Visual test system for subway tunnel mining method excavation

Abstract

The invention discloses a visual test system for mining excavation of a subway tunnel. The visual test system comprises a combined model box mounted on an optical platform, wherein a visual filling material is used for simulating surrounding rock of the subway tunnel; the tunnel excavation module divides an internal interface into a plurality of cavern areas through isolation materials to form a tunnel model planned to be excavated in a preset mode, each cavern area is filled with visual and fusible filler, and a conductive hot melting device is embedded in each cavern area to simulate excavation of a tunnel. The support system is an anchor rod simulation device which is arranged in a surrounding rock material in advance; the loading device comprises a stress loading unit for applying load to simulate original stress around the tunnel and a pressure sensor for monitoring the load; the laser instrument is used for emitting a laser beam to generate a speckle field; the imaging device is used for shooting speckle field images; in addition, an image identification and interpretation module (a special image analysis tool GEO-PIV developed based on matlab) is provided. The whole excavation process of any part of the tunnel can be visualized.

Description

Technical Field

[0001] The present invention relates to the technical field of urban subway tunnel construction, and in particular to a visualization test system for subway tunnel mining excavation. Background Art

[0002] In the construction of urban subway tunnels, the mining method, as a flexible and adaptable construction technology, is widely used in tunnel projects under complex geological conditions, including anisotropic rock formations or weak surrounding rock areas. However, the mining method causes significant disturbance to the surrounding rock during construction, which can easily lead to geotechnical engineering disasters such as stratum displacement, plastic deformation of the surrounding rock, and even vault collapse. Such disasters are usually characterized by suddenness, transientness, and concealment. Deformation and damage often show nonlinear and rapid evolution trends, and are significantly affected by factors such as loading path and structural disturbance, posing serious challenges to the safety and subsequent stability of tunnel construction. Therefore, under complex geological conditions, it is necessary to simulate actual excavation conditions through model tests and systematically study the effects of different support conditions and construction parameters on the surrounding rock response, so as to optimize support design, improve construction safety, and reduce engineering risks.

[0003] At present, traditional indoor physical model tests have the following limitations: 1. Most of them use local, single-point sensors to measure soil deformation, which makes it difficult to cover the continuous deformation process of the entire soil area; 2. The internal deformation process of the soil cannot be directly observed, and the structure-surrounding rock interaction mechanism is not easy to reveal; 3. The soil structure is easily damaged during the sensor burial process, affecting the actual deformation behavior; 4. It is impossible to capture the transient evolution characteristics of rock and soil deformation or destruction, and the delayed response is obvious; 5. Both accuracy and resolution are difficult to meet the needs of complex deformation identification; 6. The experimental function is single, and it is impossible to achieve flexible adjustment and reproduction of various excavation methods and support strategies.

[0004] Therefore, there is an urgent need for a test system that can truly reproduce the surrounding rock deformation and structural response during tunnel excavation and realize the visualization of deformation and structural response throughout the tunnel excavation process. Summary of the Invention

[0005] Purpose of the invention: In order to overcome the above shortcomings, the purpose of the present invention is to provide a visualization test system for subway tunnel mining method excavation, which can truly reproduce the surrounding rock deformation and structural response during the tunnel excavation process, and realize the visualization of the deformation and structural response of the entire tunnel excavation process.

[0006] To solve the above technical problems, the present invention provides a visualization test system for subway tunnel mining excavation, comprising: A combined model box mounted on an optical platform, which is filled with a visualization filling material; a tunnel excavation simulation device, which is sealed and installed in the combined model box and uses an insulating material to divide the interface of the tunnel excavation simulation device into a preset number of cavern areas to form a tunnel model of a predetermined shape, and each cavern area is filled with a fusible filler and embedded with an electric thermal fuse for conducting electricity and heat to simulate the excavation process; A loading device, which is installed on the combined model box, and includes a stress loading unit and a pressure sensor. The stress loading unit is used to apply a load to the tunnel excavation simulation device to simulate the original stress around the tunnel, and the pressure sensor is used to monitor the magnitude of the load applied to the tunnel model; Laser instruments are installed on both sides of the combined model box and are used to emit laser beams to both sides of the combined model box to generate a speckle field; An imaging device, configured to capture a speckle field image when the laser instrument emits a laser beam toward the combined model box; Image recognition and interpretation module, used to extract features and perform displacement recognition analysis on the acquired speckle field images to achieve visual measurement of tunnel surrounding rock deformation; The control unit is connected to the tunnel excavation simulation device, the loading device, the laser unit and the camera unit respectively, and is used to perform visual test operations of subway tunnel mining method excavation.

[0007] As a preferred method of the present application, when executing the visualization test process, the melting sequence and / or shape of the fusible filler filled in the cavern area is used to simulate the excavation method corresponding to different geological requirements in the actual construction process, wherein the method includes but is not limited to the full-section method, the step method, the middle partition wall method, and the cross middle partition wall method, and the simulation switching is achieved by adjusting the partition layout and melting sequence of the visual, fusible filler and the electric thermal fuse.

[0008] As a preferred method of the present application, when executing the visualization test process, the middle partition wall excavation method is simulated, and the step-by-step fusing of the upper step of the left area, the lower step of the left area, the upper step of the right area and the lower step of the right area are completed in sequence, and laser displacement monitoring and image acquisition are integrated in the whole process to realize the simulation test of tunnel excavation.

[0009] As a preferred method of the present application, when executing the visualization test process, the full-section upper step excavation method is simulated, and the phased observation test of excavation disturbance and support response is realized by prioritizing excavation and support of the upper step, delayed release of the lower step and synchronous closed support.

[0010] As a preferred method of the present application, when executing the visualization test process, the cross-partition wall excavation method is simulated, and the cross-sequence step-by-step fusing of the upper step of the left area, the lower step of the right area, the upper step of the right area and the lower step of the left area is completed in sequence, and laser displacement monitoring and image acquisition are integrated in the whole process to realize the simulation test of tunnel excavation.

[0011] As a preferred embodiment of the present application, in the process of making the combined model box, transparent soil material is used to simulate various rock formations encountered in urban subways, including the simulation of anisotropic rock formations.

[0012] As a preferred method of the present application, before executing the visualization test process, the pressure ratio during the simulated excavation test is determined by calculating the composite relationship between the scale ratio and the bulk density ratio between the visualization filling material and the actual soil, as follows: , , , ,in 、 、 、 、 、 、 、 They represent the similarity constants of geometry, displacement, strain, stress, elastic modulus, Poisson's ratio, bulk density, and boundary stress, respectively.

[0013] As a preferred embodiment of the present application, the system further includes an image recognition module connected to the imaging device. The image recognition module adopts a GEO-PIV image processing algorithm and has automatic control point calibration, monitoring area grid division, image registration, data filtering and visualization output functions. The module is used to digitally process and analyze the collected speckle images, realize high-precision and continuous monitoring of the deformation process of the surrounding rock and support structure in the tunnel model under non-contact, panoramic viewing conditions, and output a three-dimensional displacement vector field containing lateral, longitudinal and vertical displacement components in real time.

[0014] As a preferred embodiment of the present application, it also includes: an anchor rod component, which pre-sets an anchor rod model in a tunnel model system to simulate the tunnel support system after excavation of an urban subway tunnel, and is used to quickly assemble an anchor rod assembly with preset parameters according to different support working conditions or excavation methods to achieve an adjustable simulation effect; wherein the angle adjustment range of the anchor rod component is 0°~45°.

[0015] As a preferred method of the present application, a visualization test process of one or more cavern areas is executed according to the test requirements, and the image recognition module is synchronously coordinated to perform full-process monitoring and data output.

[0016] The above technical solution of the present application has the following advantages over the prior art: 1. This application sets up a tunnel excavation simulation system consisting of transparent soil production technology and an electrothermal excavation simulation device, which can accurately simulate the entire tunnel excavation process under "non-embedded, non-disturbance" conditions.

[0017] 2. This application can simulate different existing tunnel excavation methods (such as full-section method, full-section step method, CD method, CRD method and step method, etc.) by changing the shape of the fusible filler block casting, and can also simulate the excavation of tunnels with different cross-sections by changing the tunnel cross-sectional shape.

[0018] 3. In the process of making the combined model box, this application uses transparent soil materials with a certain degree of optical transparency to simulate various rock formations encountered in urban subways, including the simulation of anisotropic rock formations, so as to reconstruct the bedding characteristics in the actual underground rock mass.

[0019] 4. The combined model box is made of transparent materials on all sides. Combined with laser irradiation and industrial camera layout, it can capture the three-dimensional deformation speckle pattern of tunnel and slope models in a non-embedded, panoramic manner. This transparent design has significant advantages such as high resolution, continuous deformation evolution, and non-disturbance measurement while maintaining structural integrity. It helps to reveal the true mechanism of interaction between the support system and surrounding rock under complex working conditions, and facilitates subsequent digital displacement analysis and strain inversion.

[0020] 5. This application also has an image recognition module, which adopts the GEO-PIV image processing algorithm and has the functions of automatic control point calibration, monitoring area grid division, image registration, data filtering and visualization output. It digitally processes and analyzes the collected speckle images, and realizes high-precision and continuous monitoring of the deformation process of the surrounding rock and support structure in the tunnel model under non-contact, panoramic viewing conditions, and outputs a three-dimensional displacement vector field containing lateral, longitudinal and vertical displacement components in real time.

[0021] 6. This application also introduces an anchor rod component, which pre-sets an anchor rod model in the tunnel model system to simulate the tunnel support system after excavation of an urban subway tunnel. It is used to quickly assemble anchor rod components with preset parameters according to different support working conditions or excavation methods, and realize non-embedded simulation of surrounding rock response changes under different anchor rod parameter combinations (length, inclination, spacing, etc.); combined with three-dimensional visual recognition, the anchor rod support effect can be digitally analyzed under undisturbed conditions, throughout the entire process and at all times during deformation coupling, providing real and reproducible data support for the tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0023] Figure 1 It is a three-dimensional schematic diagram of a test system provided by an embodiment of the present invention.

[0024] Figure 2 It is a front view schematic diagram of the test system provided by the embodiment of the present invention.

[0025] Figure 3 2 is a schematic top view of a test system provided by an embodiment of the present invention.

[0026] Figure 4 It is a schematic diagram of the full-face excavation method of the test system provided in an embodiment of the present invention.

[0027] Figure 5 This is a first schematic diagram of the full-section step excavation method of the test system provided by an embodiment of the present invention.

[0028] Figure 6 This is a second schematic diagram of the full-section step excavation method of the test system provided by an embodiment of the present invention.

[0029] Figure 7 1 is a first schematic diagram of the CD excavation method of the test system provided in an embodiment of the present invention.

[0030] Figure 8 This is a second schematic diagram of the CD excavation method of the test system provided in an embodiment of the present invention.

[0031] Figure 9 It is a schematic diagram of the CDR excavation method of the test system provided in an embodiment of the present invention.

[0032] Description of the accompanying drawings: 10. Optical platform, 11. Combined model box, 12. Tunnel excavation simulation device, 12. Anchor component, 13. Loading device, 14. Laser instrument, 15. Imaging device, 20. Control unit, 111. Visual filling material, 121. Middle partition wall, 122. Isolation material, 123. Sealing strip, 124. Tunnel model, 125. Fusible filler, 141. Slide rail, 142. Connecting rod. DETAILED DESCRIPTION

[0033] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0034] refer to Figures 1-9 As shown, in some embodiments, the present application designs a visualization test system for subway tunnel mining excavation, which includes at least an optical platform 10, a combined model box 11, a tunnel excavation simulation device 12, an anchor member 16, a loading device 13, a laser instrument 14, an imaging device 15 and a control unit 20; wherein: The combined model box 11 is mounted on an optical platform 10. A tunnel excavation simulator 12 is housed within the combined model box 11. Except for the tunnel model 124, the entire box is filled with a visible filler material 111, such as transparent soil. The combined model box 11 is constructed from multiple transparent panels, allowing the laser 14 to illuminate the tunnel model to generate a speckle field, and the imaging device 15 to capture the speckle field generated by the sliding movement of the tunnel model 124. The optical platform 10 ensures the stability and levelness of the model box, providing a reference for subsequent optical measurements.

[0035] The interior of the tunnel excavation simulation device 12 is filled with a fusible filler 125 (such as paraffin wax to simulate the soil during excavation). According to the requirements of the excavation method (such as the CD (center partition 121 method) method or the CRD (cross center partition 121 method) method), the tunnel interface can be divided into several parts with an isolation material 122. Each part is poured and filled with the fusible filler 125 to form a tunnel model 124 of a predetermined shape; when pouring the fusible filler 125, a pre-made mold of the size of each chamber of the CD method excavation tunnel is used for pouring. During the pouring process, an electric thermal fuse is pre-buried in each cavern and arranged in a back-and-forth bending manner, which is used to conduct electricity and heat to melt the fusible filler 125 to simulate the excavation process; for example, each section of the electric thermal fuse can be independently connected to a small temperature-controlled power supply unit, and segmented timing heating and temperature closed-loop control can be achieved through PLC or single-chip microcomputer. The filler can be melted section by section according to the construction steps to avoid local collapse or material waste caused by simultaneous heating of the entire section; further, a miniature thermocouple or infrared temperature sensor group can be arranged near each section of the fuse to collect the local temperature of the filler in real time, so as to realize closed-loop monitoring of the melting process and temperature regulation feedback.

[0036] Furthermore, a micro negative pressure suction port can be embedded in the bottom or one side of the tunnel excavation simulation device 12, connected to a reusable high-temperature filtering residue recovery bag and a small vacuum pump device, to quickly suck out the liquid residue after the filler melts to prevent blockage and contamination.

[0037] The tunnel excavation simulator 12 is externally encased in an insulating material 122 that completely encases the fusible filler 125. This insulating material 122 requires excellent thermal insulation and strong plasticity to ensure uniform heating and melting of the fusible filler 125 within. This material also isolates the fusible filler 125 from the transparent soil, minimizing the impact of the melting fusible filler 125 on the transparent soil during the simulated excavation process. The contact area between the tunnel excavation simulator 12 and the model box is sealed with a sealing strip 123 to prevent the transparent soil from leaking out of the gap due to loading.

[0038] The tunnel model 124 is not limited to a specific shape, and can be a tunnel simulating various cross-sections, whether circular, horseshoe-shaped, rectangular, or elliptical. The specific shape design only requires changing the opening of the combined model box 11 and the shape of the paraffin casting.

[0039] The loading device 13 is installed on the combined model box 11. The loading device 13 includes a stress loading unit 13 and a pressure sensor. The stress loading unit 13 is used to apply a load to the tunnel excavation simulation device 12 to simulate the original stress around the tunnel. The pressure sensor is used to monitor the size of the load applied to the tunnel model.

[0040] Before simulating excavation, the loading device 13 above the model box is turned on to apply a load to the tunnel model 124 to simulate the original stress around the tunnel. The loading device 13 uses a hydraulic jack device, and a metal plate with a size similar to the internal size of the model box is connected below it. When loading, the center of the metal plate is aligned with the center of the tunnel model 124 to ensure that the tunnel model 124 is evenly stressed and simulates the actual stress conditions. The loading device 13 is also provided with a pressure sensor, which is used to monitor the size of the load applied to the tunnel model. Before simulating excavation, the pressure ratio in the simulation process is determined by calculating the composite relationship between the scale ratio and the bulk density ratio between the transparent soil and the actual soil body, so as to better simulate the actual stress conditions. The details are as follows: , , , ,in 、 、 、 、 、 、 、 They represent the similarity constants of geometry, displacement, strain, stress, elastic modulus, Poisson's ratio, bulk density, and boundary stress, respectively.

[0041] The anchor rod component 16 pre-sets the anchor rod model in the tunnel model system to simulate the tunnel support system after the excavation of the urban subway tunnel. It is used to quickly assemble the anchor rod assembly with preset parameters according to different support working conditions or excavation methods to achieve an adjustable simulation effect.

[0042] Specifically, the length of the anchor rod component 16 is designed based on the following: according to the actual tunnel support design, the anchor rod needs to pass through the loose circle and enter the stable surrounding rock layer. In the transparent soil simulation, the anchor rod anchoring section needs to cover the "disturbance-stability" interface in the model, which is usually selected to be 1 / 2 to 2 / 3 of the cross-sectional depth of the transparent soil model. Usually, the common specifications of the anchor rod component 16 provide three optional anchor rod lengths (such as 100mm to 600mm), which can be adjusted through splicing to be suitable for comparative tests of anchor lengths under different surrounding rock grades and excavation spans.

[0043] The design basis of the inclination angle of the anchor member 16 is: inclination function simulation, which is used to simulate the layout methods such as "radial layout", "elevation angle tensile resistance", and "elevation angle reinforcement of the tunnel face" in actual engineering; usually the design inclination angle of the anchor member 16 can be adjusted in the range of 0° (horizontal) to 45°, and the recommended layout angles include: 0° (horizontal), which is often used for arch foot and arch waist reinforcement; 15°~25°, which is used for inverted arch oblique support; 30°~45°, which is used for tunnel face elevation support simulation; the inclination angle can be adjusted by the universal joint set at the tail of the anchor member 16.

[0044] The spacing of the anchor members 16 is designed based on the surrounding rock grade and the extent of tunnel excavation disturbance, simulating anchor placement schemes under different support densities. The spacing of the anchor members 16 is adjustable, allowing for different pitches within the pre-set boreholes within the tunnel model 124. Commonly used design spacings are set to 50mm, 100mm, and 150mm, corresponding to dense, conventional, and sparse anchor spacing arrangements in actual projects. Adjusting the anchor spacing and placement density allows analysis of the effects of varying anchor coverage on surrounding rock deformation control.

[0045] The assembly process of the anchor rod component 16 is as follows: the anchor rod component 16 is quickly plugged in and locked at the preset anchor hole position in the tunnel model 124. The specific assembly process is as follows: the anchor rod slot layout is preset, and standard anchor rod sockets (hole diameter Φ5.25mm, depth 50~70mm) are reserved on the inner wall and top of the tunnel model 124. The socket positions are arranged according to the construction layout drawing. For example, several anchor holes are preset at typical locations such as the arch foot, arch waist, and inverted arch, and the inner wall of the socket is covered with a guide sleeve to facilitate the precise insertion of the anchor rod component 16.

[0046] The anchor rod member 16 is plugged and fixed. The anchor rod member 16 is inserted into the insertion hole along the specified inclination direction, and then the locking ring buckle is tightened at the tail to achieve a preliminary mechanical connection with the tunnel model 124.

[0047] The laser instrument 14 is installed on both sides of the combined model box 11 and is used to emit laser beams to both sides of the combined model box 11 to generate a speckle field.

[0048] Among them, a slide rail 141 is set under the laser instrument 14 on both sides, so that it can move vertically during the excavation process, so as to directly illuminate each cross-section of the model box; a connecting rod 142 is used under the slide rail 141 to connect the laser instruments 14 on both sides so that the laser instruments 14 on both sides maintain the same horizontal and vertical position.

[0049] The imaging device 15 is used to capture a speckle field image when the laser instrument 14 emits a laser beam to the combined model box 11. Exemplarily, the forming device 15 of the present application can adopt a CCD high-speed industrial camera to record the entire process of progressive tunnel destruction using the CCD high-speed industrial camera to obtain the changes in the speckle field image of the tunnel destruction over the entire time period and the entire cross-section.

[0050] The system also includes an image recognition module connected to the imaging device 15. The image recognition module uses a GEO-PIV image processing algorithm and has automatic control point calibration, monitoring area grid division, image registration, data filtering and visualization output functions. The module is used to digitally process and analyze the collected speckle images, realize high-precision and continuous monitoring of the deformation process of the surrounding rock and support structure in the tunnel model under non-contact, panoramic viewing conditions, and output a three-dimensional displacement vector field containing lateral, longitudinal and vertical displacement components in real time.

[0051] The control unit 20 is connected to the tunnel excavation simulation device 12, the loading device 13, the laser unit and the camera unit respectively, and is used to perform a visual simulation operation of subway tunnel mining method excavation.

[0052] During the simulated excavation test, the loading device 13 is first activated. Then, the laser instruments 14 on both sides are activated to generate a speckle field. The speckle field image is then captured using an imaging device 15, such as a CCD industrial camera. While the surrounding stress remains constant, the thermal fuse is energized to melt the fusible filler 125, simulating the excavation process. During the excavation process, the speckle field images are repeatedly captured. After excavation is completed, the tunnel is unlined, and the speckle field image is acquired again.

[0053] The image recognition module processes and analyzes the acquired speckle field image sequence. First, the images are registered and preprocessed to eliminate background interference and camera shake during the imaging process. Then, the particle image velocimetry (PIV) algorithm is used to extract the pixel displacement vector field of characteristic regions of the tunnel surrounding rock and support structure at different times. Combined with the image's spatial calibration parameters, the pixel displacements are converted to real-world displacement values. This allows the displacement evolution of each monitoring point in the tunnel model (such as the arch crown, arch haunch, and arch foot) throughout the construction simulation to be determined. This non-contact, full-field, high-precision, and real-time update process enables visual monitoring and quantitative analysis of the three-dimensional deformation of the tunnel structure and surrounding soil over a full time period.

[0054] The visualization test system for subway tunnel mining excavation of the present application can also be used for geotechnical centrifuge tests and shaking table tests to explore the displacement and ultimate bearing capacity of the tunnel excavation model under static and dynamic load conditions.

[0055] In some embodiments of the present application, when executing the visualization test process, the melting sequence and / or shape of the fusible filler filled in the cavern area is used to simulate the excavation method corresponding to different geological requirements in the actual construction process; wherein, the excavation method includes but is not limited to the full-section method, the full-section step method, the CD method (center partition method) or the CRD method (cross center partition method).

[0056] The shape of each part of the wax can be changed to simulate the construction method changed by different geological requirements during the actual construction process; the excavation order of each part of the wax can also be changed to simulate the construction method changed by different geological requirements during the actual construction process.

[0057] Exemplary, reference Figure 4 As shown, the full-section excavation simulation operation process of this application is as follows: Overall excavation: Paraffin wax melting and excavation face sealing: The entire cross-section of the fusible filler (125°C) was heated to 55°C for 15 minutes until it completely melted. The remaining paraffin wax was removed to create a fully excavated space. To prevent disturbance of the excavation face, a transparent silicone sheet (2mm thick) was immediately applied to the tunnel face, simulating a temporary face seal.

[0058] Initial support simulation: Transparent acrylic panels (10mm thick) were immediately installed in the excavated space as a "steel arch frame." The panels were connected with bolts. 5mm-diameter plexiglass rods (500mm long) were inserted into the arch feet to simulate locking anchors. A lateral pressure of 0.5kPa was applied to secure the arch. Diagonal braces (8mm-diameter plexiglass rods) were symmetrically placed on the left and right arch haunches. The braces were angled 45° to the horizontal and fixed at both ends between the arch frame and the side wall mold plate to enhance the arch frame's stability.

[0059] Crown filling simulation and gap control: A 1mm vertical movable gap is reserved at the connection between the arch top and the upper mold of the experimental box. An elastic rubber gasket (thickness 2mm) is used to buffer the contact and simulate the cooperative deformation characteristics between the structure and surrounding rock in actual construction.

[0060] Displacement monitoring is started: a laser emitting device 14 is arranged at the center of the tunnel section to form a speckle image projection area. The deformation process in the transparent soil is recorded in real time through the imaging device 15, realizing optical visual monitoring of the support deformation of the entire section.

[0061] Interface treatment and lining bonding: A 0.5mm soft silicone layer is set between the resin board and the acrylic arch to enhance the fitting effect and simulate the bonding effect between the lining and the primary support.

[0062] Secondary lining loading simulation (optional): After the initial support structure has stabilized for 48 hours, a transparent resin plate (5mm thick) is installed on the top of the tunnel, covering the entire arch crown to the arch waist area, and a uniformly distributed load of 1kPa is applied to simulate the load transfer process of the secondary lining structure.

[0063] Exemplary, reference Figure 5 and Figure 6 As shown, the simulation operation process of full-section step method excavation in this application is as follows: 1. Excavation of upper steps (Part ①) The fusible filler 125 in the upper half of the tunnel section (from the vault to half the height of the sidewall) was heated to 55°C for 10 minutes to fully dissolve and remove any residue. After excavation, a 2mm-thick transparent silicone sheet was used to seal the excavated face, simulating closed face support.

[0064] Initial support simulation: Transparent acrylic panels (10mm thick) were immediately arranged in cross-section within the upper bench excavation to simulate steel arches. Each frame was secured with stainless steel bolts. Plexiglas rods (5mm diameter and 500mm long) were inserted into the arch feet to simulate locking anchors. A lateral pressure of 0.5kPa was applied to the arch feet to ensure a stable support structure.

[0065] Temporary support of the middle partition wall 121: A 3mm thick elastic rubber strip (50mm wide) is pasted at the connection between the upper step and the middle partition wall 121 to simulate the contact stress transfer between the middle partition wall 121 and the surrounding rock during actual construction.

[0066] Auxiliary reinforcement of the arch waist: diagonal braces (8mm diameter organic glass rods) are added on both sides of the arch waist, with the angle with the horizontal plane controlled at 45°, connecting the arch frame and the wall of the test chamber respectively to simulate the force transmission path of the arch waist and improve the overall stability.

[0067] 2. Excavation of lower steps (section ②) Layered Fusing and Excavation: After the upper step support stabilizes for 2 hours (simulating the soil stress adjustment period), fuse the fusible filler 125 in the lower step (from the halfway point of the sidewall to below the invert) in a layered and segmented manner. The longitudinal fusing range is controlled to 300mm to prevent overall instability in the lower section. The fusing parameters are the same as for the upper step. After the operation, quickly remove the molten residue to ensure a flat bottom.

[0068] Lower step support installation: Install the lower acrylic arch frame using the same process as the upper step. Connect it rigidly to the upper arch frame with L-shaped connectors to form a closed loop. Install diagonal braces (8mm diameter organic glass rods) at the arch waist, with the braces forming a 45° angle with the horizontal plane and fixed at both ends to the arch frame and the mold sidewall.

[0069] Displacement monitoring is started: a laser instrument 14 is arranged on the excavation contour line of the left area so that it directly illuminates the cross section to create a speckle field image, and the transparent soil deformation data is recorded in real time through the imaging device 15.

[0070] Interface treatment and bonding control: A 0.5 mm silicone pad was inserted between the resin board and the acrylic arch frame to simulate the interface bonding and load synergistic transfer effect between the secondary lining and the initial support structure.

[0071] Loading the inverted arch and secondary lining (optional): After excavation and primary support are completed, allow the structure to rest for 48 hours. Once the structure is stable, simulate the lining construction process. First, apply transparent resin sheets (5mm thick) to the arch crown and side walls to simulate the secondary lining structure. Apply a uniformly distributed pressure of 1kPa along the exterior to simulate the secondary lining load transfer.

[0072] Exemplary, reference Figure 7-Figure 8 As shown, the CD method excavation simulation operation process of this application is as follows: 1. Excavation of the upper steps in the left area (Part ①) Paraffin melting and removal: The fusible filler 125 on the upper step of the left area was heated to 55 °C for 10 min, and a transparent silicone plate (thickness 2 mm) was used to temporarily seal the excavation surface to simulate the tunnel face support.

[0073] Initial support simulation: transparent acrylic plates (10 mm thick) were immediately installed in the excavation space as "steel arch frames". The plates were connected by bolts. Plexiglas rods with a diameter of 5 mm (500 mm long) were inserted into the arch feet to simulate locking anchor rods. A lateral pressure of 0.5 kPa was applied to fix them.

[0074] Temporary support of the middle partition wall 121: A 3mm thick elastic rubber strip (50mm wide) is pasted at the connection between the upper step of the left area and the middle partition wall 121 to simulate the contact stress transfer between the middle partition wall 121 and the surrounding rock during actual construction.

[0075] 2. Excavation of the lower steps in the left area (section ②) Layered Fusion and Excavation: After the upper bench support stabilizes for 2 hours (simulating the soil stress adjustment period), fuse the 125 pieces of fusible filler on the left lower bench in two layers. Each melting interval is 300mm along the longitudinal direction to prevent overall instability. Use the same fusing parameters as in the first step. Immediately remove any debris after fusing to maintain a flat excavation surface.

[0076] Lower step support installation: Install the lower acrylic arch frame using the same process as the upper step. Connect it rigidly to the upper arch frame with L-shaped connectors to form a closed loop. Install diagonal braces (8mm diameter organic glass rods) at the arch waist, with the braces forming a 45° angle with the horizontal plane and fixed at both ends to the arch frame and the mold sidewall.

[0077] Displacement monitoring is started: a laser instrument 14 is arranged on the excavation contour line of the left area so that it directly illuminates the cross section to create a speckle field image, and the transparent soil deformation data is recorded in real time through the imaging device 15.

[0078] 3. Excavation of the upper steps in the right area (section ③) Stability check of the middle partition wall 121: Before excavation, the stress difference on both sides of the middle partition wall 121 is monitored through a micro pressure box (range 0-10kPa) embedded in the transparent soil. When the stress in the left area is stable for 24 hours and the difference is less than 10%, excavation of the right area is started.

[0079] Symmetrical excavation and support: Repeat the excavation process for the upper step in the left area, melt the paraffin blocks on the upper step in the right area, and install a symmetrical acrylic arch. Note: Leave a 1mm clearance at the junction between the top of the middle partition wall 121 and the arch to simulate the coordinated deformation of the middle partition wall 121 and the support structure during actual construction.

[0080] 4. Excavation of the lower steps in the right area (Part ④) Step-by-step fusing and support closure: The same layered fusing process as the lower step of the left area is adopted. The lower arch frame of the right area is closed immediately after excavation. At the same time, a transverse connecting rod (10mm diameter organic glass rod) is added between the arch feet of the left and right areas to form a spatial support system.

[0081] Simulation of removal of the middle partition wall 121 (optional): If simulation of the secondary lining stage is required, wait for 48 hours after the left and right support structures are stable, partially melt the paraffin wax of the middle partition wall 121, and simultaneously install a transparent resin plate on the top of the tunnel to simulate the secondary lining, and apply a uniformly distributed pressure of 1 kPa to simulate the lining load.

[0082] Exemplary, reference Figure 9 As shown, the CDR (cross diaphragm method) excavation simulation operation process of this application is as follows: 1. Excavation of the upper steps in the left area (Part ①) Paraffin melting and removal: The fusible filler 125 on the upper step of the left area was heated to 55 °C for 10 min, and a transparent silicone plate (thickness 2 mm) was used to temporarily seal the excavation surface to simulate the tunnel face support.

[0083] Initial support simulation: transparent acrylic plates (10 mm thick) were immediately installed in the excavation space as "steel arch frames". The plates were connected by bolts. Plexiglas rods with a diameter of 5 mm (500 mm long) were inserted into the arch feet to simulate locking anchor rods. A lateral pressure of 0.5 kPa was applied to fix them.

[0084] Temporary support of the middle partition wall 121: A 3mm thick elastic rubber strip (50mm wide) is pasted at the connection between the upper step of the left area and the middle partition wall 121 to simulate the contact stress transfer between the middle partition wall 121 and the surrounding rock during actual construction.

[0085] 2. Excavation of the lower steps in the right area (section ②) Stepwise fusing and support closure: After the upper bench support in the left area has stabilized for 2 hours (simulating the soil stress adjustment period), the 125 pieces of fusible filler on the lower bench in the right area are fused in two layers, with a single fusing range of 300 mm along the longitudinal direction to prevent overall instability. The fusing parameters are the same as in the first step. After fusing, remove the debris immediately to maintain a flat excavation surface.

[0086] Lower step support installation: Install the lower acrylic arch frame using the same process as the upper step. Connect it rigidly to the upper arch frame with L-shaped connectors to form a closed loop. Add diagonal braces (8mm diameter plexiglass rods) at the arch waist, with a 45° angle to the horizontal. Secure the ends to the arch frame and the mold sidewalls to simulate the rigidity coordination of the initial structure.

[0087] Displacement monitoring is started: a laser instrument 14 is arranged to directly illuminate the tunnel cross section to produce a speckle field image, and an imaging device 15 is used to perform transparent soil deformation visualization monitoring throughout the entire process to obtain a multi-segment coordinated response process.

[0088] 3. Excavation of the upper steps in the right area (section ③) Stability check of the middle partition wall 121: Before excavation, the stress difference on both sides of the middle partition wall 121 is monitored through a micro pressure box (range 0-10kPa) embedded in the transparent soil. When the stress in the left area is stable for 24 hours and the difference is less than 10%, excavation of the right area is started.

[0089] Symmetrical excavation and support: Repeat the excavation process for the upper step in the left area, melt the paraffin blocks on the upper step in the right area, and install a symmetrical acrylic arch. Note: Leave a 1mm clearance at the junction between the top of the middle partition wall 121 and the arch to simulate the coordinated deformation of the middle partition wall 121 and the support structure during actual construction.

[0090] 4. Excavation of the lower steps in the left area (section ④) Layered Fusing and Excavation: After the upper bench support in the right area has stabilized for 2 hours (simulating the soil stress adjustment period), fuse the 125 pieces of fusible filler on the lower bench in the left area in two layers. Each fusing operation covers a 300mm vertical range to prevent overall instability. Use the same fusing parameters as in the first step. Immediately remove any debris after fusing to maintain a flat excavation surface.

[0091] Lower step support installation: Install the lower acrylic arch frame using the same process as the upper step. Connect it rigidly to the upper arch frame with L-shaped connectors to form a closed loop. Install diagonal braces (8mm diameter organic glass rods) at the arch waist, with the braces forming a 45° angle with the horizontal plane and fixed at both ends to the arch frame and the mold sidewall.

[0092] Displacement monitoring is started: a laser instrument 14 is arranged to directly illuminate the tunnel cross section to produce a speckle field image, and an imaging device 15 is used to perform transparent soil deformation visualization monitoring throughout the entire process to obtain a multi-segment coordinated response process.

[0093] Simulation of removal of the middle partition wall 121 (optional): If simulation of the secondary lining stage is required, wait for 48 hours after the left and right support structures are stable, partially melt the paraffin wax of the middle partition wall 121, and simultaneously install a transparent resin plate on the top of the tunnel to simulate the secondary lining, and apply a uniformly distributed pressure of 1 kPa to simulate the lining load.

[0094] In some embodiments of the present application, after the loading device 13 is activated, the lasers 14 on both sides are turned on to inject laser light, and an industrial camera is used to capture a speckle image. While the surrounding stress remains constant, the electric thermal fuse is energized to melt the fusible filler to simulate the excavation process. During the excavation process, the speckle image is repeatedly captured. After excavation is completed, an unlined tunnel is formed, and the speckle image is captured again. The speckle image is imported into a computer, and the displacement of the tunnel vault, side arch, and arch foot is analyzed using GEO-PIV, a dedicated image analysis tool developed based on MATLAB. The above steps are repeated to measure the ultimate load-bearing capacity of the tunnel model and the displacement of the surrounding tunnel.

[0095] The specific GEO-PIV operation process of this application is as follows: 1. Create an analysis folder PIV and two subfolders. One is to copy the GEO-PIV program into the folder called subroutines, and the other is to store the speckle field images in the data image folder DATE.

[0096] 2. Set the file path and select the path to create the folder to save.

[0097] 3. Direct MATLAB to the executable folder: enter geoPIV_RG_locate; in the pop-up window, select the geopiv_RG program in the subroutines folder.

[0098] 4. How to view the help file: Select IMAGE in the data file DATE, the input format of the help file .

[0099] 5. Mark control points: load('cp_xy.mat') to open the CP file on the right and enter geoCENTROID_RG(CP,'Example',50,25); select the initial image of the tunnel speckle field, and then select the control point operation from top to bottom and from left to right. Select two points in the middle of the two calibration lines to represent the maximum threshold and minimum threshold.

[0100] 6. Enter geoMESH_RG('Example', 50, 50); enter 0, then 0 again, select the initial tunnel speckle field image, and use the mouse to select points on the image to form a line to create the restricted area.

[0101] 7. Remove control points from the area: Enter geoMESH_RG('Example', 50, 50); enter 0, then 1, then 50, then 1 again. Select CENTROID_CP_Example.txt to open the initial image of the tunnel speckle field. Select an area of ​​approximately the same size as last time. Use the mouse to select points on the image to connect them into a line and finally generate the restricted area.

[0102] 8 Enter geoLAUNCH_RG(101, 116, 1, 4, 'CP_Example', 'CP_Example', 'IMG_', 'jpg', 1, 1e-5, 10, 0.7, 0.1); Select the file IMages and then enter geoLAUNCH_RG(101, 116, 1, 4, 'Example', 'Example', 'IMG_', 'jpg', 2, 1e-5, 50, 0.7, 0.1); Select the file Images twice.

[0103] 9. Enter geoPIV_RG_run('CP_Example_analysis_launcher'); the analysis will take a while and generate an M1_dat.mat file.

[0104] 10. Enter geoPIV_RG_run('Example_analysis_launcher'); the image window will pop up. Zoom to an area with small deformation and high-contrast texture. Click Enter in the window. Return to the image frame and click the yellow dot on the image. Then press Enter in the control window. Wait for the program to run for a while and generate an M2_dat.mat file.

[0105] 11. Open the analysis file Example_analysis_launcher.txt and change the value of 0 to 1 after the correlation coefficient plots (checking the quality of the calculations) on lines 17 and 18. Change the value of 0 to 1 after the displacement component plot (showing the displacements during the analysis) on line 23. Click Save and enter geoPIV_RG_run('Example_analysis_launcher'). Run the analysis and wait for a while. Three plots will pop up. Each time a calculation is added, all plots will update.

[0106] 12. Load the M2_dat.mat file, input X_data=data(:,:,1); input Y_data=data(:,:,2); input cc_data=data(:,:,3); open the X_dat file on the right.

[0107] 13. Load the M2_dat.mat file and enter filtered_data=geoFILTER_RG(data, 0.9). A folder will pop up, select the initial tunnel speckle field image in Image, and an image box will pop up (red cross: correlation coefficient < critical value (<0.9), these subsets will be deleted in clean_data; blue cross: correlation coefficient > critical value (>0.9)). Click the two date files on the right to save them to the M2_dat.mat file in the pop-up file and click Save.

[0108] 14. Load the M2_dat.mat file and enter unwild_data=geoWILD_RG(data, 1, 50, 1). In the pop-up folder, select the initial tunnel speckle field image in Image. The image box will pop up (zoom to the area of ​​interest, click the bottom of the potential uncontrolled vectors, and then clear them. Right-click and zoom out to other areas of interest and check the uncontrolled vectors). Select the three data files on the right and save them to the M2_dat.mat file in the pop-up file. Click Save.

[0109] 15. Load the M2_dat.mat file and enter XYdata=geoCALIBRATE_RG(data). In the pop-up folder, select the M1_dat.mat file. In the pop-up folder again, select CENTROID_CP_Example to open it. An image box will pop up (the output plot shows that the calibration stability standard error is less than 0.5 pixels, which is considered a good calibration). Select the four data files on the right and add them to the M2_dat.mat file. Click Save.

[0110] 16. Load the M2_dat.mat file and enter strains=geoSTRAIN_RG(XYdata). A grid image box (red triangles: invalid strain (ignore) elements) will pop up. Select the five data files on the right and save them to the M2_dat.mat file.

[0111] 17. Load the M2_dat.mat file and enter geoPLOTDISP_RG(XYdata, 1, 50, 0, 0, 1, 0, 1); the vector displacement plot, lateral displacement surface plot, longitudinal displacement surface plot, and composite displacement surface plot will pop up.

[0112] 18. Load the M2_dat.mat file and input geoPLOTSTRAIN_RG(strains, 1, 50, 0, 0, 1, 10, 0); output the strain contours.

[0113] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0114] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A visualization test system for subway tunnel mining excavation, characterized in that: include: A combined model box mounted on an optical platform, which is filled with a visualization filling material; a tunnel excavation simulation device, which is sealed and installed in the combined model box and uses an insulating material to divide the interface of the tunnel excavation simulation device into a preset number of cavern areas to form a tunnel model of a predetermined shape, and each cavern area is filled with a fusible filler and embedded with an electric thermal fuse for conducting electricity and heat to simulate the excavation process; A loading device, which is installed on the combined model box, and includes a stress loading unit and a pressure sensor. The stress loading unit is used to apply a load to the tunnel excavation simulation device to simulate the original stress around the tunnel, and the pressure sensor is used to monitor the magnitude of the load applied to the tunnel model; Laser instruments are installed on both sides of the combined model box and are used to emit laser beams to both sides of the combined model box to generate a speckle field; An imaging device, configured to capture a speckle field image when the laser instrument emits a laser beam toward the combined model box; Image recognition and interpretation module, used to extract features and perform displacement recognition analysis on the acquired speckle field images to achieve visual measurement of tunnel surrounding rock deformation; The control unit is connected to the tunnel excavation simulation device, the loading device, the laser unit and the camera unit respectively, and is used to perform visual test operations of subway tunnel mining method excavation.

2. A visualization test system for subway tunnel mining excavation according to claim 1, characterized in that: When executing the visualization test process, the melting sequence and / or shape of the fusible filler filled in the cavern area is used to simulate the excavation methods corresponding to different geological requirements in the actual construction process, wherein the methods include but are not limited to the full-section method, the step method, the middle partition wall method, and the cross middle partition wall method, and the simulation switching is achieved by adjusting the partition layout and melting sequence of the visual, fusible filler and the electric thermal fuse.

3. A visualization test system for subway tunnel mining excavation according to claim 2, characterized in that: When executing the visual test process, the middle partition wall excavation method is simulated, and the step-by-step fusing of the upper step in the left area, the lower step in the left area, the upper step in the right area and the lower step in the right area are completed in sequence. Laser displacement monitoring and image acquisition are integrated in the whole process to realize the simulation test of tunnel excavation.

4. A visualization test system for subway tunnel mining excavation according to claim 3, characterized in that: When executing the visualization test process, the full-section upper step excavation method is simulated. By prioritizing excavation and support on the upper step, delaying release on the lower step, and synchronously closing the support, a phased observation test of excavation disturbance and support response is achieved.

5. A visualization test system for subway tunnel mining excavation according to claim 4, characterized in that: When executing the visual test process, the cross-partition wall excavation method is simulated, and the cross-sequence step-by-step fusing of the upper step in the left area, the lower step in the right area, the upper step in the right area and the lower step in the left area are completed in sequence. Laser displacement monitoring and image acquisition are integrated in the whole process to realize the simulation test of tunnel excavation.

6. A visualization test system for subway tunnel mining excavation according to claim 5, characterized in that: In the process of making the combined model box, transparent soil materials are used to simulate various rock formations encountered in urban subways, including the simulation of anisotropic rock formations.

7. A visualization test system for subway tunnel mining excavation according to claim 6, characterized in that: Before executing the visualization test process, the pressure ratio during the simulated excavation test is determined by calculating the composite relationship between the scale ratio and the bulk density ratio between the visualization filling material and the actual soil, as follows: , , , ,in 、 、 、 、 、 、 、 They represent the similarity constants of geometry, displacement, strain, stress, elastic modulus, Poisson's ratio, bulk density, and boundary stress, respectively.

8. A visualization test system for subway tunnel mining excavation according to claim 1 or 7, characterized in that: The system also includes an image recognition module connected to the imaging device. The image recognition module uses a GEO-PIV image processing algorithm and has automatic control point calibration, monitoring area grid division, image registration, data filtering and visualization output functions. The module is used to digitally process and analyze the collected speckle images, realize high-precision and continuous monitoring of the deformation process of the surrounding rock and support structure in the tunnel model under non-contact, panoramic viewing conditions, and output a three-dimensional displacement vector field containing lateral, longitudinal and vertical displacement components in real time.

9. A visualization test system for subway tunnel mining excavation according to claim 8, characterized in that: Also includes: An anchor rod component, which pre-sets an anchor rod model in the tunnel model system to simulate the tunnel support system after excavation of an urban subway tunnel, is used to quickly assemble anchor rod components with preset parameters according to different support working conditions or excavation methods to achieve an adjustable simulation effect; wherein the angle adjustment range of the anchor rod component is 0°~45°.

10. A visualization test system for subway tunnel mining excavation according to any one of claims 1 to 9, characterized in that: Execute the visual test process of one or more cavern areas according to the test requirements, and synchronously coordinate the image recognition module to monitor the entire process and output data.

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