Shield tunnel excavation model test device and test method based on transparent soft rock

Abstract

The invention belongs to the field of geotechnical engineering construction, and particularly relates to a shield tunnel excavation model test device based on transparent soft rock, which comprises a test bench, and the test bench is provided with a simulation mechanism, an industrial camera, a laser and a computer; the laser is arranged on the side of the simulation mechanism to obtain a simulated tunnel end face speckle field; the industrial camera is arranged right in front of the simulation system to shoot a speckle field in the shield excavation process, and the computer analyzes test pictures by using a geoPIV technology; the simulation mechanism is used for simulating shield tunnel excavation of transparent soft rock and comprises a model box made of acrylic transparent materials, a partition plate is detachably arranged in the model box in the vertical direction, two through holes are formed in the partition plate, shield models are arranged in the through holes, a power system is arranged on the model box, and the power system is connected with the shield models. The internal deformation of the surrounding rock is visually observed, the problem of monitoring blind areas is solved, the power system drives the shield model to move at a constant speed in a controllable mode, and the disturbance mechanism of dynamic excavation on the surrounding rock is precisely restored.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering construction, and in particular to a test device and test method for a shield tunnel excavation model based on transparent soft rock. Background Technology

[0002] With the acceleration of urbanization, shield tunneling technology plays a crucial role in geotechnical engineering construction such as underground transportation and integrated utility tunnels. This technology, with its advantages of minimal construction disturbance and high safety, has become an important construction method for traversing complex strata. However, when projects extend into high-risk strata such as deep water-rich soft rock and fault fracture zones, shield tunneling faces a series of challenges, including surrounding rock instability, abnormal cutter wear, and excessive surface settlement. Traditional numerical simulation methods, due to the simplification of the constitutive model of the soil and rock mass and the uncertainty of parameters, struggle to accurately predict the three-dimensional soil and rock response under construction disturbances; while in-situ field tests are limited by high costs and non-reproducibility, restricting the depth of mechanistic research. Against this backdrop, high-fidelity physical model tests have become the core means to reveal the dynamic interaction mechanism between the shield and the surrounding rock, but their effectiveness highly depends on innovative breakthroughs in experimental equipment.

[0003] Existing shield tunnel model test devices mostly use natural rock and soil or sand-gypsum similar materials to simulate strata, which has significant limitations. The inherent opacity of the materials makes it impossible to directly observe the deformation, crack propagation, and failure processes within the surrounding rock. Researchers can only obtain discrete data through finite displacement gauges or strain gauges, making it difficult to capture the three-dimensional dynamic laws such as the evolution of the loose soil zone ahead of the excavation face and the migration of seepage paths. In addition, traditional monitoring methods that rely on contact sensors are not only complex to deploy but also interfere with the original state of the rock and soil, and cannot achieve continuous measurement of the stress and displacement fields across the entire area.

[0004] The emergence of transparent rock mass technology offers a revolutionary solution to the aforementioned bottlenecks. This technology prepares a rock-like material with optical transparency by compounding fused silica sand with a refractive index matching with a mixture of n-dodecane and 15# white oil, and then adding an appropriate amount of nano-sized hydrophobic silica powder. Its physical and mechanical parameters can be precisely controlled through proportioning to achieve a similar simulation of the mechanical behavior of natural soft rock. Its core value lies in: combining non-contact optical measurement technologies such as digital image correlation (DIC) and particle image velocimetry (PIV) to dynamically capture the full-field displacement and strain distribution inside the surrounding rock; and directly visualizing the coupling process of seepage field, damage field, and stress field.

[0005] Based on this, the present invention proposes a shield tunnel excavation model test device based on transparent soft rock. Summary of the Invention

[0006] The present invention provides a shield tunnel excavation model test device based on transparent soft rock and a test method. This device promotes the leap of the theory of surrounding rock control of shield tunnels from empirical judgment to mechanism understanding, and provides scientific support for safe and efficient construction in complex strata.

[0007] The present invention provides the following technical solutions:

[0008] A shield tunnel excavation model test device based on transparent soft rock, including a test bench, on which a simulation mechanism, an industrial camera, a laser and a computer are provided. The laser and the industrial camera are respectively connected to the computer;

[0009] The laser is arranged on the side of the simulation mechanism to obtain the speckle field of the simulated tunnel end face;

[0010] The industrial camera is arranged directly in front of the simulation system to capture the speckle field during the shield excavation process; the computer analyzes the test pictures using the geoPIV technology;

[0011] The simulation mechanism is used to simulate the excavation of a shield tunnel in transparent soft rock. The simulation mechanism includes a model box made of acrylic transparent material. Inside the model box, a partition is detachably arranged vertically. There are 2 through holes on the partition, and a shield model is clamped in the through holes. A power system is arranged on the model box, and the power system is connected to the shield model.

[0012] Further, the model box includes a first box body and a second box body. The second box body is arranged on one side of the first box body, showing a "convex" shape distribution, and the connection between the first box body and the second box body is communicated. The partition is detachably arranged at the connection between the first box body and the second box body. <0​​​​​​​​​​Furthermore, the positioning component includes a positioning tube, the inner wall of which is threaded, and a threaded rod is threadedly connected to the positioning plate and the positioning tube. One end of the threaded rod is provided with a rubber head, and the end of the positioning tube away from the rubber head abuts against the end face of the inner tube.

[0017] The test method for shield tunnel excavation model based on transparent soft rock includes the following steps:

[0018] 1) Add appropriate amounts of pore liquid, fused silica sand and silica powder to a mixing tank and stir evenly to make transparent soft rock filler;

[0019] 2) Based on the test conditions, select partitions with corresponding distribution of two through holes, place the partitions inside the model box, install the shield model and power system on the model box, and connect the power system and shield model at the same time.

[0020] 3) The transparent soft rock filler prepared in step 1 is filled into the first box according to a certain mass based on the filler volume each time, and then compacted to the specified height to form transparent soil. The air bubbles in the transparent soil are then extracted through a vacuum chamber to make the soil transparent. This step is repeated until the thickness of the transparent soil meets the test requirements.

[0021] 4) Set up the industrial camera and laser, and connect them to the computer;

[0022] 5) Set the photo capture frequency;

[0023] 6) Before the test begins, take a set of speckle field images. Then, control the movement of the outer tube by handwheel. Take a set of speckle field images every time the outer tube moves a fixed distance. Move the outer tubes corresponding to the two through holes in the correct order according to the test conditions.

[0024] 7) The acquired speckle field images were processed using geoPIV technology to obtain the soil displacement field of the tunnel cross section;

[0025] 8) After completing one set of test conditions, the transparent soil filler is excavated, collected, and recycled. At the same time, the partition and shield model are removed and cleaned to prepare for the next set of test conditions.

[0026] In this invention, an acrylic model box and transparent soft rock material are used, combined with a laser to simulate a speckle field. The speckle field images are produced by an industrial camera, allowing for intuitive observation of the internal deformation of the surrounding rock. This solves the problem of blind spots in monitoring caused by the opacity of traditional natural rock and soil materials. The shield model is moved at a uniform speed and in a controllable manner by a power system, accurately restoring the disturbance mechanism of dynamic excavation on the surrounding rock. Attached Figure Description

[0027] Figure 1This is a three-dimensional structural schematic diagram of a shield tunnel excavation model test device based on transparent soft rock provided in an embodiment of the present invention;

[0028] Figure 2 This is a three-dimensional structural diagram of the model box in a shield tunnel excavation model test device based on transparent soft rock provided in an embodiment of the present invention;

[0029] Figure 3 (a) is a front view schematic diagram of a partition in a shield tunnel excavation model test device based on transparent soft rock provided in an embodiment of the present invention;

[0030] Figure 3 (b) is a schematic diagram of another main view of the partition in a shield tunnel excavation model test device based on transparent soft rock provided in an embodiment of the present invention;

[0031] Figure 3 (c) is a front view schematic diagram of the partition in a shield tunnel excavation model test device based on transparent soft rock provided in an embodiment of the present invention;

[0032] Figure 4 A three-dimensional structural diagram of the power system in a shield tunnel excavation model test device based on transparent soft rock, provided in an embodiment of the present invention;

[0033] Figure 5 This is a three-dimensional structural diagram of the shield model in a shield tunnel excavation model test device based on transparent soft rock, provided in an embodiment of the present invention.

[0034] Figure 6 This is a schematic diagram of the initial state of the simulation mechanism in a shield tunnel excavation model test device based on transparent soft rock, provided in an embodiment of the present invention.

[0035] Figure 7 This is a schematic diagram of the final state of the simulation mechanism in a shield tunnel excavation model test device based on transparent soft rock, provided in an embodiment of the present invention.

[0036] Figure 8 The shield tunnel excavation model test method based on transparent soft rock provided in the embodiment of the present invention first moves the outer pipe located in the lower through hole to simulate the speckle field image of the lower tunnel excavation;

[0037] Figure 9 The shield tunnel excavation model test method based on transparent soft rock provided in the embodiment of the present invention first moves the outer pipe located in the upper through hole to simulate the speckle field image of the upper tunnel excavation.

[0038] Figure label:

[0039] 1. Test bench; 2. Model box; 201. Partition plate; 20101. Through hole; 20102. Locking block; 202. First box; 203. Second box; 204. Slot; 3. Laser; 4. Industrial camera; 5. Power system; 501. Connecting arm; 502. Fixing clamp; 503. Lead screw; 504. Handwheel; 6. Shield model; 601. Outer tube; 602. Inner tube; 603. Positioning tube; 604. Threaded rod; 605. Rubber head; 7. Computer. Detailed Implementation

[0040] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0041] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection" and "installation" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, "connection" can be a direct connection or an indirect connection through an intermediate medium. "Fixed" means that the devices are connected to each other and their relative positional relationship remains unchanged after the connection. The directional terms mentioned in the embodiments of the present invention, such as "inner," "outer," "top," and "bottom," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0042] In this embodiment of the invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0043] In this embodiment of the invention, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0044] References to "an embodiment" or "some embodiments" or the like described in this specification mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of the present invention. Thus, statements such as "in one embodiment", "in some embodiments", "in some other embodiments", "in still some other embodiments", etc. that appear in different places in this specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized.

[0045] Embodiment 1:

[0046] Referring to Figures 1-7 As shown, a shield tunnel excavation model test device based on transparent soft rock includes a test bench 1. A simulation mechanism, an industrial camera 4, a laser 3, and a computer 7 are provided on the test bench 1. The laser 3 and the industrial camera 4 are respectively connected to the computer 7;

[0047] The laser 3 is arranged on the side of the simulation mechanism to obtain the speckle field of the simulated tunnel end face;

[0048] The industrial camera 4 is arranged directly in front of the simulation system to capture the speckle field during the shield excavation process. The computer 7 analyzes the test pictures using the geoPIV technology;

[0049] The simulation mechanism is used to simulate the shield tunnel excavation of transparent soft rock. The simulation mechanism includes a model box 2 made of acrylic transparent material. A partition 201 is detachably arranged in the vertical direction inside the model box 2. Two through holes 20101 are opened on the partition 201. A shield model 6 is clamped in the through holes 20101. A power system 5 is arranged on the model box 2. The power system 5 is connected to the shield model 6.

[0050] By using the model box 2 made of acrylic material and transparent soft rock material, combining with the laser 3 to simulate the speckle field, producing speckle field pictures through the industrial camera 4, the internal deformation of the surrounding rock can be observed intuitively, solving the problem of monitoring blind areas caused by the opacity of traditional natural geotechnical materials. The shield model 6 is driven by the power system 5 to move uniformly and controllably, accurately restoring the disturbance mechanism of the dynamic excavation on the surrounding rock.

[0051] The two through holes 20101 on the partition 201 are used to simulate the position of the excavated tunnel.

[0052] The model box 2 includes a first box body 202 and a second box body 203. The second box body 203 is arranged on one side of the first box body 202, showing a "convex" shape distribution, and the connection between the first box body 202 and the second box body 203 is connected and communicated. The partition 201 is detachably arranged at the connection between the first box body 202 and the second box body 203.

[0053] The first chamber 202 is the test area, and the second chamber 203 is the leakage collection area. The test area and the leakage collection area are separated by a partition 201. The partition 201 is detachable, so that different partitions 201 can be selected and replaced according to different test requirements.

[0054] A slot 204 is provided along the height direction at the connection between the first box 202 and the second box 203, and a block 20102 matching the slot 204 is provided on the side of the partition 201.

[0055] The card block 20102 slides into the card slot 204, thereby positioning the partition 201 and facilitating the replacement of the partition 201.

[0056] The power system 5 includes a connecting arm 501 and a fixing clamp 502. The fixing clamp 502 is located on the side wall of the second housing 203 away from the first housing 202. The fixing clamp 502 is provided with a threaded hole, and a lead screw 503 is provided in the threaded hole. The connecting arm 501 is located inside the second housing 203 and is sleeved on the lead screw 503 and fixedly connected to the lead screw 503. One end of the lead screw 503 is connected to the shield model 6. A handwheel 504 is provided at the end of the lead screw 503 near the fixing clamp 502.

[0057] The fixed dummy is placed on the top of the side wall of the second box 203. The screw 503 is rotated by the handwheel 504, so that the screw 503 can move left and right. The connecting arm 501 is fixedly connected to the screw 503. The connecting arm 501 is connected to the shield model 6, thereby driving the shield model 6 to move.

[0058] The shield model 6 includes a solid inner tube 602 and an outer tube 601 sleeved on the outside of the inner tube 602. The inner tube 602 and the outer tube 601 are slidably connected. One end of the inner tube 602 and the outer tube 601 abuts against the inner wall of the first box 202, and the other end passes through the through hole 20101 on the partition 201. A positioning component is provided at the end of the inner tube 602 that passes through the through hole 20101.

[0059] The outer tube 601 is connected to the connecting arm 501. The connecting arm 501 drives the outer tube 601 to move, simulating tunnel excavation. The inner tube 602 is mainly used to support and position the outer tube 601. The shield model 6 is installed in the first box 202 through the cooperation of the positioning component and the inner tube 602.

[0060] The positioning assembly includes a positioning tube 603, the inner wall of which is threaded, and a threaded rod 604 is threadedly connected to the positioning tube 603. One end of the threaded rod 604 is provided with a rubber head 605, and the end of the positioning tube 603 away from the rubber head 605 abuts against the end face of the inner tube 602.

[0061] The overall length of the shield model 6 is adjusted by rotating the threaded rod 604, thereby adjusting the support force. The rubber head 605 abuts against the inner wall of the second box 203, the screw 503 abuts against one end of the inner tube 602, and the other end of the inner tube 602 abuts against the inner wall of the first box 202. The threaded rod 604 then presses the inner tube 602 against the inner wall of the first box 202, thereby completing the installation and positioning of the shield model 6.

[0062] During the test, select partition 201 as needed. The horizontal spacing between the through holes 20101 on partition 201 is not limited to 1.5d (refer to...). Figure 3 (a)), 0.75d (reference Figure 3 (b) and 0d (refer to) Figure 3 (c) (d is the diameter of the through hole 20101). After selecting the partition 201, place the partition 201 into the model box 2. Weld or glue the outer tube 601 to the connecting arm 501. Then, put the outer tube 601 on the outside of the inner tube 602. Then, pass the outer tube 601 and the inner tube 602 through the through hole 20101, so that one end of the inner tube 602 abuts against the inner wall of the first box 202. Then, one end of the threaded rod 604 abuts against the end of the inner tube 602, while the glue head 605 abuts against the inside of the second box 203. The inner wall of the shield model 6 is installed by rotating the threaded rod 604, which presses the rubber head 605 against the inner wall of the second box 203, while the other end of the threaded rod 604 presses the inner tube 602 against the side wall of the first box 202, thus completing the installation and positioning of the shield model 6. The fixing clamp 502 is installed on the top of the side wall of the second box 203, and then the lead screw 503 is passed through the fixing clamp 502. At the same time, the connecting arm 501 is fixed to the lead screw 503. Then, filler is filled into the first box 202 for use.

[0063] Rotating the handwheel 504 drives the lead screw 503 to rotate. The lead screw is threadedly connected to the fixed clamp 502, causing the lead screw 503 to move horizontally along its length while rotating. The movement of the lead screw 503 drives the connecting arm 501 to move. The connecting arm 501 is fixed to the outer cylinder, thus driving the outer cylinder to move, thereby simulating tunnel excavation. By rotating the handwheel 504 at a constant speed, the outer tube 601 can move at a constant speed. The laser 3 is set on the side of the first housing 202 to obtain the speckle field of the cross-section formed by the appearance movement. The industrial camera 4 is set on the side of the first housing 202 away from the second housing 203. The industrial camera 4 takes pictures of the speckle field and transmits the pictures to the computer 7. The computer 7 uses geoPIV technology to analyze the experimental pictures.

[0064] Based on geoPIV technology, non-contact, full-domain continuous measurement of displacement and strain fields is achieved, avoiding interference from contact sensors on the original state of soil and rock, and significantly improving data accuracy.

[0065] Example 2:

[0066] A test method for shield tunnel excavation model based on transparent soft rock includes the following steps:

[0067] 1) Add appropriate amounts of pore liquid, fused silica sand and silica powder to a mixing tank and stir evenly to make transparent soft rock filler;

[0068] 2) Based on the test conditions, select two partition plates 201 with a horizontal spacing of 1.5d (d is the diameter of the through hole 20101) and place the partition plates 201 inside the model box 2. Install the shield model 6 and the power system 5 on the model box 2, and connect the power system 5 and the shield model 6.

[0069] 3) The transparent soft rock filler prepared in step 1 is filled into the first box 202 according to a certain mass based on the volume of each filler, and then compacted to the specified height to form transparent soil. The air bubbles in the transparent soil are then extracted through a vacuum bucket to make the soil transparent. This step is repeated until the thickness of the transparent soil meets the test requirements.

[0070] 4) Set up the industrial camera 4 and laser 3, and connect them to the computer 7;

[0071] 5) Set the photo capture frequency;

[0072] 6) Before the experiment begins, a set of speckle field images are taken. Then, the movement of the outer tube 601 is controlled by the handwheel 504. First, the handwheel 504 corresponding to the outer tube 601 located in the lower through hole 20101 is moved to simulate the change of the displacement field during the tunnel excavation. A set of speckle field images is taken every 1 cm that the outer tube 601 moves.

[0073] 7) The acquired speckle field images are processed using geoPIV technology to obtain the soil displacement field of the tunnel cross-section, such as... Figure 8 As shown;

[0074] 8) After completing one set of test conditions, the transparent soil filler is excavated, collected, and recycled. At the same time, the partition 201 and the shield model 6 are removed and cleaned to prepare for the next set of test conditions.

[0075] Repeat steps 2-5 above. In step 6, control the movement of the outer pipe 601 via handwheel 504. First, move the handwheel 504 corresponding to the outer pipe 601 located in the upper through hole 20101 to simulate the displacement field changes during upper tunnel excavation. Take a set of speckle field images every 1cm movement of the outer pipe 601. Then, in step 7, process the acquired speckle field images using geoPIV technology to obtain the soil displacement field of the tunnel cross-section, such as... Figure 9 As shown;

[0076] Transparent soft rock filler is recyclable, which greatly reduces the cost of testing. The modular partition 201 design supports quick replacement of different through hole sizes and positions to meet the needs of multiple testing scenarios.

[0077] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. In the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A shield tunnel excavation model test device based on transparent soft rock, characterized in that, It includes a test bench, on which a simulation mechanism, an industrial camera, a laser and a computer are provided. The laser and the industrial camera are respectively connected to the computer; The laser is arranged on the side of the simulation mechanism to obtain the speckle field of the simulated tunnel end face; The industrial camera is arranged directly in front of the simulation system to capture the speckle field during the shield tunneling process. The computer analyzes the test pictures using the geoPIV technology; The simulation mechanism is used to simulate the shield tunneling of transparent soft rock. The simulation mechanism includes a model box made of acrylic transparent material. A partition is detachably arranged vertically in the model box. Two through holes are opened on the partition, and a shield model is clamped in the through holes. A power system is arranged on the model box and is connected to the shield model.

2. The shield tunnel excavation model test device based on transparent soft rock according to claim 1, characterized in that, The model box includes a first box body and a second box body. The second box body is arranged on one side of the first box body, showing a "convex" shape distribution, and the connection part between the first box body and the second box body is connected and communicated. The partition is detachably arranged at the connection part between the first box body and the second box body.

3. The shield tunnel excavation model test device based on transparent soft rock according to claim 2, characterized in that, A clamping groove is opened along the height direction at the connection part between the first box body and the second box body. A clamping block matched with the clamping groove is arranged on the side surface of the partition.

4. The shield tunnel excavation model test device based on transparent soft rock according to claim 3, characterized in that, The power system includes a connecting arm and a fixing clamp. The fixing clamp is arranged on the side wall of the second box body far from the first box body. A threaded hole is arranged on the fixing clamp, and a lead screw is arranged in the threaded hole. The connecting arm is located in the second box body, sleeved on the lead screw and fixedly connected to the lead screw. One end of the lead screw is connected to the shield model, and a hand wheel is arranged at one end of the lead screw close to the fixing clamp.

5. The shield tunnel excavation model test device based on transparent soft rock according to claim 4, characterized in that, ​ 6. The shield tunnel excavation model test device based on transparent soft rock according to claim 5, characterized in that, ​ 7. A test method for a shield tunnel excavation model based on transparent soft rock as described in any one of claims 1-6, characterized in that, ​ ​ ​ ​ ​ ​ ​ 7) The acquired speckle field images were processed using geoPIV technology to obtain the soil displacement field of the tunnel cross section; 8) After completing one set of test conditions, the transparent soil filler is excavated, collected, and recycled. At the same time, the partition and shield model are removed and cleaned to prepare for the next set of test conditions.

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