Tunnel dislocation indoor test fault internal structure simulation method and excavation simulation method

Abstract

The invention discloses a tunnel dislocation indoor test fault internal structure simulation method and an excavation simulation method, relates to the technical field of tunnel construction simulation, and aims to solve the technical problem that an existing simulation method cannot truly and visually reflect deformation characteristics of surrounding rock and mechanical response characteristics of a tunnel structure. The method comprises the following steps: preparing a model box body; a stratum is manufactured in the model box, the stratum comprises a first part, a second part and a sliding face arranged between the first part and the second part, and different fault motions are simulated by adjusting the friction characteristics of the sliding face; the tunnel model is accurately placed at the calibration position, the tunnel model is wrapped with a controllable excavation layer, and the edge of the controllable excavation layer is connected with a driving system; arranging data acquisition equipment at different positions of the stratum and in the tunnel model; connecting a real-time dynamic tracking visualization system to acquire a sensor signal, and analyzing and displaying the sensor signal until the model box is prepared; according to the invention, high-precision visual tracking of the whole excavation and dislocation process of the tunnel model is realized.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction simulation technology, specifically to a method for simulating the internal structure of a fault in a tunnel displacement indoor test and a method for simulating excavation. Background Technology

[0002] Physical model tests, as an important means of studying the mechanical response of tunnel structures under fault slippage, can realistically and intuitively reflect the deformation characteristics of the surrounding rock and the mechanical response characteristics of the tunnel structure. However, the following shortcomings still exist:

[0003] 1) Due to limitations in observation technology, experiments cannot achieve high-precision, full-process visualization and tracking of the detailed response of tunnels during excavation and fault slippage. Especially under conditions of non-transparent materials or enclosed media, it is impossible to directly obtain key information such as the internal deformation of the surrounding rock and structure, shear zone expansion, or displacement field evolution. This is similar to the conventional fault slippage model device mentioned in the paper "Study on the Response Law of Tunnel Structures under Multi-Fracturing Strike-Slip Fault Slippage."

[0004] 2) Meanwhile, existing model tests mostly adopt simplified methods of one-time excavation or pre-drilling, which cannot effectively simulate the dynamic construction process of tunnel excavation and ignore key processes such as the gradual release of surrounding rock stress and the time-series evolution of structural deformation, resulting in significant differences between the test results and the stress response laws in actual engineering.

[0005] 3) Furthermore, existing fault geological models often describe faults using idealized interfaces or simplified slip surfaces, neglecting the complex structural composition and mechanical heterogeneity of the fault interior. This makes it difficult to accurately reflect the interaction mechanism between the soil and rock media and the tunnel structure within the fault fracture zone. For example, the geological model in Chinese patent "An Experimental Device for Simulating Tunnel Excavation Across Faults" (Application No.: CN202010944678.0, Patent No.: CN112067789B) does not consider the internal structural characteristics of the fault. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for simulating the internal structure of a fault in a tunnel displacement indoor test and a method for simulating excavation, solving the technical problem that existing simulation methods cannot realistically and intuitively reflect the deformation characteristics of the surrounding rock and the mechanical response characteristics of the tunnel structure.

[0007] A method for simulating the internal structure of a fault in a tunnel displacement indoor test includes the following steps:

[0008] Step 1: Prepare the model housing;

[0009] Step 2: Create strata inside the model box. The strata include a first part and a second part with the same structure, as well as a sliding surface between the two. The first part includes the original rock, the fault influence zone and the fault core arranged in sequence. The friction characteristics of the sliding surface are adjusted to simulate different fault movements.

[0010] Step 3: Calibrate the elevation and horizontal position of the tunnel model's centerline within the model box, and then accurately place the tunnel model at the calibrated position. The tunnel model is covered with a controllable excavation layer, and the edge of the controllable excavation layer is connected to the drive system.

[0011] Step 4: Deploy data acquisition equipment at different locations in the strata and within the tunnel model;

[0012] Step 5: Connect to the real-time dynamic tracking visualization system to collect sensor signals and analyze and display them. At this point, the model box is ready.

[0013] Furthermore, the sliding surface fabrication process in step 2 includes: using two thin plates to form a sliding surface, using the surface of the thin plate in contact with the fault core as an enhanced friction surface, using the surface of the thin plates in contact as a controllable friction surface, and simulating creep faults and stick-slip faults by adjusting the friction coefficient of the controllable friction surface.

[0014] Furthermore, when simulating creep faults, the friction coefficient of the controllable friction surface ranges from 0.6 to 1.0; when simulating stick-slip faults, the friction coefficient of the controllable friction surface ranges from 0.2 to 0.4.

[0015] Furthermore, the thin plate has an inlet opening in the middle, through which the tunnel model passes. The size of the inlet opening is larger than the outer contour of the tunnel model, which reserves space for the deformation of the tunnel during fault displacement.

[0016] Furthermore, the process of setting up the controllable excavation layer in step 3 includes: covering the outside of the tunnel with a flexible film as the inner lining of the controllable excavation layer, uniformly laying a stratum material of a specific thickness on the outside of the film, covering the outside of the stratum material with a flexible film as the outer lining of the controllable excavation layer, with a pre-reserved pull rope on the outside of the film for connection with the drive system, and the controllable excavation layer and the prepared stratum are isolated by a film.

[0017] Furthermore, step 4 includes:

[0018] Precision strain gauges are pre-embedded at the arch crown, arch waist, and arch bottom of the tunnel model to monitor stress changes in the model in real time during excavation and displacement.

[0019] Earth pressure cells are installed in the original rock, fault influence zone and fault core to capture the evolution of earth pressure on the tunnel in various strata.

[0020] A sliding rail system is installed inside the tunnel, and a mobile laser displacement scanner is installed on the sliding rail, so that the mobile laser displacement scanner can move flexibly along the tunnel axis and record the deformation evolution process of the internal structure in real time during excavation and loading.

[0021] A data acquisition system is set up outside the model box and linked with various sensors to realize the synchronous acquisition and centralized management of multi-source data, providing complete monitoring data support for subsequent analysis of structural response and formation deformation.

[0022] Furthermore, step 5 includes:

[0023] Connect the data acquisition system to the visualization system, configure the channel parameters, set the data storage path and real-time display window, and display the monitoring results of stress, displacement and strain according to function categories;

[0024] After powering on, check whether the initial readings of each channel are within a reasonable range. If there is a significant deviation, the data acquisition system needs to be zero-point calibrated or rewired.

[0025] Subsequently, a minor disturbance loading test was conducted to confirm that all sensors responded, ensuring that the data acquisition system was working properly;

[0026] Start the data acquisition software and observe whether the monitoring data can achieve real-time curve updates.

[0027] Under equipment operating conditions, the anti-interference capability of the data acquisition system was jointly tested to ensure that the data acquisition system continues to operate stably during tunnel excavation or fault loading.

[0028] Finally, set up automatic save and backup paths, and preset backup channels and emergency power supplies to ensure data integrity and uninterrupted operation during critical stages.

[0029] A method for simulating tunnel fault excavation in an indoor test, implemented using a model box prepared by a method for simulating the internal structure of a tunnel fault in an indoor test, includes the following steps:

[0030] Tunnel excavation or tunneling simulation: The drive system is controlled to extract the controllable excavation layer from the model box to simulate tunnel excavation or tunneling using the extraction excavation simulation method; after each extraction is completed, the drive system is paused to keep the structure stationary, and the stress, strain and displacement response of the surrounding rock and lining are monitored and recorded in real time using the arranged sensors. Each extraction refers to an extraction with a pre-set extraction step size.

[0031] Slip loading simulation: A jack is set at the bottom of the model box and started to ensure that the slip load is applied at a uniform and stable speed to simulate the slip behavior of the structure under actual stress conditions; after each slip displacement is applied, the loading is stopped immediately, and key monitoring data, including the force value, displacement and strain of the corresponding step, are collected and recorded in real time to ensure the integrity and accuracy of the data.

[0032] Experimental data generation and export: During the experiment, multiple types of data are collected simultaneously, and all recorded data are named and categorized in a standardized manner, and automatically saved and backed up;

[0033] Test Summary and Damage Assessment: After the test, a comprehensive inspection and assessment of the tunnel damage was conducted, and the test results were compared and analyzed in detail with the collected image and video data.

[0034] By comparing visual data with measured damage characteristics, the accuracy and consistency of structural deformation and damage during the experiment are verified, providing a reliable basis for subsequent result analysis and ensuring the scientific validity and completeness of the experimental conclusions.

[0035] Furthermore, in the tunnel excavation or tunneling simulation, the step size S, extraction speed V, and single-step pause time T are preset for each extraction to simulate the excavation of mountain tunnels or the tunneling of shield tunnels.

[0036] In the simulation of displacement loading, the step size (δ) of each displacement and the displacement application speed (υ) are preset to control the loading process.

[0037] Furthermore, tunnel excavation or tunneling simulations can simulate various excavation methods as needed, including: completely removing the controllable excavation layer cross-section model to simulate full-section excavation; gradually removing it in upper and lower steps or multiple levels to simulate step excavation; or dividing the tunnel cross-section into multiple areas and removing them piece by piece to simulate step-by-step excavation.

[0038] The beneficial effects of this invention include:

[0039] 1. Overcome limitations in observation technology to achieve high-precision visualization and tracking of the entire process of tunnel model excavation and displacement:

[0040] Traditional tunnel model observation technology has many limitations, such as weak visualization capabilities and localized data, making it difficult to achieve comprehensive capture of the entire process of tunnel excavation and displacement.

[0041] This invention innovatively adopts a real-time dynamic tracking and visualization system, which can efficiently and accurately capture the evolution of structural deformation in space and time, significantly improving the completeness and intuitiveness of data acquisition.

[0042] 2. The excavation process considers the stress release of the surrounding rock, realizing dynamic construction simulation of tunnel excavation:

[0043] Traditional model tests often use simplified methods such as one-time excavation or pre-drilling, which makes it difficult to truly reflect the gradual release of surrounding rock stress and the dynamic evolution of structural response during tunnel excavation.

[0044] This invention innovatively adopts an extraction-type excavation simulation method, which can accurately reproduce the dynamic changes of surrounding rock deformation and tunnel structure stress throughout the entire process, more closely reflecting the actual working conditions of on-site construction and improving the engineering authenticity of model tests.

[0045] 3. The stratigraphic model considers the internal structure of the fault and the friction coefficient of the slip surface to simulate fault creep and stick-slip:

[0046] Traditional fault geological models often use idealized interfaces or simplified slip surfaces to describe faults, which makes it difficult to truly reflect the complex interaction mechanisms between soil and rock media and tunnel structures in fault fracture zones.

[0047] This invention innovatively introduces a geological model that considers the internal structural characteristics of faults. This model can not only more accurately simulate the impact of fault activity on tunnel stability, but also achieve flexible switching between fault creep and stick-slip behavior, thereby improving the applicability and accuracy of the model in the dynamic response analysis of complex faults. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating a method for simulating the internal structure of a fault in an indoor test for tunnel displacement, as described in an embodiment of this application.

[0049] Figure 2 This is a stratigraphic distribution map produced in the embodiments of this application.

[0050] Figure 3 This is a structural diagram of the controllable excavation layer involved in the embodiments of this application.

[0051] Figure 4 This is a schematic diagram showing the connection between the model box and the drive system in an embodiment of this application.

[0052] Figure 5 This is a schematic diagram showing the connection between the real-time dynamic tracking visualization system and the model box involved in the embodiments of this application.

[0053] Figure 6 This is the vertical displacement distribution of the tunnel involved in the embodiments of this application.

[0054] Figure 7 This is the longitudinal strain distribution of the tunnel involved in the embodiments of this application. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0056] Example 1

[0057] A method for simulating the internal structure of a fault in a tunnel displacement indoor test, such as... Figure 1 As shown, it includes the following steps:

[0058] Step 1: Prepare the model box; the model box adopts a high-strength aluminum alloy frame structure; the right side of the box is equipped with a dedicated interface for stepper motors, and the rear side is reserved with standard installation space for the control system and DIC display screen; the upper plate is powered by a jack, and the lower plate is rigidly fixed; before the experiment, the inside of the box must be thoroughly cleaned and PVC film is applied to the whole box to reduce the boundary friction effect and ensure the accuracy of the test data.

[0059] Step 2: Create the ground layers inside the model box, such as... Figure 2 As shown, the strata include a first part and a second part with the same structure, as well as a sliding surface between the two. The first part includes the original rock, the fault influence zone and the fault core arranged in sequence. Specifically, the entire bottom layer includes the first part (original rock, fault influence zone and fault core), the sliding surface and the second part (fault core, fault influence zone and original rock) in sequence. The friction characteristics of the sliding surface are adjusted to simulate different fault movements.

[0060] The original rock, the fault influence zone, and the fault core were all filled with a mixture of sand, machine oil, kaolin, and wood chips. The proportion of this mixture in the original rock, the fault influence zone, and the fault core was determined based on a similarity ratio. This similarity ratio refers to the proportional relationship between the model and the prototype in terms of geometric dimensions, mechanical properties, etc., during indoor model tests, and is determined by specific indoor experiments.

[0061] Step 3: Calibrate the elevation and horizontal position of the tunnel model's centerline within the model box, and then accurately place the tunnel model at the calibrated position. The tunnel model is covered with a controllable excavation layer, and the edge of the controllable excavation layer is connected to the drive system.

[0062] Step 4: Deploy data acquisition equipment at different locations in the strata and within the tunnel model;

[0063] Step 5: Connect to the real-time dynamic tracking visualization system to collect sensor signals and analyze and display them. At this point, the model box is ready.

[0064] In another embodiment, the sliding surface fabrication process in step 2 includes: using two thin plates to form a sliding surface, using the surface of the thin plate in contact with the fault core as an enhanced friction surface, using the surface in contact between the thin plates as a controllable friction surface, and simulating creep faults and stick-slip faults by adjusting the friction coefficient of the controllable friction surface.

[0065] like Figure 2 As shown, the sliding surface is located at the center of the fault core and consists of two layers of high-density polyethylene (HDPE) sheets. It is used to control the frictional characteristics of the sliding interface. Each HDPE sheet has two surfaces. The surface in contact with the fault core is the sandpaper surface, which is the enhanced friction surface. Sandpaper is applied to its surface to enhance the frictional force of the interface. The friction surface between the two HDPE sheets is the friction coefficient control surface, which is the controllable friction surface. The friction coefficient is controlled by adjusting the roughness of its surface.

[0066] The friction coefficient of the friction coefficient control surface can be determined through previous friction coefficient measurement experiments. In this experiment, friction coefficient control surfaces with different friction coefficients are selected to simulate fault creep and stick-slip.

[0067] In another embodiment, when simulating a creep fault, the friction coefficient of the controllable friction surface ranges from 0.6 to 1.0; when simulating a stick-slip fault, the friction coefficient of the controllable friction surface ranges from 0.2 to 0.4.

[0068] In another embodiment, the thin plate has an inlet opening in the middle, through which the tunnel model passes. The size of the inlet opening is larger than the outer contour of the tunnel model, thus reserving space for the deformation of the tunnel during fault displacement.

[0069] In another embodiment, the controlled excavation layer setting process in step 3 includes: covering the outside of the tunnel with a flexible film as the inner lining of the controlled excavation layer; uniformly laying a stratum material of a specific thickness on the outside of the film; covering the outside of the stratum material with a flexible film as the outer lining of the controlled excavation layer; the film has pre-installed tension ropes for connection to the drive system; and the controlled excavation layer is isolated from the prepared stratum by a film. The set controlled excavation layer is as follows: Figure 3 As shown.

[0070] Inside the model box, the elevation and horizontal position of the tunnel centerline are first precisely marked, and a limiting bracket is set at the bottom to fix the bottom position of the tunnel model and ensure its geometric stability during construction.

[0071] Subsequently, the tunnel model was accurately placed in the predetermined position and covered with a flexible plastic (PE) film as the inner lining of the controlled excavation layer.

[0072] A layer material with a thickness of 5–10 mm is evenly laid on the outside of the membrane to form a complete excavation layer simulation area.

[0073] To effectively isolate the excavated layer from the original strata, two layers of flexible plastic (PE) film are placed between them, maintaining a smooth contact between them to minimize the disturbance to the surrounding strata during the excavation process.

[0074] A pull rope is reserved at the outer edge of the inner film and connected to the stepper motor system to realize the subsequent step-by-step extraction operation, thereby simulating the process of tunnel excavation layer by layer.

[0075] Meanwhile, fixed supports are set up around the tunnel model to constrain its lateral displacement, tilting or local deformation during the excavation and loading process.

[0076] After excavation is completed, a flexible plastic (PE) film for isolation is removed from the strata to ensure that the surrounding strata structure is not disturbed during removal, thereby maintaining the overall continuity and integrity of the strata.

[0077] In another embodiment, specifically as follows: Figure 4 As shown, the drive system uses a stepper motor. After the excavated layer is closed, a hook is set up. The stepper motor and pulley device are installed on the fixed bracket. One end of the pull rope is connected to the stepper motor, and after passing through the pulley, it is connected to the hook on the excavated layer.

[0078] In another embodiment, step 4 includes:

[0079] Precision strain gauges are pre-embedded at the arch crown, arch waist, and arch bottom of the tunnel model to monitor stress changes in the model in real time during excavation and displacement.

[0080] Earth pressure cells are installed in the original rock, fault influence zone and fault core to capture the evolution of earth pressure on the tunnel in various strata.

[0081] A sliding rail system is installed inside the tunnel, and a mobile laser displacement scanner is installed on the sliding rail, so that the mobile laser displacement scanner can move flexibly along the tunnel axis and record the deformation evolution process of the internal structure in real time during excavation and loading.

[0082] A high-precision data acquisition system is set up outside the model box and linked with various sensors to realize the synchronous acquisition and centralized management of multi-source data, providing complete monitoring data support for subsequent analysis of structural response and formation deformation.

[0083] In another embodiment, step 5 includes:

[0084] A real-time dynamic tracking and visualization system was used to record the physical and mechanical states of the tunnel model and surrounding rock throughout the entire test process, such as... Figure 5 As shown.

[0085] The signal outputs of various sensors are connected to the high-precision data acquisition system through shielded wires, and the leads are laid out reasonably to ensure that they do not interfere with the loading device, stepper motor and other systems.

[0086] Connect the high-precision data acquisition system to the industrial control host or embedded display via USB or network cable, configure the channel parameters (including range, sampling frequency, unit, and channel name) in the acquisition software of the high-precision data acquisition system, set the data storage path and real-time display window, and display the monitored quantities such as stress, displacement, and strain according to their functions.

[0087] After powering on, check whether the initial readings of each channel are within a reasonable range. If there is a significant deviation, the high-precision data acquisition system needs to be zero-point calibrated or rewired.

[0088] Subsequently, a minor disturbance loading test was conducted to confirm that all sensors responded, ensuring that the high-precision data acquisition system was working properly.

[0089] Start the acquisition software and observe whether the monitoring data can be updated in real time; equip a display terminal to further check the communication stability between it and the acquisition module, and adjust the display interface layout to achieve synchronous visualization of key parameters.

[0090] Under the operating conditions of stepper motors and hydraulic jacks, the anti-interference capability of the high-precision data acquisition system is jointly tested. If signal drift or fluctuation problems occur, they can be handled by means of signal isolation and power filtering to ensure that the acquisition system continues to operate stably during tunnel excavation or fault loading.

[0091] Finally, set up automatic save and backup paths, and preset backup channels and emergency power supplies to ensure data integrity and uninterrupted operation during critical stages.

[0092] In another embodiment, a method for simulating tunnel fault excavation in an indoor test is provided, implemented using a model box prepared by a method for simulating the internal structure of a tunnel fault in an indoor test, and includes the following steps:

[0093] Tunnel excavation or tunneling simulation: The drive system is controlled to extract a controllable excavation layer from the model box to simulate tunnel excavation or tunneling using the extraction excavation simulation method. After each extraction, the motor operation is paused to keep the structure stationary. The stress, strain, and displacement response of the surrounding rock and lining are monitored and recorded in real time using equipment such as strain gauges, laser displacement scanners, and earth pressure cells. Each extraction refers to an extraction performed with a pre-set extraction step size.

[0094] Slip-load simulation: Jacks are set at the bottom of the model box and started to ensure that slip-load is applied at a uniform and stable speed to simulate the slip-load behavior of the structure under actual stress conditions. After each slip-load is applied, the loading is stopped immediately, and key monitoring data such as force, displacement and strain of the corresponding step are collected and recorded in real time to ensure the integrity and accuracy of the data.

[0095] Experimental data generation and export: During the experiment, multiple types of data are collected simultaneously, and all recorded data are named and categorized in a standardized manner, and automatically saved and backed up;

[0096] During the experiment, the system simultaneously collected various types of data to comprehensively record the response information of the tunnel model and the surrounding rock, mainly including tabular data, image data and video data.

[0097] The data in the table comes from the numerical monitoring results of equipment such as stress sensors and strain gauges, and is stored according to time series or loading steps to facilitate subsequent statistical analysis.

[0098] Image data is obtained by acquiring high-resolution images through a laser displacement scanner, which intuitively displays the deformation field, strain field and crack evolution, and supports visual tracking of the excavation and loading process;

[0099] Video data records dynamic images of the entire test process, reflecting the changes and failure processes of the structure under excavation and fault loading, which facilitates playback and analysis.

[0100] Test Summary and Damage Assessment: After the test, a comprehensive inspection and assessment of the tunnel damage was conducted, and the test results were compared and analyzed in detail with the collected image and video data; specific vertical displacements of the tunnel are as follows: Figure 6 As shown, the vertical and longitudinal strains are as follows Figure 6 As shown on the coordinate axes, vertical displacement corresponds to displacement in the Z direction, and longitudinal strain distribution corresponds to strain in the Y direction. The longitudinal strain distribution of the tunnel is shown below. Figure 7 As shown. The corresponding effect is as follows:

[0101] By monitoring data such as displacement and strain of the tunnel at different times, the positional changes and deformation / damage of various parts of the tunnel can be reflected in real time. After processing and storing the collected data, graphical output can be achieved using a display terminal, providing a more intuitive view of the tunnel's state at different times.

[0102] By comparing visual data with measured damage characteristics, the accuracy and consistency of structural deformation and damage during the experiment are verified, providing a reliable basis for subsequent result analysis and ensuring the scientific validity and completeness of the experimental conclusions.

[0103] In another embodiment, in the tunnel excavation or tunneling simulation, the step size S, the extraction speed V, and the single-step pause time T are preset for each extraction to simulate the excavation of a mountain tunnel or the tunneling of a shield tunnel.

[0104] In mountain tunnels, S represents the excavation advance, T represents the support time, and V has no practical meaning, so a slow speed can be used.

[0105] In shield tunnels, S represents the length of a single ring segment during shield excavation, V represents the excavation speed, and T represents the segment installation time.

[0106] Start the stepper motor to slowly and uniformly remove the plastic film covering the excavated soil layer at a set speed, realistically simulating the soil disturbance and support unloading process during tunnel excavation.

[0107] In the simulation of displacement loading, the step size (δ) of each displacement and the displacement application speed (υ) are preset to control the loading process.

[0108] Specifically, the above parameters are set mainly to correspond to the actual engineering situation. For example, in the construction of mountain tunnels, S corresponds to the advance of a single blast / mechanical excavation; T corresponds to the time to complete the support; and V corresponds to the mechanical or manual excavation speed, used to control the smoothness of the extraction operation.

[0109] In another embodiment, the tunnel excavation or tunneling simulation may simulate various excavation methods as needed, including: completely removing the controllable excavation layer cross-section model to simulate full-section excavation; gradually removing the model in upper and lower steps or multiple stages to simulate step excavation, for example, when simulating the upper and lower step method, the excavation layer cross-section is divided into upper and lower parts, the upper part is removed first and then the lower part is removed, and the specific division rules are explained in most tunnel specifications; or the tunnel cross-section is divided into multiple areas and removed piece by piece to simulate step excavation, for example, the excavation layer is divided into several small blocks and removed step by step in a certain order.

[0110] For example, in mountain tunnels, the excavation layer is divided into multiple areas according to excavation methods such as the bench method and the CRD method. Different areas are separated by thin plates, and only the designated area needs to be extracted during extraction.

[0111] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A method for simulating the internal structure of a fault in a tunnel displacement indoor test, characterized in that, Includes the following steps: Step 1: Prepare the model housing; Step 2: Create strata inside the model box. The strata include a first part and a second part with the same structure, as well as a sliding surface between the two. The first part includes the original rock, the fault influence zone and the fault core arranged in sequence. The friction characteristics of the sliding surface are adjusted to simulate different fault movements. Step 3: Calibrate the elevation and horizontal position of the tunnel model's centerline within the model box, and then accurately place the tunnel model at the calibrated position. The tunnel model is covered with a controllable excavation layer, and the edge of the controllable excavation layer is connected to the drive system. Step 4: Deploy data acquisition equipment at different locations in the strata and within the tunnel model; Step 5: Connect to the real-time dynamic tracking visualization system to collect sensor signals and analyze and display them. At this point, the model box is ready.

2. The method for simulating the internal structure of a fault in a tunnel displacement indoor test according to claim 1, characterized in that, The sliding surface fabrication process in step 2 includes: using two thin plates to form a sliding surface, using the surface of the thin plate in contact with the fault core as an enhanced friction surface, and using the surface between the thin plates as a controllable friction surface, and simulating creep faults and stick-slip faults by adjusting the friction coefficient of the controllable friction surface.

3. The method for simulating the internal structure of a fault in a tunnel displacement indoor test according to claim 2, characterized in that, When simulating creep faults, the friction coefficient of the controllable friction surface ranges from 0.6 to 1.0; when simulating stick-slip faults, the friction coefficient of the controllable friction surface ranges from 0.2 to 0.

4.

4. The method for simulating the internal structure of a fault in a tunnel displacement indoor test according to claim 2, characterized in that, The thin plate has an inlet opening in the middle, through which the tunnel model passes. The size of the inlet opening is larger than the outer contour of the tunnel model, which is to reserve space for the deformation of the tunnel during the fault displacement process.

5. The method for simulating the internal structure of a fault in a tunnel displacement indoor test according to claim 1, characterized in that, The process of setting up the controllable excavation layer in step 3 includes: covering the outside of the tunnel with a flexible film as the inner lining of the controllable excavation layer; laying a specific thickness of stratum material evenly on the outside of the film; covering the outside of the stratum material with a flexible film as the outer lining of the controllable excavation layer; reserving a rope on the outside of the film for connection with the drive system; and isolating the controllable excavation layer from the prepared stratum through a film.

6. The method for simulating the internal structure of a fault in a tunnel displacement indoor test according to claim 1, characterized in that, Step 4 includes: pre-embedding precision strain gauges at the arch crown, arch waist, and arch bottom of the tunnel model to monitor stress changes in the model in real time during excavation and displacement. Earth pressure cells are installed in the original rock, fault influence zone and fault core to capture the evolution of earth pressure on the tunnel in various strata. A sliding rail system is installed inside the tunnel, and a mobile laser displacement scanner is installed on the sliding rail, so that the mobile laser displacement scanner can move flexibly along the tunnel axis and record the deformation evolution process of the internal structure in real time during excavation and loading. A data acquisition system is set up outside the model box and linked with various sensors to realize the synchronous acquisition and centralized management of multi-source data, providing complete monitoring data support for subsequent analysis of structural response and formation deformation.

7. The method for simulating the internal structure of a fault in a tunnel displacement indoor test according to claim 1, characterized in that, Step 5 includes: Connect the data acquisition system to the visualization system, configure the channel parameters, set the data storage path and real-time display window, and display the monitoring results of stress, displacement and strain according to function categories; After powering on, check whether the initial readings of each channel are within a reasonable range. If there is a significant deviation, the data acquisition system needs to be zero-point calibrated or rewired. Subsequently, a minor disturbance loading test was conducted to confirm that all sensors responded, ensuring that the data acquisition system was working properly; Start the data acquisition software and observe whether the monitoring data can achieve real-time curve updates. Under equipment operating conditions, the anti-interference capability of the data acquisition system was jointly tested to ensure that the data acquisition system continues to operate stably during tunnel excavation or fault loading. Finally, set up automatic save and backup paths, and preset backup channels and emergency power supplies to ensure data integrity and uninterrupted operation during critical stages.

8. A method for simulating tunnel fault excavation in an indoor test, implemented using a model box prepared by a method for simulating the internal structure of a tunnel fault in an indoor test, includes the following steps: Tunnel excavation or tunneling simulation: The drive system is controlled to extract the controllable excavation layer from the model box to simulate tunnel excavation or tunneling using the extraction excavation simulation method; after each extraction is completed, the drive system is paused to keep the structure stationary, and the stress, strain and displacement response of the surrounding rock and lining are monitored and recorded in real time using the arranged sensors. Each extraction refers to an extraction with a pre-set extraction step size. Slip-load simulation: A jack is set at the bottom of the model box and started to ensure that the slip-load is applied at a uniform speed and stably to simulate the slip-load behavior of the structure under actual stress conditions. After each displacement is applied, loading is stopped immediately, and key monitoring data, including force, displacement and strain for the corresponding step, are collected and recorded in real time to ensure the integrity and accuracy of the data. Experimental data generation and export: During the experiment, multiple types of data are collected simultaneously, and all recorded data are named and categorized in a standardized manner, and automatically saved and backed up; Test Summary and Damage Assessment: After the test, a comprehensive inspection and assessment of the tunnel damage was conducted, and the test results were compared and analyzed in detail with the collected image and video data. By comparing visual data with measured damage characteristics, the accuracy and consistency of structural deformation and damage during the experiment are verified, providing a reliable basis for subsequent result analysis and ensuring the scientific validity and completeness of the experimental conclusions.

9. The method for simulating fault excavation in an indoor test of tunnel displacement according to claim 8, characterized in that, In tunnel excavation or tunneling simulation, the step size S, extraction speed V, and single-step pause time T are preset for each extraction to simulate the excavation of mountain tunnels or the tunneling of shield tunnels. In the simulation of displacement loading, the step size δ of each displacement and the displacement application speed υ are preset to control the loading process.

10. The method for simulating fault excavation in an indoor test of tunnel displacement according to claim 8, characterized in that, In tunnel excavation or tunneling simulation, various excavation methods can be simulated as needed, including: completely removing the controllable excavation layer cross-section model to simulate full-section excavation; gradually removing it in upper and lower steps or multiple levels to simulate step excavation; or dividing the tunnel cross-section into multiple areas and removing them one by one to simulate step-by-step excavation.

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