A fracture zone dislocation layered shear simulation test device, system and method

Abstract

A fault dislocation layered shear simulation test device, comprising a model box, wherein tempered glass plates are arranged on the outer sides of the front, rear and left sides of the model box, and the bottom part is respectively an active plate and a fixed plate of the fault. A layered shear deformation structure is arranged on the upper part of the active plate, and the bottom plate of the fixed plate is adjusted left and right in the y direction for setting the width of the bedrock fault zone. The present invention improves the boundary conditions of the existing fault dislocation model box, and proposes a layered shear model test device composed of a plurality of L-shaped structures, which can well simulate the dragging effect of the deep soil overlying the bedrock on the shallow soil during the strike-slip fault dislocation, and can carry out tests on faults with different movement modes on one device, accurately revealing the deformation evolution law of the upper foundation and subgrade under fault dislocation.

Description

Technical Field

[0001] The present invention relates to the field of railway subgrades, and relates to an experimental system and method, in particular to a fault dislocation layered shear simulation test device, system and method. Background Art

[0002] The interseismic creep dislocation and coseismic stick-slip dislocation deformation of active fault zones have a great impact on the deformation and stability of near-fault railway subgrades, which is an unavoidable problem in the construction of near-fault subgrades. In order to carry out research on the deformation evolution mechanism of railway subgrades under fault dislocation through indoor tests, it is urgent to develop a fault dislocation model test system and its supporting test method. Existing test systems at home and abroad cannot conduct tests on a single system for different fault dislocation directions, angles, and rates. For strike-slip faults, due to the limitation of the fixed boundary size of the model box, it is difficult to simulate the strike-slip dragging effect of the deep soil layer overlying the fault bedrock on the shallow soil layer in a model box of a small size. In addition, at present, wire-pulling displacement gauges and earth pressure gauges are generally used to monitor the internal stress and deformation distribution of rock and soil masses under fault dislocation, and a two-dimensional PIV system is used to monitor the two-dimensional velocity field results of rock and soil masses in the test plane, and it is impossible to effectively monitor the three-dimensional stress-strain evolution law of rock and soil masses under fault dislocation. Therefore, establishing a fault dislocation layered shear simulation test system and method will provide support for analyzing the line smoothness and evaluating the long-term service state of subgrades.

[0003] Existing fault dislocation model test systems usually consist of a model box, a guiding module, a loading system, etc. The bottom of the model box is composed of two rigid bottom plates, one side is a fixed bottom plate, and the other bottom plate is integrally connected to the right side wall of the model box and can be dislocated along the angle set by the guiding module during the test. The junction position of the two bottom plates is the fault dislocation surface of the model. The loading system is composed of a servo motor or a hydraulic jack, which is located below the fault dislocation plate and fixed on the base. Driven by the servo motor or the hydraulic jack, the dislocation plate generates displacement and the fault zone undergoes dislocation. During the test, the crack damage distribution of bridge and tunnel engineering structures is observed and measured by the naked eye and a ruler.

[0004] (1) The boundary conditions of the existing fault dislocation rock and soil mass test model are unreasonable

[0005] The fault displacement and deformation are gradually transmitted from the deep brittle crust to the surface. Therefore, when simulating the influence of fault displacement on surface deformation, the displacement force must be applied from the bottom of the model box. Existing fault displacement model test devices can simulate the deformation of rock and soil masses under dip-slip fault displacement well. However, the surface deformation under strike-slip fault displacement is affected by the deformation of deep soil layers, and the horizontal shear friction between soil layers is gradually transmitted upward from deep to shallow. Existing strike-slip fault displacement model test devices are limited by the size of the model box. Generally, the horizontal displacement force is applied integrally at the lateral boundary of the model box to simulate the strike-slip fault displacement and deformation, which is different from the actual geological structure movement state, and cannot reflect the dragging effect of the deep soil layer overlying the bedrock on the shallow soil layer, nor can it accurately reflect the distribution of the inverted triangular fault shear deformation transition zone inside the subgrade and foundation soil masses.

[0006] (2) The generality and reliability of existing fault displacement model test systems need to be improved.

[0007] According to the relative movement modes of fault blocks on both sides of the fault zone, the fault zone can be divided into dip-slip faults, strike-slip faults, oblique-slip faults, and tensile faults. Traditional fault displacement test systems are limited by the loading direction of the loading system and it is difficult to conduct tests on faults with different movement modes on one device, resulting in insufficient generality of the test system.

[0008] In addition, if the fault dip angle is adjustable at multiple angles on the test system, rotary bearings need to be installed at both ends of the dip-slip fault displacement loading system. The bearings should be fully lubricated to ensure that the test operator can easily adjust the fault displacement angle as needed. When applying the fault displacement, a limit device and a guiding module should be used to ensure that the bottom plate of the displacement disk is horizontal and that the bearings do not rotate under a certain torque, which poses high requirements for the loading system. Currently, the reliability of existing fault displacement systems is insufficient, and it is difficult to completely avoid the risk of the overall rotation and toppling of the fault displacement disk during the dip-slip displacement test while achieving adjustable fault dip angles.

[0009] (3) The monitoring means for fault displacement tests are insufficient.

[0010] During the current fault dislocation model test, technicians mainly use rulers, wire displacement gauges, and earth pressure gauges to measure the stress and deformation changes of the subgrade and foundation soil, and take pictures during and after the fault dislocation to record the surface deformation and the distribution of damage cracks. This monitoring method is inefficient and belongs to point monitoring, and it is impossible to comprehensively analyze the deformation and stress evolution law of the soil overlying the bedrock induced by fault dislocation through stress and strain nephograms. In addition, although technicians have begun to use PIV technology to monitor the fault dislocation deformation field, it only uses a two-dimensional PIV system to monitor the displacement of a certain fault deformation profile, and it is neither possible to comprehensively monitor the deformation of the rock and soil mass under oblique-slip fault dislocation, nor to monitor the vertical tensile settlement or extrusion uplift phenomenon that appears on the ground surface under horizontal strike-slip fault dislocation.

[0011] The following is the prior art:

[0012] 1. Cai Qipeng, Wu Hongwei, Hu Ping, etc. Research on the influence of hidden cracks on the propagation of normal faults in interbedded cemented soil. Rock and Soil Mechanics, 2017, 38(07): 2015-2021.

[0013] 2. Shi Jisen, Ling Daosheng, Xu Zelong, etc. Model test study on the influence of reverse fault dislocation on overlying soil mass in inclined sites. Engineering Mechanics, 2018, 35(07): 194-207.

[0014] 3. Ji Yu. Research on the influence of strike-slip fault zone activity on subgrade stability and engineering anti-fracture technology. Lanzhou Jiaotong University, 2021.

[0015] 4. Ai Shengjun. Research on the influence of dip-slip fault activity on subgrade stability and engineering anti-fracture technology. Lanzhou Jiaotong University, 2021.

[0016] Generally speaking, existing fault dislocation model test devices mostly adopt rigid boundaries, and can only simulate strike-slip faults or dip-slip fault dislocations on a set of devices. For fault dislocation deformation, the methods of direct visual observation or ruler measurement are mostly used. It is impossible to reflect the dragging effect of the deep soil overlying the bedrock on the shallow soil during strike-slip fault dislocation, impossible to simulate strike-slip dislocation and dip-slip fault dislocation on a set of devices, and impossible to accurately and quantitatively analyze the three-dimensional deformation evolution law of rock and soil mass. Summary of the Invention

[0017] In order to solve the defects existing in the prior art, the present invention discloses a layered shear simulation test device for fault zone dislocation, and its technical solution is as follows:

[0018] A device for simulating fault dislocation and layered shear test, including a model box, is characterized in that: tempered glass plates are arranged on the outer sides of the front, rear and left sides of the model box, and the bottom is respectively an active plate and a fixed plate of the fault. A layered shear deformation structure is arranged on the upper part of the active plate, and the bottom plate of the fixed plate is adjusted left and right along the y direction to set the width of the bedrock fault zone.

[0019] Preferably: the layered shear deformation structure is composed of a plurality of L-shaped steel bars. The first L-shaped steel bar at the bottom is tightly connected to the flat plate of the bottom fault dislocation. The specific number of L-shaped steel bars is determined according to the z-direction dimension of the geotechnical model; slide rails and y-direction deformation limiting structures are arranged between the L-shaped steel bars and the steel bars to ensure that each L-shaped steel bar can only move along the x-axis direction.

[0020] Preferably: a fault dislocation variable-speed loading system is arranged on the front side and the bottom of the model box to respectively control the strike-slip dislocation and dip-slip dislocation of the fault.

[0021] Preferably: if a strike-slip dislocation model test of the fault is carried out, before the model is filled, a low-density thick sponge is arranged inside the front side of the model box to fill the increased volume of the model box due to the strike-slip dislocation of the fault, and at the same time, reduce the passive earth pressure applied to the soil body when the sponge rebounds and expands; a reaction wall for arranging linear displacement gauges is arranged at the rear side of the model box.

[0022] The present invention also discloses a system for simulating fault dislocation and layered shear test, including the above-mentioned device for simulating fault dislocation and layered shear test, and is characterized in that: the monitoring system includes a high-resolution camera, an earth pressure cell, a linear displacement gauge, and a wire-pulling displacement gauge.

[0023] The linear displacement gauges are arranged between the outer surface of the L-shaped steel bars at the rear side of the model box and the reaction wall to monitor the horizontal displacement of the foundation soil layers at different depths under the strike-slip dislocation of the fault zone; a plurality of wire-pulling displacement gauges are arranged on the top surface of the subgrade along the line direction to monitor the displacement condition of the subgrade top surface during the test; the high-resolution camera is arranged on the front side and the top of the model box to carry out two-dimensional deformation monitoring of the geotechnical surface area on the front side of the model box and three-dimensional deformation monitoring of the geotechnical surface area on the top of the model box; a plurality of earth pressure cells are arranged on the inner surface at the rear side of the L-shaped steel bars and in the plane of the subgrade center line to monitor the earth pressure applied by the soil body to the boundary of the model box and the change of the earth pressure in the geotechnical body under the strike-slip dislocation of the fault. For the strike-slip dislocation model test of the fault, the earth pressure cells in the geotechnical body are placed vertically; for the dip-slip dislocation model test of the fault, the earth pressure cells in the geotechnical body are placed horizontally.

[0024] The present invention also discloses a method for simulating fault dislocation and layered shear test, and is characterized in that:

[0025] Step 1: Build the device for simulating fault dislocation and layered shear model test;

[0026] Step 2: Filling and compaction of the rock and soil mass in the model box in the test device in layers

[0027] Step 3: Layout of monitoring sensors in the monitoring system and establishment of the binocular stereo vision system

[0028] Step 4: Simulation of creep and stick-slip dislocation of the fault zone

[0029] Beneficial effects

[0030] (1) The present invention improves the boundary conditions of the existing fault dislocation model box, and proposes a layered shear model test device composed of multiple L-shaped structures, which can well simulate the dragging effect of the deep soil mass overlying the bedrock on the shallow soil mass during the strike-slip dislocation of the fault, and accurately reveals the deformation and evolution law of the overlying soil mass under the fault dislocation.

[0031] At present, existing research only qualitatively realizes that during the strike-slip fault dislocation, the horizontal dislocation of the deep bedrock block will drive the horizontal dislocation of the overlying soil layer, and the closer to the ground surface, the smaller the dislocation amount, lacking a quantitative theory. Further research needs to be carried out through this set of model test devices.

[0032] The upper model soil mass undergoes horizontal shear deformation driven by the dislocation plate, applies active earth pressure to the inner wall at the rear side of the L-shaped structure, and the soil layer generates stepped strike-slip displacement, realizing the simulation of the dragging effect of the fault strike-slip.

[0033] (2) The present invention improves the monitoring method for the fault dislocation simulation test, and comprehensively monitors the deformation and stress evolution characteristics of the rock and soil mass from point to surface through displacement gauges, earth pressure gauges and the binocular vision monitoring system.

[0034] (3) Through multiple limiting devices and variable-speed loading devices, the present invention enhances the reliability of the model test system, can realize the simulation of creep and stick-slip dislocation of strike-slip and dip-slip faults on one test device, and enhances the versatility of the model test system. Description of the drawings

[0035] Figure 1 is the overall view of the fault dislocation layered shear model test device;

[0036] Figure 2 is the detailed structure diagram of the L-shaped steel bar and the slide rail;

[0037] Figure 3 is the fault strike-slip dislocation deformation loading system;

[0038] Figure 4 is the fault dip-slip dislocation deformation loading system;

[0039] Figure 5 is the reaction wall structure diagram for laying out the linear displacement gauge;

[0040] Figure 6Schematic diagram of the layout points and methods of the linear displacement gauge at the rear side of the model box;

[0041] Figure 7 Layout points of the earth pressure gauge on the inner side of the L-shaped steel bar;

[0042] Figure 8 Layout points of the earth pressure gauge and the wire-pulling displacement gauge in the rock and soil mass;

[0043] Figure 9 Schematic diagram of the layout method of the high-resolution camera;

[0044] Figure 10 Schematic diagram of the limit device for setting the dip-slip displacement angle of the fault. Specific implementation method

[0045] The present invention first elaborates on the working principle and process of the functional components:

[0046] Working principle and process of the earth pressure gauge: The earth pressure gauge is used to monitor the change of the rock and soil pressure during the fault displacement. When the soil stress changes, the induction plate of the earth pressure gauge synchronously senses the stress change, and the induction plate will generate deformation. The deformation is transmitted to the vibrating wire and converted into the change of the vibrating wire stress, thereby changing the vibration frequency of the vibrating wire. The electromagnetic coil excites the vibrating wire and measures its vibration frequency. The frequency signal is transmitted to the reading device through the cable, and the compressive stress value of the measured object can be measured.

[0047] Working process and principle of the linear displacement gauge: The linear displacement gauge is used to monitor the horizontal deformation of each layer of soil during the strike-slip layered shear process. Its function is to convert the linear mechanical displacement into an electrical signal. The working principle is simply a movable core transformer. The core components are the core and the coil. The end of the push rod contacts the object on the north side. When the object on the north side undergoes displacement, the push rod moves, driving the core inside the displacement gauge to move within the linear range of the coil. The difference between the induced electromotive forces generated by the two coils is the output voltage, and its voltage magnitude is proportional to the displacement.

[0048] Working process and principle of the wire-pulling displacement gauge: The wire-pulling displacement gauge is used to monitor the displacement of the roadbed surface layer. The core components of the wire-pulling displacement gauge are the sensor head and the wire. The sensor head usually contains an optoelectromechanical device for detecting the position of the wire. The wire is installed on the object whose movement or deformation amount needs to be measured. Through the pull rope connecting the sensor and the measured object, the sensor can measure the displacement of the wire, thereby reflecting the movement or deformation amount of the measured object.

[0049] Working process and principle of the single camera on the front side of the model box: The front camera is used for two-dimensional deformation monitoring of the surface area. When the fault zone undergoes dip-slip displacement, the camera takes a photo of the rock and soil mass every 1 second. The first photo is divided into several interpretation areas, and the position and state of soil particles are recorded in each interpretation area. The position with the highest matching degree with the interpretation area of the previous photo is found in the next photo as the position after the displacement of the interpretation area, and then the soil displacement field at each moment is obtained.

[0050] Working principle of the dual cameras on the top of the model box: The top cameras are used for three-dimensional deformation monitoring of the surface area. When the fault zone undergoes dip-slip displacement or strike-slip displacement, two cameras are used to take a photo of the rock and soil mass simultaneously every 1 second. Each camera adopts the same processing method as the two-dimensional deformation monitoring of the surface area, and then three-dimensional reconstruction is carried out to restore the three-dimensional information of the scene from the two planar images taken by the two cameras respectively.

[0051] The earth pressure cell, linear displacement meter, and wire-pulling displacement meter can only monitor the stress and deformation states of certain points of the rock and soil mass, belonging to point monitoring. The photos taken by the cameras on the top and front sides of the model box can be used to analyze the stress and deformation states of all positions on the surface of the rock and soil mass, belonging to surface area monitoring. By combining multiple monitoring methods, the deformation and stress evolution characteristics of the rock and soil mass can be monitored comprehensively from points to the surface.

[0052] Example 1

[0053] A fault displacement layered shear simulation test device, including a model box, characterized in that: tempered glass plates are arranged on the outer sides of the front, rear, and left sides of the model box, and the bottom is respectively the active plate and the fixed plate of the fault. A layered shear deformation structure is arranged on the upper part of the active plate, and the bottom plate of the fixed plate can be adjusted left and right in the y direction to set the width of the bedrock fault zone. The layered shear deformation structure is composed of multiple L-shaped steel bars. The first L-shaped steel bar at the bottom is tightly connected to the bottom fault displacement flat plate, and the specific number of L-shaped steel bars is determined according to the z-direction dimension of the rock and soil mass model; slide rails and y-direction deformation limiting structures are arranged between the L-shaped steel bars and the steel bars to ensure that each L-shaped steel bar can only move in the x-axis direction. A fault displacement variable-speed loading system is arranged on the front side and the lower part of the model box to control the strike-slip displacement and dip-slip displacement of the fault respectively. If a fault strike-slip displacement model test is carried out, before model filling, a low-density thick sponge is arranged inside the front side of the model box to reduce the passive earth pressure exerted on the soil when the sponge rebounds and expands while filling the increased volume of the model box due to the fault strike-slip displacement; and a reaction wall for arranging a linear displacement meter is arranged on the rear side of the model box.

[0054] Example 2

[0055] A fault dislocation layered shear simulation test system, including the above-mentioned fault dislocation layered shear simulation test device and a monitoring system, is characterized in that: the monitoring system includes a high-resolution camera, earth pressure gauges, linear displacement gauges, and wire-pulling displacement gauges. The linear displacement gauges are arranged on the outer surface of the L-shaped steel bar at the rear side of the model box and between the reaction walls, and are used to monitor the horizontal displacement of the foundation soil layers at different depths under the strike-slip dislocation of the fault zone; a plurality of wire-pulling displacement gauges are arranged on the top surface of the subgrade along the line direction, and are used to monitor the displacement of the subgrade top surface during the test; the high-resolution camera is arranged on the front side and the top of the model box, and is used to carry out two-dimensional deformation monitoring of the rock and soil body area on the front side of the model box and three-dimensional deformation monitoring of the rock and soil body area on the top of the model box; a plurality of earth pressure gauges are arranged on the inner surface at the rear side of the L-shaped steel bar and in the plane of the subgrade center line, and are used to monitor the earth pressure exerted by the soil on the model box boundary and the change of earth pressure in the rock and soil body under the strike-slip dislocation of the fault zone. For the fault strike-slip dislocation model test, the earth pressure gauges in the rock and soil body are placed vertically; for the fault dip-slip dislocation model test, the earth pressure gauges in the rock and soil body are placed horizontally.

[0056] Embodiment 3

[0057] A fault dislocation layered shear simulation test method includes the following steps:

[0058] Step 1: Construction of the fault dislocation layered shear model test device.

[0059] The specific structure of the model test device is as Figure 1 shown. Tempered glass plates are provided on the three outermost sides of the front, rear, and left of the model box to facilitate real-time observation of the results of the fault dislocation test. The bottom surface of the model box is the 1st fixed plate and the 2nd movable plate of the fault respectively. An L-shaped layered shear deformation structure is arranged above the 2nd movable plate. The bottom plate of the fixed plate can be adjusted in position along the y direction to set the width of the bedrock fault zone.

[0060] The layered shear deformation structure is composed of a plurality of L-shaped steel bars. The 1st L-shaped steel bar at the bottom is tightly connected to the bottom plate of the 2nd movable plate at the bottom. The specific number of L-shaped steel bars is determined according to the z-direction dimension of the rock and soil body model. Slide rails and y-direction deformation limiting structures are arranged between the L-shaped steel bars and the steel bars to ensure that each L-shaped steel bar can only move along the x-axis direction, as shown in Figure 2.

[0061] A fault dislocation variable-speed loading system is arranged on the side and below the model box. The strike-slip fault dislocation variable-speed loading system is as Figure 3As shown in the figure. A No. 5 screw jack is provided at the end of the No. 3 motor. The No. 5 screw jack is connected to a No. 6 connecting block, and the No. 6 connecting block is connected to the side of the fault dislocation disc. The dip-slip fault dislocation variable-speed loading system is shown in Figure 4. A No. 7 gear is provided at the end of the No. 4 motor. One end of the No. 7 gear is connected to one end of an No. 8 annular chain, and the other end of the No. 8 annular chain is connected to a No. 9 gear. A rotating shaft is embedded in the middle of the No. 9 gear. A No. 10 and a No. 11 coupling are installed on the rotating shaft. The two couplings are respectively connected to a No. 12 and a No. 13 screw jack. The tops of the No. 12 and No. 13 screw jacks are respectively connected to a No. 14 and a No. 15 rotating pin and a No. 16 and a No. 17 connector. The No. 16 and No. 17 connectors are connected to a No. 18 and a No. 19 slide rail. The No. 18 and No. 19 slide rails are connected to the bottom plate of the No. 2 dislocation disc.

[0062] If a strike-slip dislocation model test is to be carried out, before the model is filled, a low-density thick sponge needs to be set inside the front side of the model box. While filling the increased volume of the model box due to the strike-slip dislocation of the fault, it is necessary to minimize the passive earth pressure exerted on the soil mass when the sponge rebounds and expands as much as possible.

[0063] Step 2: The filling and compaction of the rock and soil mass in the model box in the test device are carried out in layers.

[0064] According to the physical and mechanical parameters of the actual roadbed and foundation rock and soil mass on site, the similar material parameters and ratios are determined according to the geometric similarity ratio of 1:50, and the model is filled in layers. When carrying out the strike-slip fault dislocation test, it should be ensured that the low-density thick sponge is completely compacted after the model filling is completed. After each layer of filling is completed and compacted, ring knife sampling is required to control the compaction quality of the model and ensure that the material parameters of different layers in the same kind of rock and soil mass material are consistent. After the upper roadbed filling is completed, the excess material is cut according to the set slope ratio of the roadbed slope to form the overall contour of the roadbed.

[0065] Step 3: The layout of the monitoring sensors in the monitoring system and the construction of the binocular stereo vision system.

[0066] The monitoring system consists of a high-resolution camera, a soil pressure gauge, a linear displacement gauge, a wire-pulling displacement gauge and other auxiliary brackets.

[0067] To fix the linear displacement gauge, a reaction wall needs to be set. The structure of the reaction wall is as Figure 5 shown. The top rod of the linear displacement gauge is located between the outer surface of the L-shaped steel bar on the rear side of the model box and the reaction wall, as Figure 6 shown. When the fault zone strikes and slips, the soil mass in the model box pushes the L-shaped steel bar to move along the x direction, causing the top rod of the linear displacement gauge to have telescopic deformation. By monitoring the telescopic deformation amount, the horizontal displacement of different depth soil layers under the strike-slip of the fault zone is analyzed.

[0068] The soil pressure gauge is arranged on the inner surface of the rear side of the L-shaped steel bar on the rear side of the model box to monitor the soil pressure exerted by the soil mass on the boundary of the model box under the strike-slip of the fault, asFigure 7 as shown

[0069] To monitor the displacement of subgrade and foundation soil mass and the distribution of earth pressure, a plurality of wire - type displacement gauges are arranged on the subgrade top surface along the line direction, and a plurality of earth pressure gauges are arranged in the vertical plane where the subgrade center line is located. When the fault zone undergoes strike - slip displacement, the change of x - direction earth pressure at different depths of rock and soil mass is the key concern. Therefore, the earth pressure sensing plate needs to be arranged perpendicular to the x - axis direction, that is, the earth pressure gauge is placed vertically; when the fault zone undergoes dip - slip displacement, the change of z - direction earth pressure at different depths of rock and soil mass is the key concern. Therefore, the earth pressure sensing plate needs to be arranged perpendicular to the z - axis direction, that is, the earth pressure gauge is placed horizontally. As Figure 8 shown

[0070] A tripod is installed on the front side of the model box, and a No. 20 high - resolution camera is arranged above the tripod, facing the front side of the model box, for monitoring the two - dimensional deformation of rock and soil mass during the dip - slip displacement of the fault, as Figure 9 shown. A No. 23 gantry support is set up. The top cross - beam of the gantry support fixes the No. 21 and No. 22 high - resolution cameras. The two cameras face the top of the model box. By using the binocular vision monitoring method, the three - dimensional deformation of rock and soil mass during the strike - slip and dip - slip displacement of the fault is monitored, as Figure 9 shown

[0071] The above three cameras simultaneously take 1 photo of the rock and soil mass every 1 s. The first photo is divided into several interpretation areas. The position and state of soil particles are recorded in each interpretation area. In the next photo, the position with the highest matching degree with the interpretation area of the previous photo is found as the position after the displacement of the interpretation area, and the two - dimensional displacement field of the soil mass at each moment is obtained. The No. 20 camera only conducts two - dimensional deformation monitoring of the rock and soil mass surface area. The No. 21 and No. 22 cameras work simultaneously, and the three - dimensional coordinates of the interpretation area can be obtained in real - time. By performing three - dimensional reconstruction on the plane images taken by the two cameras respectively, the three - dimensional information of the scene can be restored, and three - dimensional deformation monitoring of the rock and soil mass surface area can be carried out. The three - dimensional deformation analysis obtains the displacement field of the subgrade and foundation soil mass

[0072] Step 4: Simulation of creep and stick - slip dislocation of the fault zone

[0073] When conducting the strike - slip displacement model test of the fault, the x - direction movement of the L - shaped steel bar is not restricted. The No. 3 motor drives the No. 5 screw jack to move. The No. 5 screw jack makes the No. 6 connecting block and the fault dislocation disk move horizontally in the x - direction, thus realizing the strike - slip fault dislocation. During the strike - slip fault dislocation process, the upper model soil mass undergoes horizontal shear deformation, applying active earth pressure to the inner wall at the back side of the L - shaped structure, and the soil layer generates stepped strike - slip displacement, realizing the simulation of the strike - slip dragging effect

[0074] When conducting the fault dip-slip displacement model test, a locking device is used to restrict the relative movement in the x-direction between the L-shaped steel bars. Fixing the limit holes in groups 23 and 26 with bolts can set the dip-slip fault displacement angle to 90 degrees; fixing the limit holes in groups 24 and 26 with bolts can set the dip-slip fault displacement angle to 75 degrees; fixing the limit holes in groups 25 and 26 with bolts can set the dip-slip fault displacement angle to 60 degrees. The limit device effectively ensures that the bottom plate of the displacement disk remains horizontal during the dip-slip fault displacement test. Subsequently, start the No. 4 motor. The No. 4 motor drives the No. 7 gear to rotate. The rotation of the No. 7 gear drives the No. 8 endless chain to move. The movement of the No. 8 endless chain drives the No. 9 gear to rotate. The No. 9 gear drives the middle rotating shaft to rotate, and drives the No. 10 and No. 11 couplings and the No. 12 and No. 13 screw jacks to move, realizing the simulation of the dip-slip fault movement at different fault displacement angles. As shown in Figure 4 and Figure 10 as shown.

[0075] By controlling the movement speeds of the motor and the jack, the slow creep displacement and rapid stick-slip displacement of the fault are simulated.

[0076] Compared with the traditional fault displacement model test method, the developed fracture zone displacement layered shear simulation test system and method of the present invention can realize the multi-parameter adjustment of the fracture zone displacement mode, displacement rate, and dip angle, and can conduct tests for different types of active fracture zones. The boundary conditions of the fault displacement model are improved, and the dragging effect of the deep soil mass on the shallow soil mass in the overlying layer above the bedrock can be reflected, enhancing the versatility and reliability of the test system. Using a variety of stress and displacement measurement sensors and a binocular stereo vision monitoring system, the three-dimensional stress and deformation field monitoring of the geotechnical body is realized. The present invention solves the boundary condition problem of the existing model test device, comprehensively monitors the deformation and stress evolution characteristics of the geotechnical body from point to surface, adopts a deformation limit device, enhances the reliability of the existing fault displacement model test system, can realize the simulation of the creep and stick-slip displacements of strike-slip and dip-slip faults on one test device, enhances the versatility of the existing fault displacement model test system, and provides support for the research on the deformation mechanism of the near-fault roadbed and the evaluation of the line smoothness under the fracture zone displacement. At the same time, the present invention provides a stable and efficient fracture zone displacement layered shear simulation test system and method, provides a new means for the indoor model test of the fracture zone displacement, can be widely promoted in the geotechnical laboratory, and improves the technical level of the laboratory equipment.

[0077] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A layered shear simulation test device for fault dislocation, including a model box, characterized in that: tempered glass plates are arranged on the outer sides of the front, rear and left sides of the model box, and the bottom is respectively an active plate and a fixed plate of the fault. A layered shear deformation structure is arranged on the upper part of the active plate, and the bottom plate of the fixed plate can be adjusted left and right along the y direction to set the width of the bedrock fault zone. The layered shear deformation structure is composed of a plurality of L-shaped steel bars. The first L-shaped steel bar at the bottom is tightly connected to the bottom fault dislocation flat plate. The specific number of L-shaped steel bars is determined according to the z-direction dimension of the geotechnical model. Slide rails and y-direction deformation limiting structures are arranged between the L-shaped steel bars and the steel bars to ensure that each L-shaped steel bar can only move along the x-axis direction.

2. The fault dislocation layered shear simulation test device according to claim 1, characterized in that: A fault dislocation variable-speed loading system is arranged on the side and lower part of the model box to control the strike-slip dislocation and dip-slip dislocation of the fault respectively.

3. The fault dislocation and layered shear simulation test device according to claim 1, characterized in that: If a strike-slip fault dislocation model test is carried out, before the model is filled, a low-density thick sponge is arranged inside the front side of the model box to reduce the passive earth pressure exerted on the soil body when the sponge rebounds and expands while filling the increased volume of the model box due to the strike-slip fault dislocation. A reaction wall for arranging linear displacement gauges is arranged on the rear side of the model box.

4. A fault dislocation layered shear simulation test system, comprising the fault dislocation layered shear simulation test device described in claim 1, characterized in that: The simulation test system includes linear displacement gauges, earth pressure gauges, wire-pulling displacement gauges, and high-resolution cameras. The linear displacement gauges are arranged between the outer surface of the L-shaped steel bars on the rear side of the model box and the reaction wall to monitor the horizontal displacement of the foundation soil layers at different depths under the strike-slip dislocation of the fault zone. A plurality of wire-pulling displacement gauges are arranged on the top surface of the subgrade along the line direction to monitor the displacement of the subgrade top surface during the test. The high-resolution cameras are arranged on the front side and the top of the model box to carry out two-dimensional deformation monitoring of the geotechnical surface area on the front side of the model box and three-dimensional deformation monitoring of the geotechnical surface area on the top of the model box. A plurality of earth pressure gauges are arranged on the inner surface of the rear side of the L-shaped steel bars and in the plane of the subgrade center line to monitor the earth pressure exerted by the soil body on the boundary of the model box and the change of the earth pressure in the geotechnical body under the strike-slip dislocation of the fault. For the strike-slip fault dislocation model test, the earth pressure gauges in the geotechnical body are placed vertically. For the dip-slip fault dislocation model test, the earth pressure gauges in the geotechnical body are placed horizontally.

5. The fault dislocation layer shear simulation test system according to claim 4, characterized in that: High-resolution cameras are respectively arranged on the front side and the top of the model box, and photos are taken at 1s intervals during the test to record the deformation and rupture process of the subgrade and foundation caused by the fault dislocation. One high-resolution camera is arranged on the front side of the model box for monitoring the plane deformation of the geotechnical body during the dip-slip fault dislocation. Two high-resolution cameras are arranged on the top of the model box to monitor the three-dimensional deformation of the geotechnical body during the strike-slip and dip-slip fault dislocations.

6. The fault dislocation layered shear simulation test system according to claim 4, characterized in that: When the dip-slip fault dislocation is carried out, a locking device is used to limit the relative x-direction movement between the L-shaped steel bars. The dip-slip dislocation control motor is connected to two screw jacks through gears, chains and rotating shafts. By controlling the rotation direction and rotation speed of the motor, the up and down movement of the two screw jacks is controlled to achieve the dip-slip fault dislocation. In addition, a plurality of limiting devices are used to jointly set the fault dislocation angle at the bottom of the model box, and the limiting devices effectively ensure that the bottom plate of the dislocation plate always remains horizontal during the dip-slip fault dislocation test.

7. The fault dislocation layered shear simulation test system according to claim 6, characterized in that: When conducting a fault strike-slip displacement model test, the L-shaped steel bar is unrestricted in the x-direction movement. The strike-slip displacement control motor is connected to the screw jack, the screw jack is connected to the connecting block, and the connecting block is connected to the side of the fault displacement plate. By controlling the rotation direction and rotation speed of the motor, the forward and backward movement of the screw jack and the connecting block is controlled to achieve the fault strike-slip displacement. At this time, the upper model soil mass undergoes horizontal shear deformation, applying an active earth pressure to the inner wall at the rear side of the L-shaped structure, and the soil layer generates a stepped strike-slip displacement, thereby simulating the fault strike-slip dragging effect.

8. A method for simulating fault displacement and layered shear test, the system is based on the fault displacement and layered shear simulation test system described in claim 4, characterized in that: Step 1: Construction of the fault displacement and layered shear model test device; Step 2: Filling and compaction of the rock and soil mass in the model box of the test device; Step 3: Layout of the monitoring sensors in the monitoring system and construction of the binocular stereo vision system; Step 4: Simulation of creep and stick-slip dislocation of the fault zone.

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