Model test device for cascade collapse of adjacent tunnels caused by continuous collapse of foundation pit

Abstract

The invention discloses a model test device for cascade collapse of adjacent tunnels caused by continuous collapse of a foundation pit, and relates to the technical field of foundation pit supporting, the model test device comprises a test box body and sandy soil arranged in the test box body, a foundation pit continuous collapse simulation system, two tunnel collapse simulation systems and a data monitoring system are arranged in the test box body, according to the invention, by simulating the condition that two foundation pits exist on two sides of a tunnel in actual engineering in the test box body, the continuous collapse risk of a certain foundation pit caused by factors such as over-excavation and the influence of the foundation pit on deformation and internal force of an adjacent tunnel model can be studied; according to the device, the whole process of cascade collapse catastrophe evolution of the foundation pit and the tunnel system can be revealed, and effective test data are provided for research on disaster prevention and control and control methods of subsequent urban underground engineering aiming at the continuous collapse problem.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit support, and in particular to a model test device for cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits. Background Art

[0002] With the development of cities and urban transportation, super-large and super-deep foundation pits, criss-crossing tunnels, and large-scale underground space structures are becoming more and more numerous and complex.

[0003] Due to the poor integrity of underground engineering structures such as foundation pit support structures and shield tunnels constructed with existing technologies, once an unexpected event occurs, the risk of large-scale damage or even continuous collapse caused by local damage is relatively high. In addition, since foundation pits and tunnels are deeply buried underground, once local damage causes an accident, the damage develops rapidly, making it difficult to carry out rescue and control during the development of the disaster. In addition, since they are located below the ground, post-disaster repair and reconstruction are relatively difficult. Therefore, it is necessary to prevent the disaster of foundation pit collapse to avoid major safety accidents. When there are existing single or multiple tunnels outside the foundation pit and the distance is relatively close, there will be strong mutual influence and coupling correlation effects between the foundation pit and the tunnel. However, the influence of continuous collapse of foundation pits on the deformation and stress of adjacent tunnel structures at different positions and the mechanism of the whole process of cascade collapse disaster evolution of foundation pits and tunnel systems are unclear, resulting in a lack of research on control methods for preventing continuous collapse of foundation pits from causing continuous collapse of adjacent tunnel structures, making it difficult to foresee the occurrence of such safety accidents and to protect the safety of major infrastructure. Summary of the invention

[0004] The purpose of the present invention is to provide a model test device for cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits, aiming to solve the technical problems raised in the above-mentioned background technology.

[0005] In order to solve the above technical problems, the present invention specifically provides the following technical solutions: A model test device for cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits, comprising a test box and sand arranged in the test box, wherein a continuous collapse simulation system for foundation pits, two parallel tunnel collapse simulation systems and a data monitoring system are arranged in the test box, and the continuous collapse simulation system for foundation pits and the tunnel collapse simulation system are both buried in the sand in the test box, the continuous collapse simulation system for foundation pits is used to simulate multiple foundation pits constructed simultaneously in actual engineering, and the two tunnel collapse simulation systems are located between two of the foundation pits, the tunnel collapse simulation system is used to simulate tunnels, and the data monitoring system is arranged on the continuous collapse simulation system for foundation pits and the tunnel collapse simulation system, as well as on top of the test box; The foundation pit continuous collapse simulation system includes two foundation pit systems arranged in a test box, each of the foundation pit systems includes two ground-connected wall groups arranged in parallel on the bottom of the test box, each ground-connected wall group includes a plurality of ground-connected walls arranged along a straight line, two adjacent ground-connected walls are connected and installed through ground-connected wall joints, and a support model is commonly arranged on two opposite side walls of the two ground-connected wall groups; The tunnel collapse simulation system comprises a tunnel model arranged in a test box, a plurality of slots are arranged on one side of the test box, and two ends of the tunnel model are respectively installed on the inner wall of the model box and in the corresponding slots, and the tunnel model is buried in sand; Among them, the compressive strength of the connection between the support model and the ground-anchored wall group is less than the compressive strength of the support model, and the foundation pit continuous collapse simulation system collapses after destroying the support model through local over-excavation, and the internal force and displacement changes of the foundation pit continuous collapse simulation system and the tunnel collapse simulation system during the collapse are monitored by the data monitoring system.

[0006] As a preferred solution of the present invention, the support model includes two waist beam groups respectively arranged on opposite side walls of two ground-connected wall groups, each of the waist beam groups includes multiple waist beams parallel to the horizontal plane, and multiple support plates are arranged on the two waist beams at the same height along the length direction. The two support plates corresponding to the same height are jointly installed with a support, and the compressive strength of the support plate is less than the compressive strength of the support.

[0007] As a preferred solution of the present invention, the test box includes a model box and an observation window arranged on the model box, and the sand is filled in the model box, the groove is arranged on the observation window, and a plurality of fixed steel beams are arranged on the top of the model box, and the plurality of fixed steel beams are provided with positioning clips for positioning the ground-connected wall when installing the ground-connected wall.

[0008] As a preferred solution of the present invention, an excavation groove is provided on the side of the model box away from the observation window, and a plurality of mutually abutting baffles are detachably installed in the excavation groove, and the plurality of baffles are arranged in sequence downward in the vertical direction and abut against each other to close the excavation groove.

[0009] As a preferred solution of the present invention, the tunnel model includes a plurality of annular sheets bonded in sequence, each of the annular sheets is formed by bonding a plurality of arcuate sheets in sequence, and the bonding strength between two adjacent arcuate sheets on the same annular sheet and the bonding strength between two adjacent annular sheets are both less than the strength of the annular sheet.

[0010] As a preferred solution of the present invention, the bonding positions of the two arc-shaped sheets on two adjacent annular sheets are staggered with each other.

[0011] As a preferred solution of the present invention, the spacing between adjacent tunnel models is 1-1.5 times the diameter of the tunnel model.

[0012] As a preferred solution of the present invention, the data monitoring system includes a PIV industrial camera, a support axial force monitoring point, a displacement meter, a laser displacement meter, a tunnel strain gauge, an earth pressure box, and a ground-connected wall bending moment measuring point. The PIV industrial camera is located outside the test box. The support axial force monitoring point is arranged on the support to monitor the axial force of the support. The displacement meter is arranged in multiple and respectively arranged on multiple fixed steel beams and located on two opposite sides of two ground-connected wall groups. The laser displacement meter is arranged in multiple and arranged on one of the fixed steel beams in a direction perpendicular to the axis of the tunnel model. The tunnel strain gauge is arranged in multiple and evenly distributed on the circumferential side of the tunnel model along the circumferential and radial directions of the tunnel model. The earth pressure box and the ground-connected wall bending moment measuring point are both located on the side wall of the ground-connected wall group close to the tunnel model.

[0013] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention simulates the situation of double foundation pits on both sides of the tunnel in actual engineering in the test box, and can study the risk of continuous collapse of a foundation pit due to factors such as over-excavation, as well as its influence on the deformation and internal force of the adjacent tunnel model, so as to evaluate whether cascading collapse will occur in the adjacent tunnel model. The device can reveal the whole process of cascading collapse disaster evolution of the foundation pit and tunnel system, and provide effective experimental data for the subsequent research on disaster prevention and control methods for continuous collapse problems in urban underground engineering.

[0014] (2) The present invention can also divide the impact area of ​​the continuous collapse of the foundation pit on the existing tunnel by adjusting the distance between the continuous collapse simulation system of the foundation pit and the tunnel collapse simulation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0016] Figure 1 It is a structural schematic diagram of a model test device for the cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits according to the present invention; Figure 2 It is a front structural schematic diagram of a model test device for the cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits according to the present invention; Figure 3It is a structural schematic diagram of a foundation pit continuous collapse simulation system and a tunnel collapse simulation system of the present invention; Figure 4 It is a structural schematic diagram of the foundation pit continuous collapse simulation system of the present invention; Figure 5 It is a structural schematic diagram of the tunnel collapse simulation system of the present invention.

[0017] The numbers in the figure represent the following: 1. PIV industrial camera; 2. Observation window; 3. Model box; 4. Ground-connected wall; 5. Tunnel model; 6. Sand; 7. Support axial force monitoring point; 8. Support; 9. Ground-connected wall joint; 10. Displacement meter; 11. Laser displacement meter; 12. Tunnel strain gauge; 13. Soil pressure box; 14. Ground-connected wall bending moment measurement point; 15. Fixed steel beam; 16. Waist beam; 17. Support plate. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The following first describes the concepts involved in the present application in conjunction with the accompanying drawings. It should be noted that the following description of each concept is only to make the content of the present application easier to understand, and does not limit the scope of protection of the present application; at the same time, the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0020] like Figures 1 to 5 As shown, the present invention provides a model test device for cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits, comprising a test box and sand arranged in the test box, wherein a continuous collapse simulation system for foundation pits, two parallel tunnel collapse simulation systems and a data monitoring system are arranged in the test box, and the continuous collapse simulation system for foundation pits and the tunnel collapse simulation system are both buried in the sand 6 in the test box, the continuous collapse simulation system for foundation pits is used to simulate multiple foundation pits constructed simultaneously in actual engineering, and the two tunnel collapse simulation systems are located between two of the foundation pits, the tunnel collapse simulation system is used to simulate tunnels, and the data monitoring system is arranged on the continuous collapse simulation system for foundation pits and the tunnel collapse simulation system, as well as on top of the test box; The foundation pit continuous collapse simulation system includes two foundation pit systems arranged in a test box, each foundation pit system includes two ground-connected wall groups arranged in parallel on the bottom of the test box, each ground-connected wall group includes a plurality of ground-connected walls 4 arranged along a straight line, two adjacent ground-connected walls 4 are connected and installed through a ground-connected wall joint 9, and a support model is commonly arranged on two opposite side walls of the two ground-connected wall groups; The tunnel collapse simulation system includes a tunnel model 5 arranged in a test box, a plurality of slots are arranged on one side of the test box, and two ends of the tunnel model 5 are respectively installed on the inner wall of the model box 3 and in the corresponding slots, and the tunnel model 5 is buried in sand 6; Among them, the compressive strength of the connection between the support model and the ground-anchored wall group is lower than the compressive strength of the support model, and the foundation pit continuous collapse simulation system collapses after destroying the support model through local over-excavation. The internal force and displacement changes of the foundation pit continuous collapse simulation system and the tunnel collapse simulation system during the collapse are monitored by the data monitoring system.

[0021] When conducting the test, the present invention places the test box at a designated location, and then buries the foundation pit continuous collapse simulation system and the tunnel collapse simulation system under the internal sand 6 foundation and fixes them. When arranging, first fill the test box with sand 6 so that the height of the sand 6 reaches the preset height of the bottom of the ground-connected wall 4, and then arrange the ground-connected wall 4. After the ground-connected wall 4 is fixed, the support model is installed, and the data monitoring system is arranged on the foundation pit continuous collapse simulation system. Finally, continue to fill the sand 6 to the top of the foundation pit simulated by the foundation pit continuous collapse simulation system. The tunnel collapse simulation system is arranged synchronously with the foundation pit continuous collapse simulation system, and the arrangement method is similar. When the height of the sand 6 reaches the preset height at the bottom of the tunnel model 5, stop filling. Sand 6, then arrange the tunnel model 5, after the tunnel model 5 is fixed, arrange the data monitoring system on the tunnel model 5, and finally fill the sand 6. After the arrangement is completed, the present invention can simulate the situation of double foundation pits (foundation pits simulated by the foundation pit continuous collapse simulation system) on both sides of the tunnel model 5 in actual engineering for research, and study the continuous collapse risk of a foundation pit due to factors such as over-excavation in a certain foundation pit, as well as its influence on the deformation and internal force of adjacent tunnels, and can evaluate whether cascading collapse will occur in adjacent tunnels. The device can reveal the whole process of cascading collapse disaster evolution of foundation pits and tunnel systems, and provide effective experimental data for subsequent research on disaster prevention and control methods for continuous collapse problems in urban underground projects.

[0022] The foundation pit continuous collapse simulation system and the tunnel collapse simulation system simulate the foundation pit and the simulated tunnel model 5 respectively, and are designed and manufactured by comparing the actual engineering strength. For example, the tunnel model 5 simulated by the tunnel collapse simulation system can be made of materials such as aluminum sheets and designed according to the actual engineering strength. After the foundation pit simulated by the adjacent foundation pit continuous collapse simulation system collapses continuously, the stress performance of the designed and manufactured tunnel model 5 after the collapse of the foundation pit continuous collapse simulation system is observed, as well as whether the tunnel model 5 is damaged after the stress exceeds the design strength, and the data monitoring system is used to monitor the entire changing process information to obtain the required test data.

[0023] After the foundation pit continuous collapse simulation system is fixed, the two ground-anchored wall groups are arranged in two rows, and the two opposite ground-anchored walls 4 are supported by multiple supports 8, so that the foundation pit simulated by the foundation pit continuous collapse simulation system remains stable, preventing the soil around the ground-anchored wall 4 from collapsing into the interior of the foundation pit during local over-excavation. The burial method is to bury the soil by spreading sand through the sand rain method.

[0024] After the foundation pit continuous collapse simulation system and the tunnel collapse simulation system are fixed, local over-excavation is carried out, and a support model is arranged between two opposite ground-connected walls 4 at the same time. After local over-excavation, the pressure of the sand 6 behind the ground-connected wall 4 causes the support model to reach its strength limit, realizing the collapse of the foundation pit simulated by the foundation pit continuous collapse simulation system. The adjacent tunnel model 5 is affected by the soil pressure change and soil deformation caused by the foundation pit collapse, so that the force on the joint of the tunnel model 5 exceeds the design strength and is damaged. The data monitoring system records the entire process of changes in the foundation pit and the tunnel model 5, obtains corresponding test data and uses it to analyze the relevant laws or information in the entire process of the cascade collapse disaster evolution of the foundation pit and the tunnel system. The device can reveal the entire process of the cascade collapse disaster evolution of the foundation pit and the tunnel system, and provide effective test data for the subsequent research on disaster prevention and control methods for continuous collapse problems in urban underground projects, which plays an important role in laying a solid foundation for ensuring the safety of major infrastructure and enhancing urban resilience.

[0025] Since two tunnel collapse simulation systems are provided, multiple tunnel models 5 are provided, and the test data of the cascade collapse of adjacent tunnel models 5 can be effectively observed and obtained. By adjusting the spacing between the tunnel models 5 and the spacing between the tunnel models 5 and the ground-connected wall 4, the impact area of ​​the existing tunnel caused by the continuous collapse of the foundation pit can be divided. Furthermore, the number of tunnel collapse simulation systems can be one, or more than two, which can be set according to the actual working conditions simulated by the test.

[0026] The test box is provided with slots, one is to fix the tunnel model 5, and the other is to lead the corresponding wires on the tunnel model 5 to the outside of the test box.

[0027] In this embodiment, the ground-anchored wall 4 is a thin steel plate, and a support model is used to stabilize the foundation pit composed of two ground-anchored walls. Of course, the ground-anchored wall 4 can also be made of other materials. It is necessary to ensure that the ground-anchored wall 4, the ground-anchored wall joint 9 and the support model are designed with stiffness according to the actual project, and ensure that local over-excavation will not cause continuous collapse of the foundation pit. The foundation pit continuous collapse simulation system simulates multiple foundation pits that are constructed simultaneously and are closely spaced, so that the test process and test results of the present invention are in line with actual engineering conditions.

[0028] The support model includes two waist beam groups respectively arranged on the opposite side walls of the two ground-connected wall groups, each waist beam group includes multiple waist beams 16 parallel to the horizontal plane, and multiple support plates 17 are arranged along the length direction on the two waist beams 16 at the same height. The two support plates 17 corresponding to the same height are jointly installed with the support 8, and the compressive strength of the support plate 17 is less than the compressive strength of the support 8, which is used to simulate the bolt connection between the support structure and the ground-connected wall 4 in the actual project.

[0029] A plurality of ground-anchored walls 4 are fixed by waist beams 16, and supports 8 and waist beams 16 are respectively connected by support plates 17, so as to simulate the support nodes in actual engineering projects. After local over-excavation, since the compressive strength of support plates 17 is less than that of support 8, the axial force of support 8 gradually increases during the excavation process, so that the force exerted on support plates 17 gradually increases and breaks, thereby causing the foundation pit to collapse.

[0030] In this embodiment, the support sheet 17 is an aluminum sheet and the waist beam 16 is made of PVC material, which is designed and selected according to the actual engineering strength. Furthermore, the support sheet 17 and the waist beam 16 can also be made of other materials as long as they meet the test requirements.

[0031] In this embodiment, the compressive strength of the support sheet 17 is much smaller than the compressive strength of the support 8, so as to ensure that the support sheet 17 can be broken after local excavation and avoid the support 8 from breaking.

[0032] The test box includes a model box 3 and an observation window 2 arranged on the model box 3, and sand 6 is filled in the model box 3. A groove is arranged on the observation window 2. A plurality of fixed steel beams 15 are arranged on the top of the model box 3. The plurality of fixed steel beams 15 are each provided with a positioning clip for positioning the ground-connected wall 4 when installing the ground-connected wall 4.

[0033] The model box 3 is used to place the buried foundation pit continuous collapse simulation system and the tunnel collapse simulation system, and is filled with sand 6 for testing. The observation window 2 is used to observe the situation inside the model box 3 from the outside of the model box 3.

[0034] In this embodiment, the model box 3 is a rectangular box made of rigid material and has the ability to implement large-scale model tests. Compared with small-scale model tests, large-scale model tests have smaller scale effects and boundary effects and are closer to actual projects, making the obtained test data more real and effective.

[0035] By setting a fixed steel beam 15 to install a positioning clamp, the foundation pit continuous collapse simulation system can be positioned during installation to ensure the accuracy of the installation position. In this embodiment, the positioning clamp is a carpenter clamp.

[0036] An excavation groove is arranged on one side of the model box 3 away from the observation window 2, and a plurality of mutually abutting baffles are detachably installed in the excavation groove, and the plurality of baffles are arranged in sequence downward in the vertical direction and abut against each other to close the excavation groove.

[0037] By setting up an excavation groove and closing the excavation groove with multiple baffles, the sand 6 in the model box 3 can be gradually excavated in the present device by removing the baffles in sequence, thereby avoiding a large disturbance to the foundation pit continuous collapse simulation system during the excavation process. This part of the structure is not shown in the attached drawings.

[0038] The tunnel model 5 comprises a plurality of annular sheets bonded in sequence, each of which is formed by bonding a plurality of arcuate sheets in sequence, and the bonding strength between two adjacent arcuate sheets on the same annular sheet and the bonding strength between two adjacent annular sheets are both smaller than the strength of the annular sheet.

[0039] Adjacent annular sheets and adjacent arc-shaped sheets are bonded by glue to achieve an equivalent design of the structural strength of the tunnel model 5 in the present device compared with the actual engineering strength, and to simulate the circumferential and radial bonding of the segments in the tunnel model 5 in the actual engineering, thereby ensuring the validity of the test results and making the test results of reference value.

[0040] When continuous collapse occurs in the foundation pit continuous collapse simulation system, the connections between the annular pieces and the arc pieces will be damaged due to the disturbance of the deformation of the sand 6 in the model box 3, resulting in cascading collapse of the tunnel model 5 and achieving the purpose of the test.

[0041] The bonding positions of the two arc-shaped sheets on two adjacent annular sheets are staggered with each other.

[0042] Ensure that the design structure and strength of tunnel model 5 are similar to those of the actual project.

[0043] The spacing between adjacent tunnel models 5 is 1-1.5 times the diameter of the tunnel model 5 .

[0044] The spacing between the tunnel models 5 is compared with the spacing in the actual project to obtain more accurate and effective test data.

[0045] The data monitoring system includes a PIV industrial camera 1, a support axial force monitoring point 7, a displacement meter 10, a laser displacement meter 11, a tunnel strain gauge 12, an earth pressure box 13, and a ground-connected wall bending moment measuring point 14. The PIV industrial camera 1 is located outside the test box. The support axial force monitoring point 7 is set on the support 8 to monitor the axial force of the support 8. There are multiple displacement meters 10 and they are respectively set on multiple fixed steel beams 15 and are located on the opposite sides of two ground-connected wall groups. There are multiple laser displacement meters 11 and they are set on one of the fixed steel beams 15 in a direction perpendicular to the axis of the tunnel model 5. There are multiple tunnel strain gauges 12 and they are evenly distributed on the circumferential side of the tunnel model 5 along the circumferential and radial directions of the tunnel model 5. The earth pressure box 13 and the ground-connected wall bending moment measuring point 14 are both located on the side wall of the ground-connected wall group close to the tunnel model 5.

[0046] The PIV industrial camera 1 is used to capture images of the entire process of cascading collapse of the tunnel caused by continuous collapse of the foundation pit. The earth pressure box 13 and the ground-connected wall bending moment measuring point 14 are used to monitor the changes in soil pressure between the foundation pit and the tunnel model 5 and the bending moment of the ground-connected wall 4 after continuous collapse of the foundation pit. The support axial force monitoring point 7 is used to monitor the axial force of the support 8. The displacement meter 10 is used to monitor the displacement of the ground-connected wall. The laser displacement meter 11 is used to monitor the ground settlement of the sand 6. The tunnel strain gauge 12 is used to monitor the bending moment at the joint of the tunnel model 5 along the tunnel.

[0047] In this embodiment, the support axial force monitoring point 7 and the ground-connected wall bending moment measuring point 14 are strain gauges, and the axial force or bending moment can be monitored according to the full-bridge / half-bridge wiring method.

[0048] The embodiments and / or implementation methods described above are only used to illustrate the preferred embodiments and / or implementation methods for realizing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any form. Any technical personnel in this field may make slight changes or modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as technologies or embodiments that are essentially the same as the present invention. This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A model test device for the cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits, characterized in that: The invention comprises a test box and sand arranged in the test box, wherein the test box is provided with a foundation pit continuous collapse simulation system, two parallel tunnel collapse simulation systems and a data monitoring system, and the foundation pit continuous collapse simulation system and the tunnel collapse simulation system are both buried in the sand (6) in the test box, the foundation pit continuous collapse simulation system is used to simulate multiple foundation pits constructed simultaneously in an actual project, and the two tunnel collapse simulation systems are located between two of the foundation pits, the tunnel collapse simulation system is used to simulate a tunnel, and the data monitoring system is arranged on the foundation pit continuous collapse simulation system and the tunnel collapse simulation system, as well as on top of the test box; The foundation pit continuous collapse simulation system comprises two foundation pit systems arranged in a test box, each of the foundation pit systems comprises two ground-connected wall groups arranged in parallel on the bottom of the test box, each ground-connected wall group comprises a plurality of ground-connected walls (4) arranged along a straight line, two adjacent ground-connected walls (4) are connected and installed via ground-connected wall joints (9), and a support model is commonly arranged on two opposite side walls of the two ground-connected wall groups; The tunnel collapse simulation system comprises a tunnel model (5) arranged in a test box, a plurality of slots are arranged on one side of the test box, and two ends of the tunnel model (5) are respectively mounted on the inner wall of the model box (3) and in the corresponding slots, and the tunnel model (5) is buried in sand (6); Among them, the compressive strength of the connection between the support model and the ground-anchored wall group is less than the compressive strength of the support model, and the foundation pit continuous collapse simulation system collapses after destroying the support model through local over-excavation, and the internal force and displacement changes of the foundation pit continuous collapse simulation system and the tunnel collapse simulation system during the collapse are monitored by the data monitoring system.

2. A model test device for cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits according to claim 1, characterized in that: The support model comprises two waist beam groups respectively arranged on opposite side walls of two ground-connected wall groups, each waist beam group comprises a plurality of waist beams (16) parallel to a horizontal plane, two waist beams (16) at the same height are each provided with a plurality of support plates (17) along a length direction, two support plates (17) corresponding to the same height are jointly mounted with a support (8), and the compressive strength of the support plates (17) is less than the compressive strength of the support (8).

3. A model test device for cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits according to claim 1, characterized in that: The test box comprises a model box (3) and an observation window (2) arranged on the model box (3), the sand (6) is filled in the model box (3), the slot is arranged on the observation window (2), a plurality of fixed steel beams (15) are arranged on the top of the model box (3), and a positioning clamp for positioning the ground-connected wall (4) when the ground-connected wall (4) is installed is arranged on each of the plurality of fixed steel beams (15).

4. A model test device for cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits according to claim 1, characterized in that: An excavation groove is provided on a side of the model box (3) facing away from the observation window (2), and a plurality of mutually abutting baffles are detachably installed in the excavation groove, and the plurality of baffles are arranged in sequence downward in a vertical direction and abut against each other to close the excavation groove.

5. The model test device for the cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits according to claim 2, characterized in that: The tunnel model (5) comprises a plurality of annular sheets bonded in sequence, each of the annular sheets being formed by bonding a plurality of arcuate sheets in sequence, and the bonding strength between two adjacent arcuate sheets on the same annular sheet and the bonding strength between two adjacent annular sheets are both smaller than the strength of the annular sheet.

6. A model test device for cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits according to claim 5, characterized in that: The bonding positions of the two arc-shaped sheets on two adjacent annular sheets are staggered with each other.

7. A model test device for cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits according to claim 3, characterized in that: The spacing between adjacent tunnel models (5) is 1 to 1.5 times the diameter of the tunnel model (5).

8. The model test device for the cascading collapse of adjacent tunnels caused by continuous collapse of foundation pits according to claim 5, characterized in that: The data monitoring system comprises a PIV industrial camera (1), a support axial force monitoring point (7), a displacement meter (10), a laser displacement meter (11), a tunnel strain gauge (12), an earth pressure box (13), and a ground-connected wall bending moment measuring point (14). The PIV industrial camera (1) is located outside the test box. The support axial force monitoring point (7) is arranged on the support (8) for monitoring the axial force of the support (8). A plurality of displacement meters (10) are arranged and are respectively arranged on a plurality of fixed steel beams (15) and are located on opposite sides of two ground-connected wall groups. A plurality of laser displacement meters (11) are arranged and are arranged on one of the fixed steel beams (15) in a direction perpendicular to the axis of the tunnel model (5). A plurality of tunnel strain gauges (12) are arranged and are evenly distributed on the circumferential side of the tunnel model (5) in the circumferential direction and radial direction of the tunnel model (5). The earth pressure box (13) and the ground-connected wall bending moment measuring point (14) are both located on the side wall of the ground-connected wall group close to the tunnel model (5).

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