How long is the pit usually. What is a pit and a well. Plan-high-altitude survey of underground communications

Parameters and methods of boring holes. By depth, exploration pits are divided into shallow - up to 5 m, average depth - from 5 to 10 m, deep - more than 10 m. In some cases, the depth of the pits reaches 40 m (from deep pits, cuts are usually made). The depth of the pits is determined not only by geological conditions, but also by the stage of exploration - during prospecting, shallow pits are cut; 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 drilling becomes more complicated, the cost of money, time and energy for lifting, ventilation, drainage and even fastening increases. In connection with a possible increase in the hardness 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.
Pits are of rectangular or round cross-section; 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 structure of the support.
The most widespread are pits with a rectangular cross-section; Recommended typical sections of rectangular exploration pits are shown in Fig. 134. In pits with a cross-sectional area of \u200b\u200b2 m2 and more, usually two sections are arranged - lifting and staircase. The cross-sectional area of \u200b\u200bthe borehole in the sinking is chosen mainly depending on the projected working depth; for pits of greater depth, a large cross-sectional area in the penetration is taken. In general cases, the following relationship can be traced between these values \u200b\u200b(within the range of depth variation from 5 to 20 m):

where Sп is the cross-sectional area of \u200b\u200bthe pit in the sinking, m2;
Hpr - design pit depth, m.
The cross-sectional areas of the pits, from which the cuts pass, are assumed to be somewhat large, providing a sufficiently productive lifting.
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 speckling (sometimes called "pipes"); when driving pits in loose loose rocks using frame-lowering support; when boring holes by drilling method.

When round shape the cross-sectional area of \u200b\u200bthe pit is used (due to the absence of corners) more fully, and the support structure, the main elements of which are made of materials stronger than wood (for example, metal), are compact. Therefore, with a round shape, the cross-sectional dimensions of the pit can be taken smaller than with a rectangular shape.
Pits of circular cross-section often have 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 circular cross-section, the borehole can have not only a cylindrical, but also a "stepped" shape - the development is passed by ledges of different diameters. The diameter of each subsequent shoulder is less than the diameter of the previous (superior) one. The stepped shape of the pits is necessary for the installation of a special type of support - "frame-sinking". The relationship between the cross-sectional area in the sinking of a cylindrical pit Sн and its depth Hпр can be expressed by the following formula:

When driving round pits with a stepped shape, the relationship between the average, maximum and minimum cross-sectional area of \u200b\u200bthe working is expressed by the formula

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

Among the methods of drilling exploration pits, it seems appropriate to single out the following: with manual rock breaking, with thawing and freezing of rocks, with the use of drilling and blasting operations and the method of drilling. This division of the methods of tunneling allows them to be characterized not only in relation to the means of performing the main production operation (rock destruction), but also determines to a certain extent the significance and technology of other basic operations of the tunneling cycle. So, for example, boring pits with manual hammering, carried out in loose or poorly connected rocks, requires special attention to the fastening operation, while the ventilation of the mine loses its importance to a certain extent. Driving is relatively often carried out with a low degree of mechanization.
A very specific method of drilling pits with thawing frozen or freezing thawed flooded rocks, including operations to change the thermal regime of rocks in order to change their mining properties.
The method of boring pits with drilling and blasting, used in rocks of various hardness, is characterized by a multi-stage tunneling cycle and usually a higher degree of mechanization. And, finally, the drilling method, which is currently becoming widespread when driving exploration pits in weak rocks, is characterized by the comprehensive mechanization of tunneling operations and the originality of the workings support.
Driving of pits with manual rock breaking. Manual hammering is typical for boring holes in soft and loose rocks; this operation is simple and usually not very labor intensive. Chipping is carried out mainly with shovels and sometimes picks; in some cases, the rock is previously 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 drilled holes.
Pits with manual hammering are of various depths, however, the largest amount of tunneling work falls on shallow pits.
When driving pits with a depth of up to 2.5 m, the operations of loading and lifting rock are excluded from the driving cycle - in this case, the rock is thrown out of the working to the surface.
Fastening of small pits penetrated in soft rocks is often not performed; airing is carried out by natural diffusion.
When driving pits to great depths, the driving cycle includes the operations of lifting the rock and securing the working, and the latter has a particularly significant effect on the technology of driving in loose (loose) rocks.
Pit drilling in soft rocks. TO preparatory work refer to the clearing of boulders and the vegetation layer of the working platform, the dimensions of which are determined taking into account the location of the stacks of the rock issued from the excavation 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. Above the mouth of the pit, a tunneling frame is installed, the dimensions of which in the light are equal to the transverse dimensions of the pit. The ends of the frame elements must protrude beyond the mouth of the pit by at least 0.5 m. After the frame is installed, the excavation of the pit begins, and the rock is discharged to the surface.
When driving a hole to a depth of 2 m, a manual crank is mounted on the tunneling frame. Lifting of rock from a single-bucket pit, buckets of small capacity (up to 0.04 m3); a ladder (usually suspended) is used to lower and climb people. Lifting installations with a mechanical drive are used in rare cases. When compiling geological documentation and sampling, performed directly in the pit, the rock released to the surface is placed in a compact dump near the mouth of the pit.
In cases where samples are taken from the rock discharged from the pit, this rock must be dumped into separate piles, sometimes called "penetrations". Calculation of "penetrations" as the pit deepens is carried out sequentially along the perimeter of the working platform.
The borehole is usually anchored after driving to a depth of 3-4 m. This part of the working is most often fixed with a solid crown support. The upper rims of the lining protrude 1 m above the pit mouth and are equipped with lids (Fig. 135).
At deeper depths, with sufficient stability of rocks in the pit, instead of a solid one, a crown support is installed on racks or, less often, suspended. Above the working face, a safety shelf is arranged. When water enters the well, it is removed, as a rule, in buckets.
The ventilation of the pits, as noted above, is carried out mainly due to diffusion. At 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 unit usually consists of three people - a tunneller and two collars. If the cross-sectional area of \u200b\u200bthe borehole is more than 2 m2, two tunnellers can simultaneously work in the face. In the practice of geological exploration, the drilling of pits in soft rocks per shift ranges from 1 to 2 m; average monthly footage ranges from 20-40 m.
During liquidation, the pits are filled up, the support in some cases is completely or partially removed, but more often left in the mine.

Driving pits in loose loose rocks. A significant difference in the technology of boring pits in loose loose rocks, which do not allow more or less significant vertical outcrops, lies in the features of the operation of securing the mine workings and support structures.
A characteristic feature of tunneling works is the use of frame-lowering support. The method of boring pits with frame-lowering support (Fig. 136) is most widely used in the exploration of gravel and boulder-pebble deposits.
The structure of the support allows passing round pits with 2-4 m high ledges; each ledge is fixed in the process of its driving. Before the start of the hole sinking, its depth Hпр is set, based on which, taking into account the selected bench parameters, the diameter of the upper bench (hole mouth) 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 Hпр / hу is the number of benches in the projected pit (hy is the height of the ledge, taken equal to 2-4 m).
Giving a pit a stepped shape leads to a rather significant increase in its volume compared to a cylindrical pit.
Table 42 shows a comparison of the volumes of pits of cylindrical and stepped shapes; the calculations were carried out at dy \u003d 1 m (the diameter of the cylindrical pit was taken equal to dy); hу \u003d 3 m and a "\u003d 0.2 m.
After marking the contour of the pit mouth on the working platform, a tunneling frame is installed and a wooden or metal pile driver is mounted, equipped with a winch and a winch for lowering and lifting the frames (Fig. 137).

The diameter of the pit mouth should exceed the outer diameter of the first lining frame by 10-20 cm. The rock separated from the bottom by shovels is thrown to the surface; the excavation is continued to the maximum depth that ensures the stability of the pit walls. Then, a frame is lowered into the pit with the help of a winch, along the outer perimeter of which boards (formwork) are installed. The borehole is driven to the depth of the first ledge with the simultaneous settling of the frame and formwork. After driving the first ledge, the space between the walls of the pit and the formwork is filled up; the frame is fastened to the tunneling frame with ties.
The operations of driving the second and next pit ledges are carried out in the same sequence: outline the ledge, make partial excavation of the rock along the ledge height, install the frame in the recess and lay out the formwork around it, deepen the ledge, pushing the frame with a sledgehammer.
The use of frame-lowering support reduces the labor intensity of fastening and the cost of tunneling the mine, and also ensures higher safety of work.

When driving holes with frame-lowering support in the North-West Geological Directorate, significant savings in material consumption and an increase in the pace of drilling holes were achieved compared to driving in the same conditions of CO holes with solid rim support. The average monthly rate of penetration of pits with a frame-sinking fortress is 25-35 m.
Driving of pits with thawing or freezing of rocks. When driving pits in frozen 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 allows to reduce the labor intensity of breaking, 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-term process and can be of practical importance only when driving in the summer a significant number of small pits located on a dense grid. Artificial defrosting is carried out by "fire", quarry and steam.
Thawing by fire is used when driving prospecting or exploration pits in forest areas. Pits, as a rule, run in winter, since in the warm season the mines are flooded with groundwater. Thawing of the rock is achieved when breeding directly at the bottom of the pit of the fire (fire). One fire consumes from 0.2 to 0.35 m3 of firewood. The thawing depth, depending on the quality of fuel and rock properties, ranges from 0.2 to 0.4 m. The average consumption of firewood is 0.4-0.5 m3 per 1 m3 of rock. 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 mine is inevitable, as well as additional work for cleaning the rock falling 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 rate of fuel combustion. Cleaning of the rock can be carried out after thorough ventilation of the pit, trimming the thawed walls and fastening the workings.
Quarry thawing consists in the following: round stones (quarry, cross-sectional size 8-10 cm) are heated on the surface in bonfires laid out near the mouth of the pit to a temperature of 200-300 ° C. The total volume of rubble, depending on the section of the pit, is from 0.5 to 1 m3. In the center of the bottom hole, a depression is made, heated stones are thrown or folded into it and covered with a layer of moss to reduce heat losses. After thawing, which lasts for several hours, the moss and rubble are removed from the excavation and the thawed layer of rock with a thickness of 0.15-0.3 m is loaded into a bucket. The consumption of firewood for heating the quarry 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 excavation remain stable and may not be fixed.
Steam thawing is characterized by a higher efficiency and can be recommended for a large volume of hole-boring works, however, it is rarely used in field exploration practice. To organize steam thawing, the following equipment is required: a steam boiler, a steam line with a distribution device, 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 borehole to a depth of 0.15-0.2 m and steam is supplied to them. As the rock thaws, the borax is 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, but the contours of the pit are indistinct. 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. With this method of penetration, the borehole may not be fixed.
In sediments with a high filtration capacity, water inflow significantly complicates, and sometimes makes it completely impossible to drill holes. One of the ways to simplify mining operations under these conditions is the freezing of rocks (pits are drilled in winter time at negative temperatures). When the bottom of the hole approaches the aquifers and, in particular, the quicksands, the sinking is stopped for a while, which is necessary for the freezing of the rock layer, followed by the sinking to a depth less than the thickness of the frozen layer, etc.
When driving pits in frozen rocks, alternating with layers of thawed flooded rocks, a combined driving is used: holes pass through frozen rocks with thawing, along thawed rocks - with freezing (Fig. 139), and the excavation of frozen aquifers is also carried out with thawing (rubble). The use in this case of explosive blasting, which is relatively often used in frozen rocks, is associated with the risk of flooding the mine after the explosion and is not recommended.

Freezing and thawing of rocks in the face is carried out at a relatively shallow 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 multi-face method in the case when the tunneling crew passes simultaneously several pits located at a short distance from one another. An approximate work organization schedule is shown in Fig. 140.
Pit boring with drilling and blasting operations. Characteristics of tunneling works. Drill-and-blast chipping is used when drilling holes in rocky and frozen rocks. This method of breaking rocks is used when driving relatively shallow pits at all stages of field exploration, when pits penetrate through soft and loose rocks, separate interlayers of rocks of IV and higher strength categories, when deepening pits into bedrocks (“finishing off” pits). However, this method is most typical for boring pits to great depths in sufficiently strong rocks.

Shallow pits with drilling and blasting operations are still often carried out without mechanization - manual drilling of boreholes, using wind power or hand fans for ventilation, lifting rock with hand cranks. This is largely due to the small volume and scattering of bore holes, the lack of efficient transport links or, in a particular case, electricity.
Deep hole driving is usually a mechanized production process; the degree of mechanization predetermines the terms of execution, material and labor costs of hole-boring works.
Means of mechanization of tunneling operations. The holes are drilled with light hand pneumatic rock drills (supplied with compressed air from mobile compressors installed at the mouth of the pits) or with hand electric drills. In some cases, motorized hammer drills can be used (provided that the exhaust pipe is connected to the suction fan pipeline and enhanced ventilation of the pit). The mechanization of loading the rock cut from the slaughter remains practically unresolved to this day. 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. The small-sized clamshell loader GShK-1 with a grab capacity of 0.01 m3 and designed for pits with a cross-sectional area of \u200b\u200bmore than 2 m3, created by the Special Design Bureau of the Ministry of Geology of Russia, did not find application due to its low productivity. It seems expedient to recommend the use of rope grabs of a slightly larger capacity not for loading rock into a bucket, but for removing it from the bottom with lifting to the surface. Exploration crews are testing the AG-1 boring machine with a hydraulic grab-lift.
Bucket lifting of the rock is carried out using small cranes, some designs of which have been described earlier. After blasting, the mine workings are ventilated with small centrifugal fans, and the drainage is carried out by electric pumps and motor pumps.
In geological prospecting parties that carry out drilling 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 driven lifting and manual auxiliary winches, a fan and an electric generator. The set of equipment includes an electric saw and electrical equipment: frequency converter, control panel, alarm, starting devices, lighting. All equipment is placed on a car trailer.
Similar boring 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). In the Yakutsk Geological Directorate, on the basis of a skidder, a self-propelled tunnel boring unit was created, equipped with a lifting and turning mechanism with a pneumatic grab and a compressor. The complex of KMSh-VITR boring machines consists of an electric portable station with a gasoline engine, a KSh-100 boring crane, a pump, a centrifugal fan and a manual electric drill. The complex is convenient for off-road transportation, it can be easily disassembled into separate units weighing less than 80 kg.
Driving technology and organization. The cycle of tunneling operations begins with drilling holes. When driving shallow pits with a small cross-sectional area, boreholes are drilled (and hollowed out in frozen rocks) manually. 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 \u200b\u200bthe excavation (up to 1.25 m2) make it possible to limit the number of holes to 2-5 holes (Fig. 141).
In pits with a large cross-section for perforating or electric rotary drilling of boreholes, their depth reaches 1.2-1.4 m, and the location and number are taken in accordance with the selected type of cut and the bottom area.

In pits with a cross-sectional area of \u200b\u200bless than 2 m2, one person drills; with a larger area, two drillers can work simultaneously. A blaster or a tunneller, who has the right to conduct blasting operations, charges and detonates the holes. Blasting holes electric, it is carried out from the earth's surface using an explosive machine. With a significant number of holes, the charging and blasting operation takes about 30 minutes (it takes 2-3 minutes to charge one hole).
With two- and three-shift work, it is advisable to time the ventilation of the pit to the break between shifts; in single-shift operation, gaseous explosion products are usually removed from the mine by diffusion or wind pressure during non-working hours of the day.
Before the start of the cleaning of the rock, the face after ventilation is brought into a safe state - the support damaged by the explosion is inspected and corrected; they rob the unsecured 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 \u200b\u200bthe pit for lifting the rock, it is advisable to use two buckets - while loading the bucket, uncoupled from the hoisting rope, another, previously filled with rock, is raised to the surface, unloaded and lowered into the pit. Cleaning of the rock takes most of the time of the tunneling cycle.
In hard rocks, usually characterized by increased stability, the borehole is fastened with a significant lag behind the face, and the fastening process is often not included in the tunneling cycle.
The installation of the support and the reinforcement of the pit are usually carried out in specially allocated shifts, after several driving cycles have been completed.
An approximate work organization schedule is shown in Fig. 142.
Average monthly penetration of pits reaches 30-40 m.

The tunneling unit usually consists of three to four people: one or two work in the tunnel, two on the surface. Sometimes the tunneling crew works according to the multi-hole method simultaneously driving several pits. This ensures a better organization of work and reduces downtime associated with blasting and ventilation.
General information about the explosive method of boring pits. Drilling of pits in relatively easily deformable rocks, which is reduced to the formation of a mine working due to irreversible deformations of rocks (clay, loam, sandy loam, loess) during the explosion of a charge, was called explosive driving. In wet clays, this method of driving is particularly effective.
The technology of penetration 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 alluvial BB; detonators, electric detonators and a detonating cord can be used as initiators. After blasting, the resulting mine working must be thoroughly ventilated. In many cases, the need for fixing the pit disappears, since the rocks, as a result of the explosion, are deformed, compacted and become sufficiently stable.
In pits formed by the explosive method, with a relatively regular circular shape of the cross-section, 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. There is an almost direct relationship between the volume of the charge (Azar) and the volume of the cavity (Avyr) formed in the rock after the explosion, Avyr \u003d kAzar. The value of the proportionality coefficient k depends on the properties of rocks and explosives.
In the practice of drilling pits in clays, loam and loes when using ammonites, the coefficient k is taken in the range from 150 to 300. For convenience of calculations, passing 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 the calculation are approximate, they should be refined during experimental explosions. The blasting method is characterized by insignificant expenditures of time and material resources, high labor productivity, it is applicable in those cases when pits are used as transport workings, and geological information is obtained when driving from these pits of scatterers.
An interesting technology of drilling pits in clays and weathered clay tuffs, adopted in the Pervomayskaya and Merkushevskaya hydraulic fracturing units of the Primorsky Geological Department. Pits up to 15 m deep with a cross-sectional area of \u200b\u200b1-1.25 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 3-5 kg \u200b\u200bcharge is placed in the resulting chamber. In the explosion of the boiler charge, the rock is partially pressed into the walls of the working and partially (with a small depth of the pit) is thrown out to the surface. Only from 25 to 50% of the blasted rock is subject to cleaning from the pit.
Pit boring. Characteristics and conditions for the use of pits boring. Over the past decade, the drilling method of borehole driving has been introduced into the practice of mining exploration.
The drilling method of boring holes is characterized by a number of essential advantages that distinguish it from other methods. Boring pits provides a significant improvement in working conditions and work safety, achieving the highest technical and economic indicators, eliminating heavy work and comprehensive mechanization of the construction of exploration workings.
Improvement of working conditions and work safety is a consequence of the fact that in the process of drilling a hole, the worker is not in the working face, but on the surface; the operation of fixing the pit is less laborious and faster; there are proposals for the mechanization of taking bulk samples from the bottom of the pit, in which the need for a person to stay in the mine generally disappears.
The high technical and economic indicators of borehole drilling include a sharp increase in the rate of penetration, a decrease 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).

Currently, only with the drilling method can we talk about a truly comprehensive mechanization of boring holes. The operations of breaking rock in the face, discharging it from the mine and placing it on the surface into dumps are mechanized; the problem of mechanizing the erection of support in a pit with a regular cylinder shape is not insoluble (there is already a design project for a portable support layer mounted on a drill string); in addition, in some cases, the borehole may not be fastened. The field of application of the drilling method is still limited to soft rocks (I-IV categories of drillability).
The institutes TsNIGRI and MGRI (Moscow Geological Prospecting Institute) have developed and are testing designs of drilling equipment for drilling exploration pits in medium-hard rocks.
The applied transportable drilling rigs provide drilling of boreholes to a depth of 30 m and more.
The drilling method is especially effective for significant volumes and concentration of borehole operations.
Applied equipment. The pits are drilled mainly in a rotary way with installations mounted on the basis of a car, tractor or trailer. Some of these rigs are suitable only for drilling boreholes, others are universal, they can be used to drill boreholes and shallow exploration wells. As a drilling tool, mainly screw and, less often, bucket cylindrical drills of various designs are used. Hole drills are designed to destroy the rock face and periodically raise the destroyed rock to the earth's surface. The rock is destroyed by the cutting edges of the flanges of the auger or the bottom of the cylindrical drill; the destroyed rock is accumulated on the flanges of the auger or in the cylindrical body and, together with the drill, rises from the working.

Rigs for drilling shallow holes are usually vehicles with a simple attachments (fig. 143).
Pits of medium depth or deep are drilled with installations mounted on the chassis of motor vehicles (Fig. 144), on trailers with independent drives or on trailers in combination with truck cranes. The UBSR-25 drilling rig is mounted on the basis of a skidder. The characteristics of the drilling rigs used for drilling holes are given in table. 44.

Technology for driving and fastening pits. After clearing and leveling the horizontal platform on the surface and bringing the drilling rig into working condition, they begin to drill holes. The production process of drilling a hole 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 to the surface. The duration of round tripping operations with an increase in the depth of the borehole increases sharply if it is necessary to build up and disassemble the drill string at each run. In some installations, this drawback is eliminated due to the design of a bucket drill sliding along the drill rods, raised and lowered on ropes without disassembling and building up the rod string.
At present, sliding auger drills and combined drill holes of the MGRI design have been developed and are being tested, which make it possible to increase the running hole by two to three times, as well as perform tripping operations without disassembling the drill string.
The bucket drills are unloaded either manually or with the help of rotary blades that form the body of the auger and are rotated during unloading by a special hydraulic drive (bucket drill installation LBU-50). Augers are usually unloaded by rotating them at an increased speed (unloading due to the developing centrifugal force). When unloading the borehole, the mouth of the borehole is blocked with lids.

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

Drilling and mining operations are the most important part of geotechnical and hydrogeological research. With the help of boreholes and mine workings (pits, adits, etc.), the geological structure and hydrogeological conditions of the construction site are clarified 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 research.

Borehole is a cylindrical vertical working (less often inclined) of small diameter, performed with a special drilling tool. In boreholes, the mouth (beginning), walls and bottom or bottom are distinguished.

The essence of drilling is the gradual and sequential destruction (or drilling) of the rock at the bottom and its extraction to the surface. Rock samples taken from wells are called drill cores. To isolate aquifers and prevent rocks from falling from the walls of the wells, the wellbore, i.e. the drilled space, is secured with casing pipes.

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

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

Wells are drilled with a drill bit, which, when connected to drill pipes (rods), creates a drill string. The blows or rotation of this projectile and the transfer of pressure to it

the drilling is carried out by drilling rigs driven by various motors.

In engineering and geological studies, the following types of well drilling are usually used: rotary-core drilling, percussion-rope annular and solid bottom, vibration and auger. Other types of drilling, with the help of which it is difficult to select a core, are not widely used in geotechnical operations. ,

Rotary core drillingallows drilling wells with a diameter of 73-219 mm in almost all types of rocks, including rocky ones, to a depth of 100 m and more. The drill string consists of a hollow core pipe 0.5-4.5 m long with a crown and a drill string. When the drill string rotates, the core pipe crown with hard alloy teeth embedded in it cuts an annular channel in the rock, that is, it drills out a rock column - the core. Shot and diamond bits are also used. After filling the core pipe with a core, the drill string is torn off the bottom and raised to the surface. Then the drill bit is unscrewed and the core is removed from the core pipe.

In clayey rocks, for sampling of soil of 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 to the bottomhole through the drill pipes. At the same time, the drilling tool is cooled, and the crushed rock (cuttings) is carried to the surface in special sedimentation tanks.

U dar no-ropedrilling is recommended in areas with insufficient geological knowledge, as it allows a thorough description of the rocks. Distinguish between percussion-rope drilling with a continuous face with a diameter of 127-325 mm using bits and a bailer (coarse and sandy watered soils) and percussion-rope annular face with a diameter of 89-325 mm in sandy and clayey non-watered or slightly watered.

Drilling depth in non-rock formations is up to 100-150 m, in rock formations - to great depths. Driving is carried out by dropping to the bottom of a weighted drill (bailer, rammed glass) suspended on a rope, and then lifting it to the surface together with the rock. In pebbles and rocks, a chisel is dropped to the bottom, and the bottom is cleaned with a thief.

One of the most productive drilling methods is vibration drilling,in which the drill is immersed in the rock due to vibration vibrations. With the help of a vibrator, clay and sandy flooded 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 drillingcharacterized by a high mechanical speed when drilling wells in sandy-clayey soils to a depth of 30 m. The destruction of rocks is carried out by a rotating chisel, and they are lifted by augers, i.e. pipes, on the surface of which a steel spiral is welded (Fig. 36.3). With this drilling method, a qualitative geological description is difficult.

Drilling wells in unstable and water-saturated formations is complicated by the collapse and collapse of the walls. For their fastening, steel casing pipes are used, which are lowered into the well, after which they continue drilling with a tip for less

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

Manual rotary percussion drillingdue to low productivity and high labor intensity, it is used in an extremely limited amount (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.

During hydrogeological studies, exploration, experimental, observation and exploration and production wells are drilled. Wells designed 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 means.

Drilling water wellsit is carried out mainly by the shock-rope and rotary method, less often by the rotary-core method.

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

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

Driving pits and other mine workings.The most common type of mine workings is a pit. During exploration, other workings are also used: clearing, ditches, pipes, adits and mines (Fig. 36.5).

Pit is a vertical mine working of rectangular or circular cross-section, passable 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 with a depth of up to 3-5 m with a cross section of 1x1.25 m. Usually they pass in sandy and clayey soils. Pits of large cross-section (more than 2 m 2) are made for special experimental work and at a great depth of the pit. The pit passes by deepening the face and ejection of soil, first with a shovel, then with the help of a bucket lifted by a crank. In rocks, the pit is deepened using jackhammers and blasting operations.

As the pit walls deepen, it is necessary to strengthen, otherwise their collapse is possible. When driving water-saturated rocks, drainage is organized. Deep pits must be ventilated.

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

At present, a mechanized method of boring holes is being used with the help of special hole-boring installations, as well as self-propelled drilling rigs URB-ZAM, URB-2A-2, UGB-1VS, etc., equipped with bucket or auger drills... Average productivity of installations 1.2-2, Ohm / h.

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

In areas composed of steeply dipping layers of rocks, there are horizontal mine workings: clearing, ditches, adits and mines.

Clearing - 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, carried out manually or with the help of technical means in order to open bedrock.

The pipe 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 fix the pipe walls.

Adits are underground horizontal workings of considerable length, laid on the slopes and opening up rock strata in the depths of the massif. They are usually used in rocks during exploration for the construction of particularly critical structures.

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

Observations while drilling wells and boring holesconsist in measuring the water level and temperature, sampling rocks, water and other works.

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

meters thin cables, at the ends of which various devices (firecrackers, whistles, etc.) are suspended, when in contact with water, these devices give a signal (whistle, clapping, etc.) and the observer determines the depth of water from surface of the earth (fig. 36.6). Electric level gauges are more accurate, when the sensor comes into contact with water, the electrical circuit is closed, the galvanometer needle deviates, and the level position is fixed according to the marks on the cable. Long-term observations of changes in the water level are carried out using float meters, and special automatic instruments are used for continuous level recording.

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 established groundwater level are determined.

Groundwater temperature is measured by mercury thermometers mounted in a metal frame. Various samplers with a volume of 0.5 to 3.0 liters are used to take water samples.

Observations of the absorption of drilling fluid and the exit of the core make it possible to preliminarily estimate the water permeability of the rocks in different intervals of the wells. Intense absorption and low core recovery indicate fracturing, fragmentation of rocks and their possible high water content.

When drilling water wells, a thorough isolation of the planned for exploitation of the aquifer from other aquifers and surface pollution is provided. Most often, for this, the shoe of the casing string is pressed into the waterproof rocks (Fig. 36.7, and)or produce annular cementation of the pipe string (with rotary drilling) (Fig. 36.7, b).

The quality of the isolation of aquifers is checked by pumping water from the 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 a drilling log and a mine log. In the logs, as wells are drilled and pits are drilled, they describe in detail the composition and condition of the rocks being exposed, indicate the depth of sampling of rocks and water, give 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 in the engineering

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

"Pits" is a word that was originally associated with geological excavations. Later it found its application in geodesy, archeology, construction, and engineering research of communications. What are the pits? What it is? We will consider their structure and features in more detail.

Pitch: definition

This word in geology was used to denote a vertical or inclined depression in the ground for prospecting and prospecting for minerals. The 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 has been 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 not destroyed monolith;
• field engineering and geological research;
• hydrogeological research.

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

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

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

By size, pits are divided into three groups:

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

Pit construction

For the installation of such objects can be used as manual wayand the use of special equipment.

The main parameters for pits are selected depending on the proposed 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 deepening up to 10,000 mm - diameter not less than 650 mm, over 10,000 mm - from 700 to 1000 mm.

What are the pits, what they are, we have sorted them out. Now let's consider the specifics of the application in construction.

Special purpose pits

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 works... Exploration pits are used in the following cases:

• The addition of an additional floor not included in the original design. The state of the foundation and the possibility of additional load on it are assessed.
• Technical re-equipment. In construction - replacement, modernization of 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 deformation of the foundation.
• Inadmissible subsidence of the structure. This disadvantage can lead to the complete destruction of the structure.
• When planning the laying of a new foundation close to the existing one. Possible negative influence one to the other.

The causes of 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 may be:

• Precipitation. They can build up and undermine the base. An excess of precipitation 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.
• Shortcomings in compaction of the base and backfilling.
• 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 site for research:

• the presence of obvious deformation in a certain area of \u200b\u200bthe building;
• the most loaded fragment of the building;
• if the house is multi-section, then each section is subjected to research;
• if additional supports are available, they are also inspected;
• during restoration, determine the places where the load-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 strip foundations, 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. Expose two adjacent sides of the support.
• Corner. Also clean the two sides of the base, but up to half the width.
• Perimetric. It is used in emergency cases when a thorough study of both the base itself and the adjacent soil is required.

Pits in construction are used shallow, occasionally medium deepening.

Research types

What research options do the pits help produce? What it is? How does this matter for assessing the condition of the foundation?

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

• The depth of the foundation. Does this value correspond to the weight, height of the building and the ground.
• Dimensions. Compliance with design 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 determine the life of a building; the possibility of carrying out restoration work, adding an additional floor.

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

The negative consequences of using pits

Sometimes the following consequences can occur when making recesses:

• noise during the destruction of concrete structures;
• dirt and dust;
• growth of moisture indicators;
• flooding, if timely pumping of atmospheric water has not been made;
• violation of the waterproofing of the base;
• the inability to operate the facilities subject to inspection;
• difficulty in movement near the surveyed areas.

It is important that all work is done 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 geodetic research is important, which makes it possible to determine the type of soil, the depth of groundwater, the presence of underground engineering networks, etc. This data helps to determine the type of foundation, the depth of its occurrence and utilities, 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 pits are there, what is it; their structure and features; importance for construction, geodetic and engineering works ”is a relevant and promising topic. With the help of these devices, it is possible to extend the life of the old building and increase the service life of the building being built.

The underground part of any building is hidden under a layer of soil, 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 structure of the building itself, the distance to nearby buildings, as well as the level of the foundation base.

When it is necessary to inspect underground structures

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

• increasing the number of storeys in the building;
• technical re-equipment of production;
• capital repairs associated with increased loads;
• the appearance of significant cracks on the facade and distortions of the openings;
• development of unacceptable drawdowns;
• the need for the construction of closely spaced foundations, etc.

Often, external damage to the walls, determined visually, as well as jamming of several doors located in the same plane or not far from each other, indicate the problems of the underground part of the structure. In these cases, experts give an unambiguous conclusion that the structure is undergoing deformation, and this happens, most likely, due to the weakness of the foundation or the beginning of the destruction of the foundation.

During the overhaul of an object, which implies increased pressure on the ground, it is imperative to inspect its underground part, for which it is necessary to dig pits.

In some cases, it is enough to study 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 direct inspection of the state of the foundation and foundation.

Unacceptable deformations, distortions and subsidence of buildings can occur for various reasons that appear immediately, over the years or after thawing of the soil. 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 tanks and heating mains;
• groundwater that has risen above the permissible level;
• insufficiently compacted base or backfilling;
• freezing or leaching of soil;
• displacement of soil layers relative to each other, etc.

When drilling, soil samples are taken at the base of the foundation, visually inspect the structure and, if necessary, take samples of materials (concrete, mortar, stone) for further laboratory research. Often, the valves are opened.

Pit construction rules

A pit is a dug hole that exposes the wall of a tape, a support of a columnar or side part slab foundation. The locations of the deepenings are determined based on specific conditions. The priority areas are problem areas, and if it is necessary to examine long zones, the choice is left to the sites that can least of all become an obstacle for passers-by or people living nearby.

When marking pits, builders should not rely only on the convenience of working conditions and the availability of the territory. Research is almost always carried out in populated areas, so you cannot get rid of the presence of pedestrians near the object. But those around you also need to remember that the foundation survey is only temporary, and the measures taken are necessary, expedient and not critical.

Without fail, the pit should be laid in places where wall deformation is clearly visible. Also, drilling can be carried out:

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

Special attention should be paid to sites where the condition of the soil or foundation is determined as emergency. In this case, in addition to the problem area, they examine the safe zones where the pit is arranged, after which the results of the study are compared. For the foundation of the reconstructed object, pitting and inspection of structures together with the base are carried out in the places where the bearing columns and walls are installed. And in the case of a partial superstructure - only in the reorganization area.

The number of pits depends on initial target 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 first floor, holes are dug in each of the watered areas, and when the basement is deepened, one hole is made near all the walls. In the most loaded areas, double-sided pits are allowed.

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

Each pit is dug half a meter below the foundation depth. Depending on the tightness of the territory and the size of the deepening, the walls of the pit are made with slopes or reinforced with vertical shields with struts. The minimum area of \u200b\u200bthe pit bottom relative 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 2.5m.

In buildings with basements, drilling is carried out from the inside, which significantly reduces labor costs when performing earthworks... 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 specify:

• the depth of the underground part;
• overall dimensions in plan;
• type and strength of the structure;
• the presence of defects and destruction;
• class of concrete and grade of stone (based on samples - in the laboratory);
• condition of the waterproofing layer;
• violation of the position relative to the vertical axis;
• the fact of the presence of any gains.

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

Opening options for foundations

One of the walls of the pit, intended for the survey of 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 on 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 edges of the foundation sole, but only half;
• perimetric - the design is completely exposed on three sides, and partially on the fourth.

The two-sided drilling scheme is used in the case of significant sedimentary deformations in the excavation zone, with the asymmetric shape of the foundation base, or when considering the possibility of increasing the loads on the supporting structures after the reconstruction of the object. An angular 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 the 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 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 performed not immediately along the entire perimeter, but only in sections that are no more than one and a half meters long, otherwise the collapse of the surveyed building may occur.

There are often cases when for a building of a small area and number of storeys it is necessary to dig much more pits than for a huge production workshophaving similar designs. The fact is that the process of responsible examination is more 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 check, significant inconsistencies in the underground structure with technical documentation and even previous research. Then 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 work with a clear indication of the location and size of the pits, as well as the permission of supervisory authorities.

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

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

At the end of the work, each pit is filled up with layer-by-layer compaction. Further, from the outside, the blind area is restored according to all the rules, and from the inside - the floor.

Negative moments of drilling

Before deciding to inspect the foundations by digging pits, you need to understand that the work will entail certain inconveniences that may affect not only the owner of the building, but also those around. Namely:

• noise when the blind area or concrete floor is destroyed;
• dust and dirt;
• the appearance of moisture;
• the likelihood of flooding due to untimely pumping of atmospheric water;
• damage to waterproofing;
• difficulty getting around the house;
• impossibility of exploiting the surveyed areas.

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

"Pits" is a word that was originally associated with geological excavations. Later it found its application in geodesy, archeology, construction, and engineering research of communications. What are the pits? What it is? We will consider their structure and features in more detail.

Pitch: definition

This word in geology was used to denote a vertical or inclined depression in the ground for prospecting and prospecting for minerals. The 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 has been 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 not destroyed monolith;
• research;
• hydrogeological research.

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

Views

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

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

By size, pits are divided into three groups:

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

Pit construction

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

The main parameters for pits are selected depending on the proposed 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 deepening up to 10,000 mm - diameter not less than 650 mm, over 10,000 mm - from 700 to 1000 mm.

What are the pits, what they are, we have sorted them out. Now let's consider the specifics of the application in construction.

Special purpose pits

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. Exploration pits are used in the following cases:

• The addition of an additional floor not included in the original design. The state of the foundation and the possibility of additional load on it are assessed.
• Technical re-equipment. In construction - replacement, modernization
• Overhaul. Assessment of the validity of the work.
• The appearance of cracks on the facade of the building, distortions of doorways. Such defects indicate deformation of the foundation.
• Inadmissible subsidence of the structure. This disadvantage can lead to the complete destruction of the structure.
• When planning the laying of a new foundation close to the existing one. The possible negative impact of one on the other is evaluated.

The causes of 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 may be:

• Precipitation. They can build up and undermine the base. An excess of precipitation 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.
• Shortcomings in compaction of the base and backfilling.
• 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 site for research:

• the presence of obvious deformation in a certain area of \u200b\u200bthe building;
• the most loaded fragment of the building;
• if the house is multi-section, then each section is subjected to research;
• if additional supports are available, they are also inspected;
• during the restoration, the places where the 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 produced both inside the building and outside. The pit is dug out in such a way that there is access to the base.

There can be three types of research deepening for:

• Double-sided... Expose two adjacent sides of the support.
• Corner... Also clean the two sides of the base, but up to half the width.
• Perimetric... It is used in emergency cases when a thorough study of both the base itself and the adjacent soil is required.

Pits in construction are used shallow, occasionally medium deepening.

Research types

What research options do the pits help produce? What it is? How does this matter for assessing the condition of the foundation?

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

• The depth of the foundation. Does this value correspond to the weight, height of the building and the ground.
• Dimensions. Compliance with design 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 determine the life of a building; the possibility of carrying out restoration work, adding an additional floor.

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

The negative consequences of using pits

Sometimes the following consequences can occur when making recesses:

• noise during the destruction of concrete structures;
• dirt and dust;
• growth of moisture indicators;
• flooding, if timely pumping of atmospheric water has not been made;
• violation of the waterproofing of the base;
• the inability to operate the facilities subject to inspection;
• difficulty in movement near the surveyed areas.

It is important that all work is done 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 geodetic research, which allows you to determine the type of presence of underground engineering networks and so on. This data helps to determine the depth of its occurrence and engineering networks, with 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 pits are there, what is it; their structure and features; importance for construction, geodetic and engineering works ”is a relevant and promising topic. With the help of these devices, it is possible to extend the life of the old building and increase the service life of the building being built.