Test model for simulating double-liquid slurry wall backfilling under water and soil pressure

Abstract

The application provides a test model for simulating double-liquid slurry back grouting under water and soil pressure, which comprises a segment, a test shield shell, a surrounding baffle, a transparent cover plate, a jack, a rigid frame, a traction mechanism, a traction rope, a grouting pipe assembly and a high-definition camera; the segment, the surrounding baffle and the transparent cover plate form a shield tail gap; the test shield shell is arranged in the shield tail gap; the jack presses the test shield shell; the traction mechanism is connected to the front side of the test shield shell through the traction rope; sealing grease is arranged between the rear side of the test shield shell and the segment and the transparent cover plate; the rear side of the test shield shell, the segment, the transparent cover plate and the surrounding baffle form a sealed cavity; the grouting pipe assembly extends into the sealed cavity from the front side of the test shield shell; and the high-definition camera is arranged above the transparent cover plate. The test model for simulating double-liquid slurry back grouting under water and soil pressure can intuitively simulate the process of shield tunnel back grouting and is used for studying the diffusion law of double-liquid slurry in a shield tail gap.

Description

Technical Field

[0001] This invention relates to the field of test models for tunnels and underground engineering, and in particular to a test model for simulating grouting behind a double-liquid grout wall under water and soil pressure. Background Technology

[0002] In shield tunnel construction, synchronous backfill grouting is an important means of controlling ground loss and surface settlement. The diffusion mechanism of the grout has a significant impact on the final forming quality and compactness. In recent years, with the continuous development of grouting technology, new grouting technology represented by two-liquid grouting has become increasingly mature and has begun to be widely used in synchronous backfill grouting of shield tunnels. However, in actual engineering, since grouting is carried out behind the tunnel lining segments, the diffusion, penetration, forming mechanism and morphology of the grout are often difficult to observe. Summary of the Invention

[0003] To address the shortcomings of the existing technology, this invention provides an experimental model for simulating grouting behind the shield tunnel wall under water and soil pressure. This model can intuitively simulate the grouting process behind the shield tunnel wall and is used to study the diffusion law of the dual-liquid grout in the shield tail gap.

[0004] To achieve the above objectives, the present invention provides a test model for simulating grouting behind a double-liquid grout wall under water and soil pressure, comprising a pipe segment, a test shield, a surrounding baffle, a transparent cover, multiple jacks, multiple rigid frames, a traction mechanism, two traction ropes, a grouting pipe assembly, and multiple high-definition cameras; the pipe segment, the surrounding baffle, and the transparent cover form a shield tail gap; the test shield is disposed within the shield tail gap; the jacks are fixed to the rigid frames and press the test shield from above through the transparent cover; the traction mechanism is connected to the front side of the test shield through the traction ropes; sealing grease is disposed between the rear side of the test shield and the pipe segment and the transparent cover, and the rear side of the test shield, the pipe segment, the transparent cover, and the surrounding baffle cooperate to form a sealed cavity; the grouting pipe assembly extends from the front side of the test shield into the sealed cavity; the high-definition cameras are disposed above the transparent cover.

[0005] Preferably, the rigid frame is a beam-frame integrated structure; the rigid frame is spaced above the transparent cover plate; the bottom of the rigid frame is fixed to the ground by fixing screws; the bending parts of the rigid frame are reinforced by ribs; a support spoke is inclinedly connected to each of the lower two sides of the rigid frame; and four jacks are evenly distributed and fixed on the bottom surface of the top plate of the rigid frame.

[0006] Preferably, the system further includes two support platforms, which are respectively disposed under both ends of the segment; the segment is fixed to the top surface of the two support platforms.

[0007] Preferably, the test shield includes a steel frame, the steel frame being welded with the grouting pipe assembly and the traction rope's force holes; the steel frame is surrounded by a layer of hard rubber material; the thickness of the test shield is close to and greater than the thickness of the shield tail gap; the length of the test shield matches the length of the segments.

[0008] Preferably, the two traction ropes are symmetrically distributed along the center of the test shield and connected between the front side of the test shield and the traction mechanism.

[0009] Preferably, the grouting pipe assembly includes a first liquid grouting pipe, a second liquid grouting pipe, a grout mixer, and a mixed grouting pipe; the first liquid grouting pipe and the second liquid grouting pipe are disposed in front of the test shield and connected to the input end of the grout mixer; the output end of the grout mixer is connected to the mixed grouting pipe; the mixed grouting pipe extends into the sealing cavity from the front side of the test shield.

[0010] Preferably, the surrounding baffle is placed on the support platform and surrounds the periphery of the pipe segment and the transparent cover plate; the portion of the surrounding baffle that connects with the support platform and the pipe segment is sealed by a sealing gasket or leak-proof material.

[0011] Preferably, the high-definition camera is mounted on the bottom surface of the top plate of the rigid frame; two high-definition cameras are mounted on each rigid frame.

[0012] Because the present invention adopts the above technical solution, it has the following beneficial effects:

[0013] This invention uses a transparent cover plate to replace the surrounding rock (soil) layer of the tunnel and designs an experimental shield shell to construct a shield tail gap similar to that in actual engineering. By simulating the entire process of synchronous grouting during the shield shell pulling out, the diffusion law of grout in the shield tail gap can be studied intuitively, which has important reference significance for grouting work in shield tunnel construction. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of an experimental model for simulating grouting behind a double-liquid grout wall under water and soil pressure, according to an embodiment of the present invention.

[0015] Figure 2 This is a partial side cross-sectional view of the test model for simulating grouting behind a double-liquid grout wall under water and soil pressure, according to an embodiment of the present invention.

[0016] Figure 3 This is a partial cross-sectional view of the working state of the test model used to simulate grouting behind a double-liquid grout wall under water and soil pressure, according to an embodiment of the present invention. Detailed Implementation

[0017] The following is based on the attached diagram. Figures 1-3 The present invention provides preferred embodiments and describes them in detail to enable a better understanding of the functions and features of the present invention.

[0018] Please see Figures 1-3 An embodiment of the present invention provides an experimental model for simulating grouting behind a double-liquid grout wall under water and soil pressure. The model includes a pipe segment 1, a test shield 2, a surrounding baffle 3, a transparent cover 4, multiple jacks 6, multiple rigid frames 71, a traction mechanism 81, two traction ropes 82, a grouting pipe assembly, and multiple high-definition cameras 5. The pipe segment 1, the surrounding baffle 3, and the transparent cover 4 form a shield tail gap 11. The test shield 2 is positioned within the shield tail gap 11. The jacks 6 are fixed to the rigid frames 71 and press the test shield 2 from above through the transparent cover 4. The traction mechanism 81 is connected to the front side of the test shield 2 via the traction ropes 82. Sealing grease 12 is provided between the rear side of the test shield 2 and the pipe segment 1 and the transparent cover 4, forming a sealed cavity with the rear side of the test shield 2, the pipe segment 1, the transparent cover 4, and the surrounding baffle 3. The grouting pipe assembly extends into the sealed cavity from the front side of the test shield 2. The high-definition cameras 5 are positioned above the transparent cover 4. The test shield 2 can move outward while being injected with two-liquid grout under the action of the traction rope 82, simulating the same process as actual grouting, and studying the diffusion and forming mechanism of the grout.

[0019] The transparent cover plate 4 is made of transparent material and has high strength. While bearing a certain load, it allows for direct observation of the diffusion process of grout after injection into the shield tail gap 11. Its inner side is relatively smooth, effectively simulating the formation of a ground interface by the cutterhead cutting through the strata. Under the action of the jack 6, the transparent cover plate 4 can be loaded to simulate the water and soil pressure during tunnel construction. The small distance between the transparent cover plate 4 and the surrounding baffles 3 facilitates sealing.

[0020] The traction mechanism 81 is used to provide a stable traction force, which is transmitted to the test shield 2 through the traction rope 82, thereby controlling the movement of the test shield 2.

[0021] The rigid frame 71 has a beam-frame integrated structure; the rigid frame 71 is spaced above the transparent cover plate 4; the bottom of the rigid frame 71 is fixed to the ground by fixing screws 73; the bending parts of the rigid frame 71 are reinforced by ribs; a support spoke 72 is inclinedly connected to the lower two sides of the rigid frame 71; four jacks 6 are evenly distributed and fixed on the bottom surface of the top plate of the rigid frame 71 to realize the loading function of the present invention.

[0022] It also includes two foundations 10, which are respectively set under both ends of the segment 1; the segment 1 is fixed to the top surface of the two foundations 10. Sufficient height is reserved between the two foundations 10 for non-destructive testing technologies such as ground penetrating radar and shock echo to detect the grouting behind the wall.

[0023] The test shield 2 includes a steel frame with welded grouting pipe assemblies and traction holes for the traction rope 82. A rigid rubber material layer surrounds the steel frame. The thickness of the test shield 2 is close to and greater than the thickness of the tail gap 11. The length of the test shield 2 matches the length of the segment 1. When the test shield 2 is subjected to the force of the top transparent cover plate 4, it undergoes a certain degree of elastic compression to achieve better sealing of the tail gap 11.

[0024] Two traction ropes 82 are symmetrically distributed along the center of the test shield 2 and connected between the front side of the test shield 2 and the traction mechanism 81. They are mainly used for the movement of the test shield 2, and the traction ropes 82 and the traction mechanism 81 should provide a stable traction force.

[0025] The grouting pipe assembly includes a first liquid grouting pipe 91, a second liquid grouting pipe 92, a grout mixer 94, and a mixed grouting pipe 93. The first liquid grouting pipe 91 and the second liquid grouting pipe 92 are located in front of the test shield 2 and connected to the input end of the grout mixer 94. The output end of the grout mixer 94 is connected to the mixed grouting pipe 93. The mixed grouting pipe 93 extends from the front side of the test shield 2 into the sealing cavity. The two liquid grouts mix and react in the grout mixer 94 in front of the test shield 2, and are injected into the sealing cavity through the mixed grouting pipe 93 in the test shield 2.

[0026] The surrounding baffle 3 is placed on the foundation 10 and surrounds the outer perimeter of the pipe segment 1 and the transparent cover plate 4; the part of the surrounding baffle 3 that connects with the foundation 10 and the pipe segment 1 is sealed by sealing gaskets or leak-proof materials to ensure that the container formed by the surrounding baffle 3, the foundation 10, the pipe segment 1 and the transparent cover plate 4 does not overflow with slurry.

[0027] High-definition cameras 5 are installed on the bottom surface of the top plate of the rigid frame 71; two high-definition cameras 5 are installed on each rigid frame 71, and the high-definition cameras 5 are responsible for recording the diffusion dynamics of the grout during the grouting process.

[0028] An embodiment of the present invention provides an experimental model for simulating grouting behind a wall using a dual-liquid grout under soil and water pressure. The process of conducting a simultaneous dual-liquid grouting test is as follows:

[0029] (1) Requirements for the test site: The actual test model is expected to occupy a site width of 7m and a length of 10m. The height should be unlimited. The site surface should meet the characteristics of hardening and flatness. In addition to the test model, sufficient space should be reserved for the hoisting of the segment 1 and other structures, and space should be reserved for the installation of the traction mechanism 81.

[0030] (2) Building the test model: The construction method of each component of the test model is as follows Figure 2 and Figure 3As shown, the construction sequence is as follows: 1) Construct a reinforced concrete foundation 10; 2) Place the segment 1; 3) Place the surrounding baffle 3 and perform leak-proof treatment on the adjacent parts of the surrounding baffle 3-segment 1-foundation 10; 4) Place the test shield 2 and install the first liquid grouting pipe 91, the second liquid grouting pipe 92, the grouting mixer and the mixed grouting pipe (93), and install the traction rope 82; 5) Place the transparent cover plate 4. Before placement, sealant grease 12 can be injected into the shield tail gap 11 to ensure the sealing of the closed cavity at the rear of the shield tail gap 11 during the test; 6) Install the jack 6; 7) Install the rigid frame 71 and fix the rigid frame 71 to the ground with fixing screws 73, and reinforce the bending position with ribs.

[0031] (3) Conduct preliminary experiments: Use water injection test to check the sealing performance of the sealing parts of the device, and repair areas with poor sealing effect.

[0032] (4) Equivalent soil and water pressure loading: The actual soil and water pressure of the tunnel is converted into the equivalent stress value of the transparent cover plate 4 by loading with jack 6, and the equivalent stress is achieved by loading with jack 6.

[0033] (5) After the pressure is applied, the jack 6 stops moving. The gap between the transparent cover plate 4 and the surrounding baffle 3 is sealed by means of asphalt pouring, etc., to achieve a sealing effect.

[0034] (6) Start the traction mechanism 81 to make the test shield 2 move slowly outward in the shield tail gap 11. During the movement, start the grouting pump to inject double liquid grout into the grouting pipe assembly and inject the entire range in one go. The diffusion process of the grout during the grouting process is recorded by the high-definition camera 5.

[0035] (7) After the grouting is completed, turn off the traction mechanism 81 and wait for the grout to solidify.

[0036] (8) 24 hours after grouting is completed, non-destructive testing techniques such as ground-penetrating radar can be used to inspect the grouting quality behind the wall from the space between the two foundations 10. During the inspection, the precise position of the measuring line should be recorded to facilitate the corresponding analysis of the imaging results later.

[0037] (9) 48 hours after grouting is completed, remove the transparent cover plate 4, accurately measure and record the shape of the grouting body, and retain the data and image information.

[0038] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A test model for simulating grouting behind a double-liquid grout wall under soil and water pressure, characterized in that, The system includes a tunnel segment (1), a test shield shell (2), a surrounding baffle (3), a transparent cover plate (4), multiple jacks (6), multiple rigid frames (71), a traction mechanism (81), two traction ropes (82), a grouting pipe assembly, and multiple high-definition cameras (5). The tunnel segment (1), the surrounding baffle (3), and the transparent cover plate (4) form a shield tail gap (11). The test shield shell (2) is located within the shield tail gap (11). The jacks (6) are fixed to the rigid frames (71) and pass through the transparent cover plate (4) from above. The test shield (2) is pressed tightly; the traction mechanism (81) is connected to the front side of the test shield (2) through the traction rope (82); a sealing grease (12) is provided between the rear side of the test shield (2), the pipe segment (1), and the transparent cover plate (4); the rear side of the test shield (2), the pipe segment (1), the transparent cover plate (4), and the surrounding baffle (3) cooperate to form a sealed cavity; the grouting pipe assembly extends into the sealed cavity from the front side of the test shield (2); the high-definition camera (5) is set above the transparent cover plate (4); The grouting pipe assembly includes a first liquid grouting pipe (91), a second liquid grouting pipe (92), a grout mixer (94), and a mixed grouting pipe (93); the first liquid grouting pipe (91) and the second liquid grouting pipe (92) are located in front of the test shield (2) and connected to the input end of the grout mixer (94); the output end of the grout mixer (94) is connected to the mixed grouting pipe (93); the mixed grouting pipe (93) extends into the sealing cavity from the front side of the test shield (2).

2. The experimental model for simulating grouting behind a double-liquid grout wall under water and soil pressure as described in claim 1, characterized in that, The rigid frame (71) is a beam-frame integrated structure; the rigid frame (71) is spaced above the transparent cover plate (4); the bottom of the rigid frame (71) is fixed to the ground by fixing screws (73); the bending part of the rigid frame (71) is reinforced by ribs; a support spoke (72) is inclinedly connected to the lower two sides of the rigid frame (71); four jacks (6) are evenly fixed on the bottom surface of the top plate of the rigid frame (71).

3. The experimental model for simulating grouting behind a double-liquid grout wall under water and soil pressure as described in claim 1, characterized in that, It also includes two support platforms (10), which are respectively disposed under both ends of the tube segment (1); the tube segment (1) is fixed to the top surface of the two support platforms (10).

4. The experimental model for simulating grouting behind a double-liquid grout wall under water and soil pressure as described in claim 1, characterized in that, The test shield (2) includes a steel frame, the steel frame is welded with the grouting pipe assembly and the traction rope (82) with force holes; the steel frame is wrapped with a hard rubber material layer; the thickness of the test shield (2) is close to and greater than the thickness of the shield tail gap (11); the length of the test shield (2) matches the length of the segment (1).

5. The experimental model for simulating grouting behind a double-liquid grout wall under water and soil pressure as described in claim 1, characterized in that, The two traction ropes (82) are symmetrically distributed along the center of the test shield (2) and connected between the front side of the test shield (2) and the traction mechanism (81).

6. The experimental model for simulating grouting behind a double-liquid grout wall under water and soil pressure as described in claim 3, characterized in that, The surrounding baffle (3) is placed on the support (10) and surrounds the periphery of the pipe segment (1) and the transparent cover plate (4); the part of the surrounding baffle (3) that is in contact with the support (10) and the pipe segment (1) is sealed by filling with a gasket or a leak-proof material.

7. The experimental model for simulating grouting behind a double-liquid grout wall under water and soil pressure as described in claim 2, characterized in that, The high-definition camera (5) is mounted on the bottom surface of the top plate of the rigid frame (71); two high-definition cameras (5) are mounted on each rigid frame (71).

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