A fluid-solidified soil filling body structure for a deep foundation pit adjacent to water and a construction method thereof

Abstract

The present application belongs to the technical field of foundation pit trench backfill construction, and particularly relates to a flow state solidified soil filling body structure for a water-adjacent deep foundation pit and a construction method thereof. The flow state solidified soil filling body structure provided by the present application comprises a backfill body filled in a foundation pit trench area and a seepage prevention curtain arranged on the periphery of the foundation pit trench area. The backfill body comprises, from bottom to top, a horizontal seepage prevention layer, a flow state solidified soil main body and a sealing layer, and a plurality of reinforcing mesh cloths are arranged horizontally in the flow state solidified soil main body. The seepage prevention curtain comprises a base structure and a main structure, the base structure is formed by flow state solidified soil, and the main structure comprises a vertical seepage prevention layer and flow state solidified soil layers arranged on the two surfaces of the vertical seepage prevention layer. The flow state solidified soil filling body structure for a water-adjacent deep foundation pit provided by the present application significantly improves the seepage prevention performance, avoids uneven subsidence of the backfill structure, and ensures long-term seepage prevention and stability of the surrounding environment of the building.

Description

Technical Field

[0001] This invention belongs to the field of foundation pit backfilling construction technology, specifically relating to a fluidized solidified soil filling structure for deep foundation pits near water and its construction method. Background Technology

[0002] Deep foundation pit projects in densely populated urban areas or near water, especially those in water-adjacent environments, present severe challenges to the construction of the core basement structure. These projects are located adjacent to high-water bodies with immense groundwater pressure and high permeability, placing extremely high demands on the integrity and reliability of the foundation pit's seepage prevention system. The seepage prevention curtain, as a crucial barrier against external water intrusion, must possess absolutely reliable seepage prevention performance. Simultaneously, the foundation pit trench area used to protect the basement sidewalls must also possess excellent sealing properties; any localized leakage defects could trigger significant risks such as soil erosion, structural uplift, and even project instability. Furthermore, the enormous buoyancy generated by high groundwater levels makes the anti-buoyancy stability of the entire foundation pit structure a core issue concerning project safety, which must be fully guaranteed.

[0003] With the acceleration of urbanization and the rapid development of the construction industry, foundation pit construction plays an increasingly important role in building engineering. However, traditional foundation pit backfilling methods have many problems. Traditional lime-soil or concrete backfilling methods are difficult to implement in narrow and deep foundation pits, making it hard to guarantee backfill quality and easily leading to settlement and leakage, affecting the stability of the building's foundation. Furthermore, conventional backfilling methods often require layered compaction, resulting in long construction periods, low efficiency, and safety hazards associated with continuous construction within limited working spaces.

[0004] To address these issues, fluidized bed solidified soil backfilling technology has gained increasing attention in recent years. Fluidized bed solidified soil possesses excellent fluidity and plasticity, allowing for rapid casting and shaping in confined spaces, effectively improving construction efficiency. However, single-component fluidized bed solidified soil backfilling still suffers from insufficient impermeability, failing to effectively prevent groundwater infiltration and easily leading to uneven settlement of the backfill structure, thus impacting the surrounding environment.

[0005] To further improve seepage prevention performance and structural stability, some projects have adopted various seepage prevention measures, such as setting up seepage barriers and using composite seepage prevention materials. However, these measures often adopt a split structure, with the seepage barrier and the backfill material of the trench being independent of each other in terms of material selection and construction sequence. This results in a weak interface between the two, becoming a weak link for leakage and making it difficult to effectively prevent leakage in the long term. Summary of the Invention

[0006] The purpose of this invention is to provide a fluidized solidified soil backfill structure for deep foundation pits near water and its construction method. The fluidized solidified soil backfill structure for deep foundation pits near water provided by this invention significantly improves the seepage prevention performance, avoids uneven settlement of the backfill structure, and ensures the long-term seepage prevention and stability of the surrounding environment of the building.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] The present invention provides a fluidized solidified soil backfill structure for deep foundation pits near water, including a backfill body filling the foundation pit trench area and a seepage-proof curtain set around the foundation pit trench area;

[0009] The backfill body comprises, from bottom to top, a horizontal impermeable layer, a fluidized solidified soil body, and a sealing layer. Several reinforcing mesh fabrics are horizontally arranged in the fluidized solidified soil body.

[0010] The seepage barrier curtain consists of a base structure and a main structure from bottom to top. The base structure is formed by fluidized solidified soil, and the main structure includes a vertical seepage barrier layer and fluidized solidified soil layers disposed on both surfaces of the vertical seepage barrier layer.

[0011] The top of the seepage barrier is flush with the top of the backfill, and the depth of the main structure of the seepage barrier is greater than the height of the backfill.

[0012] Preferably, the fluidized solidified soil slurry forming the structure of the fluidized solidified soil filling body for the deep foundation pit near water comprises the following components in parts by mass: 75-82 parts of engineering waste soil, 12-15 parts of hydrophobic cementitious material, 0.8-1.2 parts of water-reducing component, and 18-22 parts of water; the particle size of the engineering waste soil is ≤5mm; the hydrophobic cementitious material is composed of sulfoaluminate cement and calcium stearate in a mass ratio of 8-9:1; the water-reducing component is composed of polycarboxylate water-reducing agent and sodium gluconate in a mass ratio of 3-4:1.

[0013] Preferably, the horizontal impermeable layer comprises, from bottom to top, a sodium-based bentonite composite waterproof felt and a linear low-density polyethylene film;

[0014] The reinforcing mesh fabric consists of at least two layers, and the vertical spacing between any two adjacent layers of the reinforcing mesh fabric is 1.5~2m.

[0015] The sealing layer is formed by a two-component water glass sealant, which includes component A and component B, with a volume ratio of component A to component B of 4~5:1; component A is sodium silicate, and the modulus n (SiO2 / Na2O molar ratio) of the sodium silicate is 3.2~3.4; component B is potassium fluorosilicate solution, and the mass content of K2SiF6 in the potassium fluorosilicate solution is 12~15%.

[0016] Preferably, the reinforced mesh fabric comprises, from bottom to top, a styrene-acrylic emulsion impregnated nylon mesh fabric and a sulfoaluminate cement-based interface agent layer;

[0017] The styrene-acrylic emulsion impregnated nylon mesh is formed by impregnating nylon mesh with styrene-acrylic emulsion, and the nylon mesh has a pore size of 20 mm.

[0018] The sulfoaluminate cement-based interface agent layer is formed by a sulfoaluminate cement-based interface agent, which comprises the following components by mass percentage: 80-90 wt% sulfoaluminate cement, 5-15 wt% silica fume, and 3-8 wt% redispersible latex powder. The water-cement ratio of the sulfoaluminate cement-based interface agent is 0.28, and the thickness of the sulfoaluminate cement-based interface agent layer is 1.0-1.5 mm.

[0019] Preferably, the vertical impermeable layer is a linear low-density polyethylene film; the thickness of the linear low-density polyethylene film is 1.2~1.5mm, and the permeability coefficient is ≤10. -12 m / s.

[0020] Preferably, the depth d of the vertical impermeable layer is determined by formula (1):

[0021] Formula (1);

[0022] In formula (1):

[0023] ;

[0024] H b : Depth of the foundation pit trench area, in meters;

[0025] H w Total depth of the seepage-proof curtain, in meters;

[0026] k w : Permeability coefficient of the seepage-proof curtain, m / s;

[0027] k b : Permeability coefficient of vertical impermeable layer, m / s;

[0028] L: Length of the seepage-proof curtain parallel to the length direction of the foundation pit trench area, in meters;

[0029] B: Thickness of the waterproof curtain, in meters;

[0030] Δh: The difference in water head between the inside and outside of the foundation pit trench area, in meters. h1 is the depth from the groundwater level outside the foundation pit trench area to the bottom of the anti-seepage curtain, in meters; h2 is the depth from the water level inside the foundation pit trench area to the bottom of the curtain, in meters.

[0031] Preferably, the difference between the depth of the main structure of the seepage-proof curtain and the height of the backfill is 0.3~0.5m.

[0032] This invention provides a construction method for the fluidized solidified soil backfill structure for deep foundation pits adjacent to water, as described in the above technical solution, comprising the following steps:

[0033] The pre-cast structure is obtained by pouring fluidized solidified soil slurry according to the base structure of the seepage barrier. The height of the pre-cast structure is greater than the height of the base structure of the seepage barrier. Then, the vertical seepage barrier layer is hoisted to the pre-cast structure and inserted into it. The fluidized solidified soil slurry is then poured on both surfaces of the vertical seepage barrier layer to obtain the seepage barrier.

[0034] A horizontal impermeable layer is laid at the bottom of the foundation pit trench area; then, fluidized solidified soil slurry is poured in layers in the foundation pit trench area, with reinforcing mesh fabric set between the layers during the layered pouring construction; forming the fluidized solidified soil body; finally, a sealing layer is constructed before the final layer of fluidized solidified soil slurry is fully set, to obtain the fluidized solidified soil filling structure for the deep foundation pit near water.

[0035] Preferably, the height h' of the precast structure is determined by formula (2):

[0036] Formula (2);

[0037] In formula (2):

[0038] H w Total depth of the seepage-proof curtain, in meters;

[0039] h': Height of the precast structure, in meters;

[0040] d: Depth of the vertical impermeable layer, in meters (m).

[0041] Preferably, the horizontal waterproofing layer is laid using a narrow roll material combined with a mechanical spreading system, with folds made on both the inner side of the waterproofing curtain and the outer wall of the basement, and the fold height h'' satisfying 0.5m≤h''≤1.0m;

[0042] The method of layered pouring construction includes:

[0043] Divide the foundation pit into skip sections along its length, with an interval of no less than 4 hours between fillings of the fluidized solidified soil slurry in adjacent skip sections; and perform vibration compaction when using layered pouring construction.

[0044] The time t for the vibration operation is determined by formula (3):

[0045] Formula (3);

[0046] In formula (3):

[0047] t: Vibration time, in minutes;

[0048] H b : Depth of the foundation pit trench area, in meters;

[0049] W: Width of the foundation pit trench area, in meters;

[0050] l: Length of the jump section, ranging from 6 to 8 meters;

[0051] h: Height of each layer of pouring, ranging from 1.5 to 2.0 meters;

[0052] k: Vibration efficiency coefficient, k=1.0.

[0053] This invention provides a fluidized solidified soil backfill structure for deep foundation pits near water, comprising a backfill body filling the pit trench area and a seepage barrier curtain surrounding the trench area. The backfill body, from bottom to top, comprises a horizontal seepage barrier layer, a fluidized solidified soil body, and a sealing layer. The fluidized solidified soil body contains several horizontally arranged reinforcing mesh fabrics. The seepage barrier curtain, from bottom to top, comprises a base structure and a main structure. The base structure is formed of fluidized solidified soil, and the main structure includes a vertical seepage barrier layer and fluidized solidified soil layers disposed on both surfaces of the vertical seepage barrier layer. The top of the seepage barrier curtain is flush with the top of the backfill body, and the depth of the main structure of the seepage barrier curtain is greater than the height of the backfill body. This invention uses fluidized solidified soil of the same material and formula to cast the seepage barrier curtain and backfill body, ultimately forming an integrated structure. This avoids the problem of voids and cracks easily forming at the interface between the seepage barrier curtain and backfill body due to material differences, reducing the risk of leakage in this area and significantly improving the integrity and airtightness of the seepage prevention system. Furthermore, this invention utilizes fluidized solidified soil to form an integrated structure of the seepage barrier and backfill, enabling rapid casting within narrow foundation pit spaces, significantly improving construction efficiency and solving the problems of long construction periods and difficult construction associated with traditional backfilling methods. By vertically embedding a vertical seepage barrier layer inside the seepage barrier and setting a horizontal seepage barrier layer at the bottom of the foundation pit trench area, this invention forms a multi-layered seepage barrier structure, effectively blocking both vertical and horizontal groundwater infiltration, significantly improving seepage prevention performance, avoiding uneven settlement of the backfill structure, and ensuring the stability of the surrounding environment of the building.

[0054] Furthermore, the fluidized solidified soil slurry forming the structure of the deep foundation pit near water comprises the following components in parts by weight: 75-82 parts of engineering waste soil, 12-15 parts of hydrophobic cementitious material, 0.8-1.2 parts of water-reducing component, and 18-22 parts of water; the particle size of the engineering waste soil is ≤5mm; the hydrophobic cementitious material is composed of sulfoaluminate cement and calcium stearate in a mass ratio of 8-9:1; the water-reducing component is composed of polycarboxylate water-reducing agent and sodium gluconate in a mass ratio of 3-4:1. Because the foundation pit area is usually narrow and has a complex and varied shape, conventional backfill materials and construction methods are difficult to achieve sufficient filling and effective compaction, easily leaving voids and potential seepage channels. This requires the backfill material to have good self-leveling properties and high fluidity, capable of automatically filling narrow corners without dead angles, ensuring the formation of a uniform and dense backfill body. Meanwhile, the backfill material, after hardening, must possess sufficient mechanical strength to meet the requirements of providing effective lateral support for deep foundation pit projects and to withstand subsequent superstructure loads and the buoyancy of persistent groundwater over the long term. However, under the framework of traditional technologies, achieving high fluidity, high strength, and low engineering costs simultaneously presents significant challenges. This invention utilizes hydrophobic cementitious materials to impart hydrophobicity to the surface of engineering waste soil, generating a ball-bead effect. The water-reducing components synergistically enhance the effect through electrostatic repulsion, spatial hindrance, and chelation. Thus, the fluidized solidified soil slurry in this invention, by adding hydrophobic cementitious materials and water-reducing components, achieves dual regulation of fluidity and viscosity, maintaining good fluidity while reducing viscosity during construction, improving the uniformity of pouring and the convenience of construction. This results in the fluidized solidified soil slurry possessing excellent self-leveling and high fluidity during the construction phase, capable of filling narrow trenches without dead corners. After hardening, it forms a solid whole with sufficient strength, while significantly utilizing the waste engineering waste soil generated on the construction site, thus significantly reducing material costs. Furthermore, the sodium gluconate in the water-reducing component locks in the polyvalent metal ions in the slag through chelation, preventing the high-valent metal ions from binding the bound water when complexing with hydroxyl / carboxyl groups, thereby increasing the effective water-cement ratio and further improving the fluidity of the solidified soil slurry.

[0055] Furthermore, the vertical impermeable layer is a linear low-density polyethylene film (LLDPE film); the thickness of the linear low-density polyethylene film is 1.2~1.5mm, and the permeability coefficient is ≤10. -12 m / s. LLDPE film can directly cut the shrinkage cracks of fluidized solidified soil, block internal seepage, and ensure the long-term reliability of vertical seepage prevention; it makes the seepage prevention curtain form a dense seepage prevention structure, effectively blocking the seepage path inside the seepage prevention curtain, while eliminating the risk of interface slippage and improving the seepage prevention performance of the interface.

[0056] Furthermore, the horizontal seepage barrier layer comprises, from bottom to top, a sodium-based bentonite composite waterproof felt and a linear low-density polyethylene (LLDPE) film. In the horizontal seepage barrier layer, the LLDPE film blocks vertical seepage; the underlying sodium-based bentonite expands upon contact with water to form a bottom seal, effectively blocking the seepage path of groundwater around the bottom of the barrier. Through the colloidal pressure generated by its expansion and its secondary expansion capacity upon contact with high-calcium water, it actively provides anti-buoyancy force, significantly improving the overall anti-buoyancy stability of the structure and reducing or avoiding reliance on additional anti-buoyancy structures. Thus, in this invention, the horizontal seepage barrier layer, by blocking vertical groundwater seepage through the LLDPE film and utilizing the interlayer expansion reaction of the sodium-based bentonite, forms a composite structure with multiple seepage-proof and anti-buoyancy properties, effectively solving the stability problem of traditional seepage prevention measures under complex geological conditions.

[0057] Furthermore, the sealing layer is formed by a two-component water glass sealant, which includes component A and component B, with a volume ratio of component A to component B of 4-5:1. Component A is sodium silicate (Na2O·nSiO2), and the modulus n (SiO2 / Na2O molar ratio) of the sodium silicate (Na2O·nSiO2) is 3.2-3.4. Component B is a potassium fluorosilicate solution, and the mass content of K2SiF6 in the potassium fluorosilicate solution is 12-15%. This invention uses a two-component water glass sealant to form a three-dimensional silica-oxygen network sealing layer that is chemically bonded to the surface of the fluidized solidified soil through rapid reaction, and densely fills surface cracks with a micro-expansion effect. This sealing layer has the characteristic of continuing to condense upon contact with water, and can dynamically self-repair micro-cracks caused by external force damage, completely sealing the channels for rainwater intrusion from the top, greatly improving the reliability and durability of the top seepage prevention. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the fluidized solidified soil filling structure for deep foundation pits near water provided by the present invention;

[0059] Figure 2 This is a schematic diagram of the horizontal impermeable layer structure in this invention;

[0060] In the diagram: 1 is the seepage barrier curtain, 2 is the vertical seepage barrier layer, 3 is the fluidized solidified soil body, 4 is the horizontal seepage barrier layer, 5 is the reinforced mesh fabric, 6 is the basement side wall; 7 is the sodium-based bentonite composite waterproof felt, and 8 is the linear low-density polyethylene film. Detailed Implementation

[0061] The present invention provides a fluidized solidified soil backfill structure for deep foundation pits near water, including a backfill body filling the foundation pit trench area and a seepage-proof curtain set around the foundation pit trench area;

[0062] The backfill body comprises, from bottom to top, a horizontal impermeable layer, a fluidized solidified soil body, and a sealing layer. Several reinforcing mesh fabrics are horizontally arranged in the fluidized solidified soil body.

[0063] The seepage barrier curtain consists of a base structure and a main structure from bottom to top. The base structure is formed by fluidized solidified soil, and the main structure includes a vertical seepage barrier layer and fluidized solidified soil layers disposed on both surfaces of the vertical seepage barrier layer.

[0064] The top of the seepage barrier is flush with the top of the backfill, and the depth of the main structure of the seepage barrier is greater than the height of the backfill.

[0065] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0066] The structural schematic diagram of the fluidized solidified soil backfill structure for deep foundation pits near water provided by this invention is shown below. Figure 1 As shown below, in conjunction with Figure 1 The present invention provides a detailed description of the fluidized solidified soil filling structure for deep foundation pits near water.

[0067] The fluidized solidified soil backfill structure for deep foundation pits near water provided by this invention includes a backfill body filling the trench area of ​​the foundation pit. In this invention, the height of the backfill body is equal to the depth of the trench area of ​​the foundation pit. One side of the backfill body is a basement interior wall, and the other side is provided with a seepage-proof curtain; that is, the backfill body only fills the trench area (i.e., the backfill area) between the basement interior wall and the seepage-proof curtain.

[0068] In this invention, the backfill body comprises, from bottom to top, a horizontal impermeable layer, a fluidized solidified soil body, and a sealing layer, wherein the fluidized solidified soil body is provided with several horizontally arranged reinforcing mesh fabrics.

[0069] In this invention, the horizontal impermeable layer preferably comprises, from bottom to top, a sodium-based bentonite composite waterproof felt and a linear low-density polyethylene film (LLDPE film).

[0070] In this invention, the thickness of the linear low-density polyethylene film in the horizontal impermeable layer is preferably 1.2~1.5 mm, and the permeability coefficient is preferably ≤10. -12 m / s.

[0071] In this invention, the upper surface of the horizontal impermeable layer contacts the fluidized solidified soil body. The horizontal impermeable layer possesses multiple impermeable and anti-buoyancy properties. The LLDPE film in the horizontal impermeable layer can block the vertical infiltration of groundwater; when the sodium-based bentonite encounters groundwater, it undergoes an interlayer expansion reaction, and the expanded colloid is squeezed into the pores of the foundation soil to form a bottom seal, eliminating the path for groundwater to seep around the bottom of the impermeable curtain to the fertilizer trench filling area, thus improving the overall anti-buoyancy performance of the structure. When the calcium ion concentration in the groundwater is ≥100mg / L, the bentonite undergoes a reorganization reaction, and the reorganization product expands again upon contact with water, maintaining the integrity of the seal and ensuring the long-term anti-buoyancy stability of the structure.

[0072] In this invention, the principle of the expansion reaction is as follows:

[0073] .

[0074] In this invention, the principle of the recombination reaction is as follows:

[0075] .

[0076] In this invention, the fluidized solidified soil body is formed by casting fluidized solidified soil slurry. The reinforcing mesh fabric in the fluidized solidified soil body preferably consists of at least two layers, and the vertical spacing between any two adjacent layers of reinforcing mesh fabric is preferably 1.5~2m.

[0077] In this invention, the reinforced mesh fabric preferably comprises, from bottom to top, a styrene-acrylic emulsion impregnated nylon mesh fabric and a sulfoaluminate cement-based interface agent layer. The styrene-acrylic emulsion impregnated nylon mesh fabric is formed by impregnating nylon mesh fabric with a styrene-acrylate emulsion (i.e., styrene-acrylic emulsion), and the pore size of the nylon mesh fabric is preferably 20 mm. In this invention, after impregnation with the styrene-acrylic emulsion, resin anchoring points can be formed at the nylon mesh joints, improving pull-out resistance.

[0078] The sulfoaluminate cement-based interface agent layer is preferably formed by a sulfoaluminate cement-based interface agent, which preferably comprises the following components by mass percentage: 85 wt% sulfoaluminate cement, 10 wt% silica fume, and 5 wt% redispersible latex powder. The water-cement ratio of the sulfoaluminate cement-based interface agent is preferably 0.28. The thickness of the sulfoaluminate cement-based interface agent layer is preferably 1.0~1.5 mm. This invention preferably uses a composite of styrene-acrylic emulsion impregnated nylon mesh and a sulfoaluminate cement-based interface agent layer, which can significantly improve the interlayer bonding strength of the fluidized solidified soil.

[0079] In this invention, the sealing layer is preferably formed of a two-component water glass sealant. The two-component water glass sealant preferably comprises component A and component B, with the volume ratio of component A to component B preferably being 4:1. Component A is preferably sodium silicate (Na₂O·nSiO₂), and the modulus n (SiO₂ / Na₂O molar ratio) of the sodium silicate (Na₂O·nSiO₂) is preferably 3.2 to 3.4. Component B is preferably a potassium fluorosilicate (K₂SiF₆) solution, and the mass content of K₂SiF₆ in the potassium fluorosilicate solution is preferably 12% to 15%.

[0080] In this invention, the modulus n (SiO2 / Na2O molar ratio) of the sodium silicate (Na2O·nSiO2) is 3.2~3.4, and it dissociates into chain-like silicate ions [-O-Si(OH)2-O-] after dissolving in water. m (m=8~12). The potassium fluorosilicate (K2SiF6) solution concentration is 12~15%, which hydrolyzes to generate active fluoride ions and hydrogen ions. After mixing components A and B, hydrogen ions trigger the protonation of silicate ions to form silanol groups ≡Si-OH. Adjacent silanol groups undergo dehydration condensation to construct a three-dimensional silicon-oxygen network. Residual fluoride ions complex with silicon ions in the silicon-oxygen network to generate [SiF6]. 2- The unreacted silanol groups fill the pores and form ≡Si-O-Ca chemical bridges with calcium ions on the surface of the fluidized solidified soil. The reaction principle is as follows:

[0081] ;

[0082] ;

[0083] .

[0084] In this invention, the hydrogen ions released by the dehydration condensation reaction react with the residual Ca(OH)₂ and sulfate ions in the fluidized solidified soil to generate a dihydrate gypsum micro-expansion phase. The volume expansion generated by this reaction compresses the silica network, densely filling the surface micro-cracks and eliminating interfacial voids. The ≡Si-O-Ca- chemical bond bridges react with Ca in the hydration products of the fluidized solidified soil through silanol groups. 2+ Through bonding, the sealing layer and the fluidized solidified soil form an integral seepage-proof interface, improving the seepage-proof performance of the top of the foundation pit trench area. Unreacted silanol groups (≡Si-OH) remain in the solidified sealing layer, which can continue to undergo a condensation reaction upon contact with water. This reaction can automatically seal micro-cracks caused by external force damage, achieving dynamic self-repair. The reaction principle is as follows:

[0085] ;

[0086] ;

[0087] .

[0088] The fluidized solidified soil backfill structure for deep foundation pits near water provided by this invention includes a seepage barrier curtain disposed around the perimeter of the foundation pit backfill area (i.e., outside the backfill area). In this invention, the seepage barrier curtain comprises a base structure and a main structure from bottom to top. The base structure is formed of fluidized solidified soil, and the main structure includes a vertical seepage barrier layer and fluidized solidified soil layers disposed on both surfaces of the vertical seepage barrier layer. In this invention, the thickness of the base structure and the main structure are equal. The total depth of the seepage barrier curtain is the sum of the depth of the base structure and the depth of the main structure. The permeability coefficient of the seepage barrier curtain is expressed as the permeability coefficient of the fluidized solidified soil sample.

[0089] In this invention, the vertical impermeable layer is preferably a linear low-density polyethylene (LLDPE) film; the thickness of the LLDPE film is preferably 1.2~1.5 mm, and the permeability coefficient is preferably ≤10. -12 m / s.

[0090] In this invention, the depth d of the vertical impermeable layer is calculated and determined according to formula (1):

[0091] Formula (1);

[0092] In formula (1):

[0093] ;

[0094] H b : Depth of the foundation pit trench area, in meters;

[0095] H w Total depth of the seepage-proof curtain, in meters;

[0096] k w : Permeability coefficient of the seepage-proof curtain, m / s;

[0097] k b : Permeability coefficient of vertical impermeable layer, m / s;

[0098] L: Length of the seepage-proof curtain parallel to the length direction of the foundation pit trench area, in meters;

[0099] B: Thickness of the waterproof curtain, in meters;

[0100] Δh: The difference in water head between the inside and outside of the foundation pit trench area, in meters. h1 is the depth from the groundwater level outside the foundation pit trench area to the bottom of the anti-seepage curtain, in meters; h2 is the depth from the water level inside the foundation pit trench area to the bottom of the curtain, in meters.

[0101] In this invention, the vertical impermeable layer penetrates the main structure of the impermeable curtain vertically, and its LLDPE film can directly cut off the shrinkage cracks generated when the fluidized solidified soil hardens, thus blocking the seepage path inside the impermeable curtain.

[0102] In this invention, the top of the seepage-proof curtain is flush with the top of the backfill, the depth of the main structure of the seepage-proof curtain is greater than the height of the backfill, and the height of the backfill is equal to the depth of the foundation pit trench area. The difference between the depth of the main structure of the seepage-proof curtain and the height of the backfill is preferably 0.3~0.5m, and in this embodiment, it can be 0.5mm.

[0103] In this invention, the backfill material filling the foundation pit and the seepage prevention curtain set outside the backfill area are an integrated structure formed by pouring fluidized solidified soil slurry.

[0104] The fluidized solidified soil body in the backfill and the base structure of the seepage prevention curtain, as well as the fluidized solidified soil layer of the main structure of the seepage prevention curtain, are formed by pouring fluidized solidified soil slurry.

[0105] In this invention, the fluidized solidified soil slurry forming the structure of the fluidized solidified soil filling body for the deep foundation pit near water comprises the following components in parts by mass: 75-82 parts of engineering waste soil, 12-15 parts of hydrophobic cementitious material, 0.8-1.2 parts of water-reducing component, and 18-22 parts of water; the particle size of the engineering waste soil is ≤5mm; the hydrophobic cementitious material is composed of sulfoaluminate cement and calcium stearate in a mass ratio of 8-9:1; the water-reducing component is composed of polycarboxylate water-reducing agent and sodium gluconate in a mass ratio of 3-4:1.

[0106] In this invention, the particle size of the engineering waste soil is ≤5mm. The stearate anion (C0.05) generated by the hydrophobic cementitious material through the hydrolysis of calcium stearate in an alkaline environment... 17 H 35 COO - It can react with the silanol (Si-OH) on the surface of engineering waste soil to form a monomolecular hydrophobic layer, significantly increasing the contact angle of the engineering waste soil surface to 105°~110°. The formed hydrophobic film can reduce the frictional resistance between particles, giving the fluidized solidified soil slurry a ball-bearing effect and improving its fluidity. The reaction principle is as follows:

[0107] ;

[0108] .

[0109] The carboxyl groups (-COOH) in the polycarboxylic acid molecules of the water-reducing component ionize into negative ions (-COO₂) in an alkaline environment. -This generates a strong electrostatic repulsion force that breaks down the granular flocculation structure, while the polyoxyethylene side chains of polycarboxylic acid (-(CH2CH2O)) also react. n -) It extends in water to form a hydration layer, preventing particles from approaching each other through steric hindrance, reducing the viscosity of the fluidized solidified soil slurry, and improving its fluidity. The sodium gluconate, through chelation, locks in multivalent metal ions (such as Fe) in the slag soil. 3+ Al 3+ This avoids the binding of bound water by high-valence metal ions when they complex with hydroxyl / carboxyl groups, thereby increasing the effective water-cement ratio and further improving the fluidity of the solidified soil slurry. The reaction principle is as follows:

[0110] ;

[0111] .

[0112] In this invention, the preferred method for preparing the fluidized solidified soil slurry includes: dry mixing engineering waste soil, hydrophobic cementitious material, and a portion of water-reducing components to obtain a dry mixture; heating a portion of water to dissolve the remaining water-reducing components to obtain a solution of the remaining water-reducing components; mixing the dry mixture and the solution of the remaining water-reducing components, then adding the remaining water and continuing to stir to obtain the fluidized solidified soil slurry. The engineering waste soil is sieved before dry mixing, and the sieve mesh size is preferably 5 mm. The portion of water-reducing components accounts for 75% of the total mass of the water-reducing components. The dry mixing time is preferably 90 s. The portion of water accounts for 40% of the total mass of the water. The heating temperature of the portion of water is preferably 50 ± 5 °C. The mixing is carried out in a mixer, and the mixing time is preferably 100-120 s. Before adding the remaining water, this invention preferably allows the mixture obtained from stirring to stand for 1-5 minutes. The temperature at which the remaining water is added is preferably room temperature. The continued stirring time is preferably 30-60 s.

[0113] The seepage barrier curtain and horizontal seepage barrier layer in the fluidized solidified soil backfill structure for deep foundation pits near water provided by this invention preferably contain LLDPE film. High-density polyethylene (HDPE) film is commonly used as the seepage barrier membrane in existing engineering projects, while the reason for using LLDPE film in this invention is as follows:

[0114] LLDPE film exhibits excellent resistance to environmental stress cracking: the entanglement between LLDPE molecular chains and its short-branched structure allow it to disperse and absorb stress through chain slippage and reorientation when subjected to stress, making it less prone to cracking. This is crucial for addressing potential uneven settlement in foundation pits. In contrast, the rigid crystalline regions of HDPE are prone to stress concentration points under stress, leading to cracking. HDPE films are also more susceptible to rupture during soil deformation.

[0115] LLDPE film exhibits superior toughness, impact resistance, and puncture resistance: its flexible molecular structure allows it to deform significantly without being punctured or ruptured when subjected to sharp stones or external impacts. HDPE, on the other hand, while possessing high hardness, has relatively poor toughness and is more prone to cracking under significant impact or puncture forces.

[0116] LLDPE film possesses excellent flexibility and ductility. It is very soft and has a high elongation rate, making it easy to lay and better conform to uneven substrates, adapting to changes in terrain. HDPE film, on the other hand, is more rigid and less flexible, requiring a smoother substrate for installation.

[0117] This invention provides a construction method for the fluidized solidified soil backfill structure for deep foundation pits adjacent to water, as described in the above technical solution, comprising the following steps:

[0118] The pre-cast structure is obtained by pouring fluidized solidified soil slurry according to the base structure of the seepage barrier. The height of the pre-cast structure is greater than the height of the base structure of the seepage barrier. Then, the vertical seepage barrier layer is hoisted to the pre-cast structure and inserted into it. The fluidized solidified soil slurry is then poured on both surfaces of the vertical seepage barrier layer to obtain the seepage barrier.

[0119] A horizontal impermeable layer is laid at the bottom of the foundation pit trench area; then, fluidized solidified soil slurry is poured in layers in the foundation pit trench area, with reinforcing mesh fabric set between the layers during the layered pouring construction; forming the fluidized solidified soil body; finally, a sealing layer is constructed before the final layer of fluidized solidified soil slurry is fully set, to obtain the fluidized solidified soil filling structure for the deep foundation pit near water.

[0120] This invention uses fluidized solidified soil slurry to pour into the base structure of the seepage barrier to obtain a pre-cast structure. The height of the pre-cast structure is greater than the height of the base structure of the seepage barrier. Then, the vertical seepage barrier layer is hoisted into the pre-cast structure and inserted into it. Fluidized solidified soil slurry is then poured onto both surfaces of the vertical seepage barrier layer to obtain the seepage barrier.

[0121] Before excavating the foundation pit, this invention first determines the total depth d of the vertical seepage barrier layer; then, it uses fluidized solidified soil slurry to pour the precast structure according to the base structure of the seepage barrier curtain. When pouring the precast structure using fluidized solidified soil slurry, this invention pours the structure according to the base structure of the seepage barrier curtain, that is, according to the shape of the base structure, only the pouring height is greater than the height of the base structure.

[0122] In this invention, the height h' of the precast structure is preferably calculated and determined according to formula (2):

[0123] Formula (2);

[0124] In formula (2):

[0125] H w Total depth of the seepage-proof curtain, in meters;

[0126] h': Height of the precast structure, in meters;

[0127] d: Depth of the vertical impermeable layer, in meters (m).

[0128] In this invention, the top of the vertical seepage barrier is flush with the top of the seepage barrier curtain, which ensures that the bottom of the vertical seepage barrier is inserted to a depth of 0.5m in the pre-cast fluidized solidified soil to achieve the anchoring effect. At the same time, it can ensure that the vertical seepage barrier is less disturbed during the subsequent pouring process.

[0129] After obtaining the seepage-proof curtain, the present invention lays a horizontal seepage-proof layer at the bottom of the foundation pit trench area; then, a fluidized solidified soil slurry is used for layered pouring construction in the foundation pit trench area, and a reinforcing mesh is set between the layers during the layered pouring construction; forming the fluidized solidified soil body, and finally, a sealing layer is constructed before the final layer of fluidized solidified soil slurry is poured to obtain the fluidized solidified soil filling body structure for the deep foundation pit adjacent to water.

[0130] In this invention, the horizontal seepage-proof layer is preferably laid using a segmented laying method. The laying method of the horizontal seepage-proof layer preferably uses narrow-width roll material combined with a mechanical spreading system, with folds made on both the inner side of the seepage-proof curtain and the outer wall of the basement, and the fold height h'' satisfying 0.5m ≤ h'' ≤ 1.0m;

[0131] In this invention, the preferred method for layered pouring of the fluidized solidified soil body includes:

[0132] The foundation pit is divided into skip-section sections along its length, with the preferred length of each section being 6-8 meters. The filling interval between adjacent skip-section sections of the fluidized solidified soil slurry is preferably no less than 4 hours. When using layered pouring construction, vibration is preferred; the vibration is preferably performed using a high-frequency vibrator inserted at a 30° angle into the pouring area, with a preferred vibration power of 200 Hz.

[0133] The vibration operation time t is preferably calculated and determined according to formula (3):

[0134] Formula (3);

[0135] In formula (3):

[0136] t: Vibration time, in minutes;

[0137] H b : Depth of the foundation pit trench area, in meters;

[0138] W: Width of the foundation pit trench area, in meters;

[0139] l: Length of the jump section, ranging from 6 to 8 meters;

[0140] h: Height of each layer of pouring, ranging from 1.5 to 2.0 meters;

[0141] k: Vibration efficiency coefficient, k=1.0.

[0142] In a specific embodiment of the present invention, the present invention preferably performs layered pouring of fluidized solidified soil slurry according to compartments, and the layered pouring height h is preferably 1.5~2.0m. During the pouring process, a high-frequency vibrator (200Hz) is inserted into the pouring area at a 30° angle for vibration.

[0143] In this invention, when using layered pouring construction, a reinforcing mesh is placed between the layers. Preferably, the reinforcing mesh is laid before the initial setting of the lower layer (within 60 minutes after pouring).

[0144] In this invention, the preferred method for laying the reinforced mesh fabric includes:

[0145] Lay out nylon mesh cloth impregnated with styrene-acrylic emulsion; then apply sulfoaluminate cement-based interface agent.

[0146] When the present invention adopts layered pouring construction, the overlap width between adjacent skip sections is preferably 100~150mm.

[0147] The present invention preferably involves applying the sealing layer two hours before the final setting of the final layer of the fluidized solidified soil main structure. The sealing layer application preferably includes: spraying the two-component water glass sealant to form a continuous closed-cell membrane.

[0148] The construction method provided by this invention effectively controls the pouring quality of fluidized solidified soil by controlling the number of construction adoptions (such as skip-pour segmented pouring, controlling the interval time, layered pouring combined with reinforced nylon mesh interlayer treatment, precise vibration, top sealing, etc.), reducing shrinkage cracks, ensuring tight interlayer bonding and overall uniform compactness, and providing construction process guarantee for structural performance.

[0149] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0150] Example 1

[0151] This embodiment provides a construction method for a fluidized solidified soil backfill structure for deep foundation pits adjacent to water, including the following steps:

[0152] The fluidized solidified soil slurry used in this embodiment includes the following components in parts by weight: 80 parts of engineering waste soil (particle size ≤ 5mm), 13 parts of hydrophobic cementitious material, 1 part of water-reducing component, and 20 parts of water; the hydrophobic cementitious material is composed of sulfoaluminate cement and calcium stearate in a mass ratio of 9:1; the water-reducing component is composed of polycarboxylate water-reducing agent and sodium gluconate in a mass ratio of 4:1.

[0153] The preparation method of the fluidized solidified soil slurry used in this embodiment includes: passing the engineering waste soil through a 5mm sieve, adding hydrophobic cementitious material and 7% of the water-reducing component, and dry mixing for 90 seconds; preheating 40% of the total water volume to 50±5℃ and dissolving the remaining water-reducing component, then injecting it into a mixer and wet mixing for 120 seconds; letting it stand for 5 minutes, then adding the remaining 60% room temperature water and mixing for 60 seconds before discharging.

[0154] Before Phase I excavation:

[0155] S1. Determine the vertical impermeable layer insertion depth d; the vertical impermeable layer depth d is calculated according to formula (1);

[0156] S2. After the pre-cast height of the anti-seepage curtain reaches h', h' is calculated by formula (2). Then, the vertical anti-seepage layer is hoisted to the middle of the curtain, and the solidified soil on both sides is poured to wrap the anti-seepage layer simultaneously;

[0157] After the completion of the Phase II basement structure:

[0158] S3. Laying the horizontal seepage barrier in sections: The horizontal seepage barrier is laid in sections using a narrow roll material + mechanical spreading system. The roll material is folded back on the inside of the seepage barrier curtain and on the outside of the basement wall. The folding height h'' must meet the requirement of 0.5m≤h''≤1.0m.

[0159] S4. Fertilizer Tank Zoning Planning: Divide the fertilizer tank into sections with a length of 6-8m along its length;

[0160] S5. Pouring of fluidized solidified soil in the fertilizer trench area: Layered pouring construction is adopted, with reinforcing mesh cloth set between layers, and vibration operation is carried out simultaneously; the fluidized solidified soil is poured in layers according to the compartments, and the filling interval of fluidized solidified soil slurry in adjacent skip sections is not less than 4 hours; the overlap width between adjacent skip sections is 100~150mm; the layer pouring height h is 1.5~2.0m. During the pouring process, a high-frequency vibrator (200Hz) is inserted into the pouring area at a 30° angle for vibration. In addition, before the initial setting of the lower layer (within 60 minutes after pouring), a nylon mesh cloth impregnated with styrene-acrylic emulsion (nylon mesh cloth with a pore size of 20mm) is laid, and then a sulfoaluminate cement-based interface agent is applied. The mass ratio of the sulfoaluminate cement-based interface agent is: 85% sulfoaluminate cement, 10% silica fume, 5% redispersible latex powder, water-cement ratio 0.28, and coating thickness 1.0~1.5mm. The reinforced mesh fabric obtained by this method can significantly improve the interlayer bonding force of fluidized solidified soil.

[0161] In this embodiment, the vibration time t is determined by formula (3).

[0162] S6. Sealing and Molding of the Fertilizer Tank: Two hours before the final setting of the last layer of fluidized solidified soil, a two-component water glass sealant is sprayed to form a continuous closed-cell film layer. The two-component water glass sealant is composed of component A, sodium silicate (Na2O·nSiO2), and component B, potassium fluorosilicate solution (K2SiF6), mixed at a volume ratio of 4:1. The modulus n (SiO2 / Na2O molar ratio) of the sodium silicate (Na2O·nSiO2) is 3.2~3.4, and it dissociates into chain silicate ions [-O-Si(OH)2-O-] after dissolving in water. m (m=8~12); the concentration of potassium fluorosilicate solution (K2SiF6) is 12~15%, which hydrolyzes to generate active fluoride ions and hydrogen ions.

[0163] The fluidized solidified soil backfill structure for deep foundation pits near water obtained in this embodiment includes a backfill body filling the trench area of ​​the foundation pit, and a seepage-proof curtain set outside the backfill area of ​​the trench. The backfill body and the seepage-proof curtain are an integrated structure formed by pouring fluidized solidified soil slurry.

[0164] The performance of the fluidized solidified soil filling structure for deep foundation pits near water provided in this embodiment was tested. The test standards included: Beijing Geotechnical Engineering Association Group Standard T / BEGA001-2019, Sichuan Provincial Engineering Construction Local Standard DBJ51 / T188-2022, China Engineering Construction Standardization Association Standard T / CECS1037-2022, Langfang City, Hebei Province Local Standard DB1030 / T298-2023, and American ASTM D6103 standard. All of the above standards take compressive strength and fluidity as the main design performance indicators, and relevant specifications and standards for concrete can also be used as references.

[0165] Regarding the anti-buoyancy performance of basements, the main references are the basic specifications for foundation pits: Code for Design of Building Foundation GB50007-2011 and Technical Standard for Anti-buoyancy of Building Engineering JGJ 476-2019.

[0166] Laboratory test results of the fluidized solidified soil backfill structure for deep foundation pits near water provided by this invention:

[0167] Flowability and compressive strength: Initial flowability can reach 350 mm, and 28-day unconfined compressive strength can reach 5.6 MPa; Saturated permeability coefficient: Test results do not exceed 10. -6 cm / s level; Pit anti-buoyancy stability: The anti-buoyancy stability safety factor can reach more than 1.3.

[0168] As can be seen from the above embodiments, in the fluidized solidified soil backfill structure for deep foundation pits near water provided by the present invention: the present invention uses fluidized solidified soil to form a seepage barrier and backfill, realizing rapid casting in narrow foundation pit spaces, greatly improving construction efficiency, and solving the problems of long construction period and difficult construction of traditional backfill schemes; the present invention forms a multi-layer seepage barrier structure by vertically embedding a vertical seepage barrier layer inside the seepage barrier and setting a horizontal seepage barrier layer at the bottom of the pit, effectively blocking the vertical and horizontal seepage of groundwater, significantly improving seepage prevention performance, avoiding uneven settlement of the backfill structure, and ensuring the stability of the surrounding environment of the building; in the present invention, the fluidized solidified soil slurry achieves dual regulation of fluidity and viscosity by adding hydrophobic cementitious materials and water-reducing components, maintaining good fluidity while reducing the risk of water loss during construction. The viscosity of the material improves the uniformity of pouring and the convenience of construction. In this invention, sodium gluconate locks in polyvalent metal ions in the slag through chelation, preventing high-valence metal ions from binding bound water when complexing with hydroxyl / carboxyl groups, thus increasing the effective water-cement ratio and further improving the fluidity of the solidified soil slurry. In this invention, the vertical seepage barrier layer uses an LLDPE film and a surface solidified soil layer to form a dense seepage barrier structure, effectively blocking the seepage path inside the seepage barrier curtain, while eliminating the risk of interface slippage and improving the seepage barrier performance of the interface. In this invention, the horizontal seepage barrier layer blocks the vertical infiltration of groundwater through an LLDPE film and utilizes the interlayer expansion reaction of sodium-based bentonite to form a composite structure with multiple seepage barriers and anti-buoyancy properties, effectively solving the stability problem of traditional seepage barriers under complex geological conditions.

[0169] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A fluidized solidified soil filling structure for deep foundation pits adjacent to water, characterized in that, The backfill material includes the filling material in the foundation pit trench area, and the seepage prevention curtain set around the foundation pit trench area; the fluidized solidified soil slurry forming the structure of the fluidized solidified soil filling material for the deep foundation pit near water includes the following components in parts by weight: 75-82 parts of engineering waste soil, 12-15 parts of hydrophobic cementitious material, 0.8-1.2 parts of water-reducing component, and 18-22 parts of water; the particle size of the engineering waste soil is ≤5mm; the hydrophobic cementitious material is composed of sulfoaluminate cement and calcium stearate in a mass ratio of 8-9:1; the water-reducing component is composed of polycarboxylate water-reducing agent and sodium gluconate in a mass ratio of 3-4:

1. The backfill body comprises, from bottom to top, a horizontal impermeable layer, a fluidized solidified soil body, and a sealing layer. The fluidized solidified soil body contains several horizontally arranged reinforcing mesh fabrics. The sealing layer is formed by a two-component water glass sealant, comprising component A and component B, with a volume ratio of 4-5:

1. Component A is sodium silicate, and the modulus of the sodium silicate is... n The content of K2SiF6 in the potassium fluorosilicate solution is 12-15% (3.2-3.4%). The reinforced mesh fabric comprises, from bottom to top, a styrene-acrylic emulsion impregnated nylon mesh fabric and a sulfoaluminate cement-based interface agent layer. The styrene-acrylic emulsion impregnated nylon mesh fabric is formed by impregnating nylon mesh fabric with a styrene-acrylate emulsion. The sulfoaluminate cement-based interface agent layer is formed by a sulfoaluminate cement-based interface agent, which comprises the following components by mass percentage: 80-90 wt% sulfoaluminate cement, 5-15 wt% silica fume, and 3-8 wt% redispersible latex powder. The impermeable curtain comprises a base structure and a main structure from bottom to top. The base structure is formed of fluidized solidified soil. The main structure includes a vertical impermeable layer and fluidized solidified soil layers disposed on both surfaces of the vertical impermeable layer. The vertical impermeable layer is a linear low-density polyethylene film; the thickness of the linear low-density polyethylene film is 1.2~1.5mm, and the permeability coefficient is ≤10. -12 m / s; The top of the seepage barrier is flush with the top of the backfill, and the depth of the main structure of the seepage barrier is greater than the height of the backfill.

2. The fluidized solidified soil filling structure for deep foundation pits adjacent to water as described in claim 1, characterized in that, The horizontal impermeable layer comprises, from bottom to top, a sodium-based bentonite composite waterproof felt and a linear low-density polyethylene film; The reinforcing mesh fabric consists of at least two layers, and the vertical spacing between any two adjacent layers of the reinforcing mesh fabric is 1.5 to 2 meters.

3. The fluidized solidified soil filling structure for deep foundation pits adjacent to water as described in claim 1 or 2, characterized in that, The nylon mesh has a pore size of 20 mm; the water-cement ratio of the sulfoaluminate cement-based interface agent is 0.28; and the thickness of the sulfoaluminate cement-based interface agent layer is 1.0~1.5 mm.

4. The fluidized solidified soil filling structure for deep foundation pits adjacent to water as described in claim 1, characterized in that, The depth of the vertical impermeable layer d Determined by formula (1): Official (1); In formula (1): ； H b : Depth of the foundation pit trench area, in meters; H w Total depth of the seepage-proof curtain, in meters; k w : Permeability coefficient of the seepage-proof curtain, m / s; k b : Permeability coefficient of vertical impermeable layer, m / s; L : The length of the seepage-proof curtain parallel to the length direction of the foundation pit trench area, in meters; B Thickness of the waterproof curtain, in meters (m); Δ h The difference in water head between the inside and outside of the foundation pit trench area, in meters. , h 1 represents the depth from the groundwater level outside the foundation pit to the bottom of the anti-seepage curtain in the foundation pit trench area, in meters; h 2 represents the depth from the water level in the foundation pit to the bottom of the curtain wall, in meters.

5. The fluidized solidified soil filling structure for deep foundation pits adjacent to water as described in claim 1, characterized in that, The difference between the depth of the main structure of the seepage-proof curtain and the height of the backfill is 0.3~0.5m.

6. The construction method of the fluidized solidified soil backfill structure for deep foundation pits adjacent to water as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The pre-cast structure is obtained by pouring fluidized solidified soil slurry according to the base structure of the seepage barrier. The height of the pre-cast structure is greater than the height of the base structure of the seepage barrier. Then, the vertical seepage barrier layer is hoisted to the pre-cast structure and inserted into it. The fluidized solidified soil slurry is then poured on both surfaces of the vertical seepage barrier layer to obtain the seepage barrier. A horizontal impermeable layer is laid at the bottom of the foundation pit trench area; then, fluidized solidified soil slurry is poured in layers in the foundation pit trench area, with reinforcing mesh fabric set between the layers during the layered pouring construction; forming the fluidized solidified soil body; finally, a sealing layer is constructed before the final layer of fluidized solidified soil slurry is fully set, to obtain the fluidized solidified soil filling structure for the deep foundation pit near water.

7. The construction method according to claim 6, characterized in that, The height of the precast structure h Determined by formula (2): Official (2); In formula (2): H w Total depth of the seepage-proof curtain, in meters; h ': Height of the precast structure, in meters; d : Depth of the vertical impermeable layer, in meters (m).

8. The construction method according to claim 6, characterized in that, The horizontal waterproofing layer is laid using a narrow roll material combined with a mechanical spreading system, with folds made on both the inner side of the waterproofing curtain and the outer wall of the basement, and the fold height h'' satisfying 0.5m≤h''≤1.0m; The method of layered pouring construction includes: Divide the foundation pit into skip sections along its length, with an interval of no less than 4 hours between fillings of the fluidized solidified soil slurry in adjacent skip sections; and perform vibration compaction when using layered pouring construction. The time of the vibration operation t Determined by formula (3): Official (3); In formula (3): t Vibration time, in minutes; H b : Depth of the foundation pit trench area, in meters; W Width of the foundation pit trench area, in meters; l : Length of the jump section, ranging from 6 to 8 meters; h The height of each layer of pouring should be 1.5~2.0m. k Vibration efficiency coefficient k =1.0.

Images