A visual test system for metro tunnel mine method excavation

Abstract

The application discloses a kind of metro tunnel mine method excavation visual test system, comprising: installation in the combined model box of optical platform: wherein with visual filling material to simulate the surrounding rock of subway tunnel;Tunnel excavation module utilizes isolation material to divide internal interface into multiple cavern areas, to form the tunnel model of predetermined plan excavation, each cavern area is filled with visible, meltable filling, and is buried with conductive hot melting device to simulate the excavation of tunnel;Support system is the anchor rod simulation device of pre-setting in surrounding rock material;Loading device includes stress loading unit for applying load to simulate the original stress of tunnel around and pressure sensor for monitoring load size;Laser instrument is used to emit laser beam to generate speckle field;Imaging device is used to take speckle field image;There are image recognition and interpretation module (special image analysis tool GEO-PIV based on matlab development). The application can realize the whole process visualization of tunnel any part excavation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of urban subway tunnel construction, in particular to a visual test system for subway tunnel mining method excavation. BACKGROUND

[0002] In the construction of urban subway tunnels, the mining method, as a flexible and adaptable construction technology, is widely used in tunnel engineering under complex geological conditions, including anisotropic rock layers or soft surrounding rock areas. However, the mining method has a large disturbance to the surrounding rock during the construction process, which can easily cause geotechnical engineering disasters such as stratum displacement, plastic deformation of surrounding rock, and even collapse of arch crown. Such disasters usually have typical characteristics such as suddenness, transience, and concealment, and the deformation and damage often show a nonlinear and rapid evolution trend, and are significantly affected by loading path and structural disturbance, thereby posing a serious challenge to the safety and later stability of tunnel construction. Therefore, under complex geological conditions, the actual excavation conditions need to be simulated through model tests, and the influence of different support conditions and construction parameters on the surrounding rock response needs to be systematically studied, so as to optimize the support design, improve the construction safety, and reduce the engineering risk.

[0003] At present, the traditional indoor physical model test has the following limitations: 1. Local and single-point sensors are mostly used to measure soil deformation, which is 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 sensor embedding, affecting the true deformation behavior; 4. The transient evolution characteristics of the deformation or damage of the rock-soil body cannot be captured, and the delay response is obvious; 5. The precision and resolution cannot meet the needs of complex deformation identification; 6. The experimental function is single, and it is not possible to realize flexible adjustment and reproduction of various excavation methods and support strategies.

[0004] Therefore, there is an urgent need for an experimental system that can truly reproduce the deformation of surrounding rock and the response degree of structure during tunnel excavation, and realize the visualization of the deformation and structure response of the entire tunnel excavation process. SUMMARY

[0005] The purpose of the present application is to overcome the above shortcomings, and the purpose of the present application is to provide a visual test system for subway tunnel mining method excavation, which can truly reproduce the deformation of surrounding rock and the response degree of structure during tunnel excavation, and realize the visualization of the deformation and structure response of the entire tunnel excavation process.

[0006] To solve the above technical problems, the present application provides a visual test system for subway tunnel mining method excavation, comprising:

[0007] A combined model box installed on an optical platform, which is filled with visual filling materials;

[0008] The tunnel excavation simulation device is sealedly installed in the combined model box and utilizes an isolation material to divide the interface in the tunnel excavation simulation device into a preset number of chamber regions to form a tunnel model of a predetermined shape, and each chamber region is filled with a meltable filler and is embedded with an electric heating fuse for electrically heating and conducting to simulate the excavation process;

[0009] The loading device is installed on the combined model box, and the loading device includes a stress loading unit for applying a load to the tunnel excavation simulation device to simulate the original stress around the tunnel and a pressure sensor for monitoring the load applied to the tunnel model;

[0010] The laser instrument is installed on both sides of the combined model box and is used to emit a laser beam to both sides of the combined model box to generate a speckle field;

[0011] The imaging device is used to capture an image of the speckle field when the laser instrument emits a laser beam to the combined model box;

[0012] The image recognition and interpretation module is used to extract features and identify displacement of the collected speckle field image to realize visual measurement of the deformation of the tunnel surrounding rock;

[0013] 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 a visual test operation of the subway tunnel mining method excavation.

[0014] As a preferred mode of the present application, during the execution of the visual test process, the melting sequence and / or shape of the meltable filler filled in the chamber region are used to simulate the corresponding excavation method in the actual construction process according to different geological requirements, wherein the method includes but is not limited to the full-face method, the bench method, the middle partition wall method, and the cross middle partition wall method, and the simulation switching is realized by adjusting the partition layout and melting sequence of the visible and meltable filler and the electric heating fuse.

[0015] As a preferred mode of the present application, during the execution of the visual test process, the middle partition wall method excavation method is simulated, the step-by-step melting of the left upper bench, the left lower bench, the right upper bench, and the right lower bench is sequentially completed, and the laser displacement monitoring and image acquisition are integrated in the whole process to realize the simulation test of the tunnel excavation.

[0016] As a preferred mode of the present application, during the execution of the visual test process, the full-face upper bench method excavation method is simulated, and the phased observation test of the excavation disturbance and the support response is realized by the upper bench preferential excavation and support, the lower bench delayed release, and the synchronous closing support.

[0017] As a preferred mode of the present application, in the process of executing the visual test, the simulated cross diaphragm method is used to excavate the tunnel, and the cross sequential step-by-step melting is completed in the left upper step, the right lower step, the right upper step and the left lower step in sequence, and the laser displacement monitoring and image acquisition are integrated in the whole process to realize the simulation test of tunnel excavation.

[0018] As a preferred mode of the present application, in the process of making the combined model box, transparent soil material is used to simulate various rock layers encountered in urban metro, including anisotropic rock simulation.

[0019] As a preferred mode of the present application, before the visual test process is executed, the pressure ratio in the simulation excavation test process is determined by the composite relationship calculation of the scale ratio and the volume weight ratio between the visual filling material and the actual soil body, and the specific method is as follows:

[0020] The geometric, displacement, strain, stress, elastic modulus, Poisson's ratio, volume weight and boundary stress similarity constants are represented by G, D, S, T, E, P, R and B respectively.

[0021] As a preferred mode of the present application, the system further comprises an image recognition module connected with the imaging device, the image recognition module adopts GEO-PIV image processing algorithm and has the functions of automatic control point calibration, monitoring area grid division, image registration, data filtering and visual output, is used for digital processing and analysis of the collected speckle images, realizes high-precision and continuous monitoring of the deformation process of surrounding rock and supporting structure in the tunnel model under the conditions of non-contact and panoramic view, and outputs the three-dimensional displacement vector field containing horizontal, vertical and vertical displacement components in real time.

[0022] As a preferred mode of the present application, it further comprises an anchor rod component, which pre-sets an anchor rod model in the tunnel model system to simulate the tunnel supporting system after urban metro tunnel excavation, is used for quickly assembling the anchor rod component with preset parameters according to different supporting working condition requirements or excavation method, and realizes adjustable simulation effect; wherein the angle adjustment range of the anchor rod component is 0°-45°.

[0023] As a preferred mode of the present application, one or more visual test processes of the chamber area are executed according to the test requirements, and the image recognition module is synchronously coordinated to monitor and output data in the whole process. ​​​​​​​​​​​

[0024] The above technical solutions of the present application have the following advantages compared with the prior art:

[0025] 1. The tunnel excavation simulation system composed of transparent soil manufacturing technology and electric heating excavation simulation device can accurately simulate the whole process of tunnel excavation under the condition of "non-embedded and no disturbance".

[0026] 2. The present application can realize the simulation of different tunnel excavation methods (such as full-face method, full-face bench method, CD method, CRD method and bench method) by changing the shape of the block pouring of the fusible filler, and can also simulate the excavation of tunnels with different cross sections by changing the shape of the tunnel cross section.

[0027] 3. In the process of making the combined model box, by selecting transparent soil material with certain optical transparency, the simulation of various rock layers encountered in urban metro, including anisotropic rock layers, is realized to reconstruct the bedding characteristics in actual underground rock mass.

[0028] 4. The combined model box is composed of transparent material around, which cooperates with laser irradiation and industrial camera layout to capture the three-dimensional deformation speckle field of the tunnel and slope model in a non-embedded and panoramic manner. This transparent design maintains the integrity of the structure while having the advantages of high resolution, continuous deformation evolution and non-disturbance measurement, which helps to reveal the real mechanism of the interaction between the support system and the surrounding rock under complex working conditions, and facilitates subsequent digital displacement analysis and strain inversion.

[0029] 5. The present application also has an image recognition module, which adopts 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. The collected speckle images are digitally processed and analyzed to realize high-precision and continuous monitoring of the deformation process of surrounding rock and supporting structure in the tunnel model under non-contact and panoramic viewing conditions, and real-time output of three-dimensional displacement vector field containing horizontal, vertical and vertical displacement components.

[0030] 6. The present 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 urban metro tunnel excavation, and is used to quickly assemble anchor rod components with preset parameters according to different support working condition requirements or excavation methods, to realize non-embedded simulation of the response change of surrounding rock under different anchor rod parameter combinations (length, inclination, spacing, etc.). Combined with three-dimensional visual recognition, digital, whole-process and full-period deformation coupling analysis of anchor support effect can be carried out under non-disturbance condition to provide real and reproducible data support for tunnels. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained based on the provided drawings without creative labor.

[0032] Figure 1 is a perspective view of the test system provided by the embodiment of the present application.

[0033] Figure 2 is a front view of the test system provided by the embodiment of the present application.

[0034] Figure 3 is a top view of the test system provided by the embodiment of the present application.

[0035] Figure 4 is a schematic diagram of the full-face method excavation construction method of the test system provided by the embodiment of the present application.

[0036] Figure 5 is a first schematic diagram of the full-face bench method excavation construction method of the test system provided by the embodiment of the present application.

[0037] Figure 6 is a second schematic diagram of the full-face bench method excavation construction method of the test system provided by the embodiment of the present application.

[0038] Figure 7 is a first schematic diagram of the CD method excavation construction method of the test system provided by the embodiment of the present application.

[0039] Figure 8 is a second schematic diagram of the CD method excavation construction method of the test system provided by the embodiment of the present application.

[0040] Figure 9 is a schematic diagram of the CDR method excavation construction method of the test system provided by the embodiment of the present application.

[0041] Description of the drawings:

[0042] 10, optical platform, 11, combined model box, 12, tunnel excavation simulation device, 12, anchor rod component, 13, loading device, 14, laser instrument, 15, imaging device, 20, control unit, 111, visual filling material, 121, partition wall, 122, isolation material, 123, sealing tape, 124, tunnel model, 125, fusible filler, 141, slide rail, 142, connecting rod. DETAILED DESCRIPTION

[0043] Embodiments of the present application are described below in detail with reference to the accompanying drawings, wherein the same or similar components are denoted by the same or similar reference numerals throughout the drawings. The embodiments described below are exemplary and are intended to explain the present application, and are not to be understood as limiting the present application.

[0044] Reference Figures 1-9 As shown, in some embodiments, the present application designs a visual test system for subway tunnel mining method excavation, which at least includes an optical platform 10, a combined model box 11, a tunnel excavation simulation device 12, an anchor rod component 16, a loading device 13, a laser instrument 14, an imaging device 15 and a control unit 20; wherein:

[0045] The combined model box 11 is installed on the optical platform 10, the tunnel excavation simulation device 12 is arranged in the combined model box 11, and the model box is filled with visual filling materials 111, such as transparent soil, except for the tunnel model 124. The combined model box 11 is spliced by a plurality of transparent plates, so that the laser instrument 14 irradiates the tunnel model to generate a speckle field, and the imaging device 15 collects the speckle field of the sliding tunnel model 124. The optical platform 10 is used to ensure the stability and levelness of the model box, and provides a reference for subsequent optical measurement.

[0046] The tunnel excavation simulation device 12 is filled with a fusible filler 125 (such as paraffin wax, to simulate the soil body during excavation), which can be divided into several parts by an isolation material 122 according to the needs of the excavation method (such as CD (center diaphragm 121 method) or CRD (cross center diaphragm 121 method)), and each part is poured and filled with the fusible filler 125 to form a tunnel model 124 with a predetermined shape. When pouring the fusible filler 125, a CD method excavation tunnel chamber size mold is used for pouring. During the pouring process, an electric heating fuse is embedded in each chamber in a back-and-forth bending manner, which is used for heating to melt the fusible filler 125 to simulate the excavation process. For example, each section of the electric heating fuse can be independently connected to a small temperature control power supply unit, and the segmented timing heating and temperature closed-loop control can be realized by PLC or single-chip microcomputer, so that the filler can be melted step by step according to the construction steps, avoiding local collapse or material waste caused by simultaneous heating of the entire section. Further, a micro 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, and realize closed-loop monitoring and temperature adjustment feedback of the melting process.

[0047] Further, 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 filter type residue recovery bag and a small vacuum pump device, for quickly sucking out the liquid residue after the filler melts, preventing clogging and pollution.

[0048] The tunnel excavation simulation device 12 is completely wrapped with insulation material 122, which has good thermal insulation and plasticity, so that the internal meltable filler 125 is uniformly heated and melted, and the meltable filler 125 is isolated from the transparent soil, thereby reducing the influence of the transparent soil during the simulation excavation process. The contact part of the tunnel excavation simulation device 12 and the model box is sealed with a sealing strip 123 to prevent the transparent soil from seeping out of the gap due to loading.

[0049] 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 oval-shaped. The specific shape design only needs to change the opening of the combined model box 11 and the shape of the paraffin pouring.

[0050] The loading device 13 is installed on the combined model box 11, and 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 load applied to the tunnel model.

[0051] Before simulation 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 the loading device. 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 uniformly stressed and simulates the actual stress condition. The loading device 13 is also provided with a pressure sensor for monitoring the load applied to the tunnel model. Before simulation excavation, the pressure ratio during simulation is determined through the combined relationship of the scale ratio and the unit weight ratio between the transparent soil and the actual soil body, to better simulate the actual stress condition. Specifically as follows:

[0052] , , , , , , , , , , , represent geometry, displacement, strain, stress, elastic modulus, Poisson's ratio, unit weight, boundary stress similarity constant, respectively.

[0053] Anchorage member 16, which is pre-set in the tunnel model system to simulate the tunnel support system after the excavation of urban subway tunnels, is used to quickly assemble the anchorage component with pre-set parameters according to different support working conditions or excavation methods, and to realize adjustable simulation effect.

[0054] Specifically, the length design basis of the anchorage member 16 is: according to the actual tunnel support design, the anchorage rod needs to pass through the loose ring into the stable surrounding rock layer, and the anchoring segment of the anchorage rod needs to cover the "disturbance-stable" interface in the transparent soil simulation, which is usually selected as 1 / 2 to 2 / 3 of the cross-sectional depth of the transparent soil model; usually, the commonly used specifications of the anchorage member 16 provide 3 levels of anchorage rod length options (such as 100 mm to 600 mm), which can be adjusted by splicing and are suitable for anchoring length comparison tests under different surrounding rock grades and excavation spans.

[0055] The inclination design basis of the anchorage member 16 is: the inclination function simulation is used to simulate the arrangement modes such as "radial layout", "inclined tensile angle", and "inclined reinforcement of the working face" in actual engineering; the design inclination of the anchorage member 16 can be adjusted in the range of 0° (horizontal) to 45°, and the recommended arrangement angles include: 0° (horizontal), which is commonly used for arch foot and arch waist reinforcement; 15°~25°, which is used for inverted arch inclined support; 30°~45°, which is used for working face inclined support simulation; the inclination can be adjusted through the universal joint provided at the tail of the anchorage member 16.

[0056] The spacing design basis of the anchorage member 16 is: according to the surrounding rock grade and the tunnel excavation disturbance range, the anchorage rod arrangement scheme under different support density conditions is simulated. The spacing of the anchorage member 16 can be adjusted, which supports the arrangement in different pitches in the pre-set hole position in the tunnel model 124; the commonly used design spacing can be set as 50 mm, 100 mm, and 150 mm, which correspond to the dense, regular, and sparse arrangements in the actual engineering after the anchorage rod spacing is scaled. By adjusting the anchorage rod spacing and arrangement density, the influence of different anchoring coverage on the surrounding rock deformation control can be analyzed.

[0057] The assembly process of the anchorage member 16 is: the anchorage member 16 is quickly inserted and locked in the pre-set anchor hole position in the tunnel model 124, and the specific assembly process is as follows: pre-set anchor slot arrangement, standard anchor hole (hole diameter Φ5.25 mm, depth 50~70 mm) is reserved on the inner wall and top of the tunnel model 124, the hole position is arranged according to the construction arrangement diagram, such as pre-setting a plurality of anchor holes at typical positions such as arch foot, arch waist, and inverted arch, and the inner wall of the hole is covered with a guide sleeve to facilitate the accurate insertion of the anchorage member 16.

[0058] The anchor rod member 16 is inserted into the hole at a specified angle and then the tail is screwed into the locking ring to achieve the initial mechanical connection with the tunnel model 124.

[0059] The laser instrument 14 is installed on both sides of the combined model box 11 and used to emit laser beams to both sides of the combined model box 11 to generate a speckle field.

[0060] A slide rail 141 is arranged below the laser instrument 14 on both sides to move vertically during excavation, facilitating the direct shooting of each cross section of the model box; a connecting rod 142 is used below the slide rail 141 to connect the laser instruments 14 on both sides to keep the same horizontal and vertical positions.

[0061] The imaging device 15 is used to take speckle field images when the laser instrument 14 emits laser beams to the combined model box 11; for example, the imaging device 15 of the present application can use a CCD high-speed industrial camera to take pictures of the whole process of tunnel gradual destruction and obtain speckle field image changes of the whole period and cross section of tunnel destruction.

[0062] An image recognition module connected to the imaging device 15 is also included, which uses a GEO-PIV image processing algorithm and has the functions of automatic control point calibration, monitoring area grid division, image registration, data filtering and visual output, and is used for digital processing and analysis of collected speckle images to realize high-precision and continuous monitoring of the deformation process of surrounding rock and supporting structure in the tunnel model under non-contact and panoramic viewing conditions, and output real-time three-dimensional displacement vector field containing horizontal, vertical and vertical displacement components.

[0063] 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 to perform the visual simulation operation of the subway tunnel mining method excavation.

[0064] During the simulation excavation test, first, the loading device 13 is turned on, then the laser instruments 14 on both sides are turned on to emit laser beams to form a speckle field, and then the imaging device 15, such as a CCD industrial camera, is used to take speckle field images. Under the condition that the surrounding stress remains unchanged, the electric heating fuse is powered on to melt the fusible filler 125 to simulate the excavation process. During the excavation process, the speckle field images are repeatedly taken. After the excavation is completed, the tunnel without lining is formed, and the speckle field images are taken again.

[0065] The image recognition module is used for processing and analyzing the collected speckle field image sequence. Firstly, the image is registered and preprocessed to eliminate background interference and camera shaking during imaging and other factors. Then, the particle image velocimetry (PIV) algorithm is used to extract the pixel displacement vector field of the characteristic region of the tunnel surrounding rock and the supporting structure at different times. Combined with the spatial calibration parameters of the image, the pixel displacement is converted into the displacement value of the real physical order, and then the displacement evolution process of each monitoring point (such as the arch top, arch waist, arch foot and other typical parts) in the whole construction simulation process is obtained. The image recognition and displacement extraction process has the characteristics of non-contact, full-field, high precision and real-time updating, and can realize the three-dimensional deformation visualization monitoring and quantitative analysis of the tunnel structure and the surrounding soil in the whole period.

[0066] The visualization test system of the subway tunnel mining method excavation of the 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.

[0067] In some embodiments of the application, during the execution of the visualization test process, the melting sequence and / or shape of the fusible filler filled in the chamber region are used to simulate the corresponding excavation method required by different geologies in the actual construction process. The excavation method includes but is not limited to full-face method, full-face bench method, CD method (center diaphragm method) or CRD method (cross center diaphragm method).

[0068] The shape of each part of the paraffin can be changed to simulate the changed method required by different geologies in the actual construction process, and the excavation sequence of each part of the paraffin can also be changed to simulate the changed method required by different geologies in the actual construction process.

[0069] For example, referring to FIG. 1, the full-face excavation simulation operation process of the application is as follows: Figure 4

[0070] Overall excavation:

[0071] Paraffin overall melting and excavation face plugging: The fusible filler 125 in the full-face range is heated to 55°C as a whole for 15 min until it is completely melted, and the residual paraffin is removed to form an overall excavation space. In order to prevent disturbance of the excavation face, a transparent silicone rubber plate (thickness 2 mm) is immediately used to cover the working face area to simulate the temporary closure of the working face.

[0072] ​Initial support simulation: Immediately install transparent acrylic plates (thickness 10 mm) as "steel arches" in the excavation space, and connect them with bolts. Insert 5 mm diameter organic glass rods (length 500 mm) at the arch foot to simulate the lock foot anchor, and apply 0.5 kPa lateral pressure for fixation. Lay diagonal bracing rods (8 mm diameter organic glass rods) symmetrically on the left and right haunches, with a 45° angle with the horizontal plane, and fix the two ends between the arch and the side wall mold plate to enhance the stability of the arch.

[0073] Crown filling simulation and gap control: Reserve a 1 mm vertical movable gap at the top of the arch and the connection between the experimental box and the mold, and buffer the contact through an elastic rubber pad (thickness 2 mm) to simulate the cooperative deformation characteristics between the structure and the surrounding rock in actual construction.

[0074] Displacement monitoring start: Lay a laser emitting device 14 in the center of the tunnel section to form a speckle image projection area, and record the deformation process in the transparent soil in real time through an imaging device 15 to realize optical visual monitoring of the full-section support deformation.

[0075] Interface treatment and lining bonding: Set a 0.5 mm soft silicone layer between the resin plate and the acrylic arch to enhance the fitting effect and simulate the bonding effect between the lining and the initial support.

[0076] Secondary lining load simulation (optional): After the initial support structure has been stable for 48 h, install a transparent resin plate (thickness 5 mm) on the top of the tunnel to cover the entire arch crown to the haunch area, and apply a 1 kPa uniform load to simulate the secondary lining structure load transfer process.

[0077] For example, referring to Figure 5 and Figure 6 , the full-section bench method excavation simulation operation process of the present application is as follows:

[0078] 1. Upper bench excavation (① part)

[0079] Heat the fusible filler 125 in the upper half of the tunnel section (arch crown to 1 / 2 height of side wall) to 55°C, maintain for 10 min, so that it is fully melted and the residue is removed. After excavation is completed, use a transparent silicone plate with a thickness of 2 mm to block the excavation face, simulating the closed support of the face.

[0080] Initial support simulation: Immediately arrange transparent acrylic plates (thickness 10 mm) to simulate steel arches according to the section in the upper bench excavation space, and fix them with stainless steel bolts. Insert 5 mm diameter organic glass rods (length 500 mm) at the arch foot to simulate the lock foot anchor, and apply 0.5 kPa lateral pressure at the arch foot position for fixation to ensure the stability of the support structure.

[0081] Temporary support of the mid-parting wall 121: At the connection between the upper step and the mid-parting wall 121, a 3mm-thick elastic rubber strip (50mm wide) is pasted to simulate the contact stress transmission between the mid-parting wall 121 and the surrounding rock in the actual construction.

[0082] Auxiliary reinforcement of the haunch: Two inclined struts (8mm-diameter organic glass rods) are added on both sides of the haunch, with an angle of 45° with the horizontal plane, and are respectively connected to the arch and the test box wall to simulate the force transmission path of the haunch and improve the overall stability.

[0083] 2. Lower step excavation (② part)

[0084] Layered melting and excavation: After the upper step support is stable for 2h (simulating the soil stress adjustment period), the meltable filler 125 in the lower step part (from 1 / 2 of the side wall to below the inverted arch) is subjected to "layered and segmented" melting: the longitudinal melting range is controlled to be 300mm to avoid overall instability of the lower part. The melting parameters are the same as those of the upper step, and the molten residue is quickly removed after operation to keep the bottom flat.

[0085] Lower step support installation: Refer to the upper step process to install the lower acrylic arch, which is rigidly connected to the upper arch through L-shaped connectors to form a closed ring. Inclined struts (8mm-diameter organic glass rods) are added at the haunch position, with an angle of 45° with the horizontal plane, and are fixed at both ends to the arch and the mold side wall.

[0086] Displacement monitoring starts: A laser instrument 14 is arranged along the excavation contour line in the left area to make it directly intersect the section, create a speckle field image, and record real-time transparent soil deformation data through an imaging device 15.

[0087] Interface treatment and bonding control: A 0.5mm silicone pad is inserted between the resin plate and the acrylic arch to simulate the interface bonding and load cooperative transmission effect between the secondary lining and the primary support structure.

[0088] Inverted arch and secondary lining construction loading (optional): After excavation and primary support are completed, the structure is allowed to stand for 48h, and after the structure is stable, the simulation of the lining construction process can be selected. First, transparent resin plates (5mm thick) are pasted on the vault and side wall to simulate the secondary lining structure, and a uniform pressure of 1kPa is applied externally to simulate the load transmission of the secondary lining.

[0089] For example, referring to Figures 7-8 the operation flow of the CD method excavation simulation of the present application is as follows:

[0090] 1. Left area upper step excavation (① part)

[0091] Paraffin melting and removal: The meltable filler 125 in the left area upper step is heated to 55℃ for 10min, and a transparent silicone plate (2mm thick) is temporarily sealed to simulate the support of the working face.

[0092] Initial support simulation: Immediately install transparent acrylic plates (thickness 10 mm) as "steel arches" in the excavation space, and connect the plates with bolts. Insert organic glass rods (diameter 5 mm, length 500 mm) at the arch foot to simulate the locking foot anchor, and apply a lateral pressure of 0.5 kPa for fixation.

[0093] Temporary support of the septal wall 121: At the connection between the left upper step and the septal wall 121, paste a 3 mm thick elastic rubber strip (width 50 mm) to simulate the contact stress transmission between the septal wall 121 and the surrounding rock in actual construction.

[0094] 2. Excavation of the left lower step (part ②)

[0095] Layered melting and excavation: After the upper step support is stable for 2 h (simulating the soil stress adjustment period), melt the left lower step wax blocks in two layers. The single melting range is 300 mm along the longitudinal direction to avoid overall instability. The melting parameters are the same as in the first step. After melting, immediately remove the residue and keep the excavation surface smooth.

[0096] Lower step support installation: Install the lower acrylic arches according to the upper step process, and rigidly connect them with the upper arches through L-shaped connectors to form a closed ring. Add diagonal braces (diameter 8 mm organic glass rods) at the arch waist position, with an angle of 45° with the horizontal plane, and fix them at both ends to the arch and the mold side wall.

[0097] Displacement monitoring starts: Place the laser instrument 14 along the left excavation contour line to make it directly shoot the cross section, create a speckle field image, and record the transparent soil deformation data in real time through the imaging device 15.

[0098] 3. Excavation of the right upper step (part ③)

[0099] Stability check of the septal wall 121: Before excavation, monitor the stress difference on both sides of the septal wall 121 through the micro pressure box (range 0-10 kPa) embedded inside the transparent soil. When the stress in the left area is stable for 24 h and the difference is less than 10%, start the excavation of the right area.

[0100] Symmetrical excavation and support: Repeat the left upper step excavation process, melt the right upper step wax blocks, and install acrylic arches with symmetrical structure. Pay special attention to: Reserve a 1 mm clearance at the connection between the septal wall 121 top and the arch to simulate the cooperative deformation of the septal wall 121 and the support structure in actual construction.

[0101] 4. Excavation of the right lower step (part ④)

[0102] Step-by-step melting and support closure: Use the same layered melting process as the left lower step to excavate, and immediately close the right lower arch after excavation. At the same time, add a horizontal connecting rod (diameter 10 mm organic glass rod) between the arch feet of the left and right areas to form a spatial support system.

[0103] Middle diaphragm wall 121 removal simulation (optional): If the secondary lining stage needs to be simulated, after the left and right zone support structures are stable for 48 h, the paraffin of the middle diaphragm wall 121 is locally melted and broken, and a transparent resin plate is simultaneously installed at the top of the tunnel to simulate the secondary lining. A uniform pressure of 1 kPa is applied to simulate the lining load.

[0104] For example, referring to FIG. 1, the CDR (cross diaphragm wall method) excavation simulation operation process of the present application is as follows: Figure 9

[0105] 1. Left zone upper step excavation (① part)

[0106] Paraffin melting and removal: The left zone upper step meltable filler 125 is heated to 55°C for 10 min, and a transparent silicone plate (thickness 2 mm) is temporarily sealed on the excavation surface to simulate the working face support.

[0107] Initial support simulation: Transparent acrylic plates (thickness 10 mm) are immediately installed in the excavation space as "steel arches", the plates are connected by bolts, and organic glass rods (diameter 5 mm, length 500 mm) are inserted at the arch foot to simulate the lock foot anchor, and a lateral pressure of 0.5 kPa is applied for fixation.

[0108] Middle diaphragm wall 121 temporary support: At the connection between the left zone upper step and the middle diaphragm wall 121, a 3 mm thick elastic rubber strip (width 50 mm) is pasted to simulate the contact stress transmission between the middle diaphragm wall 121 and the surrounding rock in actual construction.

[0109] 2. Right zone lower step excavation (② part)

[0110] Step-by-step melting and support closure: After the left zone upper step support is stable for 2 h (simulating the soil stress adjustment period), the right zone lower step meltable filler 125 is melted in two layers, with a single melting range of 300 mm along the longitudinal direction to avoid overall instability. The melting parameters are the same as in the first step, and the residue is immediately removed after melting to keep the excavation surface smooth.

[0111] Lower step support installation: Refer to the upper step process to install the lower acrylic arch, which is rigidly connected to the upper arch through L-shaped connectors to form a closed ring. Inclined braces (diameter 8 mm organic glass rods) are added at the arch waist position, with an angle of 45° with the horizontal plane, and the two ends are fixed to the arch and the mold side wall to simulate the stiffness coordination of the initial structure.

[0112] Displacement monitoring starts: The laser instrument 14 is arranged to directly shoot the tunnel cross section, create a speckle field image, and perform whole-process transparent soil deformation visualization monitoring through the imaging device 15 to obtain the multi-section coordinated response process.

[0113] 3. Right zone upper step excavation (③ part) ​

[0114] Stability check of diaphragm 121: Before excavation, the stress difference between the two sides of diaphragm 121 is monitored by a micro pressure cell (range 0-10kPa) pre-embedded in the transparent soil. When the stress in the left zone is stable for 24 hours and the difference is <10%, the excavation of the right zone is started.

[0115] Symmetrical excavation and support: Repeat the excavation process of the upper step in the left area, melt down the paraffin blocks of the upper step in the right area, and install the symmetrical acrylic arch frame. Special note: Leave a 1mm gap at the connection between the top of the central diaphragm wall 121 and the arch frame to simulate the coordinated deformation of the central diaphragm wall 121 and the support structure during actual construction.

[0116] 4. Excavation of the lower bench in the left area (section ④)

[0117] Layered fusing and excavation: After the upper bench support in the right zone has stabilized for 2 hours (simulating the soil stress adjustment period), the 125 fusible filler blocks in the lower bench of the left zone are fusing in two layers. The fusing range for each layer is 300mm longitudinally to avoid overall instability. The fusing parameters are the same as in the first step. After fusing, the residue is immediately removed to keep the excavation surface flat.

[0118] Lower step support installation: Install the lower acrylic arch frame according to the upper step process, and rigidly connect it with the upper arch frame through L-shaped connectors to form a closed loop. Add diagonal braces (8mm diameter plexiglass rods) at the arch waist position, with the diagonal braces forming a 45° angle with the horizontal plane, and fix both ends to the arch frame and the side wall of the mold.

[0119] Displacement monitoring initiated: A laser instrument 14 is deployed to directly illuminate the tunnel cross section, creating a speckle field image. The entire process of transparent soil deformation is visualized and monitored through an imaging device 15 to obtain the coordinated response process of multiple sections.

[0120] Simulation of the removal of the central diaphragm 121 (optional): If it is necessary to simulate the secondary lining stage, after the support structure of the left and right zones has been stable for 48 hours, the paraffin of the central diaphragm 121 will be partially melted, and a transparent resin plate will be installed at the top of the tunnel to simulate the secondary lining. A uniform pressure of 1 kPa will be applied to simulate the lining load.

[0121] In some embodiments of this application, after the loading device 13 is activated, lasers are injected from both sides of the laser instrument 14, and an industrial camera is used to take pictures to obtain speckle images. With the surrounding stress remaining constant, an electrothermal fuse is energized to melt the fusible filler to simulate the excavation process. During excavation, speckle images are repeatedly taken. After excavation is completed, an unlined tunnel is formed, and speckle images are acquired again. The speckle images are imported into a computer, and the displacement of the tunnel arch, side arches, and arch feet is analyzed using GEO-PIV, a dedicated image analysis tool developed based on MATLAB. The above steps are repeated to measure the ultimate bearing capacity of the tunnel model and the displacement around the tunnel.

[0122] Wherein, the specific GEO-PIV operation process of the application is as follows:

[0123] 1. Establish analysis folder PIV, newly create two subfolders, one is to call folder subroutines to copy GEO-PIV program into, and one is data image folder DATE for storing speckle field image.

[0124] 2. Set file path, select the path of establishing folder to save.

[0125] 3. Direct matlab to executable folder: input geoPIV_RG_locate; pop-up window, select geopiv_RG program in subroutines folder.

[0126] 4. How to view help file: select IMAGE in data file DATE, input format of help file .

[0127] 5. Mark control point: load('cp_xy.mat') opens right CP file, input geoCENTROID_RG(CP,'Example',50,25); select initial image of tunnel speckle field, then select control point operation from top to bottom, from left to right, calibrate two points in the middle of two lines to represent maximum threshold value and minimum threshold value.

[0128] 6. Input geoMESH_RG('Example',50,50); input 0, then input 0, select initial image of tunnel speckle field, mouse select points on the image to connect into a line, and finally generate forbidden area.

[0129] 7. Area removes control point: input geoMESH_RG('Example',50,50); input 0, then input 1, input 50, then input 1, select CENTROID_CP_Example.txt to open initial image of tunnel speckle field, frame select area of about the same size as last time, mouse select points on the image to connect into a line, and finally generate forbidden area.

[0130] 8. Input geoLAUNCH_RG(101,116,1,4,'CP_Example','CP_Example','IMG_','jpg',1,1e-5,10,0.7,0.1); select file IMages, then input geoLAUNCH_RG(101,116,1,4,'Example','Example','IMG_','jpg',2,1e-5,50,0.7,0.1); select file IMages twice.

[0131] 9. Enter geoPIV_RG_run('CP_Example_analysis_launcher'); Analysis takes a while and generates an Ml_dat.mat file.

[0132] 10. Enter geoPIV_RG_run('Example_analysis_launcher'); Pop-up image frame, zoom to small deformations, high contrast texture, click enter in window, click on yellow dot on frame, click enter in control window, wait for a while and generate an M2_dat.mat file.

[0133] 11. Open the analysis file Example_analysis_launcher.txt, change 0 to 1 in line 17, 18 for correlation plot (check quality of calculation), change 0 to 1 in line 23 for displacement component plot (show displacement during analysis), click save file, enter geoPIV_RG_run('Example_analysis_launcher'); Run this analysis, wait for a while and pop-up 3 frames, each calculation is added and all plots are updated.

[0134] 12. Load M2_dat.mat file, enter X_data=data(:, :, 1); enter Y_data=data(:, :, 2); enter cc_data=data(:, :, 3); open X_dat file on the right.

[0135] 13. Load M2_dat.mat file, enter filtered_data=geoFILTER_RG(data, 0.9); pop-up folder, select tunnel speckle field initial image in Image, pop-up image frame (red crosses: correlation coefficient < threshold (< 0.9), these subsets will be removed in clean_data; blue crosses: correlation coefficient > threshold (> 0.9)), click on the two date files on the right to save to the pop-up M2_dat.mat file, click save.

[0136] 14. Load M2_dat.mat file, enter unwild_data = geoWILD_RG(data, 1, 50, 1); pop up folder, select initial image of tunnel speckle field in Image, pop up image box (zoom to area of interest click on bottom of potentially uncontrolled vectors then clear them, click on mouse right button to zoom out again to other areas of interest and check for uncontrolled vectors), select right 3 data files to save to pop up file M2_dat.mat, click save.

[0137] 15. Load M2_dat.mat file, enter XYdata = geoCALIBRATE_RG(data); pop up folder, select Ml_dat.mat file, pop up folder again select CENTROID_CP_Example open, pop up image box (output plot indicating stability of calibration standard error less than 0.5 pixels considered to be good calibration) select right 4 data files to M2_dat.mat file, click save.

[0138] 16. Load M2_dat.mat file, enter strains = geoSTRAIN_RG(XYdata); pop up grid image box (red triangles: invalid strain (ignore) elements) select right 5 data files to save to M2_dat.mat file.

[0139] 17. Load M2_dat.mat file, enter geoPLOTDISP_RG(XYdata, 1, 50, 0, 0, 1, 0, 1); pop up displacement plot of vectors, lateral displacement surface plot, longitudinal displacement surface plot, resultant displacement surface plot.

[0140] 18. Load M2_dat.mat file, enter geoPLOTSTRAIN_RG(strains, 1, 50, 0, 0, 1, 10, 0); output strain contours.

[0141] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0142] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A visual test system for a subway tunnel mine method excavation, characterized in that, include: The combined model box is mounted on the optical platform and filled with visual infill material; A tunnel excavation simulation device is sealed and installed inside the combined model box. The interface inside the tunnel excavation simulation device is divided into a preset number of chamber areas using isolation materials to form a tunnel model of a predetermined shape. Each chamber area is filled with a fusible filler and has an embedded electrothermal wire for simulating the excavation process by conducting heat through electricity. A micro negative pressure suction port is pre-embedded at the bottom or one side of the tunnel excavation simulation device, which is connected to a reusable high-temperature filter residue recovery bag and a small vacuum pump device to quickly suck out the fluid residue after the filler melts, preventing blockage and contamination. A loading device is installed on the combined model box. The loading device includes a stress loading unit and a pressure sensor. The stress loading unit is used to apply load to the tunnel excavation simulation device to simulate the original stress around the tunnel. The pressure sensor is used to monitor the magnitude of the load applied to the tunnel model. A laser device, which is installed on both sides of the combined model box, is used to emit laser beams to both sides of the combined model box to generate a speckle field; An imaging device is used to capture a speckle field image when the laser emits a laser beam toward the combined model box; The image recognition and interpretation module is used to extract features and analyze displacement of the acquired speckle field images in order to realize the 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; Anchor bolt components, which are pre-set anchor bolt models within a tunnel model system to simulate the tunnel support system after excavation of an urban subway tunnel, are used to quickly assemble anchor bolt assemblies with preset parameters according to different support conditions or excavation methods, achieving an adjustable simulation effect; wherein the angle adjustment range of the anchor bolt components is 0°~45°; wherein the anchoring section of the anchor bolt components needs to cover the disturbance-stability interface in the model, and the spacing of the anchor bolt components is adjustable; During the visualization test, the excavation methods corresponding to different geological requirements in the actual construction process are simulated according to the melting sequence and / or shape of the fusible filler filling the cavern area. The methods include, but are not limited to, the full-section method, the step method, the central diaphragm method, and the cross central diaphragm method. The simulation switching is achieved by adjusting the zoning layout and melting sequence of the visible, fusible filler and the electrothermal fuse.

2. A visual test system for a metro tunnel mine method excavation according to claim 1, characterized in that, During the visualization test, the tunnel excavation method was simulated, and the left upper step, left lower step, right upper step and right lower step were sequentially melted. Laser displacement monitoring and image acquisition were integrated throughout the process to realize the simulation test of tunnel excavation.

3. The visualization test system for subway tunnel mining excavation according to claim 2, characterized in that, During the visualization test, the bench excavation method on the entire cross section was simulated. The staged observation test of excavation disturbance and support response was achieved by prioritizing the excavation and support of the upper bench, delaying the release of the lower bench, and synchronously closing the support.

4. The visualization test system for subway tunnel mining excavation according to claim 3, characterized in that, During the visualization test, the cross-diaphragm excavation method was simulated, and the cross-sectional steps of the left upper step, right lower step, right upper step and left lower step were sequentially completed. Laser displacement monitoring and image acquisition were integrated throughout the process to realize the simulation test of tunnel excavation.

5. The visualization test system for subway tunnel mining excavation according to claim 4, characterized in that, In the process of creating the modular model box, transparent soil material was used to simulate various rock layers encountered by urban subways, including anisotropic rock layers.

6. The visualization test system for subway tunnel mining excavation according to claim 5, characterized in that, Before conducting the visualization test, the pressure ratio during the simulated excavation test was determined by calculating the composite relationship between the scale ratio and the unit weight ratio between the visualized filling material and the actual soil, as follows: , , , ,in , , , , , , , These represent geometric, displacement, strain, stress, elastic modulus, Poisson's ratio, unit weight, and boundary stress similarity constants, respectively.

7. A visual experimental system for mining excavation of subway tunnels according to claim 1 or 6, characterized in that, It also includes an image recognition module connected to the imaging device. The image recognition module adopts the GEO-PIV image processing algorithm and has functions such as automatic control point calibration, monitoring area grid division, image registration, data filtering and visualization output. It is used to digitally process and analyze the acquired 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 and panoramic view conditions, and output a three-dimensional displacement vector field containing lateral, longitudinal and vertical displacement components in real time.

8. A visual experimental system for mining excavation of subway tunnels according to any one of claims 1 to 7, characterized in that, Perform visualization tests on one or more cavern areas according to test requirements, and simultaneously coordinate the image recognition module to monitor the entire process and output data.

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