Back-wall grouting slurry diffusion device and test method for simulating shield tail gap

Abstract

A slurry diffusion device for behind-the-wall grouting that simulates the shield tail gap. The test device is placed vertically on the ground. One end of the air compressor is connected to the test device through a pressure gauge and a return slurry valve installed on a pipeline, and the other end is connected to a slurry storage device through a grouting valve installed on the pipeline. On the one hand, this device is used to consider the influence of the shield tail gap on behind-the-wall grouting during shield construction. On the other hand, slurry distribution holes and a filter screen are set on the laminar flow cylinder, so that the slurry can be evenly injected into the test soil. The soil pressure change curve when injecting slurry using the test method of this device is basically the same as the soil pressure change curve when injecting slurry in actual engineering. At the same time, the soil slurry diffusion can be intuitively observed. This device can be widely used in the field of simulating subway tunnel shield machine grouting devices or equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of subway tunnel engineering, and particularly relates to a test device for simulating the influence of shield tail gap on grouting slurry diffusion, and a test method for conducting relevant tests using the device. Background Art

[0002] Shield tunneling plays an important role in underground engineering construction. During shield tunneling, back-wall grouting, a key process in the shield tunneling process, plays a key role in preventing ground deformation, improving tunnel impermeability, ensuring early lining stability, and improving the combined forces between the lining, slurry, and ground. Currently, due to the complexity of the ground, the shield tail gap, the uncertainty of grouting pressure, and the diversity of grouting materials, theoretical research on back-wall grouting in shield tunnels cannot meet the requirements of engineering practice. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a behind-the-wall grouting slurry diffusion device and a test method for simulating the shield tail gap, which has a reasonable design, a simple structure, a low cost, and can visually observe and analyze the diffusion of slurry in the soil.

[0004] The technical solution adopted to solve the above technical problems is: the test device is placed vertically on the ground, one end of the air compressor is connected to the test device through a pressure gauge and a return slurry valve installed on the pipeline, and the other end is connected to the slurry storage device through a grouting valve installed on the pipeline.

[0005] The test device of the present invention is as follows: a test cylinder is arranged on a fixed bracket, the test cylinder consists of two semicircular organic glass cylinders and a sealing strip, the top of the test cylinder is provided with a clamping device passing through the fixed bracket, the bottom of the test cylinder is provided with a shield tail gap simulation device passing through the fixed bracket, and a plurality of reinforcing stirrups are evenly distributed along the length direction of the test cylinder.

[0006] The fixing bracket of the present invention is as follows: 4 reinforcing ribs are vertically arranged between the upper fixing plate and the lower fixing plate, at least one reinforcing plate is arranged in the length direction of the reinforcing ribs, a connecting rod threaded hole is processed at the center position of the upper fixing plate, a pipeline alignment pad is arranged at the center position of the upper surface of the lower fixing plate, grouting holes are arranged correspondingly at the center positions of the lower fixing plate and the pipeline alignment pad, and 3 support rod threaded holes are evenly distributed circumferentially.

[0007] The clamping device of the present invention comprises: a connecting rod is arranged in a threaded hole of the connecting rod, a clamping hand wheel is arranged on the top of the connecting rod, and a clamping plate installed on the upper part of the test cylinder is arranged on the bottom of the connecting rod.

[0008] The pressing plate of the present invention is evenly processed with a plurality of through holes.

[0009] The shield tail gap simulation device of the present invention is as follows: a grouting waterproof pad is provided at the bottom of the test tube, three support rods pass through the lower fixed plate, the pipeline alignment pad, and the grouting waterproof pad in sequence and extend into the interior of the test tube and can rotate up and down, a supporting handwheel is provided at the bottom of the support rod, a laminar flow device is provided inside the test tube and contacts the top of the support rod, a grouting pipe is provided in the grouting hole, one end of the grouting pipe extends into the grouting waterproof pad, and the other end is connected to the grouting pipe.

[0010] The laminar flow device of the present invention is as follows: the upper and lower ends of the hollow cylindrical laminar flow cylinder are closed, a slurry inlet hole is processed at the center of the lower end of the laminar flow cylinder, a plurality of slurry distribution holes are evenly processed at the upper end, and a filter layer is provided at the upper end of the laminar flow cylinder.

[0011] One end of the test device of the present invention is arranged on a fixed base and the other end is arranged on an adjustable base. The height of the fixed base is greater than or equal to the height of the adjustable base, so that the test device is placed obliquely or parallel to the horizontal plane.

[0012] A slurry outlet hole is processed on the upper side wall of the test tube of the present invention, and the height of the slurry outlet hole should be higher than the height of the filling in the test tube during the test.

[0013] The test method of the wall behind-the-wall grouting slurry diffusion device simulating the shield tail gap of the present invention comprises the following steps:

[0014] S1. Test stratum preparation: Prepare the soil used for the test. The soil should be the same as the actual stratum environment to be simulated. Stir the test soil thoroughly and mix it with phenolphthalein dye.

[0015] S2. Slurry preparation and placement: preparing the test slurry according to the injectability of the test formation in step S1 and the simulated real formation environment, and placing the slurry into the slurry storage device;

[0016] S3. Assemble the test tube and place the soil: Assemble the test tube into one piece, place the grouting waterproof pad and laminar flow device into the test tube in sequence, and place the whole thing on the fixed bracket. Align the bottom of the test tube with the pipe alignment pad and reinforce it. Install the grouting pipe, support rod, and support handwheel. Turn the support handwheel so that the laminar flow device is 10 cm away from the grouting hole. Tighten the support handwheel. Fill the test tube with soil from the top of the test barrel according to the target formation porosity and permeability coefficient. Embed the measuring unit every 40 cm. After filling, place the compression plate and connecting rod into the test tube. Install the fixed plate and compression handwheel in sequence. Turn the compression handwheel to compact the soil layer.

[0017] S4. Slurry injection: Connect the grouting system, set the air compressor parameters, return the external pressure gauge to zero, turn the support hand wheel to make the laminar flow device fall to the bottom of the test cylinder, and use the air compressor to inject slurry into the test cylinder. When the slurry is full, adjust the slurry return valve to make the grouting pressure reach the predetermined grouting pressure value of 0.2-0.4 MPa, maintain it for 15 minutes, and then close the grouting valve;

[0018] S5. Collect test data: After grouting is completed, wait for the slurry to solidify for 8-10 hours and collect measurement unit data. Disassemble the test tube and cut the grouting soil into unit lengths. Analyze the diffusion and consolidation of the slurry in the soil, observe the slurry diffusion radius, and perform strength tests on the solidified body.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The test tube of the present invention is made of high-strength organic glass and is spliced ​​by two semicircular cylinders. A sealing waterproof strip is set between the two, which can visually analyze the diffusion of slurry in the soil.

[0021] 2. The fixing frame of the present invention is composed of reinforcing ribs, reinforcing plates, and upper and lower fixing plates, which can effectively ensure the structural strength and stability of the entire device. Multiple reinforcing stirrups are provided on the test tube to increase the compressive resistance of the test tube.

[0022] 3. The design of the shield tail gap simulation device of the present invention is used, on the one hand, to consider the influence of the shield tail gap on the back-wall grouting during shield construction, and on the other hand, a laminar flow cylinder is designed to buffer and store the injected slurry, and slurry distribution holes and a filter screen are arranged on the laminar flow cylinder, so that the slurry can be evenly injected into the test soil. The soil cannot enter the laminar flow cylinder and will not affect the grouting.

[0023] 4. The present invention is provided with a compacting device, which can compact the test soil and simulate the actual situation of the engineering stratum.

[0024] 5. The present invention adds a color developer to the test soil, which can visually analyze the diffusion of the slurry in the soil. Considering that the pH value of the slurry is alkaline, when larger particles in the slurry cannot pass through, their water can still pass through and be highlighted by the color developer.

[0025] 6. The present invention can adjust the grouting direction by adjusting the base, and study the diffusion of grouting slurry behind the wall at different angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural diagram of an embodiment of the present invention.

[0027] Figure 2 yes Figure 1 Schematic diagram of the structure of the test device 1 (only half of the test cylinder 1-3 is installed).

[0028] Figure 3 yes Figure 2 Schematic diagram of the structure of the fixed bracket 1-4.

[0029] Figure 4 yes Figure 2 Schematic diagram of the upper part.

[0030] Figure 5 yes Figure 2 Schematic diagram of the lower part.

[0031] Figure 6 yes Figure 2 Schematic diagram of the structure of the meso-layer flow device 1-5-1.

[0032] Figure 7 It is a schematic diagram of another installation method of the test device 1 of the present invention.

[0033] Figure 8 This is a diagram of slurry diffusion after the grouting test of the present invention.

[0034] Figure 9 (a) and (b) are diagrams showing the states of the coagulated body after the grouting test of the present invention.

[0035] Figure: 1. Test device; 2. Slurry storage device; 3. Air compressor; 4. Pressure gauge; 5. Adjustable base; 6. Fixed base; 1-1. Sealing strip; 1-2. Reinforcement stirrups; 1-3. Test cylinder; 1-4. Fixed bracket; 1-5. Shield tail gap simulation device; 1-6. Clamping device; 1-4-1. Upper fixing plate; 1-4-2. Reinforcement bar; 1-4-3. Reinforcement plate; 1-4-4. Lower fixing plate; 1-4-5. Pipeline alignment Pad; 1-5-1, laminar flow device; 1-5-2, support rod; 1-5-3, grouting waterproof pad; 1-5-4, grouting pipe; 1-5-5, support handwheel; 1-6-1, clamping handwheel; 1-6-2, connecting rod; 1-6-3, clamping plate; 1-5-1-1, filter screen; 1-5-1-2, laminar flow cylinder; a, slurry outlet hole; b, slurry inlet hole; c, grouting hole; d, support rod threaded hole; e, connecting rod threaded hole; f, slurry distribution hole. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but the present invention is not limited to these examples.

[0037] Example 1

[0038] exist Figures 1 to 7The present invention relates to a device for diffusion of grouting slurry behind a wall that simulates the gap between shield tails. Generally, a test device 1 is placed vertically on the ground. In order to study the diffusion of grouting slurry behind a wall at different angles, one end of the test device 1 is mounted on a fixed base 6 and the other end is mounted on an adjustable base 5. The height of the fixed base 6 is greater than or equal to the height of the adjustable base 5, so that the test device 1 is tilted or parallel to the horizontal plane. The adjustable base 5 is detachably connected to the test device 1. The adjustable base 5 can adjust the height of the test device 1 so that the test device 1 is at different angles. The fixed base 6 is hinged to the test device 1. After the adjustable base 5 is removed, the test device 1 falls on the fixed base 6. The fixed base 6 fixes the test device 1 to keep it stable.

[0039] One end of the air compressor 3 is connected to the test device 1 through a pressure gauge 4 and a return slurry valve installed on the pipeline, and the other end is connected to the slurry storage device 2 through a grouting valve installed on the pipeline. The air compressor 3 can set the grouting pressure, and the pressure gauge 4 can directly observe the grouting pressure of this device. The configured slurry is placed in the slurry storage device 2.

[0040] The test device 1 of this embodiment is composed of a sealing strip 1-1, reinforcement stirrups 1-2, a test tube 1-3, a fixing bracket 1-4, a shield tail gap simulation device 1-5, and a clamping device 1-6. The test tube 1-3 is composed of two semicircular organic glass cylinders connected together. A sealing strip 1-1 is provided between the two semicircular organic glass cylinders to prevent leakage of slurry within the tube. A slurry outlet hole a is machined on the upper side wall of the test tube 1-3. The height of the slurry outlet hole a should be higher than the height of the filling material within the test tube 1-3 during the test. During grouting of this device, excess slurry is discharged from the tube through the slurry outlet hole a. Several reinforcement stirrups 1-2 are evenly distributed along the length of the test tube 1-3. The reinforcement stirrups 1-2 reinforce the test tube 1-3 to resist formation pressure and grouting pressure. The test tube 1-3 is installed on the fixed bracket 1-4. The top of the test tube 1-3 is installed with a clamping device 1-6 passing through the fixed bracket 1-4, and the bottom of the test tube 1-3 is installed with a shield tail gap simulation device 1-5 passing through the fixed bracket 1-4.

[0041] The fixing bracket 1-4 of this embodiment is composed of an upper fixing plate 1-4-1, a reinforcing rib 1-4-2, a reinforcing plate 1-4-3, a lower fixing plate 1-4-4, and a pipe alignment pad 1-4-5. Four reinforcing ribs 1-4-2 are vertically fixed between the upper fixing plate 1-4-1 and the lower fixing plate 1-4-4 through threaded fastening connectors. At least one reinforcing plate 1-4-3 is provided in the length direction of the reinforcing rib 1-4-2. The reinforcing plate 1-4-3 assists in fixing the test piece. To prevent the test cylinder 1-3 from tipping over, a connecting rod threaded hole e is processed at the center of the upper fixing plate 1-4-1, and a pipe alignment pad 1-4-5 is welded and fixed at the center of the upper surface of the lower fixing plate 1-4-4. Grouting holes c are processed correspondingly at the center of the lower fixing plate 1-4-4 and the pipe alignment pad 1-4-5, and three supporting rod threaded holes d are evenly distributed around the circumference. The pipe alignment pad 1-4-5 can calibrate the horizontal position of the grouting hole c and the test cylinder 1-3.

[0042] The clamping device 1-6 of this embodiment is composed of a clamping handwheel 1-6-1, a connecting rod 1-6-2, and a clamping plate 1-6-3. The connecting rod 1-6-2 is installed in the threaded hole e of the connecting rod. The top of the connecting rod 1-6-2 is detachably installed with a clamping handwheel 1-6-1, and the bottom is welded and fixed with a clamping plate 1-6-3 installed on the upper part of the test cylinder 1-3. A number of through holes are evenly distributed on the clamping plate 1-6-3 to release part of the pressure in the process of compacting the soil to prevent the cylinder from expanding and bursting due to excessive pressure.

[0043] The shield tail gap simulation device 1-5 of this embodiment is composed of a laminar flow device 1-5-1, a support rod 1-5-2, a grouting waterproof pad 1-5-3, a grouting pipe 1-5-4, and a support handwheel 1-5-5. The bottom of the test tube 1-3 is sealed with a grouting waterproof pad 1-5-3. The three support rods 1-5-2 pass through the lower fixed plate 1-4-4, the pipeline alignment pad 1-4-5, and the grouting waterproof pad 1-5-3 in turn and extend into the interior of the test tube 1-3 and can rotate up and down. A support handwheel 1-5-5 is fixedly installed at the bottom of the support rod 1-5-2. The laminar flow device 1-5-1 is placed inside the test tube 1-3 and contacts the top of the support rod 1-5-2. Rotating the support handwheel 1-5-5 can make the laminar flow device 1-5-1 move up and down. The laminar flow device 1-5-1 maintains a certain distance from the bottom of the test tube 1-3, which actually simulates the gap of the shield tail during grouting of the shield machine. The grouting pipe 1-5-4 is fixedly installed in the grouting hole c, one end of the grouting pipe 1-5-4 extends into the grouting waterproof pad 1-5-3, and the other end is connected to the grouting pipe.

[0044] The laminar flow device 1-5-1 is composed of a filter screen 1-5-1-1 and a laminar flow cylinder 1-5-1-2. The upper and lower ends of the hollow cylindrical laminar flow cylinder 1-5-1-2 are closed. A slurry inlet hole b is machined at the center of the lower end of the laminar flow cylinder 1-5-1-2, and a number of slurry distribution holes f are evenly distributed at the upper end. The slurry entering through the grouting pipe 1-5-4 enters the laminar flow cylinder 1-5-1-2 through the slurry inlet hole b. The laminar flow cylinder 1-5-1-2 has a buffering effect on the incoming slurry. When the slurry fills the laminar flow cylinder 1-5-1-2, it enters the soil evenly through the slurry distribution holes f. A filter layer 1-5-1-1 is fixedly installed on the upper end of the laminar flow cylinder 1-5-1-2. The filter layer 1-5-1-1 only allows the slurry to pass through, and the soil above cannot enter the laminar flow cylinder 1-5-1-2 through the filter layer 1-5-1-1.

[0045] The test method of the above-mentioned back-wall grouting slurry diffusion device simulating the shield tail gap consists of the following steps:

[0046] S1. Test stratum preparation: Prepare the soil for the test. The soil should be the same as the actual stratum environment to be simulated. Stir the test soil thoroughly and mix it with phenolphthalein dye.

[0047] This example uses sand and gravel formation simulation. The pebbles and gravels are mainly composed of limestone, sandstone, and quartzite, and are round to sub-round in shape. The pebble content is 60%, with a particle size ranging from 20 to 60 mm, and the round gravel content is about 20%. The filler is mainly medium and fine sand and clay, with the medium and fine sand content being 15% and the clay content being 5%. The test soil is thoroughly stirred and mixed with a phenolphthalein dye. The soil test size is 10 cm (inner diameter of test tube 1-3) × 200 cm (the height of the soil filling in test tube 1-3).

[0048] S2, slurry preparation and placement: Prepare the test slurry according to the injectability of the test formation in step S1 and the simulated real formation environment, and place the slurry into the slurry storage device 2;

[0049] This embodiment uses cement-water glass (CS) double slurry. The parameters of the CS double slurry are a water-cement ratio of 1:1, a water glass concentration of 40 degrees Baume, and a water glass blending amount controlled at 10%. The slurry is fully mixed and placed in the slurry storage device 2.

[0050] S3. Assemble the test tube 1-3 and place the soil: Assemble the test tube 1-3 into one piece, place the grouting waterproof pad 1-5-3 and the laminar flow device 1-5-1 into the test tube 1-3 in sequence, and place the whole on the fixed bracket 1-4. Align the bottom of the test tube 1-3 with the pipe alignment pad 1-4-5 and reinforce them. Install the grouting pipe 1-5-4, the support rod 1-5-2 and the support hand wheel 1-5-5. Turn the support hand wheel 1-5-5 to make the laminar flow device 1-5-1 10 cm away from the grouting hole, tighten the support handwheel 1-5-5, and fill the soil from the upper part of the test barrel into the test tube 1-3 according to the target formation porosity and permeability coefficient. Bury the measuring unit (the soil pressure cell in this embodiment) every 40 cm. After filling, place the pressing plate 1-6-3 and the connecting rod 1-6-2 into the test tube 1-3, install the fixing plate 1-4-1 and the pressing handwheel 1-6-1 in sequence, and turn the pressing handwheel 1-6-1 to compact the soil layer;

[0051] S4. Slurry injection: Connect the grouting system, set the parameters of the air compressor 3, return the external pressure gauge to zero, turn the support hand wheel 1-5-5 to make the laminar flow device 1-5-1 fall to the bottom of the test cylinder 1-3, and use the air compressor 3 to inject the slurry into the test cylinder 1-3. When the slurry is full, adjust the slurry return valve to make the grouting pressure reach the predetermined grouting pressure value of 0.2-0.4 MPa, maintain it for 15 minutes, and then close the grouting valve;

[0052] S5. Collect test data: After grouting, wait for the slurry to solidify for 8–10 hours and collect measurement unit data. Some of this data is shown in Table 1. Disassemble test tubes 1–3 and cut the grouting soil into unit lengths. Analyze the diffusion and consolidation of the slurry in the soil, observe the slurry diffusion radius, and perform strength tests on the solidified body.

[0053] Table 1 Earth pressure values ​​at different distances between the measuring unit and the grouting hole a

[0054]

[0055]

[0056] As can be seen from the table above, the curve of soil pressure change when injecting CS slurry by simulating the shield tail gap using this device is basically the same as the curve of soil pressure change when injecting CS slurry in actual engineering. At the same time, the diffusion of soil slurry is visually observed. Figure 8 It can be seen that the slurry diffusion radius is about 75cm. Figure 9 (a) Figure 9The strength test of the condensate (b) was carried out, and the 3-day strength of the condensate was greater than 0.5MPa, and the 28-day strength was greater than 2.5MPa. Therefore, the diffusion radius and strength of the CS slurry injected into the sand and gravel formation in the simulation experiment using this device are reliable, and can be used for simulation tests of grouting in the early stage of the project. The diffusion characteristics of the proposed slurry in the actual formation are determined through the test, and the basic parameters such as the slurry diffusion radius, grouting volume and condensate strength are determined, which provides an experimental basis for the design of the actual engineering grouting scheme and has important reference value for the grouting behind the shield tunnel wall.

Claims

1. A grouting slurry diffusion device for simulating the shield tail gap, wherein the test device (1) is placed vertically on the ground, one end of the air compressor (3) is connected to the test device (1) through a pressure gauge (4) and a slurry return valve installed on a pipeline, and the other end is connected to a slurry storage device (2) through a grouting valve installed on the pipeline, characterized in that: The test device (1) comprises: a test tube (1-3) arranged on a fixed bracket (1-4), the test tube (1-3) consisting of two semicircular organic glass cylinders and a sealing strip (1-1), a pressing device (1-6) passing through the fixed bracket (1-4) being arranged on the top of the test tube (1-3), and a shield tail gap simulation device (1-5) passing through the fixed bracket (1-4) being arranged on the bottom, and a plurality of reinforcing stirrups (1-2) being evenly distributed along the length direction of the test tube (1-3); The shield tail gap simulation device (1-5) is as follows: a grouting waterproof pad (1-5-3) is provided at the bottom of the test tube (1-3); three support rods (1-5-2) sequentially pass through a lower fixed plate (1-4-4), a pipe alignment pad (1-4-5), and a grouting waterproof pad (1-5-3) and extend into the interior of the test tube (1-3) and can rotate up and down; a supporting hand wheel (1-5-5) is provided at the bottom of the support rod (1-5-2); a laminar flow device (1-5-1) is provided inside the test tube (1-3) and contacts the top of the support rod (1-5-2); a grouting pipe (1-5-4) is provided in a grouting hole (c); one end of the grouting pipe (1-5-4) extends into the grouting waterproof pad (1-5-3) and the other end is connected to the grouting pipe; One end of the test device (1) is arranged on a fixed base (6) and the other end is arranged on an adjustable base (5). The height of the fixed base (6) is greater than or equal to the height of the adjustable base (5), so that the test device (1) is placed obliquely with respect to the horizontal plane or parallel to the horizontal plane.

2. The wall-back grouting slurry diffusion device for simulating the shield tail gap according to claim 1 is characterized in that The fixing bracket (1-4) is as follows: four reinforcing ribs (1-4-2) are vertically arranged between an upper fixing plate (1-4-1) and a lower fixing plate (1-4-4); at least one reinforcing plate (1-4-3) is arranged in the length direction of the reinforcing rib (1-4-2); a connecting rod threaded hole (e) is processed at the center position of the upper fixing plate (1-4-1); a pipeline alignment pad (1-4-5) is arranged at the center position of the upper surface of the lower fixing plate (1-4-4); grouting holes (c) are correspondingly arranged at the center positions of the lower fixing plate (1-4-4) and the pipeline alignment pad (1-4-5); and three support rod threaded holes (d) are evenly distributed circumferentially.

3. The wall-back grouting slurry diffusion device for simulating the shield tail gap according to claim 2 is characterized in that The clamping device (1-6) comprises: a connecting rod (1-6-2) arranged in a connecting rod threaded hole (e); a clamping hand wheel (1-6-1) is arranged on the top of the connecting rod (1-6-2); and a clamping plate (1-6-3) installed on the upper part of the test cylinder (1-3) is arranged on the bottom.

4. The device for grouting slurry behind the wall for simulating the shield tail gap according to claim 3 is characterized in that: The pressing plate (1-6-3) is evenly processed with a plurality of through holes.

5. The wall-back grouting slurry diffusion device for simulating the shield tail gap according to claim 1 is characterized in that The laminar flow device (1-5-1) is as follows: the upper and lower ends of a hollow cylindrical laminar flow cylinder (1-5-1-2) are closed, a slurry inlet hole (b) is processed at the center position of the lower end of the laminar flow cylinder (1-5-1-2), and a plurality of slurry distribution holes (f) are evenly distributed at the upper end; and a filter layer (1-5-1-1) is provided at the upper end of the laminar flow cylinder (1-5-1-2).

6. The device for grouting slurry behind the wall for simulating the shield tail gap according to claim 1 is characterized in that: A slurry outlet hole (a) is machined on the upper side wall of the test cylinder (1-3), and the height of the slurry outlet hole (a) should be higher than the height of the filling in the test cylinder (1-3) during the test.

7. The test method of the back-wall grouting slurry diffusion device simulating the shield tail gap according to any one of claims 1 to 6, comprising the following steps: S1. Test stratum preparation: Prepare the soil for the test. The soil should be the same as the actual stratum environment to be simulated. Stir the test soil thoroughly and mix it with phenolphthalein dye. S2. Slurry preparation and placement: Prepare the test slurry according to the injectability of the test formation in step S1 and the simulated real formation environment, and place the slurry into the slurry storage device (2); S3. Assemble the test tube (1-3) and place the soil: Assemble the test tube (1-3) into one piece, place the grouting waterproof pad (1-5-3) and the laminar flow device (1-5-1) into the test tube (1-3) in sequence, and place the whole on the fixed bracket (1-4). Align and reinforce the bottom of the test tube (1-3) with the pipe alignment pad (1-4-5). Install the grouting pipe (1-5-4) and the support rod (1-5-2) and the support hand wheel (1-5-5). Turn the support hand wheel (1-5-5) to The laminar flow device (1-5-1) is 10 cm away from the grouting hole. Tighten the support handwheel (1-5-5). Fill the soil from the upper part of the test barrel into the test tube (1-3) according to the target formation porosity and permeability coefficient. Bury the measuring unit every 40 cm. After filling, place the compacting plate (1-6-3) and the connecting rod (1-6-2) into the test tube (1-3). Install the fixing plate (1-4-1) and the compacting handwheel (1-6-1) in sequence. Turn the compacting handwheel (1-6-1) to compact the soil layer. S4. Slurry injection: connect the grouting system, set the parameters of the air compressor (3), return the external pressure gauge to zero, turn the rotation support hand wheel (1-5-5) to make the laminar flow device (1-5-1) fall to the bottom of the test cylinder (1-3), and use the air compressor (3) to inject the slurry into the test cylinder (1-3). When the slurry is full, adjust the slurry return valve to make the grouting pressure reach the predetermined grouting pressure value of 0.2 to 0.4 MPa, and keep it for 15 minutes, then close the grouting valve; S5. Collect test data: After grouting is completed, wait for the slurry to solidify for 8 to 10 hours, collect measurement unit data, disassemble the test cylinder (1-3), cut the soil after grouting according to unit length, analyze the diffusion and consolidation of the slurry in the soil, observe the slurry diffusion radius and perform strength test on the solidified body.

Images