Inverted annular slurry accommodating cavity post-grouting device and grouting method

Abstract

The present invention belongs to the field of foundation technology and relates to a post-grouting device and grouting method for an inverted annular slurry receiving chamber, comprising a grouting sleeve, an annular connecting pipe, and a slurry receiving chamber; the grouting sleeves are multiple and arranged vertically and in parallel on the upper surface of the slurry receiving chamber; the slurry receiving chamber is a hollow annular structure; the slurry receiving chamber is sleeved on the outside of the annular connecting pipe; the annular connecting pipe and the slurry receiving chamber are non-contacting; the slurry receiving chamber is provided with a slurry outlet hole that is connected to the interior of the slurry receiving chamber; there are multiple slurry outlet holes; the grouting sleeve is connected to the slurry outlet hole through the annular connecting pipe and the interior of the slurry receiving chamber. The present invention provides a post-grouting device and grouting method for an inverted annular slurry receiving chamber that can perform multi-point grouting, effectively ensure grouting reliability, and significantly improve the bearing capacity of pile foundations.

Description

Technical Field

[0001] The present invention belongs to the technical field of foundation, and relates to a grouting device and a grouting method, and in particular to a grouting device and a grouting method for a back-inverted annular slurry containing cavity. Background Art

[0002] The bearing capacity of bored cast-in-place pile foundations is provided by the pile side friction and the pile end bearing capacity. Due to the presence of mud skin around the pile shaft, the surrounding soil layer, the shrinkage gap between the pile and the soil, and the sediment (sedimentation layer) at the pile bottom, bored cast-in-place piles cannot effectively utilize the pile impedance, and the pile foundation bearing capacity cannot reach the ideal state. Using post-grouting technology to fill the soil around and at the pile bottom increases the pile side friction, expands the pile end support area, and significantly improves the pile's bearing capacity.

[0003] Currently, in the field of foundations, post-grouting of cast-in-place pile ends mainly includes three types: open grouting, closed grouting, and composite grouting. Among them, existing open grouting technology often uses a steel grouting pipe pre-set inside the pile body, connected to a steel grouting device with a flower pipe or a pre-set grouting hole at the bottom. This device has the following disadvantages: few grouting points, few grouting points, uneven grouting diffusion, easy clogging of the grouting hole, and poor pile bottom density; the steel grouting pipe has poor toughness and is easily bent and damaged during construction, making post-grouting impossible. Closed grouting often uses a closed elastic device. For example, the invention application with announcement number CN110896645A discloses a pile bottom grouting chamber and its use method, as well as a cast-in-place pile body and a cast-in-place pile body construction method. The invention includes a grouting capsule, a grouting pipe, and a fixing plate. Grout is injected into the grouting capsule through the grouting pipe to form an enlarged head. However, the volume of the grouting capsule is difficult to control as the pressure increases, and the capsule is easily damaged during the lowering process with the steel cage, thereby affecting the grouting effect. Composite grouting combines the advantages of open and closed grouting. For example, the invention application with the announcement number CN113737786A discloses a pile end bottom grouting device, a cast-in-place pile and its construction method. The invention adds a pair of open grouting pipes on the basis of a closed elastic device; for another example, the invention application with the announcement number CN114922188A discloses a grouting device and a pile end post-grouting construction method. The invention provides a bundled grouting bag with a closed area and a grouting area at the pile end. The same problem of closed grouting exists. The expansion volume of the closed elastic device as the pressure increases is difficult to control, and ultimately only the effect of open grouting is achieved. In addition, there are fewer open grouting pipes, the slurry diffusion uniformity is poor, and the grouting system is complex, with multi-stage pressure grouting and high cost. Summary of the Invention

[0004] In order to solve the above technical problems existing in the background technology, the present invention provides a multi-point grouting device and a grouting method for an inverted annular slurry containing cavity, which can effectively ensure the reliability of grouting and greatly improve the bearing capacity of the pile foundation.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A post-grouting device for an inverted annular slurry accommodating chamber, characterized in that: the post-grouting device for an inverted annular slurry accommodating chamber includes a grouting sleeve, an annular connecting pipe and a slurry accommodating chamber; there are multiple grouting sleeves, and the multiple grouting sleeves are vertically and parallelly arranged on the upper surface of the slurry accommodating chamber; the slurry accommodating chamber is a hollow circular ring structure; the slurry accommodating chamber is sleeved on the outside of the annular connecting pipe; the annular connecting pipe and the slurry accommodating chamber are non-contact; the slurry accommodating chamber is provided with a slurry outlet hole that is connected to the interior of the slurry accommodating chamber; there are multiple slurry outlet holes; the grouting sleeve is connected to the slurry outlet hole through the annular connecting pipe and the interior of the slurry accommodating chamber.

[0007] Preferably, the annular connecting pipe adopted in the present invention includes a three-way joint, which includes an inlet pipe and a slurry circulation pipe connected to the inlet pipe; the inlet pipe and the slurry circulation pipe are generally in an inverted T-shaped structure; the inlet pipe extends from the upper surface of the slurry containing chamber, and the slurry circulation pipe is placed inside the slurry containing chamber; the grouting sleeve is sleeved on the outside of the inlet pipe; an annular groove is provided between the grouting sleeve and the inlet pipe; the slurry circulation pipe is non-contact with the slurry containing chamber; a grouting hole is provided on the side wall of the slurry circulation pipe; flexible pipes are respectively connected to both ends of the slurry circulation pipe; the grouting sleeve is connected to the inside of the slurry containing chamber through the inlet pipe, the slurry circulation pipe and the grouting hole.

[0008] Preferably, the annular connecting pipe used in the present invention further includes a rubber non-return sleeve; the rubber non-return sleeve extends from the outside of the slurry circulation pipe into the inside of the slurry circulation pipe.

[0009] Preferably, the annular connecting pipe used in the present invention further comprises a clamp sleeved on the outside of the flexible pipe for fastening the flexible pipe to the outside of the slurry circulation pipe.

[0010] Preferably, the slurry holding chamber adopted in the present invention includes an annular top plate, an outer plate, an inner plate and an annular bottom plate; the annular top plate, the outer plate, the inner plate and the annular bottom plate as a whole form a hollow circular ring structure with a right-angled trapezoidal cross-section; the slurry outlet hole is arranged on the outer plate and / or the inner plate.

[0011] Preferably, the multiple slurry outlet holes used in the present invention are evenly distributed in the circumferential direction on the outer plate and / or the inner plate.

[0012] Preferably, the slurry outlet hole used in the present invention is trumpet-shaped as a whole; along the direction from the inside to the outside of the slurry containing cavity, the opening of the slurry outlet hole increases successively.

[0013] Preferably, the slurry containing chamber used in the present invention further includes a plug provided on the slurry outlet hole; the plug extends from the outside of the slurry containing chamber into the inside of the slurry containing chamber.

[0014] Preferably, the slurry containing chamber adopted in the present invention also includes a steel flower tube arranged at the bottom of the annular bottom plate and connected with the interior of the slurry containing chamber; the steel flower tube is tapered as a whole; an opening is provided at the bottom of the steel flower tube; the interior of the slurry containing chamber is connected with the opening at the bottom of the steel flower tube through the steel flower tube; the steel flower tube and the slurry outlet hole are staggered.

[0015] A grouting method based on the above-mentioned inverted annular slurry accommodating chamber rear grouting device is characterized in that the grouting method comprises the following steps:

[0016] 1) Assembling the inverted annular slurry receiving chamber and the grouting device;

[0017] 2) Connecting the assembled post-grouting device to the pile foundation reinforcement cage and the acoustic detection tube; preferably, connecting the grouting sleeve of the assembled post-grouting device to the acoustic detection tube; providing a steel lifting ring on the assembled post-grouting device, and connecting the steel lifting ring to the pile foundation reinforcement cage;

[0018] 3) Lower the steel cage equipped with the post-grouting device into the pile hole to the designed depth;

[0019] 4) pouring concrete to form cast-in-place piles;

[0020] 5) After the concrete curing is completed, grouting is carried out through the acoustic detection tube to the rear grouting device to form an expanded head of the steel-concrete composite structure at the pile end;

[0021] Preferably, the specific implementation of step 5) is:

[0022] 5.1) After concrete curing is complete, calculate the initial grouting pressure P = ρgh based on the length of the pile foundation and the physical properties of the medium filled in the acoustic detection tube, where ρ is the grout density, g is the acceleration of gravity, and h is the depth of the pile foundation into the soil. This initial grouting pressure is less than the pressure required to open the rubber check sleeve. Inject grout into one of the acoustic detection tubes. Use the same initial grouting pressure to inject grout into the remaining acoustic detection tubes, maintaining the initial grouting pressure constant. Temporarily seal the openings of the remaining acoustic detection tubes.

[0023] 5.2) increasing the initial grouting pressure until it is greater than a predetermined pressure of the rubber check sleeve (23), wherein the predetermined pressure of the rubber check sleeve (23) is determined by the strength and hardness of the rubber check sleeve (23), and the predetermined pressure can cause the rubber check sleeve (23) to expand laterally and form a gap with the slurry flow pipe, and the predetermined pressure is greater than the initial grouting pressure; under the action of the grouting pressure, the slurry expands the rubber check sleeve, and the slurry is sprayed into the slurry containing cavity through the grouting hole;

[0024] 5.3) Continue to increase the grouting pressure. The slurry in the slurry receiving chamber will push open the plug, penetrate, diffuse and split the soil from the slurry outlet and the bottom opening of the steel tube, and at the same time flow back along the outer periphery of the slurry receiving chamber until the designed grouting volume is reached, forming an enlarged head of the steel-concrete composite structure at the pile end.

[0025] The advantages of the present invention are:

[0026] The present invention provides an inverted annular slurry accommodating chamber post-grouting device and a grouting method, wherein the inverted annular slurry accommodating chamber post-grouting device includes a grouting sleeve, an annular connecting pipe, and a slurry accommodating chamber; the grouting sleeves are multiple, and the multiple grouting sleeves are vertically arranged in parallel on the upper surface of the slurry accommodating chamber; the slurry accommodating chamber is a hollow circular ring structure; the slurry accommodating chamber is sleeved on the outside of the annular connecting pipe; the annular connecting pipe and the slurry accommodating chamber are non-contacting; the slurry accommodating chamber is provided with a slurry outlet hole that is connected to the interior of the slurry accommodating chamber; there are multiple slurry outlet holes; the grouting sleeve is connected to the slurry outlet hole through the annular connecting pipe and the interior of the slurry accommodating chamber. The inverted annular slurry accommodating chamber provided by the present invention is an annular inverted trapezoidal shape, annular and hollow, the interior of the accommodating chamber is hollow, and a steel flower pipe is arranged at the bottom to be embedded in the soil. The inverted trapezoidal configuration utilizes the squeezed sediment at the bottom of the pile to ensure that the pile bottom is dense and facilitates the lowering of the steel cage to the designated position; the hollow interior of the accommodating chamber acts as a protective annular connecting pipe, and the interior is filled with slurry to form a steel-concrete composite structure expansion head; the annular hollow configuration allows the mud water and air in the pile hole to be discharged to the top of the grouting device through the hollow hole when the steel cage is lowered along the pile hole, thereby preventing the mud water from forming a vortex between the grouting device and the pile hole, scouring and damaging the hole wall, causing the hole wall to collapse, and excessive slag at the bottom of the hole, effectively improving the construction quality and progress of the pile body. At the same time, the hollow configuration facilitates secondary hole cleaning and slag removal. The present invention utilizes an acoustic detection tube as a grouting tube, and the lower part of the acoustic detection tube is annularly connected. This configuration can meet the requirements of multi-point synchronous grouting and improve grouting efficiency; simultaneous multi-point grouting can ensure that when a single acoustic detection tube is damaged or blocked and grouting cannot be implemented, the grouting point can be replaced in time, achieving repeated grouting and improving the reliability of grouting. The present invention uses a rubber check sleeve to tightly wrap the grouting hole. When the grouting pressure increases to a predetermined value, the slurry pushes the rubber check sleeve to create a gap and is sprayed into the slurry receiving chamber. At the same time, the rubber check sleeve can simply and effectively ensure one-way slurry discharge from the grouting hole, ensuring that the mixture in the slurry receiving chamber cannot enter the grouting hole, avoiding slurry backflow, and ensuring the pressure in the slurry receiving chamber, thereby providing a guarantee for the smooth subsequent grouting.

[0027] The slurry containing cavity of the present invention has multiple slurry holes arranged in an annular manner inward and outward directions. First, it can ensure the slurry discharge capacity; second, it can ensure the uniformity of slurry injection into the soil around the pile, and effectively inject the slurry into the pile bottom and pile side. At the same time, the slurry containing cavity has slurry holes arranged in an annular manner on the periphery, and the slurry will flow back along the periphery of the steel plate and the gap between the pile and the soil, reinforcing the soil on the side of the pile and improving the physical properties of the soil on the side of the pile. A steel flower pipe is arranged at the bottom of the slurry containing cavity of the present invention, and the steel flower pipe is inserted into the soil at the pile end, which can effectively ensure that the slurry penetrates, diffuses, and splits into the underlying soil at the pile end, and improves the physical properties of the underlying soil at the pile end enlarged head. The device adopts multi-point grouting, which can improve the reliability of grouting; the inverted annular slurry containing cavity and the annular staggered slurry holes can achieve controllability of the slurry injection area and uniformity of grouting. Finally, the slurry, soil and slurry containing cavity form an enlarged head of a steel-concrete composite structure with better bearing performance. The implementation effect of the present invention can better meet the standard theoretical calculation formula and has the following advantages: high rigidity, simple structure, high reliability, simple implementation and operation; multiple grouting points, multiple grouting holes, deep grouting depth, and a single grouting can simultaneously reinforce the pile end, pile side, and the underlying soil of the pile end. High rigidity, simple structure, high reliability, simple implementation and operation; multiple grouting points, multiple grouting holes, deep grouting depth, and a single grouting can simultaneously reinforce the pile end, pile side, and the underlying soil of the pile end.

[0028] The present invention solves a series of problems in open grouting, such as a small number of grouting points, a small number of grouting points, and easy damage to the grouting pipe; a closed grouting elastic device that is easy to damage and difficult to control the expansion volume; a complex composite grouting system, a cumbersome grouting procedure, and high costs. Based on the calculation theory of post-grouting in the specification, the present invention proposes a new solution that uses multi-point grouting and a pile end rigid grouting device to ensure the reliability of grouting. It can simultaneously reinforce the pile end soil, the underlying soil of the pile end, and the pile side soil 5 to 6 meters above the pile end to ensure the grouting effect, and ultimately form a steel-concrete composite structure enlarged head at the pile end, improve the physical properties of the underlying soil and the pile side soil, and significantly improve the bearing capacity of the pile foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the overall structure of the inverted annular slurry accommodating chamber rear grouting device provided by the present invention;

[0030] Figure 2 This is a schematic top view of the structure of the inverted annular slurry accommodating chamber rear grouting device provided by the present invention;

[0031] Figure 3 This is a side structural diagram of the inverted annular slurry accommodating chamber rear grouting device provided by the present invention;

[0032] Figure 4 This invention Figure 2 AA cross-sectional diagram;

[0033] Figure 5 This invention Figure 4 BB cross-sectional diagram;

[0034] Figure 6 This invention Figure 5 Schematic diagram of CC cross section.

[0035] Description of reference numerals:

[0036] 1- grouting sleeve; 2- annular connecting pipe; 21- tee joint; 22- grouting hole; 23- rubber check sleeve; 24- flexible pipe; 25- clamp; 3- slurry containing chamber; 31- annular top plate; 32- outer plate; 33- inner plate; 34- annular bottom plate; 35- slurry outlet hole; 36- plug; 37- steel flower pipe; 38- steel lifting ring. DETAILED DESCRIPTION

[0037] The present invention aims to provide a post-grouting device with an inverted annular slurry containing chamber and a method for using the same, so as to solve the deficiencies of existing open, closed and composite grouting devices.

[0038] See also Figure 1 -6. The embodiment of the present application provides an inverted annular slurry accommodating chamber post-grouting device, which is arranged at the bottom of the pile foundation reinforcement cage; the post-grouting device includes:

[0039] The grouting sleeve 1 is circumferentially positioned and has the same number as the pile foundation acoustic detection pipe. The upper end is tightly connected to the pile foundation acoustic detection pipe, and the lower end is welded to the top of the annular top plate 31 and is connected to the annular connecting pipe 2 through a tee joint 21.

[0040] The annular connecting pipe 2 is placed in the slurry receiving chamber 3. It is composed of a tee joint 21, a grouting hole 22, a rubber check sleeve 23, a flexible pipe 24, and a clamp 25. Grout is injected into the slurry receiving chamber 3 through the grouting hole 22.

[0041] The slurry chamber 3 is formed by welding an annular top plate 31, an outer plate 32, an inner plate 33, and an annular bottom plate 34. Multiple slurry outlet holes 35 are arranged circumferentially on the outer plate 32 and inner plate 33, and are sealed with plugs 36. A steel tube 37 is welded beneath the annular bottom plate 34. When the slurry chamber 3 is filled with slurry, the slurry pressure reaches a certain limit, pushing open the plug and allowing the slurry to penetrate and diffuse into the soil through the outlet holes 35 and steel tube 37.

[0042] In this embodiment, the grouting sleeve 1 is about 100 mm high and its inner diameter is about 4 to 5 mm larger than the outer diameter of the pile foundation acoustic detection tube, so that the acoustic detection tube can be easily inserted into the sleeve.

[0043] like Figures 4-5As shown, the annular connecting pipe 2 is fixed to the annular top plate 31 through the tee joint 21 to achieve the positioning of the annular connecting pipe 2 inside the slurry containing chamber 3, wherein the outer diameter of the tee joint 21 is about 4 to 5 mm smaller than the inner diameter of the pile foundation acoustic detection pipe, and the top end extends out of the annular top plate 31 by about 30 to 50 mm, forming an annular groove with the grouting sleeve 1 on the top surface of the annular top plate 31, and the end of the acoustic detection pipe is stuck in the annular groove.

[0044] like Figure 5 As shown, a plurality of grouting holes 22 are arranged on the surface of the tee joint 21, which is tightly wrapped with a rubber check sleeve 23 to prevent slurry backflow and ensure the pressure inside the slurry containing chamber 3; a flexible tube 24 is sleeved on both ends of the tee joint 21 and fixed by a clamp 25.

[0045] like Figures 1 to 3 As shown, multiple slurry outlet holes 35 are evenly distributed circumferentially on the inner and outer plates of the slurry storage chamber 3. These holes are shaped like a trumpet, larger on the outside and smaller on the inside. Sealing grease is applied to the surface of plugs 36 and pressed against the large ends of the trumpet-shaped holes 35. Steel flower tubes 37 are welded beneath the annular bottom plate 34 and arranged circumferentially in an alternating pattern with the slurry outlet holes 35. This ensures more uniform grouting and covers a wider area.

[0046] The flexible tube 24 is a rubber tube, a plastic hose, a silicone tube or other flexible tubes. The plug 36 is a rubber plug or a multi-layer waterproof tape. The steel flower tube 37 adopts a form with a tapered tip and an open tip.

[0047] The clamp 25 is mainly used to ensure the tightness of the connection between the flexible tube 24 and the three-way joint 21. A sleeve connection or other mechanical connection methods can also be used.

[0048] The rubber check sleeve 23 is a multi-layer rubber sleeve or a rubber sleeve + a clamp or a one-way valve. The steel ring 38 is welded to the annular spiral reinforcement of the pile foundation reinforcement cage to achieve the fixation of the grouting device.

[0049] Those skilled in the art may configure the above description according to actual conditions, and the present invention is not limited thereto.

[0050] An embodiment of the present invention further provides a method for using a post-grouting device, which is applied to the above grouting device and includes the following steps:

[0051] S1. Assemble the grouting device;

[0052] S2. Connect the assembled post-grouting device to the pile foundation reinforcement cage and the acoustic detection tube;

[0053] S3. Lower the steel cage equipped with the post-grouting device into the pile hole to the designed depth;

[0054] S4. pouring concrete to form cast-in-place piles;

[0055] S5. After the concrete is cured, grouting is injected into the pile end through the sonic detection tube to form a steel-concrete composite structure expansion head at the pile end, thereby improving the physical properties of the soil beside the pile and the underlying soil of the pile end expansion head.

[0056] The method for using the pile end post-grouting device provided by the present invention further includes:

[0057] S1. Replace the medium in the acoustic detection tube: The pile foundation acoustic detection tube is connected to the annular connecting pipe 2 and is in a connected state. Before grouting, the grouting pressure P = ρgh is calculated based on the length of the pile foundation and the physical properties of the medium filled in the acoustic detection tube. The grouting pressure value is less than the pressure value of the rubber check sleeve 23.

[0058] Inject slurry into one of the acoustic detection pipes, using the above-mentioned grouting pressure until the slurry is discharged from the other acoustic detection pipes, maintain the pressure constant, and temporarily seal the other acoustic detection pipes;

[0059] S2. Increase the grouting pressure to a predetermined value, the slurry props up the rubber check sleeve 23 to create a gap, and sprays the slurry into the accommodating chamber 3;

[0060] S3. Continue to increase the grouting pressure. The slurry in the slurry receiving chamber 3 opens the plug 36 and the steel tube 37, penetrates, diffuses, and splits the soil from the slurry outlet 35, and at the same time returns along the outer periphery of the slurry receiving chamber 3 until the designed grouting volume is reached.

[0061] When injecting slurry, dual control of grouting pressure and grouting volume should be adopted.

[0062] The grouting volume at different steps is calculated based on the closed dimensions of the device and the dimensions of the bored piles.

[0063] The grouting pressure at different steps is obtained based on theoretical calculations and experimental data.

[0064] Before installing the annular connecting pipe 2, a pre-pressure test should be carried out in advance. The grouting sleeve ports are closed, leaving only one grouting port. Using water as the medium, an initial pressure test is carried out to verify the tightness of the annular connecting pipe 2. The pressure value at which the slurry pushes the rubber check sleeve apart is obtained. The initial pressure is P1, and the P1 value should be calculated and determined based on the pile length and the physical properties of the medium filled in the acoustic testing tube. The pressure is gradually increased until the slurry pushes the rubber check sleeve 23 apart to create a gap and is ejected through the grouting hole 22. This pressure value is the minimum pressure for slurry ejection, P2>P1. The number of layers of rubber check sleeves and whether clamps are required are determined based on the P2 value.

[0065] The present invention utilizes an acoustic detection tube as a grouting pipe, with its lower portion circumferentially connected. This arrangement allows for simultaneous grouting at multiple points, improving grouting efficiency. Simultaneous grouting at multiple points ensures that if a single acoustic detection tube is damaged or clogged, preventing grouting, the grouting point can be promptly replaced, enabling repeated grouting and improving grouting reliability.

[0066] The pile end post-grouting device provided by the present invention has the following mechanism of action on the pile end soil:

[0067] S1. Initially, maintain low pressure grouting. After the grout enters the soil at the pile end, it diffuses and permeates until further injection is impossible at the current pressure or the grouting volume reaches the design requirement. Due to the high density and pressure of the cement slurry, the pore water and free water in the formation are replaced by the cement slurry. The cement slurry then chemically bonds with the pile end sediment and soil, forming cement soil, which significantly increases the overall strength of the soil.

[0068] S2. Gradually increase the grouting pressure, with the slurry mainly acting as a splitting agent, until the grouting volume reaches the specified design requirements. Under high pressure, the slurry splits the soil or forcibly expands and extends the original gap, and then injects cement slurry to form cement slurry veins. The cement slurry veins diffuse downward, which can effectively improve the physical properties of the underlying soil layer of the pile end expansion head and increase the standard value of the bearing capacity of the soil at the pile end. At the same time, under the action of high pressure, the slurry will flow back along the periphery of the slurry containing cavity 3 and the gap between the pile body and the soil, thereby enhancing the friction resistance on the pile side. After the grouting is completed, the slurry and the slurry containing cavity 3 are solidified to form a steel-concrete composite structure expansion head, which increases the cross-sectional area of the pile end and greatly improves the bearing capacity of the pile foundation.

Claims

1. A grouting method based on a rear grouting device with an inverted annular slurry receiving chamber, characterized in that: The grouting method comprises the following steps: 1) Assemble the inverted annular slurry receiving chamber and the grouting device; The inverted annular slurry accommodating chamber post-grouting device comprises a grouting sleeve (1), an annular connecting pipe (2) and a slurry accommodating chamber (3); the grouting sleeves (1) are multiple, and the multiple grouting sleeves (1) are arranged in parallel and vertically on the upper surface of the slurry accommodating chamber (3); the slurry accommodating chamber (3) is a hollow annular structure; the slurry accommodating chamber (3) is sleeved on the outside of the annular connecting pipe (2); the annular connecting pipe (2) and the slurry accommodating chamber (3) are non-contact; the slurry accommodating chamber (3) is provided with a slurry outlet hole (35) that is in communication with the interior of the slurry accommodating chamber (3); the slurry outlet hole (35) is multiple; the grouting sleeve (1) is in communication with the slurry outlet hole (35) through the annular connecting pipe (2) and the interior of the slurry accommodating chamber (3); The annular connecting pipe (2) includes a three-way joint (21), and the three-way joint (21) includes an inlet pipe and a slurry circulation pipe communicating with the inlet pipe; the inlet pipe and the slurry circulation pipe are in an inverted T-shaped structure as a whole; the inlet pipe extends from the upper surface of the slurry accommodating chamber (3), and the slurry circulation pipe is placed inside the slurry accommodating chamber (3); the grouting sleeve (1) is sleeved on the outside of the inlet pipe; an annular groove is provided between the grouting sleeve (1) and the inlet pipe; the slurry circulation pipe and the slurry accommodating chamber (3) are non-contact; a grouting hole (22) is provided on the side wall of the slurry circulation pipe; flexible pipes (24) are connected to both ends of the slurry circulation pipe; the grouting sleeve (1) communicates with the inside of the slurry accommodating chamber (3) through the inlet pipe, the slurry circulation pipe and the grouting hole (22); The annular connecting pipe (2) further comprises a rubber non-return sleeve (23); the rubber non-return sleeve (23) extends from the outside of the slurry circulation pipe into the inside of the slurry circulation pipe; The annular connecting pipe (2) further comprises a clamp (25) which is sleeved on the outside of the flexible pipe (24) and is used to fasten the flexible pipe (24) to the outside of the slurry circulation pipe; The slurry accommodating chamber (3) comprises an annular top plate (31), an outer plate (32), an inner plate (33) and an annular bottom plate (34); the annular top plate (31), the outer plate (32), the inner plate (33) and the annular bottom plate (34) as a whole form a hollow circular ring structure with a right-angled trapezoidal cross section; the slurry outlet hole (35) is provided on the outer plate (32) and / or the inner plate (33); The plurality of pulp outlet holes (35) are uniformly distributed in an annular direction on the outer plate (32) and / or the inner plate (33); The slurry outlet hole (35) is generally trumpet-shaped; along the direction from the inside to the outside of the slurry accommodating cavity (3), the opening of the slurry outlet hole (35) increases in sequence; The slurry accommodating chamber (3) further comprises a plug (36) provided on the slurry outlet hole (35); the plug (36) extends from the outside of the slurry accommodating chamber (3) into the inside of the slurry accommodating chamber (3); The slurry accommodating chamber (3) further comprises a steel flower tube (37) arranged at the bottom of the annular bottom plate (34) and communicating with the interior of the slurry accommodating chamber (3); the steel flower tube (37) is tapered as a whole; an opening is provided at the bottom of the steel flower tube (37); the interior of the slurry accommodating chamber (3) is communicated with the opening at the bottom of the steel flower tube (37) through the steel flower tube (37); the steel flower tube (37) and the slurry outlet hole (35) are arranged in an interlaced manner; 2) Connect the assembled post-grouting device to the pile foundation reinforcement cage and the acoustic detection tube; 3) Lower the steel cage equipped with the post-grouting device into the pile hole to the designed depth; 4) Pour concrete to form cast-in-place piles; 5) After the concrete is cured, grouting is carried out through the sonic detection tube to the rear grouting device to form the expanded head of the pile end steel-concrete composite structure. Specifically: 5.1) After the concrete is cured, the initial grouting pressure is calculated based on the length of the pile foundation and the physical properties of the medium filled in the sonic detection tube. ,in: is the slurry density, is the acceleration due to gravity, is the depth of the pile foundation into the soil; the initial grouting pressure is less than the pressure of the rubber check sleeve (23); grout is injected into one of the acoustic detection pipes, and the same initial grouting pressure is used to inject grout into the remaining acoustic detection pipes, keeping the initial grouting pressure unchanged, and temporarily closing the pipe openings of the other acoustic detection pipes; 5.2) increasing the initial grouting pressure until it is greater than the predetermined pressure of the rubber check sleeve (23); under the grouting pressure, the slurry pushes open the rubber check sleeve (23), and the slurry is sprayed into the slurry receiving chamber (3) through the grouting hole (22); 5.3) Continue to increase the grouting pressure. The slurry in the slurry receiving chamber (3) pushes open the plug (36), penetrates, spreads, and splits the soil from the slurry outlet (35) and the bottom opening of the steel flower tube (37), and at the same time flows upward along the periphery of the slurry receiving chamber (3) until the designed grouting volume is reached, forming an enlarged head of the pile end steel-concrete composite structure.

2. The grouting method according to claim 1, wherein: The specific implementation method of step 2) is to connect the grouting sleeve (1) of the assembled post-grouting device to the acoustic detection pipe; and to provide a steel hanging ring (38) on the assembled post-grouting device, and to connect the steel hanging ring (38) to the pile foundation reinforcement cage.

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