RU55796U1 - DEVICE FOR SOIL SEALING AND SOIL BASIS WITH TECHNOGENIC FRAME - Google Patents

Abstract

The proposed technical solutions relate to the field of construction, namely, to the construction of compacted soil foundation and means of compaction of the soil used in its construction during the construction of buildings and structures or during the repair and reconstruction of existing buildings and structures on dispersed bonded or unbound soils, as well as bulk (technogenic) soils and landslide slopes. The technical task is to expand the functionality by compaction of not only dispersed bonded soils - clays, loams, sandy loams, but also unbound dispersed soils - sand, as well as bulk (man-made) soils due to the mode of pumping the solution into the soil when choosing a qualitative solution characteristic that provides its high penetrating ability, as well as the use of means to ensure the creation of an array of soil reinforced with a single frame from the hardened solution. This ensures an increase in the bearing capacity of the soil, effective fixing in a single massif of landslide slopes with the formation of a skeleton in it, a decrease in the material consumption for the technological process, as well as an increase in the pace of work. This is achieved by the fact that the device for compaction of the soil is made in the form of injectors-pipes for pumping cement mortar, placed in increments of 2.0-4.0 m in the soil mass through or under the load in the form of a concrete slab located on dispersed soil with a perforated side surface , the openings of which are blocked at the same time as being destroyed at a pressure of 3.0-20.0 atm. hydraulic fracturing with plugs. The plugs are made in the form of an overlapping hole in the perforation of the tape,

located in a spiral or in the form of rings. The tape is made with a sticky layer facing the perforated pipe. The plugs are formed by several layers of tape, the amount of which is determined by a given value of hydraulic fracturing pressure in the soil. The perforated pipe is equipped with a bottom end plug that is not destructible at fracturing pressure. In a soil foundation having a technogenic frame, this is achieved by using the soil compaction apparatus described above and is a soil mass placed under a load in the form of a concrete slab pierced by injectors in the form of pipes and forming a technogenic frame which has hardened in the hydraulic fractures of the soil cement mortar. The hardened cement mortar around the injectors is located in the plan with mutual penetration into the concentric zones around the adjacent injectors.

Description

The proposed technical solutions relate to the field of construction, namely, to the construction of compacted soil foundation and means of compaction of the soil used in its construction during the construction of buildings and structures or during the repair and reconstruction of existing buildings and structures on dispersed bonded or unbound soils, as well as bulk (technogenic) soils and landslide slopes.

The closest known devices are those for compacting bound dispersed soils to create the foundations of buildings and structures by supplying a hardening mortar in the form of a sand-cement mixture, in which the solution is supplied at a pressure of 2-10 atm. through injectors arranged in increments of 2-3 m in the form of perforated pipes submerged to the depth of the active zone, as a result of which a compacted soil base is formed (RU No. 2059044 C1, E 02 D 3/12, 1996).

Known technical solutions provide soil compaction on dispersed bonded soils, which limits their scope, and the use of cement-sand mixture reduces the penetration of the solution, which negatively affects the bearing capacity of the compacted soil base.

The technical task is to expand the functionality by compaction of not only dispersed bonded soils - clays, loams, sandy loams, but also unbound dispersed soils - sand, as well as bulk (man-made) soils due to the mode of injection of the solution

into the soil when choosing the qualitative characteristics of the solution, providing its high penetrating ability, as well as - the use of tools to create an array of soil reinforced with a single frame from the hardened solution. This ensures an increase in the bearing capacity of the soil, effective fixing in a single massif of landslide slopes with the formation of a skeleton in it, a decrease in the material consumption for the technological process, as well as an increase in the pace of work.

This is achieved by the fact that the device for compaction of the soil is made in the form of injectors-pipes for pumping cement mortar, placed in increments of 2.0-4.0 m in the soil mass through or under the load in the form of a concrete slab located on dispersed soil with a perforated side surface , the openings of which are blocked at the same time as being destroyed at a pressure of 3.0-20.0 atm. hydraulic fracturing with plugs. The caps are made in the form of an overlapping hole in the perforation of a tape located in a spiral or in the form of rings. The tape is made with a sticky layer facing the perforated pipe. The plugs are formed by several layers of tape, the amount of which is determined by a given value of hydraulic fracturing pressure in the soil. The perforated pipe is equipped with a bottom end plug that is not destructible at fracturing pressure.

In a soil foundation having a technogenic frame, this is achieved by using the soil compaction apparatus described above and is a soil mass placed under a load in the form of a concrete slab pierced by injectors in the form of pipes and forming a technogenic frame which has hardened in the hydraulic fractures of the soil cement mortar. The hardened cement mortar around the injectors is located in the plan with mutual penetration into the concentric zones around the adjacent injectors.

Figure 1 shows the injector with a perforated side surface, the openings of which are closed with destructible plugs (a variant of the spiral arrangement of the tape - the upper part and the variant of the ring arrangement of the tape - the lower part);

Figure 2 presents the layout of the injectors in plan with overlapping concentric zones around them.

A device for compaction of soil includes injectors 1 for injecting cement in the form of pipes with holes (perforations) 2 on the side surface. The holes 2 are blocked by destructible plugs 3. The pressure providing hydraulic fracturing of the soil is 3.0-20.0 atm. determined in accordance with the extended categories of soil and the features of fixing it on the slopes. A decrease in pressure does not lead to hydraulic fracturing, and an increase negatively affects economic performance, requiring high performance equipment and increasing the flow rate of the solution. The supply of cement mortar to expand hydraulic fractures can be carried out continuously in a pulsating mode. When installing injectors, the distance between their longitudinal axes is selected from the range of 2.0–4.0 m, which is due to work on various categories of soil with an injection depth of 3.0–8.0 m, which in some cases requires an extension of the injector in length. When compaction of clay flooded soils or water-saturated loams and sandy loams, the water contained in them is pressed and drained. With this compaction of the soil, the injectors in the plan are arranged, as an option, in rows, and the cement mortar in their rows is supplied from the center to the periphery, preferably in a spiral plan, sequentially into each injector or in increments of 1-3 injectors. It is possible, as another option, the arrangement of injectors in the plan in rows, and when cement is supplied in their rows, it is carried out sequentially from the center to the periphery, preferably in the direction radial in the plan, sequentially into each injector or in increments of 1-3 injectors in the radial

direction or alternating between adjacent injectors in adjacent radial directions. The simultaneous destruction of the plugs ensures the formation of hydraulic fracturing in the soil in all directions. The plugs 3 are made in the form of an overlapping hole 2 of the perforation of the tape located in a spiral (figure 1) or in the form of rings. The tape of the plugs 2 is made with a sticky layer facing the perforated pipe. The plugs 2 are formed, as a rule, by several layers of tape, the amount of which is determined by a given value of hydraulic fracture pressure in the soil. In the lower part of the pipe, the lower end plug 4, which is not destroyed by hydraulic fracturing pressure, is placed. The cement mortar around the injectors is located in the plan in the form of a frame 5 with mutual penetration into concentric zones around adjacent injectors

The inclusion of sand and industrial soils in the field of application became possible due to the formation of hydraulic fractures, as without fracturing, the cement slurry penetrated into the pores of the sandy soil without compacting it. Pumping is carried out if there is a foundation plate over several fortified massifs and several (2-Зх) floors of the building. The base plate is a screen that prevents the solution from leaving the massif of soil, and the presence of several floors creates a load that allows you to create pressure, because in the absence of a slab and a load, the injection of a compacting solution leads to a rise (swelling) of the soil stratum above the injection point and sometimes to a breakthrough of the cement mortar to the surface. In order to ensure the formation of hydraulic fractures, the injectors are wrapped in tape, for example with adhesive tape, in several layers. The number of layers of adhesive tape depends on the required pressure at which fractures are formed. As a result of injection, the pressure in the hoses and the injector rises to the hydraulic fracture pressure characteristic of this type of soil and after the adhesive tape ruptures, the solution instantly enters the soil mass and forms hydraulic fractures. The pitch and depth of the location of the injectors depend on the properties of the soil stratum, loads from

structures and power of compressible stratum. The injection volumes depend on the porosity of these soils and the load from a particular structure. If the finely dispersed cement mortar is too liquid, then hydraulic fractures do not form in sandy soils, but cement milk penetrates into the pores of the soil according to the principle of classical cementation. If the solution is too viscous, hydraulic fractures do not form at all and the walls of the well expand and the soil around the well becomes denser.

It is carried out as follows.

The foundation pit is opened to the level of the foundation plate. Standard concrete preparation is being arranged. After hardening of concrete preparation, leader wells are drilled from it. Injectors (a perforated pipe) with a diameter of 30-50 mm are lowered into the leader wells in increments of 2.5 × 2.5 - 3.0 × 3.0 meters to the depth of propagation of soft soils within the compressible zone. The compound of the injector and concrete preparation is packed with a special cement mortar. The release of the injector above the foundation slab is 5-10 cm. After that, the reinforcing cage is knitted according to the design of the foundation slab. After arranging the foundation plate through the reinforcing cage, the injectors are built up with blind pipes so that the injectors rise 10-20 cm above the future foundation plate and the foundation plate is poured with concrete. Before lowering, the injectors are wrapped with adhesive tape to create hydraulic fracturing pressure, which ensures the formation of hydraulic fractures. After arranging the foundation slab, a clay solution is poured into the injector in order to prevent squeezing of weak clay soils into the injector. After completion of the arrangement of the foundation slab, 2-3 floors of the building are erected to create the necessary load, because otherwise, the injection of the sealing solution will not lead to soil compaction, but to the rise of the building. The cement slurry is injected at

fracturing pressure characteristic of this type of soil. As a result, hydraulic fractures form 2-3 meters long in the most weakened areas of the soil mass. The compaction solution, which continues to enter the fractures, expands them and the expanding crack begins to work as an intramuscular jack, compacting an array of soil around itself. When compacting clay flooded and water-saturated loams and sandy loams, water is squeezed out and, accordingly, their consistency changes. The consistency of clay soils changes into 2 categories, i.e. if the soils were fluid plastic, they become stiff, and if soft plastic, they are semi-solid. Frozen sealing solution in hydraulic fractures, which are interconnected, forms a single reinforced frame. After the completion of the injection process, the valve installed on the injector is closed, because otherwise, the elastic deformations of the soil mass will be pushed out by the sealing solution through hydraulic fractures and the injector and the compaction will only partially occur. The valve remains closed until the sealing solution has set. After hardening of the sealing solution, the injector is cut flush with the foundation plate.

As a result of the actions taken, the following occurs:

- Dispersed soils are compacted, while clay dispersed soils at the same time change their texture to harder categories. As a result, all physical and mechanical properties are improved 1.5-2 times.

- The soil mass contains a hardened compacting solution, which forms a single reinforced cage, which increases (due to the presence of hard inclusions) indicators of physical and mechanical properties by another 1.3-1.5 times.

- Injectors, monolithic in the foundation plate, from which hard inclusions of the compacting mortar solidified in the hydraulic fractures are turned into root piles, which take part of the load. At the same time, experiments conducted by evaluation

bearing capacity of root piles, show that their bearing capacity is at least 7-8 tons.

Thus, the resulting pile-frame system in a compacted mass of soil works as a whole and significantly increases the bearing capacity and reliability of the base as a whole.

The use of this particular pile-frame system in a compacted soil mass makes it possible, at lower material costs, to obtain a reliable and efficient-functioning base. Savings are achieved by increasing the pitch of the location of the injectors and reducing the injection volume. Reliability and efficiency are enhanced by the operation of root piles.

Example 1

In an array of weak soft-plastic loams, soil was strengthened under the foundations of the building under construction with a step of 3.5 m × 3.5 m to a depth of 5 meters. Through 160 injectors, a weakly viscous (liquid) solution was injected under the hydraulic fracturing pressure characteristic of these soils (12 atm). As a result, hydraulic fractures formed, which, with further injection, expanded and compacted soft-plastic loams. The hardened cement mortar formed a reinforcing technogenic framework in a compacted and improved soil mass.

Example 2

On a landslide-hazardous slope, folded with loose and refractory clay loams of natural composition, injectors are immersed with a step of 4 × 4 m to a depth of 3 to 8 meters and through them a low-viscosity cement mortar is injected under hydraulic fracturing pressure of 7 atm. Further injection of cement mortar through hydraulic fractures leads to compaction of the soil and the formation of a single reinforcing cage, the presence of which will completely eliminate the possibility of a landslide.

Claims (7)

1. A device for compaction of the soil, made in the form of injectors-pipes for pumping cement mortar, placed in increments of 2.0-4.0 m in the soil mass through or under the load in the form of a concrete slab located on dispersed soil with a perforated side surface, holes which are overlapped simultaneously destructible at a pressure of 3.0-20.0 atm. hydraulic fracturing with plugs. 2. The device for compaction of soil according to claim 1, in which the plugs are made in the form of a covering hole perforation of the tape located in a spiral or in the form of rings. 3. The device for compaction of soil according to claim 1 or 2, in which the tape is made with an adhesive layer facing the perforated pipe. 4. The device for compaction of soil according to claim 1 or 2, in which the plugs are formed by several layers of tape, the amount of which is determined by a given value of the fracturing pressure in the soil. 5. The device for compaction of soil according to claim 1 or 2, in which the perforated pipe is provided with a bottom end cap that is not destructible at fracturing pressure. 6. A soil base with a man-made skeleton made using the soil compaction device according to any one of claims 1 to 5, which is a mass of soil placed under a load in the form of a concrete slab pierced by injectors in the form of pipes and forming a man-made skeleton located in hydraulic fractures soil hardened cement mortar. 7. The soil base with the technogenic framework according to claim 6, in which the hardened cement mortar around the injectors is located in plan with mutual penetration into the concentric zones around adjacent injectors.