A joint grouting reinforcement and repair technology suitable for soft soil conditions

Abstract

The present invention discloses a joint grouting reinforcement and repair technology for floors under soft soil geological conditions, and relates to the technical field of building floor reinforcement and repair. The present invention drills holes at the settlement of the building floor to install a polyurethane grouting pipe, injects a two-component polyurethane foaming agent under the floor, and injects foamed cement slurry in the gaps formed by lifting, so as to fill the gaps and make up for the defect of insufficient elastic modulus of the polyurethane material. The innovation of the present invention is to use polyurethane grouting reinforcement technology to solve the settlement problem of building floors under soft soil geological conditions. The injected two-component polyurethane and foamed cement slurry have a smaller bulk density than the soil, and the slurry remains in a floating state in the soil body and is not easy to flow downward; and the permeability coefficient of soft soil is extremely low, and the water in the injected foamed cement slurry is not easy to penetrate and lose, and the lifting force formed by grouting is not easy to dissipate through the drainage and consolidation of the environmental soil body. The secondary grouting uses foamed cement slurry, which greatly reduces the construction cost.

Description

Technical Field

[0001] The invention belongs to the field of building floor reinforcement and repair, and specifically relates to a joint grouting reinforcement and repair technology for floors in soft soil conditions. Background Art

[0002] The soft soil in the prior art is a kind of soil with specific engineering characteristics, which has a large natural porosity, high compressibility, poor permeability, high disturbance, low shear strength, and contains fine-grained soil such as organic matter and minerals. Due to these characteristics, soft soil is difficult to drain and consolidate, and compaction operations are also difficult. In the construction field, especially for buildings built on soft soil, the floor disease problems caused by uneven settlement of the foundation soil are very common. Generally speaking, after 3 to 5 years of construction on soft soil, new buildings may experience obvious uneven settlement of the floor, and the settlement difference can even reach tens of centimeters. This will cause serious defects such as cracking, hollowing, and misalignment on the floor, which will seriously affect the use function of the floor.

[0003] Traditional grouting reinforcement methods mainly use inorganic materials represented by cement slurry and water glass for grouting. Commonly used grouting methods include static pressure method and high-pressure rotary spraying method. However, cement slurry takes a long time to solidify, and its bulk density is greater than that of the soil. When cement slurry is injected into the soil, due to the effect of gravity, the cement slurry tends to flow downward, resulting in material waste and possible groundwater pollution. In addition, inorganic grouting materials themselves do not have expansion properties, resulting in the lifting effect of pressure grouting being unclear and uncontrollable, making it difficult to achieve precise lifting.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a joint grouting reinforcement and repair technology for floors under soft soil geological conditions.

[0006] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0007] A joint grouting reinforcement and repair technology suitable for soft soil geological conditions, including the following process:

[0008] Step 1: A grid line of polyurethane grouting pipes is arranged on the ground cloth;

[0009] Step 2: Inject foamed cement slurry into the hole in the center of the grid to fill the hollow area under the floor;

[0010] Step 3: Drill holes at the intersection of the grid lines and install the two-component polyurethane grouting pipe;

[0011] Step 4: Inject two-component polyurethane foaming agent into single or multiple points synchronously. The polyurethane foaming agent will react with polyamine and polyurea to lift and reinforce the subsidence floor.

[0012] Step 5: Drill holes and inject foamed cement slurry into the gaps where the polyurethane grouting pipe group is arranged to fill the gaps formed after the floor is lifted and form cement reinforcement bodies;

[0013] Step 6: After the foamed cement slurry is injected, maintenance is carried out.

[0014] Optionally, grid lines for polyurethane grouting pipes are laid out on the ground. The polyurethane grouting pipes are laid out in a matrix or in a plum blossom shape. In areas with larger settlement, the spacing between the polyurethane grouting pipes is 0.5-1.5m, and in areas with smaller settlement, the spacing between the polyurethane grouting pipes is 1-5m. At the foamed cement slurry grouting points, holes are drilled and injected with foamed cement slurry to fill the hollow areas under the floor to form reinforced soil under the floor. The bulk density of the injected foamed cement slurry is 12-20kN / m³, and the grouting pressure of the first grouting is 0-3MPa.

[0015] Optionally, a polyurethane grouting pipe is installed by drilling at the intersection of the grid lines. The outer diameter of the polyurethane grouting pipe is 10mm to 30mm. The diameter of the drilled hole is 1 to 2mm larger than the outer diameter of the polyurethane grouting pipe. The installation depth of the polyurethane grouting pipe can be between 0 and 2m below the floor. The gap between the outer wall of the polyurethane grouting pipe and the hole is sealed with sealing materials. The two-component polyurethane grouting pipe consists of three branch pipes that are mixed into a main pipe at the end. The branch pipes are a polyether polyol slurry outlet pipe, a polyisocyanate slurry outlet pipe and a high-pressure air pipe.

[0016] Optionally, a two-component polyurethane foaming agent is mixed with polyether polyol (material A) and polyisocyanate (material B) and various additives. The polyurethane materials A and B are injected into the mixing pipe through two branch pipes at the same time and injected into the soil under the floor. During grouting, the main pipe can be connected to high-pressure gas to help mixing and pressurizing. The high-pressure gas can be compressed air, nitrogen, carbon dioxide, argon, etc. The input pressure of the high-pressure gas is 2 to 10 MPa, the single pressure is 0 to 10 MPa, the single grouting time is 5 to 30 s, the interval time of a single grouting is 5 to 30 s, the single grouting amount is 0.5 to 3 kg, and a check device is provided on the grouting pipe to prevent the slurry from being re-injected due to the foaming pressure.

[0017] Optionally, 15 to 60 minutes after the two-component polyurethane grouting foaming lifting is completed, the strength of the polyurethane foamed solid reaches 90% to 95% of the final strength, and holes are drilled in the gaps where the polyurethane grouting pipes are arranged to install foamed cement slurry grouting pipes. The outer diameter of the grouting pipes is 20 to 30 mm, and the installation depth of the grouting pipes is 0.1 to 1.5 m below the floor. The two-component polyurethane mixture undergoes polyamine and polyurea reactions under the action of catalysts and various additives, and its volume expansion can reach 2 to 10 times in a confined space, and its expansion stress reaches 0.5 to 10 MPa. The elastic modulus of the polyurethane foam solid body is generally low, in the range of 50 to 500 MPa. The secondary injection of foamed cement slurry has a bulk density of 12 to 20 kN / m³, and its cubic compressive strength design value should be 1.0 to 10 MPa. The secondary injection of foamed cement slurry has a grouting pressure of 0 to 3 MPa. After the secondary injection of foamed cement slurry is completed, it is cured for 14 to 28 days according to the daily average temperature.

[0018] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art. Of course, any product implementing the present invention does not necessarily need to achieve all the advantages described below at the same time:

[0019] 1. This joint grouting reinforcement and repair technology for soft soil geological conditions solves the settlement problem of building floors in soft soil geological conditions by using polyurethane grouting reinforcement technology. The density of the injected two-component polyurethane and foamed cement slurry is smaller than that of the soil. The slurry remains in a floating state in the soil and is not easy to flow downward; and the permeability coefficient of soft soil is extremely low, and the water in the injected foamed cement slurry is not easy to penetrate and lose. The lifting force formed by grouting is not easy to dissipate through the drainage and consolidation of the environmental soil. The secondary grouting uses foamed cement slurry, which greatly reduces the construction cost. This process is very suitable for the repair and reinforcement of soft soil geological floor settlement.

[0020] The combined grouting reinforcement and repair technology for floors under soft soil geological conditions adopts a method of combined grouting of two-component polyurethane and foamed cement slurry to effectively control uneven settlement of the floor and improve the stability and safety of the floor. The key to this technology is to use foamed cement slurry to make up for the problem of insufficient elastic modulus of polyurethane foam material, so that the stress state of the floor is better, while significantly reducing costs. The technology of the present invention is suitable for reinforcing and repairing building floors under soft soil geological conditions. The particles of soft soil are extremely small and the permeability coefficient is extremely low. The lifting pressure formed by the polyurethane material during the foaming process is not easy to dissipate through the drainage and consolidation of the environmental soil. The bulk density of ordinary cement slurry is relatively large. During grouting, it will flow downward due to gravity. The bulk density of the two-component polyurethane foaming agent and the foamed cement slurry is smaller than that of the soil. During grouting, they will not penetrate downward and flow away. The slurry is in a floating state in the soil, with good reinforcement effect and no pollution to the environment.

[0021] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described below are only some embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0023] Figure 1 A schematic diagram of a process flow of an embodiment of the present invention;

[0024] Figure 2 This is a plane schematic diagram of the grid lines of the grouting pipe arrangement of the present invention;

[0025] Figure 3 It is a cross-sectional schematic diagram of floor settlement and hollowing disease under soft soil conditions of the present invention;

[0026] Figure 4 This is a cross-sectional schematic diagram of the present invention for filling hollows and gaps with pressure-injected foamed cement slurry;

[0027] Figure 5 It is a schematic diagram of the polyurethane grouting equipment and grouting pipe of the present invention;

[0028] Figure 6 This is a schematic cross-sectional view of the injection molding of the two-component polyurethane foam material according to the present invention.

[0029] Figure 7 This is a schematic diagram of filling gaps with secondary injection of foamed cement slurry according to the present invention.

[0030] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0031] The present invention will now be described in further detail with reference to the accompanying drawings.

[0032] See also Figure 1 As shown, in this embodiment, a joint grouting reinforcement and repair technology for flooring under soft soil conditions is provided, including the following process flow:

[0033] Step 1: A grid line of polyurethane grouting pipes is arranged on the ground cloth;

[0034] Step 2: Inject foamed cement slurry into the hole in the center of the grid to fill the hollow area under the floor;

[0035] Step 3: Drill holes at the intersection of the grid lines and install the two-component polyurethane grouting pipe;

[0036] Step 4: Inject two-component polyurethane foaming agent into single or multiple points synchronously. The polyurethane foaming agent will react with polyamine and polyurea to lift and reinforce the subsidence floor.

[0037] Step 5: Drill holes and inject foamed cement slurry into the gaps where the polyurethane grouting pipe group is arranged to fill the gaps formed after the floor is lifted and form cement reinforcement bodies;

[0038] Step 6: After the foamed cement slurry is injected, maintenance is carried out.

[0039] The two-component polyurethane foaming agent of this embodiment is mixed with materials A and B and various additives, wherein:

[0040] Material A: polyether polyol, polyester polyol, colorless or light yellow oily liquid, including but not limited to the following compounds: polyethylene glycol, polypropylene glycol, copolymer of ethylene oxide and propylene oxide, ethylene oxide polyoxypropylene ether, etc. Its main characteristics are polyhydroxy-containing alcohols and ether polymers, with a molecular weight of 200-2000 and a hydroxyl value of 30-600.

[0041] Material B: polyisocyanate, brown oily liquid, including but not limited to the following compounds: diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (PMDI), etc. Its main feature is that it is a macromolecular compound containing polyisocyanate. The amount of material B is 1.0 to 1.5 times the mass of material A.

[0042] Catalyst: When the reaction starts, a large amount of gas is generated within 5 to 10 seconds, which catalytically accelerates the reaction speed of polyurethane materials A and B, and rapidly expands their volume. Polyurethane foaming reaction catalysts include but are not limited to the following compounds: dicyandiamide, azobisisobutyronitrile, azodicarbonamide, triethylenediamine, bis(dimethylaminoethyl)ether, etc. The catalyst dosage is 0.5% to 3% of the mass of material A.

[0043] Flame retardant: Two-component polyurethane materials react with polyamine and polyurea in a confined space, generating a large amount of heat. The internal temperature can rise to over 160°C, causing the reaction core to carbonize, affecting the foaming effect and posing a safety hazard. When two-component polyurethane foams, adding an appropriate amount of flame retardant can prevent the reaction core temperature from being too high and ensure the safety of the reaction. Polyurethane foaming reaction flame retardants include but are not limited to the following compounds: tris(2-chloropropyl) phosphate (TCPP), triphenyl phosphate (TPP), etc. The amount of flame retardant is 0.5% to 7% of the mass of material A.

[0044] Cross-linking agent: When the two-component polyurethane material undergoes polyamine and polyurea reactions, adding a small amount of small molecular weight polyol compounds into the reaction system will help expand the molecular weight of the polymer, making its internal structure more integrated and having better mechanical properties. The cross-linking agent for polyurethane foaming reaction includes but is not limited to the following compounds: ethylene glycol, propylene glycol (glycerol), 1,4-butanediol, dimethylaminopropanol, etc. The amount of cross-linking agent is 0.5% to 5% of the mass of material A.

[0045] Foam stabilizer: When two-component polyurethane materials react with polyamine and polyurea, adding a small amount of surfactant into the reaction system helps stabilize the foaming of the reaction, make the internal pores uniform and closed, and improve its impermeability and mechanical properties. Foam stabilizers for polyurethane foaming reactions include but are not limited to the following compounds: methyl silicone oil, monolauryl phosphate, lauryl ether phosphate, etc. The amount of foam stabilizer is 0.1% to 2% of the mass of material A.

[0046] Diluent: When two-component polyurethane material is pressure grouting, a certain amount of diluent can be added to reduce the viscosity of the grouting liquid, so that the grouting penetration and diffusion effect is better. Polyurethane foaming reaction diluents include but are not limited to the following compounds: propylene glycol, ethylene glycol, small molecular polyhydroxy polyether compounds, etc. The diluent dosage is 1% to 20% of the mass of material A.

[0047] The polyurethane A and B materials and various additives of this embodiment are injected into the soil under the floor, and polyamine and polyurea chemical reactions occur. The foaming expansion lifting force is 0-10MPa, and the single-hole grouting foaming lifting radius is 0.5-2m. After the polyurethane foam material is grouted, it is cured within 15 minutes to 1 hour, and its strength reaches 90%-95% of the final strength. After the polyurethane foaming agent is cured, its unconfined compressive strength is 0.5-25MPa, and its elastic modulus is 50-500MPa.

[0048] The injection of two-component polyurethane foaming agent in this embodiment can be a single-hole sequential grouting and lifting, or a multi-hole synchronous grouting. The burial depth of the polyurethane grouting pipe and the foamed cement slurry grouting pipe is 0 to 2m below the floor. The single grouting pressure of the two-component polyurethane material is 0 to 10MPa. Part of the grouting pressure is provided by a double-material grouting machine dedicated to polyurethane, and part of it can be pressurized by an external gas in the grouting pipe. The external gas can be compressed air, nitrogen, carbon dioxide, argon, etc., and the gas pressure is 2 to 10MPa. The grouting pressure of the foamed cement slurry is 0 to 3MPa. The single grouting time of the polyurethane slurry is 5 to 30s, the single grouting lifting amount is 0.1 to 5mm, and the number of single-hole grouting times is 5 to 30 times.

[0049] The foamed cement slurry of this embodiment has a bulk density of 12 to 20 kN / m³ and a cubic compressive strength of 1.0 to 10 MPa. The process of injecting foamed cement slurry starts 15 minutes to 1 hour after the polyurethane foam lifting is completed. The foamed cement slurry can be injected once or divided into 2 to 5 injections. The interval between injections should not exceed the final setting time of the foamed cement slurry. It is advisable to carry out the injection after the initial setting and before the final setting. When the polyurethane grouting lifting height reaches about 100 to 250 mm, its lifting effect gradually decreases. The foamed cement slurry is injected, and the two-component polyurethane foaming agent is injected again after the curing period, and the lifting effect is significantly improved. After the floor settlement exceeds 150 mm, the floor can be lifted and reinforced by recycling this technology, which can improve the repair effect and significantly reduce costs.

[0050] This embodiment uses a two-component polyurethane material to perform continuous and multiple grouting operations to achieve rapid and accurate lifting of the floor. This polyurethane material reacts quickly and can effectively control the lifting height. The bulk density of the two-component polyurethane material and the foamed cement material is lower than that of the soil, so that the slurry remains in a floating state in the soil and is not easy to flow downward. Since the soft soil has extremely fine soil particles and an extremely small permeability coefficient, the water in the injected foamed cement slurry is not easy to penetrate and flow, ensuring that it has sufficient hydration time. The pre-buried grouting hole design allows for secondary grouting at a later stage, increasing the flexibility of construction.

[0051] The technical steps 1 to 7 of the present invention constitute a cycle process. When the floor settlement value exceeds 150 mm, a cycle process should be adopted to achieve floor repair and reinforcement. The cycle interval is 4 to 12 hours. This time range ensures that the initial setting time of the foamed cement slurry is met and the cycle is completed before its final setting time.

[0052] Step 1: Draw the grid lines for the grouting pipes. According to the design requirements, lay out the grid lines for the polyurethane grouting pipes on the ground. The polyurethane grouting pipes can be laid out in a matrix or in a plum blossom shape, as shown below. Figure 1 In the area with large settlement, the spacing of polyurethane grouting pipes is 0.5-1.5m; in the area with small settlement, the spacing of polyurethane grouting pipes is 1-5m.

[0053] Process 2: Drill holes and inject foamed cement slurry for the first time. At the injection point of foamed cement slurry, drill holes and inject foamed cement slurry to fill the hollow area under the floor and form reinforced soil under the floor, as shown below Figure 2 , 3 As shown. The bulk density of the injected foamed cement slurry is 12-20 kN / m³, and the injection pressure of the first injection is 0-3 MPa. After the first injection of foamed cement slurry is completed, it can be cured for 7-14 days according to the temperature conditions during construction before entering the next process.

[0054] Step 3: Drilling and installing polyurethane grouting pipes, such as Figure 3 As shown, a polyurethane grouting pipe 7 is drilled and installed at the intersection of the grid lines. The outer diameter of the polyurethane grouting pipe is 10 to 30 mm, and the diameter of the drilled hole is 1 to 2 mm larger than the outer diameter of the polyurethane grouting pipe. The drilling installation depth of the polyurethane grouting pipe can be between 0 and 2 m below the floor 1. The gap between the outer wall of the polyurethane grouting pipe and the channel is sealed with sealing materials.

[0055] Two-component polyurethane grouting pipe consists of three branch pipes that are mixed into a main pipe at the end. The branch pipes are polyether polyol slurry outlet pipe (material A), polyisocyanate slurry outlet pipe (material B), and high-pressure air pipe. The function of the high-pressure air pipe is to input high-pressure gas to help the slurry mix evenly and increase the grouting pressure.

[0056] Process 4: Preparation of two-component polyurethane foaming agent. The two-component polyurethane foaming agent is a mixture of polyether polyol (material A) and polyisocyanate (material B) and various additives. Before grouting, material A is mixed with catalyst, cross-linking agent and flame retardant to form a mixture; material B is mixed with diluent and foam stabilizer to form a mixture. When the temperature is lower than 20℃ during construction, materials A and B should be preheated before grouting, and the initial temperature should not be lower than 20℃. When grouting in winter, the preheating temperature can reach 30-35℃. Grouting construction is not suitable when the average daily temperature in winter is lower than 5℃.

[0057] Process 5: Two-component polyurethane pressure grouting, polyurethane A and B materials are injected into the main pipe (mixing pipe) through two branch pipes and injected into the soil under the floor. During grouting, the main pipe can be connected to high-pressure gas to help mix and pressurize. The high-pressure gas can be compressed air, nitrogen, carbon dioxide, argon, etc. The input pressure of the high-pressure gas is 2-10MPa.

[0058] The single pressure is 0-10MPa, the single grouting time is 5-30s, the interval time of single grouting is 5-30s, the single grouting volume is 0.5-3kg, and a check device is provided on the grouting pipe to prevent the slurry from being back-injected due to foaming pressure.

[0059] Step 6: Drill holes and install cement grouting pipes, such as Figure 4 As shown, 15 to 60 minutes after the two-component polyurethane grouting foaming is lifted, the strength of the polyurethane foamed solid reaches 90% to 95% of the final strength, and holes are drilled in the gaps between the polyurethane grouting pipes to install the foamed cement slurry grouting pipes. The outer diameter of the grouting pipes is 20 to 30 mm, and the installation depth of the grouting pipes is 0.1 to 1.5 m below the floor.

[0060] Process 7: Secondary injection of foamed cement slurry. Under the action of catalysts and various additives, the dual-combination polyurethane mixture undergoes polyamine and polyurea reactions. The reaction is completed within 15 to 60 seconds. The volume expansion in the confined space can reach 2 to 10 times, and its expansion stress reaches 0.5 to 10 MPa. The high-pressure expansion produces compaction and splitting reinforcement effects on the surrounding soil. By controlling the process parameters such as the single grouting volume, grouting pressure, interval time, and grouting times, the influence range of polyurethane grouting can be controlled. The solidified body formed by the previous grouting and foaming serves as the horizontal constraint for the next grouting and foaming, so that the polyurethane material continuously foams within a certain influence range to form a cylindrical vertical jacking. As the floor is lifted, a large gap will be formed away from the polyurethane grouting point. The lifted floor is subjected to the vertical reaction force of the polyurethane reinforcement near the grouting point, generating negative bending moment and positive bending moment at the hollow. When the lifting height of the polyurethane grouting reaches 100 to 250 mm, the foamed cement slurry can be injected. Step 7 operation method is as follows Figure 6As shown in the figure, the elastic modulus of the polyurethane foam solidified body is generally low, in the range of 50-500MPa. The low elastic modulus causes a certain elastic deformation when the floor is loaded after grouting reinforcement. After the floor is lifted by polyurethane grouting, the foamed cement slurry is injected into the newly formed gaps to fill the gaps. The floor is evenly stressed, and the elastic modulus of the foamed cement slurry after curing is between 1000-3000MPa, which largely makes up for the disadvantage of insufficient elastic modulus of polyurethane materials.

[0061] The bulk density of the secondary injection foamed cement slurry is 12-20 kN / m³, and the design value of its cubic compressive strength should be 1.0-10 MPa. When the foamed cement slurry is prepared, an appropriate amount of expansion agent should be added to avoid the shrinkage of the foamed cement slurry during solidification; when the foamed cement slurry is prepared, an appropriate amount of early strength agent should be added to reduce the time of initial setting and final setting, reduce the water loss before final setting, and ensure sufficient hydration reaction. The grouting pressure of the secondary injection foamed cement slurry is 0-3 MPa. The grouting pressure should be controlled during grouting to prevent the soil from splitting and causing slurry loss.

[0062] Process 8: Curing: After the second injection of foamed cement slurry is completed, cure for 14 to 28 days depending on the daily average temperature.

[0063] The present invention is not limited to the above-mentioned embodiments. Anyone should be aware that any structural changes made under the enlightenment of the present invention, and any technical solutions that are the same or similar to the present invention, fall within the protection scope of the present invention. The technology, shape, and structural parts not described in detail in the present invention are all well-known technologies.

Claims

1. A joint grouting reinforcement and repair method for soft soil floors, characterized in that: Including the following process: Step 1: Lay out the grid lines of polyurethane grouting pipes on the ground to be repaired; the polyurethane grouting pipes are laid out in a matrix or plum blossom shape. In areas with large settlement, the spacing of the polyurethane grouting pipes is 0.5 to 1.5 m, and in areas with small settlement, the spacing of the polyurethane grouting pipes is 1 to 5 m; Step 2: Inject foamed cement slurry into the holes drilled in the center of the grid to fill the hollows in the underground floor; form a reinforced soil under the floor, the bulk density of the injected foamed cement slurry is 12-20 kN / m³, and the grouting pressure of the first grouting is 0-3 MPa; Step 3: Drill holes at the intersection of the grid lines to install the two-component polyurethane grouting pipe; the outer diameter of the polyurethane grouting pipe is 10mm to 30mm, the diameter of the drill hole is 1 to 2mm larger than the outer diameter of the polyurethane grouting pipe, the drilling installation depth of the polyurethane grouting pipe is between 0m and 2m below the floor, and the gap between the outer wall of the polyurethane grouting pipe and the hole should be sealed with sealing materials; Step 4: Inject two-component polyurethane foaming agent into single or multiple points synchronously. The two-component polyurethane foaming agent reacts with polyamine and polyurea to lift and reinforce the subsidence floor. The two-component polyurethane grouting pipe is composed of three branch pipes mixed into a main pipe at the end. The branch pipes are polyether polyol slurry pipe, polyisocyanate slurry pipe and high-pressure air pipe. The two-component polyurethane foaming agent is a mixture of material A: polyether polyol and material B: polyisocyanate and various additives. Material A and material B are mixed into a main pipe. The material is injected into the grouting pipe through two branch pipes at the same time and injected into the soil under the floor. During grouting, the main pipe can be connected to high-pressure gas to help grouting and pressurization. High-pressure gas includes compressed air, nitrogen, carbon dioxide, and argon. The input pressure of high-pressure gas is 2-10MPa, the single pressure is 0-10MPa, the single grouting time is 5s-30s, the interval time of single grouting is 5s-30s, and the single grouting volume is 0.5-3kg. The grouting pipe is equipped with a check device to prevent the slurry from being re-injected due to foaming pressure; Step 5: Drill holes and inject foamed cement slurry in the gaps where the polyurethane grouting pipe group is arranged to fill the gaps formed after the floor is lifted and form a cement reinforcement body; 15 to 60 minutes after the two-component polyurethane grouting foaming is completed, the strength of the polyurethane foamed solid reaches 90% to 95% of the final strength, and drill holes in the gaps where the polyurethane grouting pipe is arranged to install the foamed cement slurry grouting flower pipe. The outer diameter of the grouting flower pipe is 20 to 30 mm, and the installation depth of the grouting flower pipe is 0.1 to 1.5 m below the floor. Under the action of catalysts and various additives, the two-component polyurethane mixture undergoes polyamine and polyurea reactions, and the volume expansion can reach 2 to 10 in a confined space. times, and its expansion stress reaches 0.5-10MPa. By using two-component polyurethane materials for continuous and multiple grouting operations, the floor can be lifted quickly and accurately. The bulk density of two-component polyurethane materials and foamed cement materials is lower than that of soil, so that the slurry remains in a floating state in the soil and is not easy to flow downward. The pre-buried grouting flower pipe design allows for secondary grouting at a later stage. Step 6: After the foamed cement slurry is grouted, it is cured; the elastic modulus of the polyurethane foam solidified body is in the range of 50-500MPa, the secondary injection of foamed cement slurry, its bulk density is 12-20kN / m³, its cubic compressive strength design value should be 1.0-10MPa, and its grouting pressure is 0-3MPa. After the secondary injection of foamed cement slurry is completed, it is cured for 14-28 days according to the daily average temperature. The injection of foamed cement slurry process starts 15 minutes to 1 hour after the polyurethane foam lifting is completed. The foamed cement slurry is injected once, or divided into 2-5 injections. The grouting interval should not exceed the final setting time of the foamed cement slurry, which is carried out after the initial setting and before the final setting. When the polyurethane grouting lifting height reaches 100-250mm, its lifting effect gradually decreases, and the foamed cement slurry is injected. After the curing period, the two-component polyurethane foaming agent is injected again. When the floor settlement exceeds 150mm Finally, the floor is lifted and reinforced in a cycle.

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