SU1760013A1 - Method for consolidation of mass of subsiding ground - Google Patents

Abstract

Use: compaction of sediment soils by sediment under its own weight by soaking and seismic effects. SUMMARY OF THE INVENTION: the formation of a pit, the drilling of drainage and blast holes with the fixing of their walls, the soaking of the soil, the placement of explosive charges in the wells and the implementation of an explosion with charges of soil under its own weight. The walls of the boreholes are fixed by firing at the SHO-1000 C temperature in the form of an annular layer to a depth equal to 2/3 of the subsidence. The thickness of the annular layer is determined from the dependence t Pa.r / (R - Pa), where r is the well radius, PO is the pressure of the water-saturated soil at the bottom of the well, R is the compressive strength of the burnt soil. 3 il.

Description

The invention relates to the construction, in particular to the compaction of passing soils.

There is a known method of compaction of subsurface soils (see Recommendations for compaction of high-capacity subsiding soils using the hydraulic blasting method. M. Stroyizdat, 19, pp. 3-12, Fig. 2.6j l by setting up a pit, drilling drainage and explosive wells, drainage wells fill the drainage material, which in the process of soaking wells, drains the water and ensures the stability of the walls of the wells, i.e., prevents them from melting, and

transporting explosives (explosives) to the required depth, then soaked the prosodynomu thickness through the pit and drainage wells, or only through the drainage wells, after water saturation of the subsidence surface, transporting explosives into the explosive wells and exploding it, while structural connections saturated soil is destroyed and intensive soil compaction occurs.

The disadvantages of this method: a large amount of drilling work, since it is necessary to drill both drainage and explosive wells, high costs

H

ABOUT

oh oh

Sl)

drainage material and blasting pipes.

The well-known method is directed at reducing drilling operations (see ibid. 1, pp. 12-22, Fig. 2.6, 7, 8, 9), using drainage-explosive wells, i.e. when the drainage and blast holes are combined, all other technological operations of the method remain the same as in the method of the divided drainage and blast wells. Combined drainage-blasting wells consist of an explosive chamber for placing explosive charge, a transport tube and a drainage material interlayer between the borehole wall, an explosive chamber and a transport tube, while the transport tubes and blasting chambers can be of different designs and in different designs.

Disadvantages of the method: a greater need for drainage material, transport pipes and blasting chambers, in addition, the practice of introducing a hydraulic blasting method has shown that it is not possible to use transport pipes for reuse, because of the explosion of the explosive charge located in the container, the transport pipe is also damaged, as a result of which it is either impossible to remove due to significant friction in the compacted soil and formation of a core at the point of pipe rupture, or it is significantly deformed due to din nomic effects

with the explosion and extraction. I

To reduce the consumption of pipes

Flax is a known method of compacting an array of subsiding soil along a.s. P 1392201 2, which consists in drilling drainage wells to the top of the subsidence zone from its own weight and filling them with drainage material, as well as drilling explosive wells to a depth of 0.9-1.0 depth of the subsidence depth, blasting wells are made by filling up with a slurry.

The disadvantages of this method are a large amount of drilling work, because Drilling of both drainage and blastholes is required, in

a significant consumption of drainage material, in addition, suspended particles of the suspension, which fill the blast holes, precipitate

g 0

50

0

5 p

ъ

five

during the soaking of the subsidence, which can last 1-1.5 months j, which leads to the complication of free lowering of containers with an explosive and then additional measures are required to immerse the containers, which complicates the safety technique.

A method of soil compaction is also known, the technical solution of which is closest to the proposed one and accepted by the authors as a prototype, which consists in drilling drainage and explosive wells. Drainage wells are filled with drainage material, and blasting wells are protected against melting during soaking by fixing the walls of the wells with chemical methods, for example, silicatization, while securing the walls of the well with chemical methods

H $ y sm-p 18 --- 20 SF

Oh y

where PH is the initial pressure of subsidence;

g is the volume mass of the wetted soil, i.e. soil fixing in the borehole walls is carried out to the depth of the initial subsidence pressure.

After that, they begin to soak the subsiding strata and, after it is saturated with water, the explosive is dipped into the explosive wells in the containers and torn off. As a result of soaking and dynamic effects, intensive compaction of the subsurface strata occurs.

The disadvantages of this method are as follows. Chemical reagents, such as sodium silicate (water glass) in large quantities, which are scarce, are not needed to consolidate soils in the walls of blast holes, which is why this method is not used in practice. In addition, the fixed soil chemical methods become waterproof (chemical soil fixing is used in the practice for the device of water shields), which makes it impossible to use wells with fixed walls chemical methods as filtering51760013

that requires a large amount of drilling, because there is a need to drill both drainage and explosive wells, as well as a large amount of drainage materials, in addition, the depth of fixation of the walls of explosive wells by silicatization, and, consequently, the charging depth by an amount corresponding to the depth of the initial subsidence pressure, which for loess subsidence loam does not exceed 6 ... 7 m, is insufficient to ensure good compaction of subsidence soils of high power, which, for example, in the Middle Dnieper reaches 30 ... AO meters .

The aim of the invention is to increase the compaction efficiency of the subsurface soil by reducing the volume of drilling, increasing the filtration capacity of the borehole walls and eliminating the use of drainage material.

This goal is achieved by fixing the walls of the wells by firing them at a temperature of 400 ... 1000 ° C. in the form of an annular layer to a depth equal to 2/3 of the transverse mass of the massif, and the thickness of the annular layer is taken to be equal to the value determined from the dependence (

t Pa r (R - Pq),

ten

15

20

sk ny no zh y from pr sk sk k ra z no

ra

ra gno shp dve szh

25

thirty

35

kra l no pe re Ka Ka ha ve Po with.

where r is the well radius;

Ra - water saturated pressure

soil at the bottom of the well;

R is the compressive strength of the burnt soil.

When one or several soil layers with low filtration capacity, lying below the depth of 2/3 of the subsidence layer, are included in the subsidence, soil firing in the borehole walls is carried out to the depth of the bottom of the bottom layer with low filtration capacity.

FIG. 1 shows the process of strengthening the walls of wells; in fig. 2 - the process of soaking subsiding strata of soil; in fig. 3 - immersion of containers in a well with an explosive and their blasting.

The method is carried out as follows.

0

five

Drilled well wells, i.e. wells that will simultaneously perform drainage and blasting functions. The wells are then equipped with a known technological tool for burning soils, and they burn fuel in a known manner, by advancing from the bottom up, starting from the bottom of the well, as a result of which the soil around the wells is subjected to calcination along the entire depth. The fuel is burned in the well until the width of the burned ring reaches its size, Pa-g

equal t

R - P „

For control on

The distance r + t from the well axis, where d is the well radius, t is the width of the soil soil ring, the test hole is drilled into which the mobile thermocouple is installed and, when the temperature of the AOO ° C is reached on the wall of the hole, the fuel is stopped.

As a result of fuel combustion, a hollow cylinder of burned soil is formed around the well with a wall thickness equal to t with a burning temperature of up to 1000 ° C on the inner surface of the well and 00 ° C at the periphery of the burned cylinder. As it is known, the soil at a heating temperature within the AOO-900 ° C reaches compressive strength R, respectively, and more than kg / cm2 (see BC Pods. Thermal hardening of soils at the foundations of buildings and structures. N .: Stroyizdat, 1968, p. 21 ... 22 U), which provides

the stability of the walls of the wells during soaking and prevents them from melting,

It is also known that the filtration ability of burnt soil

increases by a factor of burn-up of organic inclusions and an increase in the porosity of burned soil (see 3J p. 21, and Matoshin VI. Study of the effect of gas permeability of loess soils on the efficiency of their heat treatment, K., 1971, p. 10 OJ , Litvinov IM. Strengthening and compaction of subsiding soils in residential and industrial construction, K., Buller, 1977,

127) chth dramatically increases the effectiveness of soaking of the subsidence of the soil, and, consequently, the effectiveness of its compaction.

71

The thus formed hollow cylinder around the borehole of burnt soil ensures the stability of the walls and effective filtration of water from the well-into the subsiding thickness, which eliminates the need for drainage material.

After burning the soil in the walls of the well, the equipment for burning fuel is dismantled and the soaking of the subsidence through the excavation and burned wells is started. Since the walls of the well with burned around soil do not melt and provide a high degree of filtration of water into the surrounding soil, soaking of the subsidence is carried out without filling the wells with drainage material. Soaking is continued until full water saturation of the subsidence. At the same time, in order to increase the effectiveness of soaking, it is necessary to cut through all the layers of low-permeable soils with wells, and to burn the walls of the wells to the bottom of the water

ra-, below which subsidence layers lie. Then the containers with the explosive are freely lowered into the wells. Dipping containers into wells after soaking is possible without the use of transport and blasting pipes, since the burnt soil ensures the stability of the walls during the entire soaking period.

I

After which explosions are carried out.

The charges, as a result of which the soaked subsiding stratum is subjected to a dynamic effect, thus destroying the natural bonds between the soil particles and their aggregates and compacting the subsidence stratum, while the burned soil around the well is destroyed by the action of the blast wave and mixed with the compacted saturated soil does not prevent its compaction.

Example. When building microdistricts n ° 15, 16, 17 in Zaporozhye, the method of compaction of sanding soils by presoaking using explosive energy is widely used. For the base unit of a 9-storey large-panel dwelling house of a paired block section of a series 96 with dimensions in plan of 12x50 m, it is necessary to compact subsurface soils lying at a depth of 30 m.

eight

Since water glass is a large deficit, and it is required in significant quantities, the technical solution of the prototype - protection of well walls against melting during soaking by strengthening the soil in the walls of the well by silicification does not apply.

Compaction of subsidence soils was carried out so far with the use of combined drainage-explosive wells. At the same time, the consumption of materials for one block-section is: pipes - 1200 m., Gravel for a drainage device - 170 m3. In connection with the high consumption of disposable materials and their considerable cost, a new method of compacting the subsiding thickness without the use of these materials is proposed, which is carried out as follows.

I

Under the whole building with exit

beyond its limits by 5 m in each direction along the contour of the borehole in the longitudinal and transverse directions with a step of 5-6 m with a diameter of 250 ... 300 mm to a depth of 2/3 of the depth of the subsidence. In this example, the depth of the well is 20 m. The wellhead is sealed with a shutter 1 and a pipe is installed at its base — an extension 2 of the nozzles 3. At a distance of 2R from the axis of the control wells {2-3 pieces from

the total volume of wells) drilled holes 4 with a diameter of 50 ... 70 mm and multilayer or mobile thermocouples 5 are installed in them. Then, fuel and air are supplied through the nozzle 3, which, mixing, form a combustible mixture igniting at the outlet of the pipe nozzle extension from the electric igniter 6. The combustion temperature in the well is maintained within 800 ...

1000 ° C. Soil firing is carried out with traces 7 from the bottom up, starting from the bottom of the well. As a result of the temperature effect on the soil 8 around the walls of the wells by convective, radiation and heat-conducting heat transfer, intense soil firing occurs. Combustion of fuel is carried out until a temperature C at a temperature of 400 ° C is reached on the wall of the hole, which is controlled by a thermocouple 5. This means that the soil at a distance t has been fired at temperatures of 400 ... 1000 ° C. At the same time, the compressive strength of the soil increased from

91

1 ... 1.5 to 10 ... 40 kg / cm2, which ensures the stability of the walls of the wells during subsequent soaking. In the process of burning in the soil, organic impurities burn out, micro cracks appear as a result of drying of the soil, as a result of which the filtration properties increase by 35 ... 5 times, which provides a significant increase in the water permeability of the borehole walls.

The firing of the soil in the walls of the wells is carried out by grippers of 25 ... 30 wells simultaneously in each. The firing of the soil of one grab lasts 2 ... 3 days, then the technological equipment is remounted to the next grab. After the burning of the soil in the walls of the wells throughout the site, they begin to soak the subsidence through the wells 9 and the excavation pit 10, which unites all the wells. Soaking of the subsidence through burned wells occurs much more intensively compared to prototype soaking, since the drainage material filling the wells has a resistance to the flow of water, moreover, the pores of the soil in the unfired walls of the wells collate, which reduces significantly the degree of filtration of water.

Soaking is continued until complete saturation of the soil of the subsidence, while monitoring is carried out through observation wells. I

At the end of soaking in each

the well is lowered into containers with explosive charges and exploded. Soaking and dynamic effects lead to intensive compaction of soils throughout the depth of the subsidence of the future building. In the process of explosions, the burned walls of the wells destroy-} s, since the pressure from the blast wave exceeds by k order the strength of the burnt soil. As a result of soil compaction of the subsidence, its daily surface sinks to 1–2 m, and subsidence is completely eliminated. While the soil is compacted, it has a low deformation modulus, since is in a fluid consistency. Therefore, there is a need to arrange a soil cushion, the compaction of which is carried out by rolling or tamping.

eat. Then proceed to the installation of foundations.

In the proposed method of soil compaction, a well-known technological procedure is used - soil firing (see Methodological recommendations on the technology of thermal fixing of subsurface soils to a depth of 25 m. K., NIISK, 1982) 6, as well as L.V. Goncharova. , M., MSU, p. 12A, however, the goal and the final result are completely different,

Firstly, in the proposed method of soil compaction, the known technological procedure is used for firing the soil only in the borehole walls with a thickness of 10 ... 15 cm around it to obtain a cylinder of burned soil replacing the Functions of the pipe in order to protect the borehole walls from melting and maintaining its stability so that after soaking it would be possible to immerse explosive charges in its cavity to the required depth of the subsidence and thereby exclude scarce pipes from the compaction technology. Secondly, soil firing in the walls of wells is used to increase the filtration capacity of wells, i.e. its flow rate in order to accelerate the process of soaking soils subsiding thickness, while excluding the drainage material (crushed stone or sand) from the compaction technology. At the same time, soil firing in the walls of the wells is carried out only by 2/3 of the depth of the subsidence.

The final result of applying soil burning in the proposed method is to increase the efficiency of compaction of subsiding soils by reducing the volume of drilling operations, speeding up the process of soaking subsidence, saving pipes and drainage material, while the final result of burning soils in the known method Ј6j - eliminating subsidence of soils due to their thermal hardening in the subsidence. In this case, the purpose of burning the soil is to obtain fixed arrays (ground columns) with a diameter of 2 ... 3 m each. Moreover, soil firing becomes effective only if it is carried out to the full depth of the subsidence.

1117

If in the proposed method, ultimately, the elimination of subsidence occurs due to the destruction of the natural bonds between the soil particles and, consequently, the structure of the soil and its compaction, in the well-known method 6J, the elimination of subsidence occurs vice versa due to the strengthening of the natural connections.

A distinctive feature of the proposed method in comparison with the prototype is that the blast holes are simultaneously drainage, and the protection of their walls against melting is carried out by firing the soil around them, while firing the soil to a depth of 2/3 of the propel power. Sadochnaya stratum.

In the prototype, the protection of the walls of explosive wells against melting is carried out by chemical methods, for example, by silicification. At the same time, liquid glass or other reagents are injected into the pores of the soil, where the formation of gel of silicic or other acids occurs as a result of chemical reactions, as a result of which soil is strengthened in the walls of the wells, however, they become water-tight. with explosive wells, drill drainage wells, and the protection of their walls against water flow and ensure the filtration of water should be filled with rubble or coarse sand; the depth of fixing of explosive wells does not exceed the depth of Our initial landing pressure, i.e., no more than 6 ... 7 m, which, with a large thickness of the landing thickness, for example, 30 ... 40 m, is not enough, since the effect of a blast wave at such a depth is very weak.

These distinctive features of the proposed method in comparison with the prototype provide the following effect: the volume of drilling operations is reduced, the time of spudding is reduced

- Q

0 5 0

0

five

312

vanilla subsiding strata, there is no need for drainage material. In addition, since in the practice of introducing the method of compaction of subsiding soils by presoaking using explosive energy, the fixation of the walls of explosive wells by chemical methods is not used due to the absence of chemical reagents in large quantities, pipes are used to ensure transportation of charges to the required depth, The proposed method saves pipes.

Claims (1)

Invention Formula A method of compacting an array of priming soil, including the formation of a pit, drilling drainage-explosive wells with securing their walls from melting, soaking the soil through the wells, placing explosive charges in the wells, and carrying out a ground own-weight explosion, differing from that, in order to increase the efficiency of compaction by reducing the volume of drilling, increasing the filtering ability of the borehole walls and eliminating debris, the consolidation of the borehole walls dissolved by their calcination at fOO-1000 ° C in the form of an annular layer at a depth equal to 2/3 subsidence column array, wherein the thickness of the layer is taken equal koltsevrgo ,, determined by the magnitude of the function t-pa- Е R - Р p ha where r is the well radius; Pq - water saturated pressure soil at the bottom of the well; R is the compressive strength of the burnt soil. VOLHH. Fuel. / / 7 / // / ss / s / / / / / / s / s / ig.1 YU, W77V U /// /// /// a $ rz% Zamamivank prokladnoy Blasting thicker Figg Fig.Z