Centrifugal model test device and method for simulating slurry retaining wall and confined water environment

Abstract

The invention discloses a centrifugal model test device and method for simulating a slurry retaining wall and a confined water environment, and relates to the technical field of underground engineering groove wall stability physical simulation, and the centrifugal model test device comprises a centrifugal machine platform, a model box, a gas-liquid control module and a comprehensive monitoring module. A centrifugal model test technology is adopted, liquid in a water tank is accurately regulated and controlled to be injected into a latex film or a sand layer of a model box through cooperation of a groove section plate and a gas-liquid control module, and the wall protection effect of slurry with different specific gravities and the confined water layer environment are simulated; a pore water pressure sensor, a displacement meter and a particle image velocimetry (PIV) system in the comprehensive monitoring module are used for collecting stress, displacement and deformation field data of a soil sample around the tank wall in real time. According to the invention, the failure law and the instability mechanism of the groove wall under the action of different mud performance parameters and confined water pressure can be systematically disclosed, and a key theoretical basis and a technical support are provided for design and construction of an underground diaphragm wall in actual engineering.

Description

Technical Field

[0001] This invention relates to the field of physical simulation technology for the stability of underground engineering trench walls, specifically to a centrifugal model test device and method for simulating mud wall protection and confined water environment. Background Technology

[0002] As a primary retaining structure in deep foundation pit engineering, the stability of the diaphragm wall during the construction phase is a core issue for ensuring project safety. During trenching, the hydrostatic pressure generated by the slurry and the resulting mud cake effect are crucial for maintaining wall stability; while confined water in the strata, especially seepage caused by hydraulic head differences, constitutes the main risk source for wall instability. Therefore, in-depth research into the coupling mechanism between slurry performance parameters (such as specific gravity) and confined water on wall stability has significant theoretical and engineering value for systematically identifying engineering risks, optimizing design schemes, and preventing collapse accidents.

[0003] Existing research methods include numerical simulation, field experiments, and physical model experiments. Numerical simulation relies on constitutive models and experimental verification; field experiments are costly, involve many variables, and are difficult to conduct systematic research; centrifuge model experiments can reproduce the prototype stress field, but have obvious limitations: existing devices have limited functionality and cannot simulate the coupling of multiple working conditions such as "mud-seepage-leakage"; mud simulation lacks accuracy, fixed liquid level methods cannot dynamically adjust specific gravity, and are prone to clogging pipelines or are costly; confined water simulation lacks real-time precise control and cannot accurately reflect changes in the seepage field; it cannot actively trigger leakage conditions, making it difficult to study the entire instability process. Therefore, there is an urgent need to develop a multifunctional experimental system that can highly integrate mud control, confined water simulation, and leakage triggering, so as to support the comprehensive assessment of the stability of the trench wall under different mud indices, confined water heads, and soil sample stress histories, providing a solid foundation and effective experimental means for in-depth revelation of the instability mechanism of the trench wall. Summary of the Invention

[0004] The purpose of this invention is to provide a centrifugal model test device and method for simulating mud wall protection and pressurized water environment, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a centrifugal model test device for simulating mud wall protection and confined water environment, comprising a centrifuge platform, a model box, a gas-liquid control module and a comprehensive monitoring module;

[0006] The gas-liquid control module includes an air compressor, a gas pressure control system, and a water tank. An air compressor is installed at the upper end of the rotating arm. The gas pressure control system and the water tank are installed inside the air compressor. The air compressor connects the gas pressure control system, the water tank, the latex membrane, and the soil sample inside the model box through control pipelines.

[0007] The integrated monitoring module includes a pore water pressure sensor, a displacement sensor, a strain gauge, and a particle image velocimetry (PIV) system. The PIV system is equipped with a high-definition motion camera, which is placed on one side of the upper end of the rotating arm. The strain gauge is placed on the other side of the upper end of the rotating arm. The displacement sensor is located on the surface of the soil sample inside the model box. The pore water pressure sensor is embedded in the latex membrane and inside the soil sample in the model box.

[0008] A bracket is installed on the upper end of the model box, and a first servo control loading system and a second servo control loading system are respectively installed on the two sides above the bracket. A mud storage chamber is installed below the model box, and baffles and latex film are installed inside the model box. An opening is provided at the upper end of the model box.

[0009] The first servo-controlled loading system includes a first hydraulic cylinder, a first displacement meter, a first servo control device, and a penetrator. The first hydraulic cylinder is installed on one side of the upper end of the bracket, the first displacement meter is installed on one end of the first hydraulic cylinder, the first servo control device is installed on the upper end of the first hydraulic cylinder, and the penetrator is installed on the lower end of the first hydraulic cylinder.

[0010] The second servo-controlled loading system includes a second hydraulic cylinder, a second displacement meter, a groove plate, and a second servo control device. The second hydraulic cylinder is installed on one side of the upper end of the bracket, the second displacement meter is installed at one end of the second hydraulic cylinder, the groove plate is installed at the lower end of the second hydraulic cylinder, and the second servo control device is installed at the upper end of the second hydraulic cylinder.

[0011] The centrifuge platform includes a conical base, bearing components, a rotating arm, a signal ring, and a rotary platform. There are two rotary platforms. The model box is located on the rotary platform. The bearing components are installed on the upper end of the conical base, the rotating arm is installed on the upper end of the bearing components, and the signal ring is installed above the rotating arm.

[0012] Preferably, one end of the model box is made of transparent plexiglass, and the other end of the model box is made of stainless steel plate.

[0013] Preferably, the baffle is L-shaped and located at the rear and right side of the model box, with the latex film installed on one side of the baffle.

[0014] Preferably, the groove plate is installed inside the latex film.

[0015] Preferably, a regulating valve is installed at one end of the mud storage chamber, and a three-way pneumatic valve is installed at the upper end of the mud storage chamber. One end of the three-way pneumatic valve is connected to the bottom end of the latex membrane through a pipe, and the upper end of the three-way pneumatic valve forms a closed loop with an air compressor through a hose.

[0016] Preferably, a circular plastic sheet is installed at the bottom of the displacement sensor guide rod.

[0017] A centrifugal model test method simulating mud wall protection and confined water environment includes the following steps:

[0018] S1 first places the prepared soil samples inside the model box and performs solidification treatment. The prepared soil samples include saturated clay samples or layered soil samples containing sand interlayers. The saturated clay samples are divided into two types: normally consolidated clay and overconsolidated clay. The centrifugal acceleration of normally consolidated clay is 70g during both the early consolidation and later testing of the soil sample; while the centrifugal acceleration of overconsolidated clay is 100g during the early consolidation of the soil sample, and the centrifugal acceleration is reduced to 70g during the test, with an overconsolidation ratio of 1.4.

[0019] S2 starts the centrifuge and adjusts the centrifuge to an acceleration that matches the target.

[0020] S3 injects liquid into the latex membrane to a predetermined level through the gas-liquid control module to simulate mud wall protection, and injects sodium chloride solution as mud medium.

[0021] S4 controls the second hydraulic cylinder to shorten, and the second hydraulic cylinder drives the trench section plate to rise, simulating trench excavation.

[0022] During the excavation process, S5 performs one or more of the following operations through the gas-liquid control module:

[0023] S51. Maintain the liquid level inside the latex membrane to simulate normal support conditions;

[0024] S52. Inject liquid into a designated sand layer to simulate the action of confined water;

[0025] S6 collects pore water pressure, surface settlement, and soil sample deformation image data throughout the entire process through a comprehensive monitoring module.

[0026] S7. After the test, analyze the data, study the stability of the tank wall and the instability mechanism, and improve the above content.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. This centrifugal model test device and method for simulating mud wall protection and confined water environment, through an integrated gas-liquid control module, can accurately simulate the individual or coupled effects of various working conditions such as mud wall protection, confined water seepage and sudden slurry leakage in one system, which greatly expands the scope of experimental research and changes the traditional centrifugal model test device's inability to simulate complex and variable actual working conditions.

[0029] 2. The centrifugal model test device and method for simulating mud wall protection and confined water environment, by setting up a first servo control loading system and a second servo control loading system, adopts two independent servo control loading systems, which can simultaneously complete the T-bar penetration test and trench excavation simulation, realize the precise synchronization of data acquisition and construction process, and improve the reliability and consistency of test data.

[0030] 3. This centrifugal model test device and method for simulating mud wall protection and confined water environment achieves stable and reliable simulation of confined water environment in high-speed centrifugal field by directly injecting liquid into a specified sand layer and accurately controlling the water head (0-0.78m). Traditional simulation methods for simulating confined water often rely on complex external pipelines and have poor stability, thus this method is effectively improved.

[0031] 4. This centrifugal model test device and method for simulating mud wall protection and pressurized water environment actively and controllably simulates the leakage condition, and can extract liquid from the latex membrane at a predetermined rate to systematically study the evolution law of the whole process from stability to instability, overcoming the limitation of traditional methods that can only passively wait for instability.

[0032] 5. The centrifugal model test device and method for simulating mud wall protection and confined water environment integrates pore water pressure sensor, displacement meter and PIV technology into the comprehensive monitoring module, which can collect stress, displacement and deformation data in real time and synchronously, providing comprehensive and multi-dimensional data support for revealing the instability mechanism of the tank wall.

[0033] 6. This centrifuge model test device and method for simulating mud wall protection and confined water environment, through systematic study of the influence of soil stress history, and consolidation under 100g and 70g conditions, successfully simulated the stability change of the trench wall under overconsolidation ratio (OCR=1.4), filling the gap in existing research which is mostly focused on normally consolidated soil.

[0034] 7. The centrifugal model test device and method for simulating mud wall protection and confined water environment is compact in structure, highly integrated in function, easy to operate, highly efficient in test, and has good repeatability. It provides an advanced test research platform for the design and construction of diaphragm walls under complex geological conditions. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the model box of the present invention;

[0036] Figure 2 This is a schematic diagram of the structure of the groove segment model of the present invention;

[0037] Figure 3 This is a schematic diagram of the overall structure of the present invention.

[0038] In the diagram: 2. Model box; 3. Gas-liquid control module; 4. Support; 5. First servo control loading system; 6. Second servo control loading system; 7. Mud storage chamber; 8. Baffle; 9. Latex membrane; 10. High-definition action camera; 11. Adjusting valve; 12. Three-way pneumatic valve; 101. Conical base; 102. Bearing component; 103. Rotating arm; 104. Signal ring; 105. Rotary platform; 301. Air compressor; 302. Air pressure control system; 303. Water tank; 501. First hydraulic cylinder; 502. First displacement gauge; 503. First servo control device; 504. Penetrator; 601. Second hydraulic cylinder; 602. Second displacement gauge; 603. Trench section plate; 604. Second servo control device. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] like Figures 1 to 3 As shown, the centrifugal model test device and method for simulating mud wall protection and confined water environment in this embodiment includes a centrifuge platform, a model box 2, a gas-liquid control module 3 and a comprehensive monitoring module. The centrifuge platform adopts the beam centrifuge platform of the National University of Singapore, which can reach a maximum centrifugal acceleration of 200g and a maximum load capacity of 40g∙t, that is, the maximum effective load that can be applied under 200g and 100g conditions is 200kg and 400kg respectively.

[0042] The gas-liquid control module 3 includes an air compressor 301, a pneumatic control system 302, and a water tank 303. The air compressor 301 is installed on the upper end of the rotating arm 103. The pneumatic control system 302 and the water tank 303 are installed inside the air compressor 301. The air compressor 301 connects the pneumatic control system 302, the water tank 303, the latex membrane 9, and the soil sample inside the model box 2 through control pipelines. The gas-liquid control module 3 is used to simulate the grouting process during trench excavation and to increase the pore water pressure in the sand layer to achieve the purpose of simulating a sand layer containing confined water.

[0043] The integrated monitoring module includes a pore water pressure sensor, a displacement sensor, a strain gauge, and a particle image velocimetry (PIV) system. The PIV system is equipped with a high-definition motion camera 10, which is placed on one side of the upper end of the rotating arm 103. The strain gauge is placed on the other side of the upper end of the rotating arm 103. The displacement sensor is located on the surface of the soil sample inside the model box 2. The pore water pressure sensor is embedded in the latex membrane 9 and inside the soil sample in the model box 2. The integrated monitoring module is used to monitor the mechanical response and deformation field of the soil sample during the experiment. The PIV system acquisition device uses DaVis 8.0 series image processing software. Davis 8.0 mainly consists of a computer, analysis software, electronic equipment, an external trigger signal digital-to-analog converter, and a TTL input / output card. Davis 8.0 has a built-in digital-to-analog converter, providing analog-to-digital conversion and signal amplification functions. The high-definition motion camera 10 uses an SJ5000X motion camera, which is equipped with a high-performance image sensor with a resolution of 3840 pixels × 2160 pixels (4K). The device features UHD resolution, a pixel size of 1.34μm × 1.34μm, and supports a wide range of manual and automatic exposure adjustment from 1 / 10000s to 120s. It boasts a maximum video capture rate of 240fps (at 1080P resolution) and a maximum capture frequency of 30Hz (at 4K resolution). High-speed data transmission is achieved via Micro HDMI and USB-C multi-function interfaces, meeting the measurement accuracy requirements of the experiment and providing hardware support for its successful completion.

[0044] Specifically, a support 4 is installed on the upper end of the model box 2. A first servo control loading system 5 and a second servo control loading system 6 are installed on the two sides above the support 4, respectively. A mud storage chamber 7 is installed below the model box 2. A baffle 8 and a latex film 9 are installed inside the model box 2. An opening is provided at the upper end of the model box 2. The latex film 9 is 0.5mm thick, 200mm long, 10mm wide, and 330mm high. It is used to simulate the impermeable boundary between the mud and the soil sample in the trench section. When preparing the soil sample, a trench section plate 603 is placed inside the latex film 9 to provide lateral support. Its length is 200mm, width is 10mm, and height is 350mm.

[0045] The first servo-controlled loading system 5 includes a first hydraulic cylinder 501, a first displacement gauge 502, a first servo control device 503, and a penetrometer 504. The first hydraulic cylinder 501 is installed on one side of the upper end of the bracket 4. The first displacement gauge 502 is installed on one end of the first hydraulic cylinder 501. The first servo control device 503 is installed on the upper end of the first hydraulic cylinder 501. The penetrometer 504 is installed on the lower end of the first hydraulic cylinder 501. The penetrometer 504 consists of a front cylindrical detector and a penetration shaft perpendicularly connected to it. The front detector is 25mm long and 5mm in diameter. Strain gauges are attached to the part where the penetration shaft is connected to the crossbar. It can be used to measure the resistance experienced during T-bar penetration and can obtain the undrained shear strength profile of the soil sample based on the linear relationship between the load and the output voltage established during T-bar calibration.

[0046] The second servo-controlled loading system 6 includes a second hydraulic cylinder 601, a second displacement meter 602, a trough plate 603, and a second servo control device 604. The second hydraulic cylinder 601 is installed on one side of the upper end of the bracket 4. The second displacement meter 602 is installed on one end of the second hydraulic cylinder 601. The trough plate 603 is installed on the lower end of the second hydraulic cylinder 601. The second servo control device 604 is installed on the upper end of the second hydraulic cylinder 601.

[0047] Furthermore, the centrifuge platform includes a conical base 101, a bearing component 102, a rotating arm 103, a signal ring 104, and a rotary platform 105. There are two rotary platforms 105, and the model box 2 is located on the rotary platform 105. The planar geometric dimensions of each rotary platform 105 are 750mm × 700mm, and the maximum height of the model box 2 that it can accommodate is 1.29m. The effective rotation radius from the centrifuge rotation center to the bottom of the model box 2 is approximately 2m. The bearing component 102 is installed on the upper end of the conical base 101, and the rotating arm 103 is installed on the upper end of the bearing component 102. The signal ring 104 is installed above the rotating arm 103. The signal ring 104 can provide DC power to various sensors embedded in the model box 2 and can transmit sensor signals to the control room. The computer in the control room is equipped with DasyLab data acquisition software, which can collect and process the signals output by the sensors in the model box 2.

[0048] Furthermore, the second servo control loading system 6 includes a second hydraulic cylinder 601, a second displacement meter 602, a groove plate 603, and a second servo control device 604. The second hydraulic cylinder 601 is installed on one side of the upper end of the bracket 4, the second displacement meter 602 is installed on one end of the second hydraulic cylinder 601, the groove plate 603 is installed on the lower end of the second hydraulic cylinder 601, and the second servo control device 604 is installed on the upper end of the second hydraulic cylinder 601.

[0049] Furthermore, one end of model box 2 is made of transparent plexiglass, while the other end is made of stainless steel. Model box 2 is 550mm long, 250mm wide, and 450mm high. The front transparent plexiglass plate is 60mm thick, facilitating full-process observation of the experiment by high-definition action cameras 10.

[0050] Furthermore, the baffle 8 is L-shaped and is located on the rear and right side of the model box 2, with the latex film 9 installed on one side of the baffle 8.

[0051] Furthermore, the groove plate 603 is installed inside the latex film 9.

[0052] Furthermore, a regulating valve 11 is installed at one end of the mud storage chamber 7. The regulating valve 11 is used to regulate the flow of mud. A three-way pneumatic valve 12 is installed at the upper end of the mud storage chamber 7. One end of the three-way pneumatic valve 12 is connected to the bottom end of the latex membrane 9 through a pipe. The upper end of the three-way pneumatic valve 12 forms a closed loop with the air compressor 301 through a hose. The hose is a high-pressure transparent hose.

[0053] Furthermore, a circular plastic piece is installed at the bottom of the displacement sensor guide rod to prevent the displacement sensor guide rod from being inserted into the soil sample.

[0054] The measuring elements used include: 6 displacement gauges for measuring surface settlement (2 LP-100A displacement gauges near the trench wall with a range of 100mm, and the remaining 4 displacement gauges with a range of 50mm), 2 LP-300C displacement gauges for controlling the movement of hydraulic cylinders with a range of 300mm, 3 PDCR81 pore water pressure sensors with a range of 7bar, 1 SJ5000X motion camera, and 1 custom T-bar; the 6 displacement gauges placed on the ground surface are mainly used to measure the surface settlement of soil samples. The bottom of the guide rods of the 6 displacement gauges is also attached with circular plastic pieces to prevent the guide rods from piercing the soil during the test; the 2 LP-300C displacement gauges are used to measure the movement of the two vertical hydraulic cylinders on the top support 4 of the model box 2; the change in the length of the displacement gauge guide rod will change its resistance value, thereby changing the output voltage of the displacement gauge; the output voltage of the displacement gauge can be linearly related to the extension and retraction of its guide rod, thus obtaining the displacement change data of the measured part; 3 Druck The PDCR81 miniature pore water pressure sensor is embedded in the bottom of the latex membrane 9 and in the soil sample to measure the changes in pore water pressure at the test location. Before the test, the air pressure in the cavity of the pore pressure gauge is changed by an air pump, and the linear relationship between the two can be established by the output voltage reading of the pore pressure gauge displayed by the multimeter, so as to calibrate the pore water pressure sensor before the test.

[0055] Sodium fluorescein tracer is added to the slurry to mark the slurry movement trajectory using its colorimetric properties. When sodium fluorescein penetrates into the sand layer with the slurry, it exhibits a fluorescent effect under light, clearly showing the slurry intrusion path and diffusion range.

[0056] A centrifugal model test method simulating mud wall protection and confined water environment includes the following steps:

[0057] S1 First, the prepared soil sample is placed inside the model box 2 and solidified. The prepared soil sample includes saturated clay sample or layered soil sample containing sand interlayer. The saturated clay sample is divided into two types: normally consolidated clay and overconsolidated clay. The centrifugal acceleration of normally consolidated clay is 70g during the early consolidation and later test of the soil sample; while the centrifugal acceleration of overconsolidated clay is 100g during the early consolidation of the soil sample, and the centrifugal acceleration is reduced to 70g during the test, with an overconsolidation ratio of 1.4.

[0058] S2 starts the centrifuge and adjusts the centrifuge to an acceleration that matches the target.

[0059] S3 injects liquid into the latex membrane 9 to a predetermined level through the gas-liquid control module to simulate mud wall protection, and injects sodium chloride solution as mud medium.

[0060] S4 controls the second hydraulic cylinder 601 to shorten, and the second hydraulic cylinder 601 drives the trench section plate 603 to rise, simulating trench excavation;

[0061] During the excavation process, S5 performs one or more of the following operations through the gas-liquid control module:

[0062] S51. Maintain the liquid level inside the latex membrane 9 to simulate normal support conditions;

[0063] S52. Inject liquid into a designated sand layer to simulate the action of confined water;

[0064] S6 collects pore water pressure, surface settlement, and soil sample deformation image data throughout the entire process through a comprehensive monitoring module.

[0065] S7. After the test, analyze the data, study the stability of the tank wall and the instability mechanism, and improve the above content.

[0066] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A centrifugal model test device for simulating mud wall protection and confined water environment, characterized in that: It includes a centrifuge platform, a model box (2), a gas-liquid control module (3), and a comprehensive monitoring module; The gas-liquid control module (3) includes an air compressor (301), a pressure control system (302), and a water tank (303). The air compressor (301) is installed on the upper end of the rotating arm (103). The pressure control system (302) and the water tank (303) are installed inside the air compressor (301). The air compressor (301) connects the pressure control system (302), the water tank (303), the latex membrane (9), and the soil sample inside the model box (2) through control pipelines. The integrated monitoring module includes a pore water pressure sensor, a displacement sensor, a strain gauge and a particle image velocimetry (PIV) system. The PIV system is equipped with a high-definition motion camera (10). The high-definition motion camera (10) is placed on one side of the upper end of the rotating arm (103), and the strain gauge is placed on the other side of the upper end of the rotating arm (103). The displacement sensor is located on the surface of the soil sample inside the model box (2), and the pore water pressure sensor is buried in the latex membrane (9) and inside the soil sample of the model box (2).

2. The centrifuge model test device for simulating mud wall protection and confined water environment according to claim 1, characterized in that: The model box (2) is equipped with a bracket (4) at the top. The first servo control loading system (5) and the second servo control loading system (6) are respectively installed on the two sides above the bracket (4). The mud storage chamber (7) is installed below the model box (2). The model box (2) is equipped with a baffle (8) and a latex film (9). The model box (2) has an opening at the top. The first servo-controlled loading system (5) includes a first hydraulic cylinder (501), a first displacement meter (502), a first servo control device (503), and a penetrator (504). The first hydraulic cylinder (501) is installed on one side of the upper end of the bracket (4), the first displacement meter (502) is installed on one end of the first hydraulic cylinder (501), the first servo control device (503) is installed on the upper end of the first hydraulic cylinder (501), and the penetrator (504) is installed on the lower end of the first hydraulic cylinder (501). The second servo control loading system (6) includes a second hydraulic cylinder (601), a second displacement meter (602), a groove plate (603), and a second servo control device (604). The second hydraulic cylinder (601) is installed on one side of the upper end of the bracket (4), the second displacement meter (602) is installed on one end of the second hydraulic cylinder (601), the groove plate (603) is installed on the lower end of the second hydraulic cylinder (601), and the second servo control device (604) is installed on the upper end of the second hydraulic cylinder (601).

3. The centrifuge model test device for simulating mud wall protection and confined water environment according to claim 1, characterized in that: The centrifuge platform includes a conical base (101), a bearing component (102), a rotating arm (103), a signal ring (104), and a rotary platform (105). There are two rotary platforms (105). The model box (2) is located on the rotary platform (105). The bearing component (102) is installed on the upper end of the conical base (101). The rotating arm (103) is installed on the upper end of the bearing component (102). The signal ring (104) is installed above the rotating arm (103).

4. The centrifuge model test device for simulating mud wall protection and confined water environment according to claim 1, characterized in that: One end of the model box (2) is made of transparent organic glass, and the other end of the model box (2) is made of stainless steel plate.

5. The centrifuge model test device for simulating mud wall protection and confined water environment according to claim 2, characterized in that: The baffle (8) is L-shaped and is located on the rear and right side of the model box (2). The latex film (9) is installed on one side of the baffle (8).

6. The centrifuge model test device for simulating mud wall protection and confined water environment according to claim 1, characterized in that: The groove plate (603) is installed inside the latex film (9).

7. The centrifuge model test device for simulating mud wall protection and confined water environment according to claim 1, characterized in that: A regulating valve (11) is installed at one end of the mud storage chamber (7), and a three-way pneumatic valve (12) is installed at the upper end of the mud storage chamber (7). One end of the three-way pneumatic valve (12) is connected to the bottom end of the latex membrane (9) through a pipe, and the upper end of the three-way pneumatic valve (12) forms a closed loop through a hose and an air compressor (301).

8. The centrifuge model test device for simulating mud wall protection and confined water environment according to claim 1, characterized in that: A circular plastic sheet is installed at the bottom of the displacement sensor guide rod.

9. The centrifuge model test method for simulating mud wall protection and confined water environment according to any one of claims 1-8, comprising the following steps: S1 First, the prepared soil sample is placed inside the model box (2) and solidified. The prepared soil sample includes saturated clay sample or layered soil sample containing sand interlayer. The saturated clay sample is divided into two types: normally consolidated clay and overconsolidated clay. The centrifugal acceleration of normally consolidated clay is 70g during the early consolidation and later test of the soil sample. The centrifugal acceleration of overconsolidated clay is 100g during the early consolidation of the soil sample, and the centrifugal acceleration is reduced to 70g during the test. The overconsolidation ratio is 1.

4. S2 starts the centrifuge and adjusts the centrifuge to an acceleration that matches the target. S3 injects liquid into the latex membrane (9) to a predetermined level through the gas-liquid control module to simulate mud wall protection, and injects sodium chloride solution as mud medium; S4 controls the second hydraulic cylinder (601) to shorten, and the second hydraulic cylinder (601) drives the trench section plate (603) to rise, simulating trench excavation; During the excavation process, S5 performs one or more of the following operations through the gas-liquid control module: S51. Maintain the liquid level inside the latex membrane (9) to simulate normal support conditions; S52. Inject liquid into a designated sand layer to simulate the action of confined water; S6 collects pore water pressure, surface settlement, and soil sample deformation image data throughout the entire process through a comprehensive monitoring module. S7. After the test, analyze the data, study the stability of the tank wall and the instability mechanism, and improve the above content.

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