Test device and test method for simulating catastrophe of shield tunneling face in composite stratum slurry

Abstract

The present application relates to the field of slurry shield construction, and particularly to a test device and a test method for simulating slurry shield face disaster in composite stratum, comprising a model box, a shield system, a slurry generating system and a monitoring system; the present application discloses a test device for simulating slurry shield face disaster in composite stratum; the test device disclosed by the present application can be applied to round gravel-mudstone composite stratum; meanwhile, the present application adopts fluctuation type slurry pressure to supply slurry to the slurry bin; the actual working condition of the slurry shield can be better simulated, so that the test device disclosed by the present application can be used to reveal the passive failure mechanism of the round gravel-mudstone composite stratum slurry shield face, and provide technical support for the slurry burst early warning; meanwhile, the test device can provide indoor test ideas for the failure process of the shield face in similar binary composite stratum.

Description

Technical Field

[0001] This invention relates to the field of slurry shield tunneling, specifically to a test device and test method for simulating catastrophic events at the excavation face of a slurry shield tunnel in composite strata. Background Technology

[0002] Over the past two decades, with the increasing maturity of shield tunneling technology, shield tunneling construction technology has been widely used in tunnel construction.

[0003] Slurry leakage during slurry shield tunneling in complex strata is a typical consequence of passive damage to the excavation face. Slurry leakage accidents during slurry shield tunneling in urban core areas not only cause personal and property losses, but also pollute the environment and cause adverse social impacts.

[0004] Current research on the passive failure mechanism of slurry shield tunneling faces focuses on single strata, with ultimate support pressure as the research target; there is no research on the passive failure of excavation faces in binary differential composite strata of gravel-mudstone, and there is a lack of triggering mechanisms for passive failure of excavation faces under strong fluctuating slurry pressure, as well as a lack of indoor experimental research on the diffusion law of slurry in gravel strata and its impact on the ground during slurry spillage.

[0005] At the same time, it lacks consideration of the slurry pressure fluctuation characteristics of the excavation face in typical composite strata, and cannot more accurately reflect the passive damage process of the excavation face caused by slurry shield blockage in gravel-mudstone composite strata.

[0006] Therefore, in order to better solve the above problems, a new type of simulation test device is needed. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a test device that can simulate the disaster at the excavation face of a slurry shield tunnel in composite strata.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] An experimental device for simulating catastrophic events at the excavation face of a slurry shield tunneling machine in complex geological formations includes a model box, a shield tunneling system, a slurry generation system, and a monitoring system.

[0010] The model box includes a box body; at least one side of the box body is made of plexiglass; the box body is filled with a composite stratum.

[0011] The tunnel boring machine system includes a tunnel boring machine, which includes a cutterhead connected to a drive mechanism; the cutterhead is connected to a slurry chamber; and the slurry chamber is connected to a slurry generation system.

[0012] The mud generation system includes a mud inlet system and a mud discharge system. The mud inlet system includes a mud inlet tank, which is connected to a pressure supply component. The mud inlet tank is connected to the mud-water tank through a mud inlet pipe.

[0013] The slurry discharge system includes a slurry discharge pipe connected to the mud and water tank, and a slurry discharge tank is connected to the end of the slurry discharge pipe away from the mud and water tank.

[0014] The monitoring system includes displacement gauges and 3D cameras arranged on the composite strata;

[0015] The mud generation system uses fluctuating mud pressure to supply mud to the mud-water tank.

[0016] The mud in the feed tank is dyed using a tracer.

[0017] The pressure supply component includes an air compressor, which is connected to an air compressor control system.

[0018] The drive mechanism includes a threaded steel shaft that passes through the housing and is connected to the cutter head; the threaded steel shaft is connected to a drive motor.

[0019] The composite strata include a mudstone layer, on which a gravel layer is laid.

[0020] The gravel layer is covered with black coarse sand.

[0021] The monitoring system also includes multiple cross-section monitoring components; each of the cross-section monitoring components includes multiple detection units, including water pressure gauges and earth pressure gauges.

[0022] The monitoring components of adjacent sections are distributed at intervals; the detection parts in each monitoring component are connected by steel wires; the water pressure gauge and earth pressure gauge in each detection part are arranged on a connecting steel plate, which is connected to the steel wire.

[0023] A test method for an experimental device based on a simulated catastrophic event at the excavation face of a slurry shield tunneling machine in composite strata; the test method includes the following steps:

[0024] Step 1: Assemble the test device; the shield tunneling machine in the shield tunneling system must pass through the box hull and be arranged in the composite stratum;

[0025] Step 2: The cutterhead is rotated by the drive mechanism to excavate the composite strata; at the same time, the mud generation system supplies mud to the mud chamber; mud at different pressures is supplied to the end of the tunnel boring machine through the pressure supply component; during the above operations, the working status of each area of ​​the composite strata is monitored in real time through the monitoring system and PIV technology; and the measured data is recorded.

[0026] Step 3: Repeat Step 2 after changing the ratio of mudstone height at the tunnel boring machine and / or the tunnel face to the cutterhead excavation diameter, and record the relevant test data.

[0027] In step 2, when the mud generation system supplies mud to the mud-water tank, the initial mud inlet pressure is set to a constant pressure without fluctuation. Once the mud film is generated and stabilized at the excavation face, the mud inlet pressure is changed to a fluctuating pressure.

[0028] The advantages of this invention are:

[0029] This invention discloses an experimental device for simulating the catastrophic failure of a slurry shield tunneling face in composite strata. The experimental device disclosed in this invention is applicable to gravel-mudstone composite strata. Furthermore, this invention employs a fluctuating slurry pressure to supply slurry to the slurry chamber, which can better simulate the actual working conditions of a slurry shield tunneling machine. This allows the experimental device disclosed in this invention to reveal the passive failure mechanism of the slurry shield tunneling face in gravel-mudstone composite strata, providing technical support for slurry leakage early warning. Simultaneously, it can provide indoor experimental ideas for the failure process of shield tunneling faces in similar binary composite strata. Attached Figure Description

[0030] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0031] Figure 1 This is a schematic diagram of the structure of the present invention.

[0032] The markings in the above figures are all:

[0033] 1. Model box, 2. Composite strata, 3. Shield tunneling system, 4. Mud generation system, 5. Monitoring system. Detailed Implementation

[0034] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0035] An experimental device for simulating the catastrophic failure of a slurry shield tunneling face in composite strata includes a model box 1, a shield tunneling system 3, a slurry generation system 4, and a monitoring system 5. This invention discloses an experimental device for simulating the catastrophic failure of a slurry shield tunneling face in composite strata. The experimental device disclosed in this invention is applicable to gravel-mudstone composite strata 2. Furthermore, this invention employs a fluctuating slurry pressure to supply slurry to the slurry chamber, which can better simulate the actual working conditions of a slurry shield tunneling machine. This allows the experimental device disclosed in this invention to reveal the passive failure mechanism of the slurry shield tunneling face in gravel-mudstone composite strata 2, providing technical support for slurry leakage early warning. It can also provide indoor experimental ideas for the failure process of shield tunneling faces in similar binary composite strata 2.

[0036] Specifically, this invention discloses a test device that can simulate a disaster at the excavation face of a slurry shield tunneling machine in a composite stratum 2. The device mainly includes a model box 1, which serves as the foundation of the entire test device, facilitating the placement of the composite stratum 2 and providing constraint and positioning for the shield machine's excavation operation. The model box 1 includes a box body; at least one side of the box body is made of plexiglass; the box body is filled with the composite stratum 2. The purpose of having at least one side of the model box 1 made of plexiglass is to facilitate the camera in the monitoring component to capture images of the composite stratum 2. Furthermore, the shield tunneling system 3 in this invention includes a shield machine, which includes a cutterhead 31 connected to a drive mechanism. The drive mechanism is used to drive the cutterhead rotation and subsequent excavation operations, simulating the actual operating state of the shield machine. Additionally, a slurry shield is connected to the cutterhead 31. A water tank; the mud tank is connected to a mud generation system 4; the mud generation system 4 includes a mud inlet system and a mud discharge system. The mud inlet system includes a mud inlet tank 41, which is connected to a pressure supply component. The mud inlet tank 41 is connected to the mud tank via a mud inlet pipe 43. Through the pressure supply component, the mud inlet system can input mud at a certain pressure into the mud tank of the tunnel boring machine, simulating the mud at the end of the tunnel boring machine under actual working conditions, and is used to simulate the failure process and mud leakage disaster process of the excavation face of the composite stratum 2. The mud discharge system includes a mud discharge pipe 44 connected to the mud tank, and the end of the mud discharge pipe 44 away from the mud tank is connected to a mud discharge tank 45. The mud discharge system facilitates the collection of mud generated during the experiment and avoids pollution of the experimental environment. At the same time, in this invention, the monitoring system 5 includes a displacement meter 52 and a 3D camera 51 arranged on the composite stratum 2. Using 3D... The DIC camera 51 and displacement meter 52 monitor surface deformation in real time. Simultaneously, three displacement meters 52 are deployed on the composite stratum 2 to correct the surface deformation measured by the 3D DIC camera 51, especially the area near the plexiglass plate. Furthermore, as a further optimization, the mud generation system 4 in this invention employs a fluctuating mud pressure to supply mud to the mud-water chamber. Here, fluctuating mud pressure refers to changing mud pressure. The main difference from traditional mud supply is that traditional mud supply is a constant pressure operation, while this invention, in actual testing, is a variable pressure mud supply operation. The mud supply method disclosed in this invention is more in line with actual production because the mud pressure formed at the excavation face during actual production is variable, not a constant value. The mud supply method adopted in this invention provides better and more accurate measurement results.

[0037] Furthermore, in this invention, the mud in the slurry tank 41 is dyed with a tracer; by setting the tracer and combining it with PIV technology, this invention facilitates the camera to capture the mud diffusion process and the PIV technology to obtain the mud diffusion displacement field.

[0038] Furthermore, the pressure supply component in this invention includes an air compressor 42, which is connected to an air compressor control system 47. The air compressor 42 is mainly used to pressurize the slurry tank 41 to realize the slurry supply operation to the mud and water silo. In addition, the air compressor 42 is connected to the air compressor control system 47, which is used to control the output pressure of the air compressor 42, thereby controlling the slurry supply pressure.

[0039] Furthermore, the drive mechanism in this invention includes a threaded steel shaft 32, which passes through the housing and is connected to the cutter head 31; the threaded steel shaft 32 is connected to a drive motor 33; in this invention, the threaded steel shaft 32 serves as a transmission component, which not only enables the rotational transmission of the cutter head 31, but also provides a good obstacle avoidance function, facilitating the arrangement of the slurry inlet pipe 43 and the slurry outlet pipe 44, and avoiding interference.

[0040] Furthermore, in this invention, the composite stratum 2 includes a mudstone layer 21, on which a gravel layer 22 is laid. By stacking the mudstone layer 21 and the gravel layer 22, this invention can simulate the composite stratum 2, and thus simulate the working conditions of the tunnel boring machine in the composite stratum 2.

[0041] Furthermore, black coarse sand particles are laid on the gravel layer 22 described in this invention; the purpose of laying black coarse sand particles as speckles on the surface of the gravel layer is for subsequent three-dimensional surface deformation treatment.

[0042] Furthermore, the monitoring system 5 in this invention also includes multiple cross-section monitoring components 53; each of the cross-section monitoring components includes multiple detection units 531, and the detection units 531 include water pressure gauges 5312 and earth pressure gauges 5311; through the setting of water pressure gauges 5312 and earth pressure gauges 5311, this invention can be used to monitor earth pressure and pore water pressure in real time during the test.

[0043] Furthermore, in this invention, adjacent cross-section monitoring components 53 are spaced apart; this arrangement allows for greater detection of the composite strata 2 within the entire model box 1. Additionally, in this invention, the detection sections 531 in each cross-section monitoring component 53 are connected by steel wires; the steel wires ensure the integrity of each detection section 531. Furthermore, the water pressure gauge 5312 and earth pressure gauge 5311 in each detection section 531 are arranged on connecting steel plates, which are connected to the steel wires; the connecting steel plates ensure the integrity between the water pressure gauge 5312 and the corresponding earth pressure gauge 5311; simultaneously, this facilitates the overall installation and disassembly of the actual cross-section monitoring components 53, avoiding the problem of inconvenient installation and disassembly due to cluttered arrangements.

[0044] A test method for an experimental device based on a simulated catastrophic event at the excavation face of a slurry shield tunneling machine in a composite geological formation; the test method includes the following steps:

[0045] Step 1: Assemble the test device; the shield machine in shield system 3 is required to pass through the box and be arranged in the composite stratum 2;

[0046] Step 2: The cutterhead 31 is rotated by the drive mechanism to excavate the composite stratum 2; at the same time, the mud generation system 4 supplies mud to the mud chamber; mud of different pressures is supplied to the end of the tunnel boring machine through the pressure supply component; during the above operations, the working status of each area of ​​the composite stratum 2 is monitored in real time through the monitoring system 5 and PIV technology; and the measured data is recorded.

[0047] Step 3: Repeat Step 2 after changing the ratio of the mudstone height of the tunnel boring machine and / or the excavation face to the excavation diameter of the cutterhead 31, and record the relevant test data.

[0048] This invention, through the aforementioned experimental methods, designs different experimental conditions, considers the slurry pressure fluctuation characteristics obtained from measured shield tunneling parameters, and utilizes advanced observation methods to observe the failure process and slurry leakage characteristics of the excavation face during the experiment. This invention can be used to reveal the passive failure mechanism of the slurry shield tunneling face in gravelly mudstone composite strata 2, providing technical support for slurry leakage early warning; at the same time, it can provide indoor experimental ideas for the failure process of shield tunneling faces in similar binary composite strata 2.

[0049] In addition, in step 2 of this invention, when the mud generation system 4 supplies mud to the mud-water chamber, the initial mud inlet pressure is set to a constant pressure without fluctuation. After the mud film is generated and stabilized at the excavation face, the mud inlet pressure is changed to a fluctuating pressure. This setting can ensure a smooth transition of the entire device during use and reduce or avoid the impact of sudden pressure fluctuations on the entire test measurement value.

[0050] specific:

[0051] The purpose of this invention is to provide an indoor test device for slurry leakage disaster at the excavation face of a slurry shield tunneling machine in a composite stratum 2. It mainly targets the slurry leakage disaster process in a slurry shield tunneling machine in a gravel-mudstone composite stratum 2, designing a similar model test device for slurry leakage failure at the excavation face of a slurry shield tunneling machine in a gravel-mudstone composite stratum 2. By tracing and staining the slurry, combined with PIV technology, the characteristics of the slurry diffusion displacement field during the slurry leakage failure process in the gravel-mudstone composite stratum 2 are captured. Furthermore, the ground deformation development mode under different test conditions is obtained using 3D DIC cameras 51 and other means. In other words, this invention can not only reveal the passive failure mechanism of the excavation face of a slurry shield tunneling machine in a gravel-mudstone composite stratum 2, but also provide relevant experimental ideas for the instability failure process of the excavation face of a similar binary composite stratum 2 slurry shield tunneling machine, and provide a new approach to combining on-site measured data from shield tunneling construction with indoor tests.

[0052] The experimental apparatus disclosed in this invention mainly includes a model box 1, a mud generation system 4, a shield tunneling system 3, and a monitoring system 5. The experiment can consider the mud-water pressure fluctuation characteristics extracted from the measured shield tunneling data as the input pressure. The mud diffusion displacement field characteristics during the mud leakage failure process of the gravel-mudstone composite stratum 2 are observed through PIV technology. The ground deformation development mode under different test conditions is obtained by means of 3D DIC camera 51, etc., providing technical support for revealing the mud leakage disaster mechanism of the shield excavation face of the composite stratum 2.

[0053] Working condition design

[0054] Actual working condition design needs to consider the size of the cutterhead 31, which is the diameter of the tunnel boring machine's excavation face. Generally, two burial depth conditions need to be considered: 2.6D and 4.2D (D is the diameter of the tunnel boring machine's excavation face in the model test, in mm). At the same time, three types of stratum composite ratios (the ratio of the mudstone height of the tunnel boring machine's excavation face to the excavation diameter of the cutterhead 31) are considered: 0.2, 0.5, and 0.8. Tests are carried out on the entire process of passive instability of the excavation face, mud diffusion, and even ground slurry leakage caused by typical mud fluctuation input under different composite ratios. Earth pressure gauge 5311 and micro pore pressure gauge are used to measure the changes in water and soil pressure during mud diffusion. In order to better observe the slurry leakage process, a symmetrically arranged tunnel boring machine model is used, and the mud diffusion displacement field is obtained by high-speed camera + DIC. Ground settlement changes are observed using 3D DIC camera 51, and displacement gauge 52 is used for verification.

[0055] In this invention, model box 1:

[0056] The device measures 1000mm×500mm×750mm, with three sides made of steel plates and one side of plexiglass. The excavation face damage and mud infiltration process can be observed in real time through the camera system 51 in the monitoring system. However, this model test only focuses on the damage mechanism at the excavation face.

[0057] For composite stratum 2, soil samples from the actual construction area can be used. Specifically, for the mudstone part, after sampling on site, the samples are processed by the factory to the required composite ratio thickness and cut into a shape that fits the shield machine model. The gravel stratum is taken from the site, and excessively large particles are removed to prevent clogging of the grout pipe. The groundwater conditions are simulated based on the actual water level.

[0058] Mud generation system 4:

[0059] The characteristics of mud pressure fluctuation under different composite ratio strata were extracted by on-site measured shield tunneling parameters. The input pressure of the model test was calculated by similarity criteria. A fluctuating mud generation system 4 was developed. The air compressor 42 was automatically generated on demand by PLC programming control. The mud pressure generated by the slurry tank 41 was tested by pressure gauge 46 and feedback correction was performed to ensure that the required mud pressure input value was generated.

[0060] Pressurized mud enters the slurry chamber of the tunnel boring machine (TBM) through the inlet pipe 43. It then acts on the gravel-mudstone stratum through an opening on the cutterhead 31. The mud and soil mixture flows into the discharge tank 45 through the discharge pipe 44. The dimensions of the inlet and discharge pipes 44 are determined based on the mud pressure and the gradation of the gravel stratum. Initially, the inlet pressure is set to a stable, non-fluctuating pressure to allow a mud film to form at the excavation face and stabilize for a period before a fluctuating pressure test is conducted. Measures are taken during the test to ensure the mud generation system 4 is leak-proof. During the test, the presence of dyed mud breaking through the mud film and entering the gravel stratum is observed as an indicator of passive damage to the excavation face. Changes in the excavation face and the diffusion of mud within the soil are constantly recorded.

[0061] Based on the principle of similarity, a suitable mud mix ratio was prepared, with a focus on the mud's viscosity, density, and filtration loss. The mud was composed of bentonite, CMC (sodium carboxymethyl cellulose), and water. Viscosity was measured using a Martens viscometer, density using a mud hydrometer, and filtration loss using a mud filtration loss meter. The mud was dyed with a tracer to facilitate camera recording of the mud diffusion process and PIV technology to obtain the mud diffusion displacement field.

[0062] Shield Tunneling System 3:

[0063] The tunnel boring machine (TBM) is shaped like a semi-cylinder. The cutterhead 31 has a diameter of 100mm and is made of steel plate. Considering the opening ratio of 35% to 40%, it needs to be determined according to the gradation curve of the gravel strata. The cutterhead 31 is connected to the rear drive motor 33 through the main drive. The main drive uses threaded steel pipe. The propulsion and rotation of the cutterhead 31 are composed of guide rails, threaded steel pipes, drive motors and their gears. The tunneling speed of the TBM is determined by the speed of the main bearing, which is controlled by the gear ratio between the motor gear and the steel shaft gear.

[0064] The tunnel boring machine (TBM) is shaped like a semi-cylinder. The cutterhead 31 has a diameter of 100mm and is machined from steel plates. Considering an opening ratio of 35%–40%, the exact ratio needs to be determined based on the gradation curve of the gravel strata. The cutterhead 31 is connected to the rear drive motor 33 via a main drive unit. The main drive unit uses threaded steel pipes. The propulsion and rotation of the cutterhead 31 are achieved through guide rails, threaded steel pipes, the drive motor, and its gears. The TBM's tunneling speed is determined by the main bearing speed, which is controlled by the gear ratio between the motor gears and the steel shaft gears. A slurry chamber is located 15mm behind the cutterhead 31 for slurry inlet and outlet. During testing, slurry blockage can be simulated by limiting the flow rate of the discharge pipe.

[0065] Monitoring System 5:

[0066] It is used for real-time measurement and testing of changes in soil and water pressure caused by mud diffusion, the diffusion process of mud in gravel strata, and the resulting surface deformation.

[0067] Earth pressure gauge 5311 and micro pore pressure gauge were used to measure the changes in water and soil pressure during mud diffusion. To better observe the mud seepage process, a symmetrically arranged shield machine model was used, and the mud diffusion displacement field was obtained by high-speed camera + DIC. Ground settlement changes were observed using 3DDIC camera 51, and displacement gauge 52 was used for verification.

[0068] Miniature earth pressure gauges 5311 and pore water pressure gauges 5312 were used to monitor earth pressure and pore water pressure in real time during the test. Five monitoring sections were arranged, with a distance of 100 mm between each section. Section #1 was located 50 mm behind and 50 mm in front of the initial position of the cutterhead 31. The earth pressure gauges 5311 and pore water pressure gauges 5312 were fixed to a prism formed by steel sheets. The sensors in each section were connected in series by steel wires, with the vertical spacing varying between 100 and 150 mm depending on the burial depth ratio. The lowest sensor in each section was 50 mm vertically from the top of the tunnel boring machine. Section #2 had four monitoring points, with the lowest sensor located 10-25 mm above the mudstone layer 21. A total of 16 earth pressure gauges 5311 and pore water pressure gauges 5312 were required for the entire model test.

[0069] By using tracer staining to highlight the contrast with the gravel strata while minimizing the impact on the physical and mechanical properties of the mud, a high-speed camera system was used on the side of the plexiglass plate of model box 1 to track and measure the mud diffusion process at the excavation face in real time, capturing the passive failure mode of the excavation face. The images obtained were processed by PIV to obtain the mud diffusion displacement field at the excavation face under different burial depth ratios and composite ratios.

[0070] Real-time monitoring of surface deformation is achieved using 3D DIC and displacement gauges 52. The 3D DIC dual camera 51 is positioned on one side of the model box 1. Black coarse sand particles are laid on the surface of the gravel layer as speckles for subsequent three-dimensional surface deformation processing. Three displacement gauges 52 are arranged at the surface locations of monitoring sections #2, #3, and #4 to correct the surface deformation measured by the 3D DIC camera 51, especially at the location near the plexiglass plate.

[0071] Obviously, the specific implementation of this invention is not limited to the above-described methods. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A test device for simulating catastrophic events at the excavation face of a slurry shield tunneling machine in composite strata, characterized in that, This includes a model box, a tunnel boring machine system, a mud generation system, and a monitoring system; The model box includes a box body; at least one side of the box body is made of plexiglass; the box body is filled with a composite stratum. The tunnel boring machine system includes a tunnel boring machine, the tunnel boring machine includes a cutterhead, and the cutterhead is connected to a drive mechanism; The cutterhead is connected to a slurry tank; the slurry tank is connected to a slurry generation system; The mud generation system includes a mud inlet system and a mud discharge system. The mud inlet system includes a mud inlet tank, which is connected to a pressure supply component. The mud inlet tank is connected to the mud-water tank through a mud inlet pipe. The slurry discharge system includes a slurry discharge pipe connected to the mud and water tank, and a slurry discharge tank is connected to the end of the slurry discharge pipe away from the mud and water tank. The monitoring system includes displacement gauges and 3D cameras arranged on the composite strata; The pressure supply component includes an air compressor, and the air compressor is connected to an air compressor control system; The composite strata include a mudstone layer, on which a gravel layer is laid; The gravel layer was covered with black coarse sand particles; The mud in the feed tank is dyed using a tracer. The mud generation system uses fluctuating mud pressure to supply mud to the mud-water tank. When the mud generation system supplies mud to the mud-water tank, the initial mud inlet pressure is set to a constant pressure without fluctuation. Once a mud film is generated and stabilized at the excavation face, the mud inlet pressure is changed to a fluctuating pressure.

2. The experimental device for simulating catastrophic events at the excavation face of a slurry shield tunneling machine in composite strata, as described in claim 1, is characterized in that... The mud in the feed tank is dyed with a tracer.

3. The experimental device for simulating catastrophic events at the excavation face of a slurry shield tunneling machine in composite strata, as described in claim 1, is characterized in that... The drive mechanism includes a threaded steel shaft that passes through the housing and is connected to the cutter head; the threaded steel shaft is connected to a drive motor.

4. The experimental device for simulating catastrophic events at the excavation face of a slurry shield tunneling machine in composite strata, as described in claim 1, is characterized in that... The monitoring system also includes multiple cross-section monitoring components; each cross-section monitoring component includes multiple detection units, including water pressure gauges and earth pressure gauges.

5. The experimental device for simulating catastrophic events at the excavation face of a slurry shield tunneling machine in composite strata, as described in claim 4, is characterized in that... The monitoring components of adjacent sections are distributed at intervals; the detection parts in each monitoring component are connected by steel wires; the water pressure gauge and earth pressure gauge in each detection part are arranged on a connecting steel plate, which is connected to the steel wire.

6. A test method for a test apparatus based on any one of claims 1-5 to simulate catastrophic events at the excavation face of a slurry shield tunneling machine in composite strata, characterized in that... ； The experimental method includes the following steps: Step 1: Assemble the test device; the shield tunneling machine in the shield tunneling system must pass through the box hull and be arranged in the composite stratum; Step 2: The cutterhead is rotated by the drive mechanism to excavate the composite strata; at the same time, the mud generation system supplies mud to the mud chamber; mud at different pressures is supplied to the end of the tunnel boring machine through the pressure supply component; during the above operations, the working status of each area of ​​the composite strata is monitored in real time through the monitoring system and PIV technology; and the measured data is recorded. Step 3: Repeat Step 2 after changing the ratio of mudstone height at the tunnel boring machine and / or the tunnel face to the cutterhead excavation diameter, and record the relevant test data.

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