clearing of boulders and the vegetation layer of the working platform, the dimensions of which are determined taking into account the placement of stacks of rock issued from the workings near the mouth of the pit and the convenience of working on the surface. Then the mouth of the pit is marked and the rock is removed along its contour to a depth of 0.5-1 m. A tunneling frame is installed above the mouth of the pit, the dimensions of which in the clear are equal to the transverse dimensions of the pit. The ends of the frame elements should protrude beyond the mouth of the pit by at least 0.5 m.
When driving a pit to a depth of 2 m, a manual wrench is mounted on the tunneling frame. Raising rock from a single-tank pit, a tub of small capacity (up to 0.04 m3); a ladder (usually suspended) is used to lower and raise people. Lifting installations with a mechanical drive are used in rare cases. When compiling geological documentation and testing directly in the pit, the rock brought to the surface is placed in a compact dump near the mouth of the pit.
In cases where samples are taken from the rock issued from the pit, this rock must be poured into separate piles, sometimes called “driving”. The laying out of "driving" as the pit deepens is carried out sequentially around the perimeter of the working platform.
The pit is usually fixed after driving to a depth of 3-4 m. This part of the working is most often fixed with a continuous crown lining. The upper rims of the support protrude 1 m above the mouth of the pit and are equipped with pits (Fig. 135).
At greater depths, with sufficient stability of the rocks in the pit, instead of a solid one, a crown support is installed on racks or, more rarely, suspended. A safety shelf is arranged above the working face. When water enters the pit, it is removed, as a rule, with buckets.
Ventilation of pits, as noted above, is carried out mainly due to diffusion. With a significant depth of the pits, wind pressure is used for ventilation, mounting inclined shields or sockets above the mouth of the pit.
The tunneling link usually consists of three people - a sinker and two turners. With a cross-sectional area of ​​​​a pit more than 2 m2, two sinkers can work simultaneously in the face. In the practice of geological exploration, the penetration of pits in soft rocks per shift is from 1 to 2 m; the average monthly penetration ranges from 20-40 m.
During the liquidation, the pits fall asleep, the lining in some cases is completely or partially removed, but more often they are left in the development.

Sinking of pits in loose loose rocks. A significant difference in the technology of driving pits in non-cohesive loose rocks that do not allow more or less significant vertical outcrops lies in the features of performing the operation of fixing the excavation and lining structures.
A characteristic feature of sinking operations is the use of frame-descent lining. The method of driving pits with frame-lowering support (Fig. 136) is most widely used in the exploration of gravel and boulder-pebble deposits.
The design of the support allows passing round pits with ledges 2-4 m high; each ledge is fixed in the process of its penetration. Prior to the start of drilling, the pit is set by its depth Hpr, based on which, taking into account the selected parameters of the ledges, the diameter of the upper ledge (the mouth of the pit) is determined by the formula

where dу is the diameter of the lower ledge, usually taken equal to 0.8-1.1 m;
a" - the difference in the diameters of adjacent ledges, determined depending on design features lining (0.2-0.3 m);
ny \u003d Hpr / hu - the number of ledges in the designed pit (hy - the height of the ledge, taken equal to 2-4 m).
Giving the pit a stepped shape leads to a rather significant increase in its volume compared to a cylindrical pit.
In table. 42 shows a comparison of the volumes of cylindrical and stepped pits; the calculations were made at dy=1 m (the diameter of the cylindrical pit is taken equal to dy); hу = 3 m and a" = 0.2 m.
After marking the contour of the mouth of the pit on the working platform, a tunneling frame is installed and a wooden or metal pile driver is mounted, equipped with a crank and a winch for lowering and raising the frames (Fig. 137).

The diameter of the mouth of the pit should exceed the outer diameter of the first support frame by 10-20 cm. The rock separated from the face with shovels is thrown to the surface; the excavation is continued to the maximum depth, which ensures the stability of the walls of the pit. Then, with the help of a winch, a frame is lowered into the pit, along the outer perimeter of which boards (formwork) are installed. Pit penetration to the depth of the first ledge is carried out with simultaneous settling of the frame and formwork. After driving the first ledge, the space between the walls of the pit and the formwork is packed; the frame is attached to the tunneling frame with the help of screeds.
The operations of sinking the second and next ledges of the pit are carried out in the same sequence: the contour of the ledge is outlined, the rock is partially excavated along the height of the ledge, a frame is installed in the recess and a formwork is laid around it, the ledge is deepened, upsetting the frame with a sledgehammer.
The use of a frame-lowering support reduces the labor intensity of fastening and the cost of excavation, and also ensures a higher safety of work.

When driving pits with a frame-lowering support in the North-Western Geological Administration, significant savings in the consumption of materials and an increase in the rate of drilling of pits were achieved compared to driving CO pits under the same conditions with a solid ring support. The average monthly rate of penetration of pits with a frame-lowering strength is 25-35 m.
Sinking of pits with thawing or freezing of rocks. When driving pits in the frozen strata of sedimentary rocks, the breaking operation becomes laborious due to the significant strength of the rocks in the frozen state. Natural or artificial thawing of frozen rocks makes it possible to reduce the labor intensity of blasting, reducing this operation to manual loading of soft rocks into a bucket. Natural thawing of rock, carried out under the influence of solar radiation, is a long process and can be of practical importance only when driving into summer period a significant number of small pits arranged in a dense grid. Artificial thawing is carried out by "burning", boot and steam.
Defrosting by fire is used when driving prospecting or exploration pits in forest areas. The pits, as a rule, pass in winter, since in the warm season the workings are flooded with groundwater. The thawing of the rock is achieved by breeding a bonfire (burn) directly at the bottom of the pit. One burn consumes from 0.2 to 0.35 m3 of firewood. The depth of thawing, depending on the quality of the fuel and the properties of the rocks, is from 0.2 to 0.4 m. The average consumption of firewood is 0.4-0.5 m3 per 1 m3 of rocks. When fuel is burned, the walls of the pit also thaw, losing their stability. As a result, an increase in the cross section of the working is inevitable, as well as additional work for cleaning the rock that has fallen out of the walls and fixing the pit. With a significant ice content of the rocks, water accumulates in the bottomhole, as a result of which part of the fuel does not burn. With the deepening of the pit, insufficiently efficient air circulation reduces the intensity of fuel combustion. Rock removal can be carried out after thorough ventilation of the pit, defrosting of thawed walls and fixing of workings.
Rubble thawing is as follows: rounded stones (stone, cross-sectional size 8-10 cm) are heated on the surface in fires laid out near the mouth of the pit to a temperature of 200-300 ° C. The total volume of buta, depending on the section of the pit, is from 0.5 to 1 m3. A recess is made in the center of the bottom of the pit, hot stones are thrown or stacked into it and covered with a layer of moss to reduce heat loss. After thawing, which lasts several hours, moss and rubble are removed from the working and the thawed layer of rock with a thickness of 0.15-0.3 m is loaded into a tub. The consumption of firewood used to heat the buta is from 0.2 m3 or more per 1 m3 of rocks. With rubble thawing, there is no need for artificial ventilation of the pit, the walls of the working remain stable and may not be fixed.
Steam thawing is characterized by higher efficiency and can be recommended for a large amount of drilling operations, however, it is rarely used in field exploration practice. To organize steam defrosting, the following equipment is required: a steam boiler, a steam pipeline with a switchgear, rubber hoses and hollow drills (Fig. 138). The operation of steam thawing consists in the fact that hollow drills are driven into the bottom of the pit to a depth of 0.15-0.2 m and steam is supplied to them. As the rock thaws, the drills are driven into the face with a hammer to a depth of 0.6 to 1.2 m, and when steam is supplied, the rock is thawed for 2-4 hours.

The thawing of frozen rocks by steam proceeds very intensively, however, the contours of the pit are fuzzy. It is advisable to excavate the rock after 2-3 hours after turning off the steam, since at this time thawing continues due to the heat of the rock heated near the drills. The pit with this method of penetration can not be fixed.
In sediments with a high filtration capacity, water inflow significantly complicates, and sometimes makes it impossible to drill holes at all. One of the methods that simplify mining operations in these conditions is the freezing of rocks (driving pits is carried out in winter time at negative temperatures). When the bottom of the pit approaches water-bearing rocks and, in particular, quicksands, the drilling is stopped for some time, which is necessary for the freezing of the rock layer, after which the drilling is carried out to a depth less than the thickness of the frozen layer, etc.
When driving pits in frozen rocks, interspersed with layers of thawed watered rocks, a combined sinking is used: a pit is passed through frozen rocks with thawing, through thawed rocks - with freezing (Fig. 139), and the excavation of frozen water-bearing rocks is also carried out with thawing (rubble). The use in this case of explosive breaking, which is relatively often used in frozen rocks, is associated with the risk of flooding the working after the explosion and is not recommended.

Freezing and thawing of rocks in the face is carried out at a relatively small depth of the layer removed per cycle. The duration of these operations depends on climatic conditions and the thawing method used. Productive work is achieved with the multilateral method in the case when the tunneling team simultaneously passes several pits located at a short distance from one another. An approximate work organization schedule is shown in fig. 140.
Sinking of pits with drilling and blasting. Characteristics of tunneling works. Drilling and blasting is used when conducting pits in rocky and frozen rocks. This rock breaking method is used when driving relatively shallow pits at all stages of field exploration, when pits traversed in soft and loose rocks, individual interlayers of rocks of IV and higher categories of strength, when pits are deepened into bedrock (“finishing” pits). However, this method is most typical for driving pits to a great depth in fairly strong rocks.

Shallow blastholes are still often carried out without mechanization - manual drilling of holes, the use of wind power or hand fans for ventilation, rock lifting with hand cranks. This is largely due to the small volumes and dispersal of drilling operations, the lack of effective transport links or, in a particular case, electricity.
The sinking of deep pits, as a rule, is a mechanized production process; the degree of mechanization predetermines the deadlines, material and labor costs of drilling operations.
Means of mechanization of tunneling operations. Holes are drilled with light manual pneumatic perforators (supplied with compressed air from mobile compressors installed at the mouth of the pits) or hand-held electric drills. In some cases, motor-operated hammers can be used (provided that the exhaust pipe is connected to the suction fan pipeline and the pit is strengthened to ventilate). The mechanization of the loading of broken rock remains practically unresolved to date. The use of clamshell loaders of the type used in the sinking of mine shafts is difficult due to the small cross sections of the pits. Created by the Special Design Bureau of the Ministry of Geology of Russia, the small-sized grab loader GShK-1 with a grab capacity of 0.01 m3 and designed for pits with a cross-sectional area of ​​​​more than 2 m3 has not found application due to low productivity. It seems appropriate to recommend the use of rope grabs of a slightly larger capacity not for loading the rock into a bucket, but for removing it from the face and lifting it to the surface. In exploration parties, the AG-1 drilling unit with a hydraulic grab-lifter is being tested.
Bucket lifting of the rock is carried out using small cranes, some of the designs of which have been described previously. After blasting, the workings are ventilated with small centrifugal fans, and drainage is carried out with electric pumps and motor pumps.
In geological exploration parties that carry out mining operations in significant volumes, along with the use of individual machines and mechanisms, complex units are used.
The ShPA-2 unit consists of a diesel engine, a compressor, a drive lifting and manual auxiliary winch, a fan and an electric generator. The set of equipment includes an electric saw and electrical equipment: a frequency converter, a control panel, an alarm system, starting devices, lighting. All equipment is placed on a car trailer.
Similar drilling units are manufactured in the West Kazakhstan complex expedition (the unit consists of a Pioneer crane, an electric generator, a compressor, a fan, a remote control and an alarm). On the basis of a skidder, the Yakutsk Geological Administration has developed a self-propelled drilling unit equipped with a lifting and turning mechanism with a pneumatic grab and a compressor. The complex of tunneling mechanisms KMSh-VITR consists of an electric portable station with a gasoline engine, a boring crane KSH-100, a pump, a centrifugal fan and a hand-held electric drill. The complex is convenient for transportation in off-road conditions, it can be easily disassembled into separate units weighing less than 80 kg.
Technology and organization of penetration. The cycle of tunneling operations begins with the drilling of holes. When driving shallow pits with a small cross-sectional area, the holes are drilled (and hollowed out in frozen rocks) by hand. Their depth is usually small (0.2-0.4 m when chiselling holes with crowbars and less than 1 m when drilling with chisel drills).
The small depth of the holes, their increased diameter during chiselling (up to 10-12 cm) and the insignificant cross-sectional area of ​​​​the working (up to 1.25 m2) make it possible to limit oneself to drilling sets of 2-5 holes (Fig. 141).
In pits of large cross-section during perforating or electric rotary drilling, the depth of holes reaches 1.2-1.4 m, and the location and quantity are taken in accordance with the selected type of cut and the area of ​​the bottom.

In pits with a cross-sectional area of ​​​​less than 2 m2, holes are drilled by one person; with a larger area, two drillers can work simultaneously. Charges and explodes the holes of the explosive or sinker, who has the right to conduct blasting. Explosion of holes is electric, it is carried out from the earth's surface with the help of an explosive machine. With a significant number of boreholes, approximately 30 minutes are allotted for the operation of charging and blasting (2-3 minutes are spent on charging one borehole).
With two- and three-shift work, it is advisable to time the ventilation of the pit to coincide with the break between shifts; during one-shift operation, the gaseous products of the explosion are usually removed from the mine due to diffusion or wind pressure during non-working hours of the day.
Before starting to clean up the rock, the face after ventilation is brought to a safe state - they inspect and fix the support damaged during the explosion; rob the loose walls of the pit; pump out, if necessary, the water accumulated during the ventilation.
The breed is loaded manually or by mechanical loaders. With a sufficient cross-sectional area of ​​​​the pit to lift the rock, it is advisable to use two buckets - while loading the bucket uncoupled from the lifting rope, the other, previously filled with rock, is lifted to the surface, unloaded and lowered into the pit. Rock harvesting takes up most of the tunneling cycle time.
In hard rocks, which are usually characterized by increased stability, the pit is fastened with a significant lag from the bottom, and the fastening process is often not included in the cycle of tunneling operations.
The installation of the lining and the reinforcement of the pit is usually carried out in shifts specially allocated for this, after several tunneling cycles have been completed.
An approximate work organization schedule is shown in fig. 142.
The average monthly penetration of pits reaches 30-40 m.

The tunneling link usually consists of three or four people: one or two work in the mine, two work on the surface. Sometimes the tunneling team works using the multilateral method simultaneously on the sinking of several pits. This ensures better organization of work and reduces downtime associated with blasting and ventilation.
General information about the explosive method of driving pits. The sinking of pits in relatively easily deformable rocks, which is reduced to the formation of a mine working due to irreversible deformations of rocks (clays, loams, sandy loams, loess) during the explosion of a charge, is called explosive driving. In wet clays, this driving method is particularly effective.
The drilling technology is very peculiar and boils down to the following: a well is drilled to the design depth of the pit; the well is backfilled with placer BB; detonators, electric detonators and a detonating cord can be used as initiators. After blasting, the resulting development is subject to thorough ventilation. The need for fastening the pit in many cases disappears, since the rocks, as a result of the explosion, are deformed, compacted and become quite stable.
In pits formed by explosives, with a relatively regular round cross-sectional shape, the diameter of the working along its height does not remain constant; the formation of an ejection funnel in the upper part of the pit is also characteristic. Between the volume of the charge (Azar) and the volume of the cavity (Avyr), formed in the rock after the explosion, there is an almost direct relationship Avyr=kAzar. The value of the coefficient of proportionality k depends on the properties of rocks and explosives.
In the practice of driving pits in clays, loam and loess, when using ammonites, the coefficient k is taken in the range from 150 to 300. For the convenience of calculations, moving from volumes to diameters of workings and charges and taking the value of k in the recommended values, we will have

The data obtained by calculation are approximate, they should be refined during experimental explosions. The blasting method is characterized by low time and material costs, high labor productivity, it is applicable in cases where the pits are used as transport workings, and geological information is obtained when driving cuts from these pits.
The technology of drilling holes in clays and weathered clay tuffs, adopted in Pervomaiskaya and Merkushevskaya GRPs of the Primorsky Geological Administration, is of interest. Shafts up to 15 m deep with a cross-sectional area of ​​1-1.25 m2 are drilled and blasted, a feature of which is the use of boiler charges. A central hole is drilled in the face, shot through it, and a charge weighing 3-5 kg ​​is placed in the resulting chamber. During the explosion of the boiler charge, the rock is partially pressed into the walls of the working and partially (at a small depth of the pit) is ejected to the surface. Only 25 to 50% of the blasted rock is subject to cleaning from the pit.
Penetration of pits by drilling. Characteristics and conditions for the use of drilling pits. During the last decade, the drilling method of driving pits began to be introduced into the practice of mining exploration.
The drilling method of driving pits is characterized by a number of significant advantages that distinguish it from other methods. The penetration of pits by drilling provides a significant improvement in working conditions and safety of work, the achievement of the highest technical and economic indicators, the exclusion of hard work and the comprehensive mechanization of the construction of exploration workings.
The improvement of working conditions and safety of work is a consequence of the fact that in the process of drilling a pit, the worker is not in the working face, but on the surface; the operation of fastening the pit is less laborious and faster; there are proposals for the mechanization of the selection of bulk samples from the bottom of the pit, in which the need for a person to stay in the development generally disappears.
High technical and economic indicators of pit penetration by drilling include a sharp increase in penetration rate, and a reduction in labor and material costs.
Let us illustrate this with practical data from one of the expeditions of the Ministry of Geology of Russia, which introduced the drilling of small pits on a large scale (Table 43).

At present, only with the drilling method, one can speak of a truly comprehensive mechanization of pit driving. Operations of breaking rock in the face, issuing it from the development and placing it on the surface in dumps are mechanized; the problem of mechanization of the construction of lining in the pit, which has the correct shape of a cylinder, is not unsolvable (there is already a design project for a portable support layer mounted on a drill string); in addition, in some cases, the fastening of the pit may not be carried out. The scope of the drilling method is still limited to weak rocks (I-IV categories of drillability).
The institutes TsNIGRI and MGRI (Moscow Geological Prospecting Institute) have developed and are testing the designs of drilling rigs for drilling exploratory pits in medium-hard rocks.
The used transportable drilling rigs provide drilling of pits up to 30 m deep and more.
The drilling method of sinking is especially effective with significant volumes and concentration of drilling operations.
Applied equipment. Pit holes are drilled mainly in a rotary way with units mounted on the basis of a car, tractor or trailer. Some of these rigs are suitable only for drilling pits, others are universal, they can drill pits and shallow exploration wells. As a drilling tool, mainly auger and less often bucket cylindrical drills of various designs are used. Shaft drills are designed to destroy the rock face and periodically lift the destroyed rock to the earth's surface. The rock is destroyed by the cutting edges of the auger flanges or the bottom of the cylindrical drill; the destroyed rock is accumulated on the shelves of the auger or in a cylindrical body and, together with the drill, rises from the working.

Shallow hole drilling rigs are usually vehicles with a simple attachments(Fig. 143).
Pit holes of medium depth or deep drill with installations mounted on the chassis of vehicles (Fig. 144), on trailers with independent drives or on trailers in combination with truck cranes. The drilling rig UBSR-25 is mounted on the basis of a skidder. The characteristics of drilling rigs used for drilling pits are given in Table. 44.

Technology of penetration and fastening of pits. After clearing and leveling the horizontal platform on the surface and bringing the drilling rig into working condition, they start drilling pits. Manufacturing process Pit drilling consists of lowering the drill to the bottom, drilling (usually to a depth of 200-400 mm), lifting the drill filled with rock, and unloading it on the surface. The duration of round-trip operations increases sharply with the increase in the depth of the pit, if it is necessary to build up and dismantle the string of drill rods with each run. In some installations, this drawback is eliminated due to the design of a bucket-type hole drill sliding along the drill rods, which is raised and lowered on cables without disassembling and building up the rod string.
At present, sliding auger drills and combined rock drills of the MGRI design have been developed and are being tested, which make it possible to increase the trip depth by two or three times, as well as to perform tripping operations without disassembling the drill string.
Bucket augers are unloaded either manually or with the help of rotary blades that form the body of the drill and are rotated during unloading by a special hydraulic drive (bucket drill LBU-50 installation). Auger drills they are usually unloaded by rotating them at an increased speed (unloading due to the developing centrifugal force). When unloading the pit drill, the mouth of the pit is covered with holes.

The fastening of the pits passed by drilling is simplified due to the relatively regular cylindrical shape of the workings, while creating favorable conditions for the use of reusable, prefabricated, sometimes called "inventory" lining. As the main fastening material, wood is losing its importance and is being replaced by metal or plastics.
It is possible to use a round frame lowering support, however, a significant difference in the diameter of the steps of the pit requires the use of a set of pit drills of different diameters. When replacing wooden puffs with fiberglass plates, the difference in the diameters of the steps of the pit decreases and, at the same time, it is possible to use one pit drill equipped with an expander.
The use of spacer split rings made of angle or channel steel with wooden or fiberglass puffs can provide fastening of a cylindrical pit.
Installation UBSR-25 drill holes with casing metal pipes serving as a reliable support.
In the practice of drilling pits in the Ural complex expedition, the workings are fixed with metal rings, consisting of two half-cylinders, bolted together.
Good results were obtained during production tests of annular support made of polyethylene and vinyl plastic rings with longitudinal cuts, reinforced at the ends with angle steel. The assembly of the rings into a column and its installation in the working was carried out after the completion of the drilling of the pit using a drill string equipped with a support frame at the end. The support made of fiberglass cylinders with a cut along the generatrix has a significant elasticity and. therefore, it can be considered "universal" - allowing the use of standard rings for pits of various diameters (from 600 to 1150 mm). Rings enter one another to a depth of 150 mm; the rigidity of the support is provided by special locks.
When the pit is eliminated, the considered structures provide the extraction of the support for reuse.

Drilling and mining operations are the most important part of engineering-geological and hydrogeological studies. With the help of boreholes and mine workings (pits, galleries, etc.), the geological structure and hydrogeological conditions of the construction site are determined to the required depth, soil and groundwater samples are taken, experimental work and stationary observations are carried out.

Well drilling is the main type of exploration work in engineering-geological and hydrogeological studies.

Borehole - a cylindrical vertical working (rarely inclined) of small diameter, performed by a special drilling tool. In boreholes, a mouth (beginning), walls and bottomhole or bottom are distinguished.

The essence of drilling lies in the gradual and consistent destruction (or drilling) of the rock at the bottom and extracting it to the surface. Rock samples taken from wells are called drill cores. To isolate aquifers and prevent rock fall from the walls of wells, the wellbore, i.e., the drilled space, is fixed with casing pipes.

The advantages of drilling include: high speed of well drilling, the ability to achieve great depths, the mechanization of tripping operations, the mobility of drilling rigs (Fig. 36.2). Drilling also has disadvantages: the impossibility of inspecting the walls of the well due to its small diameter, the small size of the samples, the need to flush wells during drilling, etc.

The diameter of wells used in the practice of engineering and geological surveys is usually in the range of 33-325 mm. For hydrogeological purposes, wells of larger diameter are drilled. The depth of wells is determined by the objectives of research and rarely exceeds 30-50 m for engineering structures. When searching for and exploring groundwater for water supply, the depth of wells can reach 800 m or more.

Well drilling is carried out with a drill tip, which, when connected to drill pipes (rods), creates a drill string. Hitting or rotating this projectile and transferring pressure to it

leniya carried out by drilling rigs driven by various engines.

In engineering and geological research, the following types of well drilling are usually used: rotary core drilling, percussion cable with annular and continuous slaughter, vibration and auger. Other types of drilling, with the help of which it is difficult to take a core, are not widely used in engineering and geological work. ,

Rotary core drilling allows drilling wells with a diameter of 73-219 mm in almost all types of rocks, including rocky ones, up to a depth of 100 m or more. The drill string consists of a hollow core barrel 0.5-4.5 m long with a crown and a string of drill rods. When the drilling tool rotates, the crown of the core pipe with teeth made of hard alloys caulked in it cuts an annular channel in the rock, i.e., drills out a column of rock - a core. Shot and diamond crowns are also used. After filling the core barrel with a core, the drill string is torn off from the bottom and lifted to the surface. Then the drill bit is unscrewed and the core is removed from the core barrel.

In clayey rocks, for sampling soil of an undisturbed structure (monoliths), tips of a special design are used - soil carriers, with a diameter of at least 100-125 mm.

During core drilling, mud, water or compressed air is fed through drill pipes to the bottom hole. At the same time, the drilling tool is cooled, and the crushed rock (sludge) is brought to the surface in special sedimentation tanks.

Have a gift but a cable car drilling is recommended in areas with insufficient geological knowledge, as it allows for a thorough description of the rocks. There are percussion-rope drilling with a solid face with a diameter of 127-325 mm using bits and bailers (coarse-clastic and sandy watered soils) and percussion-rope annular bottomhole with a diameter of 89-325 mm in sandy and clay non-watered or slightly watered.

Drilling depth in non-rocky rocks - up to 100-150 m, in rocky - to a great depth. Sinking is carried out by dropping a weighted drilling tool (bailer, driving glass) suspended on a rope to the bottom, and then lifting it to the surface along with the rock. In pebbles and rocks, a chisel is dropped onto the bottom, and the bottom is cleaned with a bailer.

One of the most productive drilling methods is vibration drilling, in which the drill string plunges into the rock due to vibrational vibrations. With the help of a vibrator, clay and sandy watered rocks pass to a depth of 15-20 m. It should be remembered that under the influence of vibration, clay soils change their structure and become compacted.

Auger drilling characterized by high mechanical speed when drilling wells in sandy-clay soils to a depth of 30 m. Rocks are destroyed by a rotating bit, and they are lifted by augers, i.e. pipes, on the surface of which a steel spiral is welded (Fig. 36.3). With this method of drilling, a qualitative geological description is difficult.

Drilling wells in unstable and water-saturated rocks is complicated due to collapse and slumping of the walls. For their fastening, steel casing pipes are used, which are lowered into the well, after which they continue drilling with the tip already less

diameter. At the end of drilling, the casing pipes are removed, and the well is liquidated by plugging with clay or cement-sand mortar.

Manual rotary percussion drilling due to low productivity and high labor intensity, it is used to an extremely limited extent (hard-to-reach terrain, dense urban development, etc.). Wells are drilled manually in loose soils to a depth of 10-15 m, less often 30 m.

In hydrogeological studies, exploratory, experimental, observational and exploration and production wells are drilled. Wells intended for water intake are called water wells, they differ from others in their large diameter, which is associated with the significant size of submersible water-lifting facilities.

Water well drilling It is carried out mainly by shock-rope and rotary methods, less often by rotary-column.

rotary method- this is rotary drilling with a continuous bottomhole, with flushing or purging with air, with a rotator (rotor) on the surface. Rotary drilling is used to drill wells

of various depths (usually more than 150 m) to aquifers, previously well studied and tested. Drilling speed is very high. The rock at the bottom is destroyed completely with the help of ball bits. For rotary drilling, self-propelled rigs URB-2A, URB-ZAM (Fig. 36.4), URB-4PM are used, and when drilling up to 100 m - AVB-3-100.

Sinking of pits and other mine workings. The most common type of mining is the pit. During surveys, other workings are also used: clearings, ditches, pipes, adits and mines (Fig. 36.5).

A pit is a vertical excavation of a rectangular or circular section, traversed from the surface to a depth of 20 m, less often more. A round pit is called a pipe.

The most common in surveys are shallow pits up to 3-5 m deep with a section of 1x1.25 m. Usually they are carried out in sandy and clayey soils. Large-section pits (more than 2 m 2) are performed for special experimental work and at a large depth of the pit. The pit is passed by deepening the face and ejecting the soil, first with a shovel, then with the help of a bucket raised by a crank. In rocky rocks, the pit is deepened using jackhammers and blasting.

As the walls of the pit deepen, it is necessary to strengthen them, otherwise they may collapse. When driving water-saturated rocks, drainage is organized. Deep pits are sure to ventilate.

Pit holes have great importance in engineering-geological surveys for construction. They allow you to study in detail the geo-logo-lithological section of the site, select samples of any size, perform soil testing with stamps and other field experimental work. The disadvantage of pits is their high cost and laboriousness of work, especially in water-saturated and hard rocks.

At present, a mechanized method of driving pits is being used with the help of special boring machines, as well as self-propelled drilling rigs URB-ZAM, URB-2A-2, UGB-1VS, etc., adapted for this purpose, equipped with bucket or auger drills. The average productivity of installations is 1.2-2, Ohm / h.

At the end of the field work, the pits are carefully filled up, the soil is compacted, and the surface of the earth is leveled.

In areas composed of steeply dipping rock layers, horizontal mine workings take place: clearings, ditches, adits and mines.

Clearings - shallow workings used to remove a loose thin cover of deluvium or eluvium from inclined surfaces.

Ditches (trenches) - narrow (up to 0.8 m) and shallow (up to 2 m) workings, performed manually or with the help of technical means in order to open bedrock.

Dudka is a vertical mine working with a circular cross-section with a diameter of up to 1.0 m. As a rule, there is no need to fasten the walls of the pipe.

Adits - underground horizontal workings of considerable length, laid on the slopes and revealing rock strata in the depths of the massif. They are usually used in rocks during surveys for the construction of especially critical structures.

Mines (exploratory) - vertical mine workings, which differ from pits in much larger sizes. In the practice of engineering-geological surveys, the depth of mines reaches 30 m, and the cross section is 6 m 2.

Observations while drilling wells and driving pits consist in measuring the water level and temperature, sampling rocks, water and other works.

For measuring the water level in wells ipppgtt.™to noowmxa

thin cables per meter, at the ends of which various devices are suspended (crackers, whistles, etc.), when in contact with water, these devices give a signal (whistling, clapping, etc.) and the observer determines the depth of the water from the marks of the cable the surface of the earth (Fig. 36.6). More accurate electrical level gauges when the sensor comes into contact with water electrical circuit closes, the galvanometer needle deviates, and the position of the level is fixed according to the marks on the cable. Long-term observations of changes in the water level are carried out with the help of float meters, and special automatic devices are used to continuously record the level.

Water level measurements are made from one point at the wellhead with an accuracy of ±1.0 cm. In each well, the depth of occurrence and the steady level of groundwater are determined.

Groundwater temperature is measured with mercury thermometers mounted in a metal frame. For water sampling, various samplers with a volume of 0.5 to 3.0 liters are used.

Observations of drilling fluid absorption and core output allow a preliminary assessment of the permeability of rocks in various intervals of wells. Intense absorption and low core recovery indicate fracturing, fragmentation of rocks and their possible high water content.

When drilling water wells, careful isolation of the aquifer planned for operation from other aquifers and surface contaminants is provided. Most often, for this, the shoe of the casing string is crushed into water-resistant rocks (Fig. 36.7, A) or perform annular cementation of a pipe string (during rotary drilling) (Fig. 36.7, b).

The quality of isolation of aquifers is checked by pumping water from a well and monitoring the position of the level. The constancy of the water level indicates the reliability of the insulation.

Geological documentation of drilling and mining operationsbot. The main geological documents of exploration work are the drilling log and the mining log. In the journals, as wells are drilled and pits are drilled, they describe in detail the composition and condition of the exposed rocks, indicate the depth of rock and water sampling, provide the results of observations of the appearance of groundwater levels, core output, the quality of isolation of aquifers, etc. According to drilling and mining logs are sections (columns) of individual wells and pits (Fig. 36.8). Data from several sections (columns) are combined into an engineering

nerno-geological or hydrogeological profiles (sections), the stages of construction of which are shown in fig. 36.9.

"Shafts" is a word that was originally associated with geological excavations. In the future, it found its application in geodesy, archeology, construction, and engineering studies of communications. What are the shafts? What it is? We will consider their device and features in more detail.

Pit: definition

This word in geology denoted a vertical or inclined depression in the ground for the search and exploration of minerals. The cross section of such devices is round (they are also called pipes), rectangular, square. The main feature is small parameters from 800 to 4000 mm, depth - up to 40 m. These geological workings are used for lowering / lifting people, cargo into the mine / to the surface. In loose soils, these devices require fixing with beams to prevent shedding.

Given the above, it is impossible to underestimate the pits. The meaning of the word was sorted out, the specifics of use, types, device should be considered.

Applications

There are four main areas of use of pits:

• for a detailed study of the geological section;
• selection of soil samples of an undestroyed monolith;
• field engineering-geological studies;
• hydrogeological research.

As you can see, the scope of pits has greatly expanded over time.

Research work of this kind is carried out in two main directions:

• engineering-geological;
• special purpose (used to assess the state of the foundation; the main objective- find out the cause of the deformations that have arisen).

The pits are divided into three groups according to their size:

• Small. The depth of occurrence is up to 3 m. As a rule, such devices do not require fixation. Often used in engineering research (about 60%).
• Medium. The depth is no more than 10 m. When they are installed, a ventilation system is already provided. Deepening is carried out using drilling rigs.
• Deep. The occurrence parameter is from 10 m. They are used to solve special problems.

Pit device

For the installation of such objects can be used as manual way and the use of specialized equipment.

The main parameters for the pits are selected depending on the intended work, the type of soil. Recommended dimensions:

• Rectangular, square section: 1000 x 1250 mm, 1000 x 1500 mm, 1500 x 1500 mm, 2000 x 1500 mm. The selected parameter also depends on the depth of the device: with a pit height of 3000 mm - 1250 mm, 10,000 mm - 1500 mm, up to 20,000 mm - 2000 mm, over 20,000 mm - 4000 mm.
• Round section: from 700 to 1000 mm. Pipes with a recess up to 10,000 mm - a diameter of at least 650 mm, over 10,000 mm - from 700 to 1000 mm.

What are the pits, what is it, we sorted it out. Now consider the specifics of application in construction.

Holes for special purposes

The foundation is the foundation of the house. The integrity of the entire structure depends on its quality and condition. Therefore, timely assessment is an important component in restoration and construction work. Pit holes for research are used in the following cases:

• Addition of an additional floor, not taken into account in the original project. The condition of the foundation and the possibility of additional load on it are assessed.
• Technical retooling. In construction - replacement, modernization engineering networks.
• overhaul. Assessment of the validity of the work.
• The appearance of cracks on the facade of the building, distortions doorways. Such defects indicate the deformation of the foundation.
• Inadmissible subsidence of the building. This deficiency can lead to the complete destruction of the structure.
• When planning to lay a new foundation near an existing one. Possible Negative influence one to another.

The causes of the deformation can be identified through the pits.

The significance of such studies is the possibility of identifying the factor of destruction of the foundation and its elimination. The main reasons that have a direct impact on the foundation of the building can be:

• Precipitation. They can accumulate and undermine the foundation. An excess of rainfall above average can provoke a rise in groundwater, which also has a negative impact on the condition of the foundation.
• Leakage of water from communications. In parallel, a study of their condition can be carried out.
• Defects in the compaction of the base and backfill.
• Displacement of soil layers in relation to each other and others.

Timely identification of the causes of the destruction of the foundation and their elimination can extend the life of the structure.

Features of pits in construction

Factors influencing the choice of a place for research:

• the presence of obvious deformation in a certain section of the building;
• the most loaded fragment of the building;
• if the house is multi-section, then each section is subjected to research;
• if there are additional supports, they are also inspected;
• during restoration, determine the places where they are installed bearing walls and supports.

The pits are deepened below the level of the foundation so that it is possible to examine the condition of the foundation.

For a strip foundation, the survey can be carried out both inside the building and outside. The pit is dug out in such a way that there is access to the base.

For columnar foundations, there can be three types of research recesses:

• Bilateral. Two adjacent sides of the support are exposed.
• Angular. Also clean the two sides of the base, but up to half the width.
• Perimetric. It is used in emergency cases when thorough studies of both the base itself and the adjacent soil are required.

Pit holes in construction are used in shallow, occasionally medium-sized deepening.

Research types

What research options help to produce pits? What it is? What does this mean for assessing the condition of the foundation?

To answer these questions, consider the list research work:

• Foundation depth. Does this value correspond to the weight, height of the building and the ground.
• Dimensions. Compliance with project documentation.
• Type and strength data.
• Detection of defects and their causes.
• The quality of the materials used. Detected by taking samples and examining them in the laboratory.
• Safety and quality of waterproofing.
• Vertical change.
• Foundation condition.
• The presence of reinforcements.

Such studies help to determine the life of the building; the possibility of carrying out restoration work, building an additional floor.

Apparently, to overestimate the importance of such devices as a pit for construction industry difficult.

Negative consequences of the use of pits

Sometimes when arranging recesses, the following consequences may occur:

• noise during the destruction of concrete structures;
• dirt and dust;
• increase in humidity indicators;
• flooding if timely pumping of atmospheric waters is not made;
• violation of the waterproofing of the base;
• impossibility of operation of the objects to be surveyed;
• obstruction of movement near the surveyed areas.

It is important that all work is carried out under the guidance of professionals. This will help avoid a number of negative consequences.

Geodetic surveys and pits

Even at the design stage, the result of a geodetic study is important, which allows you to determine the type of soil, the depth of groundwater, the presence of underground engineering networks, and so on. This data helps to determine the type of foundation, the depth of its occurrence and engineering networks, the type of materials for construction, and much more.

Therefore, the use of research with the help of pits at the design stage determines the quality and duration of the service life of the future structure. “What are the shafts, what is it; their device and features; importance for construction, geodetic and engineering works” is a relevant and promising topic. With the help of these devices, you can extend the life of the old building and increase the service life of the building under construction.

The underground part of any building is hidden under the ground, so it is not even possible to visually inspect it, unlike ground structures. A qualitative survey of the foundation of existing buildings is facilitated by pits dug from the outside of the structure or from the inside. Their location is determined depending on the design of the building itself, the distance to nearby buildings, and also on the level of the foundation footing.

When is an Underground Inspection Necessary?

Checking the condition of the foundation and the base under it is required in the following cases:

• increase in the number of storeys of the building;
• technical re-equipment of production;
• overhaul associated with increased loads;
• the appearance of significant cracks on the facade and distortions of openings;
• development of unacceptable drawdowns;
• the need to build nearby foundations, etc.

Often, the problems of the underground part of the structure are indicated by external damage on the walls, which are determined visually, as well as the jamming of several doors at once, located in the same plane or not far from each other. In these cases, experts give an unequivocal conclusion that the structure is experiencing deformations, and this is most likely due to the weakness of the base or the beginning of the destruction of the foundation.

During the overhaul of the facility, which involves increased pressure on the ground, it is mandatory to conduct a survey of its underground part, for which it is necessary to dig pits.

In some cases, it is enough to study the technical documentation. But in the absence of it or the occurrence of significant subsidence, confirmed by systematic observations, as well as during work related to the reconstruction of old buildings, it is impossible to do without a direct examination of the state of the foundation and foundation.

Inadmissible deformations, distortions and subsidence of buildings can occur for various reasons that appear immediately, over the years or after the soil thaws. The sources of problems are:

• atmospheric water seeping into the ground and soaking the base;
• groundwater resulting from leaks from water supply or sewerage networks, as well as reservoirs and heating mains;
• groundwater rising above the permissible level;
• insufficiently compacted base or backfill;
• freezing or washing out of the soil;
• displacement of soil layers relative to each other, etc.

When pitting, soil samples are taken at the base of the foundation, the structure is visually inspected and, if necessary, samples of materials (concrete, mortar, stone) are taken for further laboratory research. Often they open the fittings.

Rules for the construction of pits

The pit is a dug hole, exposing the wall of the tape, the support of the columnar or side part slab foundation. The locations of the recesses are determined based on specific conditions. Problem areas are prioritized, and if it is necessary to survey long-length zones, the choice is left to sites that can least of all become an obstacle to passers-by or people living nearby.

When marking pits, builders should not start only from the convenience of working conditions and accessibility of the territory. Research is almost always carried out in populated areas, so the presence of pedestrians near the object cannot be eliminated. But others also need to remember that the foundation survey is only temporary, and the ongoing activities are necessary, appropriate and not critical.

Without fail, the pit must be laid in places where the deformation of the walls is clearly visible. Also drilling can be done:

• in the busiest areas of the building;
• in each independent part of a multi-section house;
• in the areas of additional supports.

Sites where the condition of the soil or foundation is defined as emergency require special attention. In this case, in addition to the problem area, reliable zones are examined where a pit is arranged, after which the results of the study are compared. For the foundation of the reconstructed object, drilling and inspection of structures together with the base is carried out at the installation sites of load-bearing columns and walls. And in the case of a partial superstructure - only in the area of ​​reorganization.

The number of holes depends on initial goal foundation revisions. When reconstructing or overhauling a building that does not provide for an increase in loads, it will be enough to perform 2-3 control pits. When eliminating the flow of water in the basement or on the ground floor, pits are dug in each of the flooded areas, and when the basement is deepened, one pit is made near all walls. In the most loaded areas, double-sided pits are allowed.

In places of change in the level of laying the foundation or a significant jump in the height of the structure, additional pits are often arranged.

Each hole is dug below the depth of the foundation by half a meter. Depending on the tightness of the territory and the size of the deepening, the walls of the pit are made with slopes or strengthened with vertical shields with spacers. The minimum area of ​​the bottom of the pit in relation to its depth is:

• 1.25 m2 - up to 1.5m;
• 2 m2 - from 1.5 to 2.5 m;
• more than 2.5 m2 - from 2.5 m.

In buildings with basements, drilling is carried out from the inside, which significantly reduces labor costs when performing earthworks. The pits, in this case, have, as a rule, a depth of 0.8-1.2 m and dimensions along the bottom - 1.0 * 1.0 m.

As a result of the foundation survey, they find out or clarify:

• the depth of the underground part;
• overall dimensions in plan;
• type and strength of the structure;
• the presence of defects and damage;
• class of concrete and brand of stone (according to samples - in the laboratory);
• condition of the waterproofing layer;
• violation of the position relative to the vertical axis;
• the presence of any amplification.

The state of the artificial and natural base is determined by the soil sample taken in the same pits. In some situations, additional drilling is required.

Options for opening foundations

One of the walls of the pit, designed to examine the strip foundation, is the vertical surface of the underground structure itself. For free-standing columnar foundations, there are three options for opening them:

• double-sided - the pit is dug out along two adjacent sides of the foundation reinforced concrete pad;
• angular - the pit is also located on both sides, but not for the full length of the faces of the base of the foundation, but only half;
• perimetric - the structure is exposed from three sides completely, and from the fourth - partially.

A two-sided pitting scheme is used in case of significant sedimentary deformations in the pit digging zone, with an asymmetric shape of the foundation sole, or when considering the possibility of increasing loads on bearing structures after the reconstruction of the building. The corner pit is arranged with the same dimensions of the sides of the reinforced concrete base in terms of and the absence of subsidence processes. For industrial buildings, they also take into account the uniformity of loads from equipment and the inadmissibility of its dismantling or moving to another place in the future.

Digging a hole around the perimeter is used in critical situations when a maximum inspection of the underground part of the building or a thorough analysis of soil conditions is required. But the opening of the foundation, in this case, is allowed to be carried out not immediately around the entire perimeter, but only in sections that are no more than one and a half meters long, otherwise the building under investigation may collapse.

It is not uncommon for a building that is small in area and number of storeys to dig much more pits than for a huge one. production shop, which has similar constructions. The fact is that the process of responsible examination in more are influenced by specific conditions, visual assessments, as well as preliminary control measurements and studies, rather than the human factor. It happens that with a minimum inspection, significant inconsistencies of the underground structure with technical documentation and even previous studies. It is then that additional research is required.

Inspection of foundations with the help of pits is carried out by specialized organizations in the presence of terms of reference, project documentation for the work with a clear indication of the location and size of the pits, as well as permission from supervisory authorities.

The presence of professionals and the guidance of engineers when digging holes is necessary in order to:

• excess soil from under the foundation was not accidentally removed to avoid additional subsidence;
• when the pit is flooded, problem areas could be quickly examined, since with intensive pumping of water, the rock is additionally washed out, including the sand cushion;
• the specialist was able to adjust the dimensions of the pit to be able to perform more accurate measurements;
• correct soil samples and samples of materials were taken.

Upon completion of work, each pit is filled with layer-by-layer compaction. Further, from the outside, the blind area is restored in accordance with all the rules, and from the inside - the floor.

Negative moments of drilling

Before you decide to examine the foundations by digging out the pits, you need to understand that the work will entail certain inconveniences that can affect not only the owner of the building, but also others. Namely:

• noise during the destruction of the blind area or concrete floor;
• dust and dirt;
• the appearance of moisture;
• the probability of flooding in case of untimely pumping of atmospheric waters;
• damage to waterproofing;
• difficulty in moving around the house;
• the impossibility of exploitation of the surveyed areas.

But, despite the difficulties, it is necessary to understand the importance of the arrangement of pits, provided for a visual acquaintance with the problems of foundations and the foundation under them. Inconvenience, in this case, is temporary.

"Shafts" is a word that was originally associated with geological excavations. In the future, it found its application in geodesy, archeology, construction, and engineering studies of communications. What are the shafts? What it is? We will consider their device and features in more detail.

Pit: definition

This word in geology denoted a vertical or inclined depression in the ground for the search and exploration of minerals. The cross section of such devices is round (they are also called pipes), rectangular, square. The main feature is small parameters from 800 to 4000 mm, depth - up to 40 m. These geological workings are used for lowering / lifting people, cargo into the mine / to the surface. In loose soils, these devices require fixing with beams to prevent shedding.

Given the above, it is impossible to underestimate the pits. The meaning of the word was sorted out, the specifics of use, types, device should be considered.

Applications

There are four main areas of use of pits:

• for a detailed study of the geological section;
• selection of soil samples of an undestroyed monolith;
• research;
• hydrogeological research.

As you can see, the scope of pits has greatly expanded over time.

Kinds

Research work of this kind is carried out in two main directions:

• engineering-geological;
• special purpose (used to assess the state of the foundation; the main goal is to find out the cause of the resulting deformations).

The pits are divided into three groups according to their size:

• small. The depth of occurrence is up to 3 m. As a rule, such devices do not require fixation. Often used in engineering research (about 60%).
• Medium. The depth is no more than 10 m. When they are installed, a ventilation system is already provided. Deepening is carried out using drilling rigs.
• Deep. The occurrence parameter is from 10 m. They are used to solve special problems.

Pit device

For the installation of such objects, both the manual method and the use of special equipment can be used.

The main parameters for the pits are selected depending on the intended work, the type of soil. Recommended dimensions:

• Rectangular, square section: 1000 x 1250 mm, 1000 x 1500 mm, 1500 x 1500 mm, 2000 x 1500 mm. The selected parameter also depends on the depth of the device: with a pit height of 3000 mm - 1250 mm, 10,000 mm - 1500 mm, up to 20,000 mm - 2000 mm, over 20,000 mm - 4000 mm.
• Round section: from 700 to 1000 mm. Pipes with a recess up to 10,000 mm - a diameter of at least 650 mm, over 10,000 mm - from 700 to 1000 mm.

What are the pits, what is it, we sorted it out. Now consider the specifics of application in construction.

Holes for special purposes

The foundation is the foundation of the house. The integrity of the entire structure depends on its quality and condition. Therefore, timely assessment is an important component in restoration and construction work. Pit holes for research are used in the following cases:

• Addition of an additional floor, not taken into account in the original project. The condition of the foundation and the possibility of additional load on it are assessed.
• Technical retooling. In construction - replacement, modernization
• Capital repairs. Assessment of the validity of the work.
• The appearance of cracks on the facade of the building, distortions of doorways. Such defects indicate the deformation of the foundation.
• Inadmissible subsidence of the building. This deficiency can lead to the complete destruction of the structure.
• When planning to lay a new foundation near an existing one. The possible negative impact of one on the other is assessed.

The causes of the deformation can be identified through the pits.

The significance of such studies is the possibility of identifying the factor of destruction of the foundation and its elimination. The main reasons that have a direct impact on the foundation of the building can be:

• Precipitation. They can accumulate and undermine the foundation. An excess of rainfall above average can provoke a rise in groundwater, which also has a negative impact on the condition of the foundation.
• Leakage of water from communications. In parallel, a study of their condition can be carried out.
• Defects in the compaction of the base and backfill.
• Displacement of soil layers in relation to each other and others.

Timely identification of the causes of the destruction of the foundation and their elimination can extend the life of the structure.

Features of pits in construction

Factors influencing the choice of a place for research:

• the presence of obvious deformation in a certain section of the building;
• the most loaded fragment of the building;
• if the house is multi-section, then each section is subjected to research;
• if there are additional supports, they are also inspected;
• during restoration, the places where load-bearing walls and supports are installed are determined.

The pits are deepened below the level of the foundation so that it is possible to examine the condition of the foundation.

For tape, it can be done both inside the building and outside. The pit is dug out in such a way that there is access to the base.

For there can be three types of research recesses:

• double sided. Two adjacent sides of the support are exposed.
• Angular. Also clean the two sides of the base, but up to half the width.
• Perimetric. It is used in emergency cases when thorough studies of both the base itself and the adjacent soil are required.

Pit holes in construction are used in shallow, occasionally medium-sized deepening.

Research types

What research options help to produce pits? What it is? What does this mean for assessing the condition of the foundation?

To answer these questions, consider the list of research papers:

• Foundation depth. Does this value correspond to the weight, height of the building and the ground.
• Dimensions. Compliance with project documentation.
• Type and strength data.
• Detection of defects and their causes.
• The quality of the materials used. Detected by taking samples and examining them in the laboratory.
• Safety and quality of waterproofing.
• Vertical change.
• Foundation condition.
• The presence of reinforcements.

Such studies help to determine the life of the building; the possibility of carrying out restoration work, building an additional floor.

As you can see, it is difficult to overestimate the importance of such devices as a pit for the construction industry.

Negative consequences of the use of pits

Sometimes when arranging recesses, the following consequences may occur:

• noise during the destruction of concrete structures;
• dirt and dust;
• increase in humidity indicators;
• flooding if timely pumping of atmospheric waters is not made;
• violation of the waterproofing of the base;
• impossibility of operation of the objects to be surveyed;
• obstruction of movement near the surveyed areas.

It is important that all work is carried out under the guidance of professionals. This will help avoid a number of negative consequences.

Geodetic surveys and pits

Another important thing is the result of a geodetic study, which allows you to determine the type of presence of underground engineering networks and so on. These data help determine the depth of its occurrence and engineering networks, the type of materials for construction, and much more.

Therefore, the use of research with the help of pits at the design stage determines the quality and duration of the service life of the future structure. “What are the shafts, what is it; their device and features; importance for construction, geodetic and engineering works” is a relevant and promising topic. With the help of these devices, you can extend the life of the old building and increase the service life of the building under construction.