Model test device and method for shallow-buried tunnel passing through rich-water complex stratum adjacent construction area

Abstract

The application discloses a model test device and method for shallow-buried tunnel underpassing rich-water complex stratum near construction area, which can be used for indoor test simulation research on the influence of underground water level, the influence of adjacent engineering construction, and the tunnel stability engineering measures such as engineering dewatering / recharge and prestress adjustment of the underpassing tunnel in the complex stratum. The device can accurately lay uneven complex stratum and position the tunnel model in the model test box, so as to carry out indoor model test when the shallow-buried tunnel underpasses the rich-water complex stratum. The device has the functions of dynamic change of underground water level, load change, stratum excavation, real-time monitoring and adjustment of underground water level and ground load. The device can design special working condition adjustment mode to realize mutual coupling influence and finally reach a stable state, so as to be applied to the influence research of different types of working conditions on the deformation and stability of the tunnel when the shallow-buried tunnel underpasses the rich-water complex stratum near the construction area.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of tunnel construction, and particularly relates to a model test device and method for shallow-buried tunnel underpassing through a complex water-rich stratum adjacent to a construction area. BACKGROUND

[0002] In recent years, with the rapid development of cities and the continuous increase in population, the problem of urban traffic congestion is becoming increasingly serious. At the same time, due to the shortage of urban land resources, it is difficult to build too many ground roads in road traffic planning, and the development of underground space such as subways and underground passages has made great progress.

[0003] Research shows that more than 90% of urban subways and building foundation pits in the Yangtze River Delta region are built in Quaternary soil, and the geological conditions are mostly soft soil, among which the water-rich complex stratum with uneven thickness, low strength and poor stability is the most common, and is composed of various types such as silt, silt soil, clay, and fine sand. With the rapid development of urban subways and the further development and utilization of underground space, due to the diversity of underground engineering construction conditions, when the shallow-buried tunnel underpasses through the water-rich complex stratum, it is inevitably affected by the changes in underground water level and dynamic water pressure caused by the load changes and soil excavation of the adjacent area engineering construction. In the case of soil excavation spanning multiple strata, the permeation failure characteristics of different strata are different; water level changes can also be caused by engineering geological and hydrogeological conditions in addition to the influence of adjacent construction; water level and stratum changes, in turn, affect the construction itself, bringing uncertainty factors to the safety of engineering construction. SUMMARY

[0004] Considering the uneven thickness of the water-rich complex stratum, which is composed of various types such as silt, silt soil, clay, and fine sand, the shallow underground water level and the influence of the adjacent construction area, including changes in underground water level and dynamic water pressure, and the permeation failure characteristics of different strata, the present application provides a model test device and method for shallow-buried tunnel underpassing through a water-rich complex stratum adjacent to a construction area, which simulates the influence of different working conditions of the adjacent construction area on the deformation and stability of the water-rich complex stratum shallow-buried tunnel, and makes up for the shortcomings of existing indoor test models.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] According to a first aspect of the present application, a model test device for shallow-buried tunnel underpassing through a water-rich complex stratum adjacent to a construction area is provided, which comprises a groundwater module, a stress module, an excavation module, a monitoring module and a test module.

[0007] The underground water module comprises a porous PVC pipe, a filter geotextile, a water tower and an electronic water level regulator; the stress module comprises a load plate and a hydraulic jack; the excavation module comprises a shovel and a lifting and rotating support; the monitoring module comprises a water level sensor, a soil pressure sensor, a pore water pressure sensor, a displacement meter, a stress meter, a strain meter, a cable and a data acquisition instrument; the test module comprises a model test box, a tunnel model, a sliding rail, a universal ball, a movable fixing rod, a leveling plate and a server;

[0008] The surface of the porous PVC pipe in the underground water module is covered with a filter geotextile and is installed in the model test box; the porous PVC pipe is connected with the water tower; the water tower simulates the one-way fluctuation and cyclic fluctuation of the underground water level through the electronic water level regulator;

[0009] The load plate in the stress module is placed on the laid soil layer; the hydraulic jack is connected with the load plate, and the hydraulic jack simulates the one-way change and cyclic change of the load in the construction area through pressure adjustment;

[0010] The shovel in the excavation module is installed on the lifting and rotating support, and the shovel digs the uneven thickness of the filled soil layer in the model test box through lifting and rotating, thereby simulating the earthwork excavation across the soil layer;

[0011] The water level sensor in the monitoring module is installed in the porous PVC pipe; the soil pressure sensor and the pore water pressure sensor are both buried in the uneven thickness of the filled soil layer in the model test box; the displacement meter is installed on the outer surface of the tunnel model and is used for monitoring the depth direction displacement of the tunnel model; the stress meter and the strain meter are installed on the inner surface of the tunnel model along the ring direction and are used for monitoring the stress and strain of the tunnel model; the above-mentioned sensors are led out from the model test box through the cable and are connected with the data acquisition instrument, thereby realizing the real-time monitoring of the water level, the soil pressure, the pore water pressure, the tunnel settlement, the tunnel deformation and the tunnel segment stress;

[0012] The sliding rails are arranged on the inner walls of the two sides of the model test box in the test module, and the universal balls capable of freely moving are placed in the sliding rails; the two ends of the tunnel model are linked to the universal balls of the sliding rails on the two sides of the model test box; the movable fixing rod has a ring buckle at the upper end, and the tunnel model angle adjustment and fixation can be realized by pulling and rotating the ring buckle to drive the universal balls;

[0013] After the installation of the underground water module in the model test box, the strong weathered bedrock, the sandy soil, the silty clay and the fill are sequentially laid from bottom to top according to the actual complex stratum, the leveling plate is used for leveling, the sensors in the monitoring module are buried at the designed positions during the layer-by-layer stratum laying; when the stratum laying reaches the layer where the tunnel model is located, the tunnel model and the leveling plate are first fixed, and then the stratum laying is continued from bottom to top until the designed height is reached;

[0014] The server in the test module is connected with the data acquisition instrument in the monitoring module and the electronic water level regulator in the underground water module and the hydraulic jack in the stress module through cables; when the sensor data in the monitoring module reaches the design warning value, the electronic water level regulator and the hydraulic jack start to adjust the underground water level and the ground load, which are used to simulate the two tunnel stability engineering measures of engineering dewatering / recharge and prestress adjustment.

[0015] Further, in the underground water module, the one-way fluctuation rate of the underground water level can be varied by 5-30 mm / h to achieve constant fluctuation or rapid fluctuation; the cyclic fluctuation can be in the form of a sine wave function f1(x) = A1sin(ω1x1), with a fluctuation amplitude of 2A1 and a period T1 = 2π / |ω1|.

[0016] Further, in the stress module, the one-way change of the load can be set at a rate according to the requirement of the similarity ratio; the cyclic change of the load can be in the form of a sine wave function f2(x) = A2sin(ω2x2), with a fluctuation amplitude of 2A2 and a period T2 = 2π / |ω2|.

[0017] Further, the water level sensor has a diameter of 10 mm and a range of 0-0.5 m; the soil pressure sensor has a diameter of 15 mm and a range of 0.1-1 MPa; the pore water pressure sensor has a size of φ13 mm x 12 mm and a range of 0-50 kPa; the displacement meter has a range of 5-100 mm; and the side wall holes of the model test box are sealed and impermeable.

[0018] Further, the model test box is of a box type structure, and the size of the model test box is set according to the requirement of the similarity ratio; the box body structure material is T-shaped steel, and the side wall and the bottom plate of the box body are made of organic glass plates; the tunnel model is made of U-PVC material according to the similarity ratio, and the distance from the side wall of the model test box is 5 times the diameter D of the tunnel.

[0019] Further, the monitoring content of the monitoring module includes the load change caused by building construction and the change of underground water and stratum characteristics caused by earth excavation, and the tunnel stability engineering measures adopted by the test module are based on the above real-time monitoring content to adjust the underground water level and the ground load.

[0020] According to the second aspect of the present specification, the influence of the deformation and stability of a shallow-buried tunnel when the shallow-buried tunnel encounters changes in underground water conditions when the upper load near the construction area changes or the earth excavation across the soil layer is simulated by indoor test in a water-rich complex stratum; mainly including the following steps:

[0021] (1) installing a tunnel model in the model test box, laying uneven complex strata, and installing a monitoring module at the same time;

[0022] (2) Load changes in the construction area are realized through the stress module, including unidirectional load changes and cyclic load changes; earthwork excavation across soil layers in the construction area is realized through the excavation module.

[0023] (3) The groundwater level can be unidirectionally fluctuating and cyclically fluctuating through the groundwater module;

[0024] (4) The monitoring module obtains the real-time monitoring results of groundwater level, soil pressure in different strata, pore water pressure, tunnel settlement, deformation and segment stress, and analyzes the impact of changes in the upper load of the adjacent construction area or changes in groundwater conditions when excavating across soil layers on the deformation and stability of shallow buried tunnels.

[0025] According to the third aspect of this specification, indoor tests simulate shallow-buried tunnels in water-rich and complex strata. When the load on the superstructure near the construction area changes or earthwork excavation crosses soil layers, and the monitoring data reaches the design warning value, the corresponding water level and stress are automatically adjusted. This simulates two tunnel stabilization engineering measures: dewatering / recharge and prestress adjustment, and analyzes their impact on the deformation and stability of the shallow-buried tunnel. The main steps include:

[0026] (1) A tunnel model is installed in the model test box, and a monitoring module is installed while laying uneven and complex strata;

[0027] (2) Load changes in the construction area are realized through the stress module, including unidirectional load changes and cyclic load changes; earthwork excavation across soil layers in the construction area is realized through the excavation module.

[0028] (3) Real-time monitoring results of groundwater level, soil pressure in different strata, pore water pressure, tunnel settlement, deformation and segment stress are obtained through the monitoring module;

[0029] (4) After the monitoring data acquired by the data acquisition instrument reaches the design warning value, the server realizes the tunnel stabilization engineering measures of simulating engineering dewatering / recharge through the groundwater module; and realizes the tunnel stabilization engineering measures of simulating prestress adjustment through the stress module;

[0030] (5) The monitoring module continues to monitor and record the data acquisition instrument and analyze the impact of tunnel stability engineering measures on the deformation and stability of shallow buried tunnels.

[0031] The beneficial effects of this invention are: by designing an indoor model test device, special working condition adjustment methods, monitoring methods and burial methods are designed to simulate the influence of different types of working conditions on tunnel deformation and stability when a shallow-buried tunnel passes under a water-rich and complex stratum near the construction area, thereby providing a reference for the design and construction of parameters such as tunnel strength, pre-reinforcement range, and burial depth. Attached Figure Description

[0032] Figure 1 A model test box sectional view provided for the embodiment of the present application is shown in the figure;

[0033] Figure 2 A model test box left view provided for the embodiment of the present application is shown in the figure;

[0034] Figure 3 An adjusting and fixing assembly view provided for the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0035] In order to better understand the technical solutions of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0036] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0038] In order to simulate the influence of different types of working conditions of shallow-buried tunnel underpassing complex water-rich strata near construction area on tunnel deformation and stability, and to provide reference for the design and construction of tunnel strength, pre-reinforcement range, buried depth and other parameters, the present application provides a model test device and method for shallow-buried tunnel underpassing complex water-rich strata near construction area, and the implementation process of the technical solutions of the present application is described in detail below.

[0039] The model test device for shallow-buried tunnel underpassing complex water-rich strata near construction area provided by the embodiment of the present application mainly comprises a groundwater module, a stress module, an excavation module, a monitoring module and a test module. The groundwater module comprises a porous PVC pipe, a filter geotextile, a water tower and an electronic water level regulator. The stress module comprises a load plate, a hydraulic jack and a fastening bolt. The excavation module comprises a shovel and a lifting and rotating support. The monitoring module comprises a water level sensor, a soil pressure sensor, a pore water pressure sensor, a displacement meter, a stress meter, a strain meter, a cable and a data acquisition instrument. The test module comprises a model test box 1, a tunnel model 2, a sliding rail 3, a universal ball 4, a moving fixing rod 5, a leveling plate and a server.

[0040] The porous PVC pipe surface in the groundwater module is covered with a filter geotextile installed in the model test box. The filter geotextile avoids direct contact between the soil layer and the groundwater, reducing the possibility of hole and pipe blockage. The porous PVC pipe and the water tower are connected by a hard hollow pipe. The water tower is connected to an electronic water level regulator to simulate the one-way fluctuation and cyclic fluctuation of the groundwater level. The one-way fluctuation rate of the groundwater level can be varied between 5-30 mm / h to achieve constant fluctuation or rapid fluctuation. The cyclic fluctuation can be simulated by a sine wave function f1(x) = A1sin(ω1x1), with a fluctuation amplitude of 2A1 and a period T1 = 2π / |ω1|.

[0041] The load plate in the stress module is made of 304 stainless steel and placed on the prepared soil layer. The hydraulic jack is connected to the load plate through a tightening bolt. The hydraulic jack is adjusted by pressure to simulate the one-way change (loading / unloading) and cyclic change of the load in the construction area. The one-way change (loading / unloading) can be set at a rate according to the similarity ratio. The cyclic change can be simulated by a sine wave function f2(x) = A2sin(ω2x2), with a fluctuation amplitude of 2A2 and a period T2 = 2π / |ω2|.

[0042] The shovel in the excavation module is installed on a lifting and rotating support to excavate the prepared non-uniform thickness soil layer in the model test box, simulating the soil excavation across the soil layer.

[0043] The water level sensor in the monitoring module has a diameter of 10 mm and a range of 0-0.5 m, installed in the porous PVC pipe. The soil pressure sensor has a diameter of 15 mm and a range of 0.1-1 MPa, and the pore water pressure sensor has a size of φ13 mm x 12 mm and a range of 0-50 kPa, both buried in the prepared non-uniform thickness soil layer in the model test box. The displacement meter has a range of 5-100 mm and is installed on the outer surface of the tunnel model to monitor the depth direction displacement of the tunnel model. The stress meter and strain meter are installed along the ring direction on the inner surface of the tunnel model to monitor the stress and strain of the tunnel model. The above sensors are connected to the data acquisition instrument through cables from the side wall holes of the model test box. The side wall holes are sealed to prevent seepage, achieving real-time monitoring of water level, soil pressure, pore water pressure, tunnel settlement, tunnel deformation, and tunnel segment stress.

[0044] As Figure 1 , 2As shown, the model test box in the test module is of box type structure, in order to realize the influence research of different types of working conditions on the deformation and stability of the tunnel when the shallow buried tunnel passes through the complex stratum with rich water and adjacent construction area, the model test box panel is required to have good compressive strength, and the connection part is required to have good airtight and anti-permeability performance. The size of the model test box is set according to the requirement of the similarity ratio, the box body structure material is T-shaped steel, the box body side wall and bottom plate are made of organic glass plate, the inner walls of the two sides of the box body are respectively provided with longitudinal sliding rails, and universal balls are placed in the sliding rails.

[0045] The tunnel model in the test module is made of U-PVC material according to the similarity ratio, and the distance from the side wall of the model test box is 5 times the diameter D of the tunnel. The two ends of the tunnel are linked to the universal balls on the sliding rails of the inner walls of the two sides of the model test box, as shown in Figure 3 As shown, the universal ball can freely move in the corresponding inner wall sliding rail; the upper end of the moving fixed rod is a ring buckle 6, which can drive the universal ball to realize the angle adjustment and fixation of the tunnel model by pulling and rotating the ring buckle.

[0046] After the installation of the underground water module is completed, the strongly weathered bedrock, sand, silty clay and fill are sequentially laid from bottom to top according to the actual complex stratum condition; due to the existence of uneven stratum, after the side wall of the model test box is slotted and the angle fixing leveling plate is fixed, the lower stratum of the leveling plate is laid first, and then the upper stratum of the leveling plate is laid, then the leveling plate is pulled out from the side wall gap, and the laying is repeated until the top layer of fill is reached, until the design height is reached to form the uneven stratum. The sensors in the monitoring module are buried layer by layer at the designed position when the stratum is laid layer by layer. When the tunnel model is laid to the layer where the tunnel model is located, the tunnel model and the leveling plate are fixed first, and then the stratum is laid according to the principle of sequentially laying from bottom to top.

[0047] The server in the test module is connected with the data acquisition instrument in the monitoring module, the electronic water level regulator in the underground water module and the hydraulic jack in the stress module through cables. When the sensor data in the monitoring module reaches the design warning value, the electronic water level regulator and the hydraulic jack start to adjust the underground water level and the ground load, which are used to simulate the tunnel stability engineering measures such as engineering dewatering / recharge and prestress adjustment.

[0048] The monitoring content of the monitoring module includes the load change caused by building construction and the change of underground water and stratum characteristics caused by earth excavation, and the tunnel stability engineering measures adopted by the test module adjust the underground water level and the ground load based on the above real-time monitoring content, which is not a simple superposition effect, but a mutual coupling influence in the real situation, and finally reaches a stable state, so as to be applied to the influence research of different types of working conditions on the deformation and stability of the tunnel when the shallow buried tunnel passes through the complex stratum with rich water and adjacent construction area.

[0049] The main steps of the model test based on the model test device include: firstly, installing the tunnel model in the model test box, laying the uneven complex stratum, and installing the monitoring module; then, realizing the load change of the construction area through the stress module, realizing the earthwork excavation of the construction area across the soil layer through the excavation module; the purpose of the groundwater module can be divided into simulating the actual situation of the water-rich complex stratum and simulating the tunnel stability engineering measures such as engineering dewatering / recharge; the monitoring module can obtain real-time monitoring results of different types in real time, and automatically implement the tunnel stability engineering measures on the monitoring data reaching the design warning value through the server.

[0050] As a preferred embodiment of the present application, the following is described in detail for two model test simulation conditions.

[0051] In this embodiment, construction areas A and B are set. According to the actual situation of the project, the corresponding load is applied to the construction area A of the model test box in the form of loading, unloading, cyclic loading, etc.; and the corresponding tunnel stability measures such as preloading, unloading, etc. are applied to the construction area B of the model test box; that is, when some working conditions occur in the construction area A, the construction area B correspondingly simulates the stability measures through the stress module to realize the reduction of tunnel deformation and the improvement of stability. The positions of the construction areas A and B are determined according to the actual situation of the project simulated by the model test, and the positions should not be too close to each other, otherwise the stress will interfere with each other, and the axial symmetry should be adopted in the model test box.

[0052] Scheme 1: Through indoor test, the influence of the change of the underground water condition on the deformation and stability of the shallow-buried tunnel when the shallow-buried tunnel in the water-rich complex stratum is close to the upper load change of the construction area or the earthwork excavation across the soil layer. The main implementation scheme steps are briefly described as follows:

[0053] (1) The tunnel model is installed in the model test box, and the water level sensor, soil pressure sensor, pore water pressure sensor, displacement meter, stress meter, strain meter, cable and data acquisition instrument in the monitoring module are installed while laying the uneven complex stratum.

[0054] (2) Different load changes of the construction areas A and B are realized through the stress module, such as unidirectional change (loading / unloading) of the load, cyclic change of the load, and earthwork excavation across the soil layer is realized through the excavation module.

[0055] (3) The unidirectional fluctuation and cyclic fluctuation of the underground water level are realized through the groundwater module.

[0056] (4) Real-time monitoring results of the underground water level, different stratum soil pressure, pore water pressure, tunnel settlement, deformation and segment stress are obtained through the monitoring module, and the influence of the change of the underground water condition on the deformation and stability of the shallow-buried tunnel when the shallow-buried tunnel in the water-rich complex stratum is close to the upper load change of the construction area or the earthwork excavation across the soil layer is analyzed.

[0057] Scheme 2: Through indoor test, simulate shallow tunnel in water-rich complex stratum, near construction area upper load change or cross stratum earthwork excavation, when monitoring data reaches design warning value, automatically adjust corresponding water level, stress, namely simulate tunnel stability engineering measures such as engineering dewatering / recharge, prestress adjustment, and analyze the influence on shallow tunnel deformation and stability. The main implementation scheme steps are briefly described as follows:

[0058] (1) Install tunnel model in model test box, lay uneven complex stratum, and install water level sensor, soil pressure sensor, pore water pressure sensor, displacement meter, stress meter, strain meter, cable, and data acquisition instrument in monitoring module.

[0059] (2) Realize construction area A load change through stress module, such as load unidirectional change (loading / unloading), load cycle change working condition; realize construction area cross stratum earthwork excavation through excavation module.

[0060] (3) Obtain real-time monitoring results of underground water level, different stratum soil pressure, pore water pressure, tunnel settlement, deformation, segment stress through monitoring module.

[0061] (4) When monitoring data acquired by data acquisition instrument reaches design warning value, realize tunnel stability engineering measures such as simulated engineering dewatering / recharge through underground water module; realize construction area B preloading, unloading and other tunnel stability engineering measures through stress module.

[0062] (5) Continue monitoring and recording of data acquisition instrument by monitoring module, analyze the influence of tunnel stability engineering measures on shallow tunnel deformation and stability.

[0063] The above only describes the preferred embodiment of one or more embodiments of the present application, and does not limit one or more embodiments of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of one or more embodiments of the present application shall be included in the protection scope of one or more embodiments of the present application.

Claims

1. A model test device for shallow-buried tunnels passing under water-rich and complex strata near a construction area, characterized in that, It includes a groundwater module, a stress module, an excavation module, a monitoring module, and a testing module; The groundwater module includes porous PVC pipes, geotextile filter, water tower, and electronic water level regulator; the stress module includes a load plate and hydraulic jacks; the excavation module includes a bucket and lifting and rotating support; the monitoring module includes a water level sensor, soil pressure sensor, pore water pressure sensor, displacement gauge, stress gauge, strain gauge, cables, and data acquisition instrument; the testing module includes a model test chamber, tunnel model, sliding rails, omnidirectional ball, movable fixed rod, leveling plate, and server. The porous PVC pipe in the groundwater module is covered with a reverse filter geotextile and installed in the model test chamber; the porous PVC pipe is connected to the water tower; the water tower simulates the unidirectional and cyclic fluctuation conditions of the groundwater level through an electronic water level regulator; The load plate in the stress module is placed on the laid soil layer; the hydraulic jack is connected to the load plate, and the hydraulic jack simulates the unidirectional change and cyclic change of load in the construction area by adjusting the pressure. The bucket in the excavation module is installed on a lifting and rotating support. It lifts and rotates to excavate the unevenly thick soil layer filled in the model test box, simulating the earthwork excavation condition of crossing soil layers. The water level sensor in the monitoring module is installed inside a porous PVC pipe; the soil pressure sensor and the pore water pressure sensor are both buried in the unevenly thick strata filled in the model test box. Displacement gauges are installed on the outer surface of the tunnel model to monitor displacement in the depth direction; stress gauges and strain gauges are installed circumferentially on the inner surface of the tunnel model to monitor stress and strain; the above sensors are led out from the side wall holes of the model test box to the outside of the box via cables and connected to the data acquisition instrument to realize real-time monitoring of water level, soil pressure, pore water pressure, tunnel settlement, tunnel deformation, and tunnel segment stress. The model test box in the test module is equipped with slide rails on both sides of its inner wall, and a omnidirectional ball that can move freely is placed in the slide rails; the two ends of the tunnel model are connected to the omnidirectional balls on the slide rails on both sides of the model test box; the upper end of the movable fixing rod is a ring, and the angle of the tunnel model can be adjusted and fixed by pulling and rotating the ring to drive the omnidirectional ball; After the groundwater module is installed inside the model test chamber, according to the actual complex geological conditions, strongly weathered bedrock, sand, silty clay, and fill are laid from bottom to top. The leveling plate is used to level the ground. Sensors in the monitoring module are buried at the designed positions when laying the layers. When laying to the layer where the tunnel model is located, the tunnel model and the leveling plate are fixed first, and then the layers are laid from bottom to top until the designed height is reached. The server in the test module is connected to the data acquisition instrument in the monitoring module, the electronic water level regulator in the groundwater module, and the hydraulic jack in the stress module via cables. When the sensor data in the monitoring module reaches the design warning value, the electronic water level regulator and the hydraulic jack start to adjust the groundwater level and ground load to simulate two tunnel stabilization engineering measures: engineering dewatering / recharge and prestress adjustment.

2. The model test device for a shallow-buried tunnel passing under a water-rich and complex stratum near a construction area according to claim 1, characterized in that, In the groundwater module, the unidirectional fluctuation rate of the groundwater level can vary from 5 to 30 mm / h, achieving constant or rapid fluctuation; the cyclic fluctuation can follow a sinusoidal waveform function, i.e., f1(x) = A1sin(ω1x1), with a fluctuation amplitude of 2A1 and a period T1 = 2π / |ω1|.

3. The model test device for a shallow-buried tunnel passing under a water-rich and complex stratum near a construction area as described in claim 1, characterized in that, In the stress module, the unidirectional change of the load can be set at a rate according to the requirements of the similarity ratio; the cyclic change of the load can be based on a sinusoidal waveform function, i.e., f2(x)=A2sin(ω2x2), with a fluctuation amplitude of 2A2 and a period T2=2π / |ω2|.

4. The model test device for a shallow-buried tunnel passing under a water-rich and complex stratum near a construction area as described in claim 1, characterized in that, The water level sensor has a diameter of 10mm and a range of 0-0.5m; the soil pressure sensor has a diameter of 15mm and a range of 0.1-1MPa; the pore water pressure sensor has a size of φ13mm×12mm and a range of 0-50kPa; the displacement sensor has a range of 5-100mm; and the side wall holes of the model test chamber are sealed to prevent seepage.

5. The model test device for a shallow-buried tunnel passing under a water-rich and complex stratum near a construction area as described in claim 1, characterized in that, The model test chamber has a box-shaped structure, and its dimensions are set according to the similarity ratio requirements. The box structure material is T-shaped steel, and the side walls and bottom plate of the box are made of plexiglass. The tunnel model is made of U-PVC material according to the similarity ratio, and the distance from the side wall of the model test chamber is 5 times the tunnel diameter D.

6. The model test device for a shallow-buried tunnel passing under a water-rich and complex stratum near a construction area as described in claim 1, characterized in that, The monitoring module monitors load changes caused by building construction and groundwater and stratum characteristics changes caused by earthwork excavation. The tunnel stabilization engineering measures adopted by the test module adjust the groundwater level and ground load based on the monitoring content of the monitoring module.

7. A method for implementing the model testing apparatus according to any one of claims 1-6, characterized in that, Indoor tests were conducted to simulate the impact of changes in the upper load near the construction area or changes in groundwater conditions on the deformation and stability of shallow-buried tunnels in water-rich and complex strata.

8. The method according to claim 7, characterized in that, Includes the following steps: (1) A tunnel model is installed in the model test box, and a monitoring module is installed while laying uneven and complex strata; (2) Load changes in the construction area are realized through the stress module, including unidirectional load changes and cyclic load changes; earthwork excavation across soil layers in the construction area is realized through the excavation module. (3) The groundwater level can be unidirectionally fluctuating and cyclically fluctuating through the groundwater module; (4) The monitoring module obtains the real-time monitoring results of groundwater level, soil pressure in different strata, pore water pressure, tunnel settlement, deformation and segment stress, and analyzes the impact of changes in the upper load of the adjacent construction area or changes in groundwater conditions when excavating across soil layers on the deformation and stability of shallow buried tunnels.

9. A method for implementing the model testing apparatus according to any one of claims 1-6, characterized in that, Indoor tests were conducted to simulate shallow-buried tunnels in water-rich and complex strata. When the load on the upper part of the adjacent construction area changes or earthwork is excavated across soil layers, the monitoring data reached the design warning value and the corresponding water level and stress were automatically adjusted. This simulated two tunnel stabilization engineering measures: dewatering / recharge and prestress adjustment, and analyzed their impact on the deformation and stability of shallow-buried tunnels.

10. The method according to claim 9, characterized in that, Includes the following steps: (1) A tunnel model is installed in the model test box, and a monitoring module is installed while laying uneven and complex strata; (2) Load changes in the construction area are realized through the stress module, including unidirectional load changes and cyclic load changes; earthwork excavation across soil layers in the construction area is realized through the excavation module. (3) Real-time monitoring results of groundwater level, soil pressure in different strata, pore water pressure, tunnel settlement, deformation and segment stress are obtained through the monitoring module; (4) After the monitoring data acquired by the data acquisition instrument reaches the design warning value, the server implements the tunnel stabilization engineering measures of simulated engineering precipitation / recharge through the groundwater module. The stress module is used to simulate prestress adjustment and implement tunnel stability engineering measures. (5) The monitoring module continues to monitor and record the data acquisition instrument and analyze the impact of tunnel stability engineering measures on the deformation and stability of shallow buried tunnels.

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