Air bag type grouting simulation device for simulating grouting of shield tail of shield tunnel

Abstract

The invention discloses an air bag type grouting simulation device for simulating shield tunnel tail grouting, which belongs to the technical field of shield tunnel back grouting simulation test, and comprises a test box, a loading plate, a jack, a test segment, a soil body, a support cylinder, an air bag, an air pipe, an air compressor, a first strain gauge, a second strain gauge, a pressure meter and a displacement meter, the two ends of the supporting cylinder are connected with the box walls of the two opposite sides of the test box respectively and located in the soil body, the test pipe pieces are arranged in the supporting cylinder and are the same in axial direction, the cylinder wall of the supporting cylinder is provided with an annular hole penetrating through the inside and the outside in the radial direction, and the air bag is arranged in the annular hole and located outside the test pipe pieces and in the soil body at the same time and connected with the air compressor through an air pipe. A first strain gauge is arranged on the inner wall of the test segment, a second strain gauge is arranged on the outer wall of the test segment, a pressure gauge is arranged on the outer wall of the air bag, and a displacement meter is arranged on the inner wall of the test segment. According to the invention, the influence of the grouting pressurization process and the pressure dissipation process on the stress deformation of the stratum and the duct piece can be simulated.

Description

Technical Field

[0001] This invention belongs to the technical field of shield tunnel tail grouting simulation test, specifically relating to an airbag-type grouting simulation device for simulating shield tunnel tail grouting. Background Technology

[0002] During shield tunnel construction, after the shield tail detaches, a gap exists between the shield segments (a cylindrical segment composed of multiple arc-shaped segments connected together, hereinafter referred to as segments) and the ground, known as the shield tail gap. To maintain the stability between the segments and the ground, grouting is generally used to reinforce the shield tail gap. Grouting needs to reach a certain pressure to achieve a good reinforcement effect; if the grouting pressure is too low, the ground will lack effective support and collapse; if the grouting pressure is too high, the ground will heave.

[0003] When grouting is used to reinforce the shield tail gap, the grout pressure gradually dissipates during the solidification process. During this process, the supporting effect of the gradually solidifying grout within the shield tail gap on the formation weakens due to the decreasing pressure. Therefore, understanding the impact of grouting pressure and the grout pressure dissipation process on the formation is directly related to project safety.

[0004] Due to the complexity of the grouting process, achieving grouting pressure control and its dissipation simulation in indoor experiments is extremely difficult. For example, the invention patent with patent number "ZL 202110965403.X" and titled "A Combined Shield Tunnel Backwall Grouting Simulation Device and Test Method" employs a highly scalable modular device and test method. Replacing only some components can meet the needs of different working conditions, making it not only environmentally friendly but also significantly reducing preparation time and investment. However, this invention is not only structurally complex but can only simulate the grouting pressurization process, not the pressure dissipation process. Therefore, it cannot simulate the impact of pressure dissipation during grout solidification on the strata and the stress deformation of the tunnel segments, making it difficult to meet application requirements. Summary of the Invention

[0005] The purpose of this invention is to provide an airbag-type grouting simulation device for simulating shield tail grouting in shield tunnels, which can simulate the effects of grouting pressurization process and pressure dissipation process on the strata and segment stress deformation, in order to solve the above-mentioned problems.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] A bladder-type grouting simulation device for simulating shield tail grouting in a tunnel boring machine includes a test chamber and a loading plate, jacks, test segments, and soil placed inside the test chamber. The lower ends of the telescopic rods of multiple jacks, installed on the upper inner wall of the test chamber, are connected to the transverse loading plate. The soil is located below the loading plate, and the transverse test segments are placed inside the soil. The bladder-type grouting simulation device further includes a support cylinder, an air bladder, air pipes, an air compressor, a first strain gauge, a second strain gauge, a pressure gauge, and a displacement gauge. The two ends of the transverse support cylinder are respectively connected to… The test chamber has its opposite side walls connected and located within the soil. The test tube is placed within the support cylinder and has the same axial direction. The support cylinder has an annular hole that runs radially through one end of the test tube near the end of the test tube. The airbag is placed within the annular hole and is located both outside the test tube and within the soil. The airbag is connected to the air compressor via the air pipe. The test tube has a first strain gauge on its inner wall corresponding to the airbag and a second strain gauge on its outer wall. The pressure gauge is located on the outer wall of the airbag, and the displacement gauge is located on the inner wall of the test tube.

[0008] Preferably, to facilitate the installation of the air pipe and its connection to the air compressor, the air pipe includes a transverse air pipe and a radial air pipe connected to each other. One end of the transverse air pipe is connected to the outlet of the air compressor located outside the test chamber. A pressure regulating valve and a pressure gauge are sequentially installed on the transverse air pipe near the air compressor. The other end of the transverse air pipe is placed in the central through hole of the test tube and connected to one end of the radial air pipe. The other end of the radial air pipe passes through the corresponding through hole on the test tube and is connected to the air bag.

[0009] Preferably, in order to facilitate accurate simulation of grouting and pressure dissipation at different circumferential positions outside the test segment, and to meet the construction objectives such as posture correction by adjusting the grouting pressure at different positions in the project, multiple airbags are evenly distributed circumferentially within the annular hole. One end of each of the multiple transverse air pipes is connected to the outlet of the air compressor, and the other end of each of the multiple transverse air pipes is connected to one end of a corresponding multiple radial air pipe. The other end of each of the multiple radial air pipes is connected to a corresponding multiple airbag. Each transverse air pipe is equipped with a pressure regulating valve and a pressure gauge.

[0010] Specifically, there are eight airbags.

[0011] Preferably, in order to facilitate the measurement of pressure at different positions of the test tube segment and the pressure on the outer wall of different air bladders, there are multiple first strain gauges, multiple second strain gauges and multiple pressure gauges. Each second strain gauge and each pressure gauge is installed between two adjacent air bladders, and the multiple first strain gauges are radially corresponding to the multiple second strain gauges.

[0012] Preferably, in order to facilitate the measurement of displacement at different positions of the test tube segment, the displacement gauge is a differential displacement gauge and there are multiple displacement gauges, which are evenly distributed on the inner circumference of the test tube segment.

[0013] Preferably, to facilitate the installation of the support cylinder, the opposite side walls of the test chamber are respectively provided with through holes, and both ends of the support cylinder are fixedly connected to the walls of these through holes (e.g., by welding). A mounting bracket passes through the central through hole of the support cylinder and the central through hole of the test tube segment. Multiple displacement gauges are fixedly mounted on the mounting bracket, and the movable ends of the multiple displacement gauges are respectively mounted on the inner wall of the test tube segment. Depending on actual needs, the position of the support cylinder within the test chamber can also be connected to the inner wall or bottom of the test chamber via support strips to improve the installation stability of the support cylinder.

[0014] Preferably, in order to facilitate real-time monitoring of pressure and displacement signals, the signal output terminals of the first strain gauge, the second strain gauge, the pressure gauge, and the displacement gauge are respectively connected to the signal input terminal of the signal processor.

[0015] The beneficial effects of this invention are as follows:

[0016] This invention simulates the actual process of grouting and pressure dissipation within the shield tail gap by installing a support cylinder inside a test chamber, setting an annular hole on the support cylinder, and placing an airbag inside the annular hole. The inner wall of the airbag contacts the outer wall of the test segment, while the outer wall of the airbag contacts the soil. The air pressure inside the airbag is controlled by an air compressor. Furthermore, by detecting the pressure on the inner and outer walls of the test segment, the pressure on the outer wall of the airbag, and the displacement of the test segment, the invention provides real-time monitoring of pressure changes and displacement changes on the test segment and airbag. This achieves the goal of simulating the impact of grouting pressurization and pressure dissipation processes on the strata and the stress and deformation of the test segment using physical loading, thus better meeting application requirements and improving construction safety and reliability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the front cross-sectional structure of the airbag-type grouting simulation device for simulating shield tail grouting of a shield tunnel as described in this invention;

[0018] Figure 2 yes Figure 1 Enlarged image of the letter "A" in the image;

[0019] Figure 3 yes Figure 1 BB section view in the middle;

[0020] Figure 4 yes Figure 3 An enlarged view of the letter "C". Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings:

[0022] like Figures 1-4 As shown, the airbag-type grouting simulation device for simulating shield tail grouting of a shield tunnel, as described in this invention, includes a test chamber 1, an air compressor 16, an air pipe 8, and a loading plate 2, jacks 4, test segments 6, soil 3, a support cylinder 13, an airbag 5, a first strain gauge 12, a second strain gauge 11, a pressure gauge 10, and a displacement gauge 7, all placed inside the test chamber 1. The lower ends of the telescopic rods of the multiple jacks 4 installed on the upper inner wall of the test chamber 1 are connected to the transverse loading plate 2. The soil 3 is located below the loading plate 2, and the transverse test segments 6 are placed inside the soil 3. The two ends of the transverse support cylinder 13 are respectively connected to the test chamber. The two opposite side walls of the test tube 1 are connected and located inside the soil 3. The test tube 6 is placed inside the support cylinder 13 and is axially aligned. The support cylinder 13 has a radially penetrating annular hole (not marked in the figure) near one end of the test tube 6. The airbag 5 is placed inside the annular hole and is located both outside the test tube 6 and inside the soil 3. The airbag 5 is connected to the air compressor 16 through the air pipe 8. The inner wall of the test tube 6 corresponding to the airbag 5 is provided with a first strain gauge 12 and the outer wall is provided with a second strain gauge 11. The outer wall of the airbag 5 is provided with a pressure gauge 10 and the inner wall of the test tube 6 is provided with a displacement gauge 7.

[0023] like Figures 1-4 As shown, the present invention also discloses the following more optimized specific structures:

[0024] To facilitate the installation of the air pipe 8 and its connection with the air compressor 16, the air pipe 8 includes a transverse air pipe 82 and a radial air pipe 81 connected to each other. One end of the transverse air pipe 82 is connected to the outlet of the air compressor 16 located outside the test chamber 1. A pressure regulating valve 15 and a pressure gauge 14 are installed on the transverse air pipe 82 near the air compressor 16. The other end of the transverse air pipe 82 is placed in the central through hole of the test tube 6 and is connected to one end of the radial air pipe 81. The other end of the radial air pipe 81 passes through the corresponding through hole on the test tube 6 and is connected to the air bag 5.

[0025] To facilitate accurate simulation of grouting and pressure dissipation at different circumferential positions outside the test segment 6, and to meet the construction objectives such as posture correction by adjusting the grouting pressure at different positions in the project, multiple airbags 5 are evenly distributed circumferentially within the annular hole. One end of multiple transverse air pipes 82 is connected to the outlet of the air compressor 16, and the other end of multiple transverse air pipes 82 is connected to one end of multiple corresponding radial air pipes 81. The other end of multiple radial air pipes 81 is connected to multiple corresponding airbags 5. Each transverse air pipe 82 is equipped with a pressure regulating valve 15 and a pressure gauge 14.

[0026] There are eight airbags 5.

[0027] To facilitate the measurement of pressure at different positions of the test tube segment 6 and the pressure on the outer wall of different airbags 5, multiple first strain gauges 12, second strain gauges 11 and pressure gauges 10 are used. Each second strain gauge 11 and each pressure gauge 10 is installed between two adjacent airbags 5, and multiple first strain gauges 12 correspond to multiple second strain gauges 11 in the radial direction.

[0028] To facilitate the measurement of displacement at different positions of the test tube segment 6, multiple differential displacement gauges 7 are used, and the multiple displacement gauges 7 are evenly distributed on the inner circumference of the test tube segment 6.

[0029] To facilitate the installation of the support cylinder 13, the opposite side walls of the test chamber 1 are respectively provided with through holes, and both ends of the support cylinder 13 are fixedly connected to the walls of these through holes (e.g., by welding). The mounting bracket 9 (the specific structure and shape of the mounting bracket 9 are determined according to actual needs and are not specifically limited, as long as they meet the relevant matching functions with the support cylinder 13 and the displacement gauges 7, as well as the reliable positioning function) passes through the central through hole of the support cylinder 13 and the central through hole of the test tube 6. Multiple displacement gauges 7 are fixedly mounted on the mounting bracket 9, and the movable ends of the multiple displacement gauges 7 are respectively mounted on the inner wall of the test tube 6. Depending on actual needs, the position of the support cylinder 13 within the test chamber 1 can also be connected to the inner wall or bottom of the test chamber 1 via support strips (not shown in the figure) to improve the installation stability of the support cylinder 13.

[0030] To facilitate real-time monitoring of pressure and displacement signals, the signal output terminals of the first strain gauge 12, the second strain gauge 11, the pressure gauge 10, and the displacement gauge 7 are respectively connected to the signal input terminals of a signal processor (not shown in the figure, but a conventional CPU, MCU, or computer can be used) located outside the test chamber 1 via wires.

[0031] like Figures 1-4As shown, during use, the air compressor 16 and signal processor are started. According to the grouting pressure required for a certain airbag 5, the pressure regulating valve 15 corresponding to that airbag 5 is adjusted and the corresponding pressure gauge 14 is observed to make the air pressure inside the airbag 5 reach the set value. Then the corresponding pressure regulating valve 15 is closed. The same operation is performed to complete the high-pressure gas injection of all airbags 5, thus simulating the external grouting process of the shield tail segment under actual working conditions. The output values ​​of the first strain gauge 12, the second strain gauge 11, the pressure gauge 10 and the displacement gauge 7 are recorded by the signal processor to obtain the pressure values ​​at each position of the inner wall of the test segment 6, the pressure values ​​at each position of the outer wall of the test segment 6 (which is also the inner wall of the airbag 5), the pressure values ​​at each position of the outer wall of the airbag 5 (which is also the corresponding position of the soil 3), and the displacement of the test segment 6. This simulates the influence of the grouting pressurization process on the strata and the stress deformation of the segment under actual working conditions.

[0032] Then, turn off the air compressor 16, disconnect the connection between the transverse air pipe 82 and the air compressor 16, adjust the pressure regulating valve 15 and observe the pressure gauge 14. According to actual needs, gradually exhaust each airbag 5 multiple times to simulate the pressure dissipation process during the grout solidification process in actual working conditions. Record the output values ​​of the first strain gauge 12, the second strain gauge 11, the pressure gauge 10 and the displacement gauge 7 one by one to simulate the impact of pressure dissipation on the formation and the stress deformation of the tunnel segments during the grout solidification process in actual working conditions. This will provide more and more comprehensive data for the shield tail gap grouting reinforcement construction, better meet application needs, and improve construction safety and reliability.

[0033] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the technical solutions of the present invention. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of the patent of the present invention.

Claims

1. A bladder-type grouting simulation device for simulating shield tail grouting in a shield tunnel, comprising a test chamber and a loading plate, jacks, test segments, and soil placed inside the test chamber; the lower ends of the telescopic rods of a plurality of jacks installed on the upper inner wall of the test chamber are connected to the transverse loading plate; the soil is located below the loading plate; and the transverse test segments are placed inside the soil, characterized in that: The airbag-type grouting simulation device for simulating shield tail grouting in a shield tunnel further includes a support cylinder, an airbag, an air pipe, an air compressor, a first strain gauge, a second strain gauge, a pressure gauge, and a displacement gauge. The two ends of the transverse support cylinder are connected to opposite side walls of the test chamber and located within the soil. The test tube segment is placed within the support cylinder and has the same axial direction. A radially penetrating annular hole is provided on the cylinder wall near one end of the test tube segment. The airbag is placed within the annular hole and simultaneously located outside the test tube segment and within the soil. The airbag is connected to the air compressor via the air pipe. The first strain gauge is located on the inner wall of the test tube segment corresponding to the airbag, and the second strain gauge is located on the outer wall. The pressure gauge is located on the outer wall of the airbag, and the displacement gauge is located on the inner wall of the test tube segment.

2. The airbag-type grouting simulation device for simulating shield tail grouting in a shield tunnel according to claim 1, characterized in that: The air pipe includes a transverse air pipe and a radial air pipe connected to each other. One end of the transverse air pipe is connected to the outlet of the air compressor located outside the test chamber. A pressure regulating valve and a pressure gauge are installed sequentially on the transverse air pipe near the air compressor. The other end of the transverse air pipe is placed in the central through hole of the test tube and connected to one end of the radial air pipe. The other end of the radial air pipe passes through the corresponding through hole on the test tube and is connected to the air bag.

3. The airbag-type grouting simulation device for simulating shield tail grouting in a shield tunnel according to claim 2, characterized in that: Multiple airbags are evenly distributed circumferentially within the annular hole. One end of each of the multiple transverse air pipes is connected to the outlet of the air compressor. The other end of each of the multiple transverse air pipes is connected to one end of a corresponding multiple radial air pipe. The other end of each of the multiple radial air pipes is connected to a corresponding multiple airbag. Each transverse air pipe is equipped with a pressure regulating valve and a pressure gauge.

4. The airbag-type grouting simulation device for simulating shield tail grouting in a shield tunnel according to claim 3, characterized in that: There are eight airbags.

5. The airbag-type grouting simulation device for simulating shield tail grouting in shield tunnels according to claim 3 or 4, characterized in that: There are multiple first strain gauges, multiple second strain gauges and multiple pressure gauges. Each second strain gauge and each pressure gauge is installed between two adjacent air bladders. The multiple first strain gauges are radially corresponding to the multiple second strain gauges.

6. The airbag-type grouting simulation device for simulating shield tail grouting in shield tunnels according to any one of claims 1-4, characterized in that: The displacement gauges are differential displacement gauges and there are multiple of them, which are evenly distributed on the inner circumference of the test tube segment.

7. The airbag-type grouting simulation device for simulating shield tail grouting in a shield tunnel according to claim 6, characterized in that: The test chamber has through holes on its opposite sides, and the two ends of the support cylinder are fixedly connected to the walls of the through holes. The mounting bracket passes through the central through hole of the support cylinder and the central through hole of the test tube. Multiple displacement gauges are fixedly mounted on the mounting bracket, and the movable ends of the multiple displacement gauges are respectively mounted on the inner wall of the test tube.

8. The airbag-type grouting simulation device for simulating shield tail grouting in shield tunnels according to any one of claims 1-4, characterized in that: The signal output terminals of the first strain gauge, the second strain gauge, the pressure gauge, and the displacement gauge are respectively connected to the signal input terminal of the signal processor.

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