Test device and method for face failure mode of shield tunnel in water-rich complex strata

Abstract

The present invention discloses a test device and method for the failure mode of the face of a shield tunnel in water-rich and complex strata. The test device for the failure mode of the face of a shield tunnel in water-rich and complex strata includes a model group unit, an upper loading unit and a shield drive unit. In the present invention, the instability of the active and passive failures of the tunnel face is fully and truly simulated, and the groundwater seepage action path is detected by using a fluorescent agent tracing method, and the soil changes during the shield tunnel in water-rich and complex strata are intuitively and clearly displayed. Not only is the test operation simple and easy to implement, but it is also convenient for studying construction-related mechanisms, enriching the theoretical research on the three-dimensional failure mode of the face of the shield tunnel in water-rich and complex strata and the evaluation of the face soil pressure, providing a more comprehensive, intuitive, real and reliable scientific basis for the efficient and safe construction of urban subways.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnels, and in particular to a device and method for testing the face failure mode of a shield tunnel in water-rich and complex strata. Background Art

[0002] With the rapid development of urban subway construction in my country and the continuous accumulation of experience in shield tunnel construction, shield technology has been continuously strengthened, and the use of composite shield machines for shield construction has been increasingly applied in soft upper and hard lower strata. Compared with uniform strata, shield tunneling in "unevenly soft and hard" strata is generally more difficult. Taking the sand layer-argillaceous siltstone composite stratum as an example, when constructing a shield tunnel in this stratum, the coarse-grained soil in the upper part requires a larger face support pressure to meet the stability requirements, while the argillaceous siltstone in the lower part has a high self-stabilizing ability and requires a small face support pressure. If it encounters a large pressure, it is easy to cause the cutter head to wear, the slag to lose water at high temperature, and the formation of mud cakes.

[0003] In the prior art, the research on face instability is mostly limited to the stability analysis of shield tunnel faces in homogeneous strata. However, in actual engineering, tunnel shields will inevitably pass through complex strata, and the failure mode of the face needs to be further clarified. In the three-dimensional failure mode testing device and method for cross-river and sea shield tunnel face soil, which is proposed in the publication number CN 113432997 A, although the influence mechanism of the stratum under seepage conditions on the deformation and earth pressure of the shield tunnel face has been tested and evaluated, the evaluation system is not comprehensive and intuitive. It lacks consideration of multi-layer variable factors for complex strata and construction environment, and it is difficult to directly and clearly show the changes in the soil inside the stratum as the test progresses. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a more comprehensive and intuitive device and method for testing the face failure mode of a shield tunnel in water-rich and complex strata.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: a shield tunnel face failure mode test device in water-rich complex strata, comprising a model group unit, an upper loading unit and a shield driving unit;

[0006] The model group unit includes a test box model and a tunnel model. The test box model is composed of a plurality of transparent glass plates tightly connected to form an uncapped box structure with a rectangular cross section. The lower and upper parts of the test box model are filled with muddy siltstone layers and gravel sand layers in sequence. A semicircular excavation entrance is opened on one side of the test box model and close to the back. The tunnel model is a semi-enclosed arc-shaped arch plate structure with a semicircular cross section. The tunnel model is placed in the test box model and is located at the boundary between the gravel sand layer and the muddy siltstone layer. The side end of the tunnel model is welded and connected to the excavation entrance, and the open end of the tunnel model contacts the transparent glass plate on the back.

[0007] The upper loading unit includes a horizontal loading beam, an earth pressure jack and a concrete pressure layer, the concrete pressure layer is pressed on the top of the gravel sand layer, a plurality of water injection holes for injecting a test liquid containing a colored fluorescent agent are evenly opened on the concrete pressure layer, and the earth pressure jack is fixed to the bottom of the horizontal loading beam and pressed against the concrete pressure layer;

[0008] The shield driving unit is erected on one side of the test box model where the excavation entrance is provided, and is pushed into the tunnel model through the excavation entrance.

[0009] Furthermore, the upper loading unit also includes a linear guide column, which has multiple linear guide columns and stands at the four corners of the test box model respectively. The horizontal loading beam is located above the test box model. The horizontal loading beam is slidably assembled with the linear guide column. There are multiple earth pressure jacks, which are evenly fixed at the bottom of the horizontal loading beam in an array structure.

[0010] Furthermore, the transparent glass plates are made of organic anti-corrosion material, and angle steel edging is fixed at the joint positions of two adjacent transparent glass plates. A sealing plate that matches the excavation entrance is detachably installed on the side transparent glass plates. The tunnel model is made of stainless steel, and the opening of the tunnel model faces the back of the test box model, and the arch of the tunnel model faces the front of the test box model. The cross-sectional length of the tunnel model is smaller than the cross-sectional length of the test box model.

[0011] Furthermore, the shield drive unit includes a reaction frame, a horizontal jack, a support frame, a jacking rod and an excavation baffle. The reaction frame is erected on the side end of the test box model and maintained on the same horizontal line as the tunnel model. There are multiple horizontal jacks, which are laterally fixed between the reaction frame and the support frame. The jacking rod is laterally fixed on the support frame, and the top is inserted into the top support groove of the excavation baffle. The excavation baffle can be pushed into the tunnel model through the excavation entrance.

[0012] Furthermore, the excavation baffle is a transparent plexiglass plate with a semicircular cross-section, a sealing rubber ring is arranged around the outer circle of the excavation baffle, a waterproof sealing layer is fixedly attached to the inner wall surface of the tunnel model, and the excavation baffle is slidably matched with the tunnel model.

[0013] Furthermore, the model group unit also includes an injection pipe and a slag improvement layer, the slag improvement layer is preset at a position close to the excavation entrance in the tunnel model, the excavation baffle pushes the slag improvement layer inward along the tunnel model, and the gravel sand layer and mud siltstone layer in the tunnel model are shield excavated forward, the cross-section of the slag improvement layer is consistent with the cross-section size of the excavation baffle, and a plurality of water permeable holes are evenly distributed along the outer arc edge of the excavation baffle, and the injection pipe is inserted into the slag improvement layer through any of the water permeable holes for injecting soil improver into the slag improvement layer.

[0014] Furthermore, it also includes a wireless data acquisition unit, which includes a displacement sensor, an earth pressure sensor and a pore water pressure sensor. There are multiple displacement sensors, earth pressure sensors and pore water pressure sensors, which are respectively buried in the gravel sand layer and the mud siltstone layer at intervals.

[0015] Furthermore, the wireless acquisition unit also includes an earth pressure box, which is installed in a mounting groove located on the front side of the excavation baffle, and the displacement sensor, the earth pressure sensor or the pore water pressure sensor is not provided in the tunnel model.

[0016] Furthermore, it also includes a testing unit, which includes a camera module, an ultraviolet module, a floodlight and a computer. The camera module and the ultraviolet module are installed side by side on the back of the test box model, and both face the test box model and the soil layer in the tunnel model. The floodlight is installed behind the camera module and the ultraviolet module and faces the test box model. The camera module and the ultraviolet module are respectively connected to the computer via data transmission lines, and the wireless acquisition unit is wirelessly connected to the computer.

[0017] The test method for the failure mode of the shield tunnel face in water-rich complex strata includes the following steps:

[0018] S1: Arrange the model group unit: the soil sample in the test box model is divided according to different proportions of the soil layer of the tunnel model excavation surface, the lower part is filled with the muddy siltstone layer, the upper part is filled with the gravel sand layer, and the slag improvement layer is pre-filled inside the tunnel model and close to the excavation entrance. At the same time, a plurality of displacement sensors, earth pressure sensors and pore water pressure sensors wirelessly connected to the computer are pre-buried in the gravel sand layer and the muddy siltstone layer around the tunnel model, and the sensors on the same section are kept spaced apart;

[0019] S2: Arrange the upper loading unit, shield driving unit and test unit in sequence on the top, side and back of the test box model according to the requirements of the above test device;

[0020] S3: starting the horizontal jack, driving the excavation baffle to be pushed from the excavation entrance into the tunnel model via the jacking rod, simulating shield excavation in the tunnel model, and changing the jacking force by adjustment. Meanwhile, during the excavation process, the soil improver is added into the slag improvement layer through the injection pipe;

[0021] S4: starting the electric linear guide module on the linear guide column, driving the horizontal loading beam to press down the earth pressure jack, and the earth pressure jack simultaneously pushes down the concrete pressure layer, simulating applying pressure to the soil in the test box model or unloading pressure, and changing the load pressure of the soil by adjustment;

[0022] S5: injecting the test liquid containing the colored fluorescent agent from the water injection hole into the soil in the test box model, and irradiating the soil with the ultraviolet module. At the same time, the camera module starts shooting and recording from the moment the excavation baffle is pushed into the tunnel module, automatically photographing the soil damage mode in the test box model and the tunnel module, and the flow direction of the test liquid containing the colored fluorescent agent, and uploading the video data to the computer for PIV image analysis. On the one hand, the active damage degree of the tunnel model face caused by the shield drive unit and the passive damage degree of the upper loading unit are observed and detected. On the other hand, the content of the fluorescent agent at different positions in the soil is observed and detected to determine the seepage direction and flow rate of the test liquid.

[0023] S6: As the upper loading unit performs downward pressure operation and the shield driving unit performs excavation operation, the displacement sensor, earth pressure sensor, pore water pressure sensor and earth pressure box respectively collect and transmit the measured test data to the computer in real time, and the computer performs simulation comparison and analysis processing in combination with the video data to obtain a displacement-load curve variation law diagram of the tunnel model face, and judge the ultimate support force of the face;

[0024] S7: When the excavation baffle is excavated to the preset position in the tunnel model, the upper loading unit and the shield drive unit are stopped, the layout in the test box model is reset, and the above SS is repeated to obtain accurate and reliable test results, truly and comprehensively simulating the influence of water, soil pressure and three-dimensional soil failure mode on the shield tunnel face under different construction environments.

[0025] The beneficial effects of the present invention are embodied in:

[0026] In the present invention, according to one or more factors such as different upper loading pressures, different propulsion forces, different stratum proportions, different water levels, different cover thicknesses, etc., the instability of the tunnel face due to active and passive damage is fully and truly simulated, and the groundwater seepage path is detected by using the fluorescent tracing method, so that the soil changes during shield tunneling in water-rich and complex strata are intuitively and clearly displayed. Not only is the test operation simple and easy to implement, but it is also convenient for studying construction-related mechanisms, enriching the theoretical research on the three-dimensional failure mode of the face soil of the shield tunnel in water-rich and complex strata and evaluating the face soil pressure, providing a more comprehensive, intuitive, real and reliable scientific basis for the efficient and safe construction of urban subways. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a front view of the overall structure of a test device according to an embodiment of the present invention.

[0028] Figure 2 It is a rear perspective view of a shield driving unit pushed into a model group unit according to an embodiment of the present invention.

[0029] Figure 3 It is a side perspective view of a model assembly unit and a test unit according to an embodiment of the present invention.

[0030] Figure 4 It is a front view of a tunneling baffle according to an embodiment of the present invention.

[0031] The components in the attached figure are marked as follows: 1. Model group unit; 2. Upper loading unit; 3. Shield drive unit; 4. Wireless acquisition unit; 5. Test unit; 6. Test box model; 601. Angle steel edging; 602. Transparent glass plate; 603. Excavation entrance; 604. Sealing plate; 7. Tunnel model; 701. Waterproof sealing layer; 8. Injection pipe; 9. Gravel sand layer; 10. Mud siltstone layer; 11. Slag improvement layer; 12. Linear guide column; 13. Horizontal loading beam; 14. Earth pressure jack Top; 15, concrete pressure layer; 1501, water injection hole; 1502, steel bar; 16, reaction frame; 17, horizontal jack; 18, support frame; 19, jacking rod; 20, excavation baffle; 2001, installation groove; 2002, top support groove; 2003, water permeable hole; 2004, sealing rubber ring; 21, displacement sensor; 22, earth pressure sensor; 23, pore water pressure sensor; 24, earth pressure box; 25, camera module; 26, ultraviolet module; 27, floodlight; 28, computer. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly; the components, equipment and modules involved in the present invention are all prior art and can be obtained through purchase.

[0033] See also Figure 1-Figure 4 .

[0034] The present invention provides a shield tunnel face failure mode test device in water-rich complex strata, comprising a model group unit 1, an upper loading unit 2 and a shield driving unit 3;

[0035] The model group unit 1 includes a test box model 6 and a tunnel model 7. The test box model 6 is composed of a plurality of transparent glass plates 602 closely connected and assembled to form an uncapped box structure with a rectangular cross section. The lower and upper parts of the test box model 6 are filled with muddy siltstone layers 10 and gravel sand layers 9 in sequence. A semicircular excavation entrance 603 is opened on one side of the test box model 6 and close to the back. The tunnel model 7 is a semi-enclosed arc-shaped arch plate structure with a semicircular cross section. The tunnel model 7 is placed in the test box model 6 and is located at the boundary between the gravel sand layer 9 and the muddy siltstone layer 10. The side end of the tunnel model 7 is welded and connected to the excavation entrance 603, and the open end of the tunnel model 7 contacts the transparent glass plate 602 on the back.

[0036] The upper loading unit 2 includes a horizontal loading beam 13, an earth pressure jack 14 and a concrete pressure layer 15. The concrete pressure layer 15 is pressed on the top of the gravel sand layer 9. A plurality of water injection holes 1501 for injecting a test liquid containing a colored fluorescent agent are evenly opened on the concrete pressure layer 15. The earth pressure jack 14 is fixed at the bottom of the horizontal loading beam 13 and pressed against the concrete pressure layer 15.

[0037] The shield driving unit 3 is installed on one side of the test box model 6 where the excavation entrance 603 is provided, and is pushed into the tunnel model 7 through the excavation entrance 603 .

[0038] In the present invention, according to one or more factors such as different upper loading pressures, different propulsion forces, different stratum proportions, different water levels, different cover thicknesses, etc., the instability of the tunnel face due to active and passive damage is fully and truly simulated, and the groundwater seepage path is detected by using the fluorescent tracing method, so that the soil changes during shield tunneling in water-rich and complex strata are intuitively and clearly displayed. Not only is the test operation simple and easy to implement, but it is also convenient for studying construction-related mechanisms, enriching the theoretical research on the three-dimensional failure mode of the face soil of the shield tunnel in water-rich and complex strata and evaluating the face soil pressure, providing a more comprehensive, intuitive, real and reliable scientific basis for the efficient and safe construction of urban subways.

[0039] In one embodiment, the upper loading unit 2 further includes a linear guide column 12, and the linear guide column 12 has multiple columns, which stand at the four corners of the test box model 6 respectively. The horizontal loading beam 13 is located above the test box model 6, and the horizontal loading beam 13 is slidably assembled with the linear guide column 12. The earth pressure jack 14 has multiple columns, which are evenly fixed at the bottom of the horizontal loading beam 13 in an array structure. In this design, the electric linear guide module on the linear guide column 12 is started to drive the horizontal loading beam 13 to press down the earth pressure jack 14, and the earth pressure jack 14 simultaneously pushes down the concrete pressure layer 15, simulating the application of pressure or unloading pressure to the soil in the test box model 6, and changing the load pressure of the soil by adjustment, so as to realize the application of multi-level loads to the soil in the test box model 6, and truly simulate the road surface load in the actual construction process.

[0040] In one embodiment, a plurality of steel bars 1502 are evenly spaced and penetrated inside the concrete compression layer 15. Such a design helps to improve the overall structural hardness and strength of the concrete compression layer 15 and prevent it from being crushed.

[0041] In one embodiment, the transparent glass plate 602 is made of organic anticorrosive material, and angle steel edging 601 is fixed at the joint position of two adjacent transparent glass plates 602. A sealing plate 604 matching the excavation entrance 603 is detachably installed on the side transparent glass plate 602. The tunnel model 7 is made of stainless steel. The opening of the tunnel model 7 faces the back of the test box model 6, and the arch of the tunnel model 7 faces the front of the test box model 6. The cross-sectional length of the tunnel model 7 is less than the cross-sectional length of the test box model 6. With this design, the angle steel edging 601 can enhance the structural strength of the test box model 6. During the test, the test personnel can directly and clearly observe the changes in the soil in the test box model 6 and the tunnel model 7 as the shield excavation operation is carried out through the transparent glass plate 602. At the beginning of the test, the sealing plate 604 can be removed. Conversely, after the test is completed, the sealing plate 604 can be installed.

[0042] In one embodiment, the shield driving unit 3 includes a reaction frame 16, a horizontal jack 17, a support frame 18, a jacking rod 19 and an excavation baffle 20. The reaction frame 16 stands on the side end of the test box model 6 and is kept on the same horizontal line as the tunnel model 7. There are multiple horizontal jacks 17, which are transversely fixed between the reaction frame 16 and the support frame 18. The jacking rod 19 is transversely fixed on the support frame 18 and the top is inserted into the jacking groove 2002 of the excavation baffle 20. The excavation baffle 20 can pass through the excavation entrance 603 and be pushed into the tunnel model 7. In this design, the horizontal jack 17 is started, and the excavation baffle 20 is driven to be pushed from the excavation entrance 603 to the tunnel model 7 via the jacking rod 19, simulating the shield excavation in the tunnel model 7, and the jacking force is changed by adjustment, so as to realize the active destruction of the tunnel model 7 face by the shield driving unit 3.

[0043] In one embodiment, the excavation baffle 20 is a transparent organic glass plate with a semicircular cross section, a sealing rubber ring 2004 is arranged around the outer ring of the excavation baffle 20, a waterproof sealing layer 701 is fixedly attached to the inner wall surface of the tunnel model 7, and the excavation baffle 20 is slidably matched with the tunnel model 7. With this design, during the test, the excavation baffle 20 will not block the test personnel's line of sight of the inside of the tunnel model 7, and the sealing rubber ring 2004 is used in conjunction with the waterproof sealing layer 701 to effectively prevent the leakage of slag from the edge during the test.

[0044] In one embodiment, the model group unit 1 further includes an injection pipe 8 and a slag improvement layer 11, the slag improvement layer 11 is preset at a position near the excavation entrance 603 in the tunnel model 7, the excavation baffle 20 pushes the slag improvement layer 11 inward along the tunnel model 7, and the gravel sand layer 9 and the mud siltstone layer 10 in the tunnel model 7 are shield excavated forward, the cross section of the slag improvement layer 11 is consistent with the cross section of the excavation baffle 20, and a plurality of water holes 2003 are evenly spaced along the outer arc edge of the excavation baffle 20, and the injection pipe 8 is inserted into the slag improvement layer 11 through any of the water holes 2003, and is used to inject soil improver into the slag improvement layer 11. In this design, the soil improver is added to the slag improvement layer 11 through the injection pipe 8 during the excavation process, and the pressure is transmitted through the slag improvement layer 11, and the soil improver is used to improve the fluidity and plasticity of the soil and the stability of the excavation surface.

[0045] In one embodiment, a wireless acquisition unit 4 is also included, and the wireless acquisition unit 4 includes a displacement sensor 21, an earth pressure sensor 22 and a pore water pressure sensor 23. There are multiple displacement sensors 21, earth pressure sensors 22 and pore water pressure sensors 23, which are respectively buried in the gravel sand layer 9 and the mud siltstone layer 10 at intervals. In this design, as the upper loading unit 2 performs the downward pressure operation and the shield driving unit 3 performs the excavation operation, the displacement sensor 21, earth pressure sensor 22 and pore water pressure sensor 23 respectively collect and transmit the measured test data to the computer 28 in real time. The computer 28 obtains the instability of the active and passive destruction of the tunnel face under the influence of one or more factors such as different upper loading pressures, different propulsion forces, different stratum proportions, different water levels, and different cover thicknesses through simulation comparison and analysis.

[0046] In one embodiment, the wireless acquisition unit 4 further includes an earth pressure box 24, which is installed in the installation slot 2001 located on the front of the tunneling baffle 20, and the displacement sensor 21, the earth pressure sensor 22, or the pore water pressure sensor 23 are not provided in the tunnel model 7. With this design, the earth pressure box 24 collects and transmits the earth pressure borne by the tunneling baffle 20 in real time to the computer 28 in a timely manner, obtains the displacement-load curve change law diagram of the tunnel face of the tunnel model 7, and determines the ultimate support force of the tunnel face.

[0047] In one embodiment, a test unit 5 is also included, and the test unit 5 includes a camera module 25, an ultraviolet module 26, a floodlight 27 and a computer 28. The camera module 25 and the ultraviolet module 26 are arranged side by side on the back of the test box model 6, and both face the test box model 6 and the soil layer in the tunnel model 7. The floodlight 27 is arranged behind the camera module 25 and the ultraviolet module 26 and faces the test box model 6. The camera module 25 and the ultraviolet module 26 are respectively connected to the computer 28 via data transmission lines, and the wireless acquisition unit 4 is wirelessly connected to the computer 28. In this design, the test liquid containing colored fluorescent agent is injected into the soil in the test box model 6 from the water injection hole 1501, and the soil is irradiated by the ultraviolet module 26. At the same time, the camera module 25 starts shooting and recording from the time when the excavation baffle 20 is pushed into the tunnel module 7, and automatically shoots the soil damage mode in the test box model 6 and the tunnel module 7, and the flow direction of the test liquid containing colored fluorescent agent, and uploads the video data to the computer 28 for PIV image analysis. On the one hand, the active damage degree of the tunnel model 7 face caused by the shield drive unit 3 and the passive damage degree of the upper loading unit 2 are observed and detected. On the other hand, the content of fluorescent agent in different positions of the soil is observed and detected to determine the seepage direction and flow rate of the test liquid. If the image result is too rough, the position and lighting angle of the floodlight 27 are adjusted, and the test is repeated until a clear and ideal analysis result is obtained.

[0048] The test method for the failure mode of the shield tunnel face in water-rich complex strata includes the following steps:

[0049] S1: Arrange the model group unit 1: The soil sample in the test box model 6 is divided according to different proportions of the soil layer of the excavation surface of the tunnel model 7, the lower part is filled with the muddy siltstone layer 10, the upper part is filled with the gravel sand layer 9, and the slag improvement layer 11 is pre-filled inside the tunnel model 7 and close to the excavation entrance 603. At the same time, a plurality of displacement sensors 21, earth pressure sensors 22 and pore water pressure sensors 23, which are all wirelessly connected to the computer 28, are pre-buried in the gravel sand layer 9 and the muddy siltstone layer 10 around the tunnel model 7, and the sensors on the same section are kept spaced apart;

[0050] S2: Arrange the upper loading unit 2, the shield driving unit 3 and the test unit 5 in sequence on the upper side, the side and the back side of the test box model 6 according to the requirements of the above test device;

[0051] S3: starting the horizontal jack 17, driving the excavation baffle 20 to be pushed from the excavation entrance 603 into the tunnel model 7 via the jacking rod 19, simulating shield excavation in the tunnel model 7, and changing the jacking force by adjustment. Meanwhile, during the excavation process, the soil improver is added into the slag improvement layer 11 through the injection pipe 8;

[0052] S4: Start the electric linear guide module on the linear guide column 12, drive the horizontal loading beam 13 to press down the earth pressure jack 14, and the earth pressure jack 14 pushes down the concrete pressure layer 15 synchronously, simulating applying pressure or unloading pressure to the soil in the test box model 6, and changing the load pressure of the soil by adjustment;

[0053] S5: inject the test liquid containing the colored fluorescent agent from the water injection hole 1501 into the soil in the test box model 6, and use the ultraviolet module 26 to irradiate the soil. At the same time, the camera module 25 starts shooting and recording from the time when the excavation baffle 20 is pushed into the tunnel module 7, and automatically shoots the soil damage mode in the test box model 6 and the tunnel module 7, and the flow direction of the test liquid containing the colored fluorescent agent, and uploads the video data to the computer 28 for PIV image analysis. On the one hand, observe and detect the active damage degree of the tunnel model 7 face caused by the shield drive unit 3 and the passive damage degree of the upper loading unit 2. On the other hand, observe and detect the content of the fluorescent agent at different positions in the soil to determine the seepage direction and flow rate of the test liquid;

[0054] S6: As the upper loading unit 2 performs downward pressure operation and the shield driving unit 3 performs excavation operation, the displacement sensor 21, the earth pressure sensor 22, the pore water pressure sensor 23 and the earth pressure box 24 respectively collect and transmit the measured test data to the computer 28 in real time. The computer 28 performs simulation comparison and analysis processing in combination with the video data to obtain the displacement-load curve variation law diagram of the tunnel face of the tunnel model 7 and judge the ultimate support force of the tunnel face.

[0055] S7: When the excavation baffle 20 is excavated to the preset position in the tunnel model 7, the upper loading unit 2 and the shield drive unit 3 are stopped, the layout in the test box model 6 is reset, and the above S1-S6 are repeated to obtain accurate and reliable test results, truly and comprehensively simulating the influence of water, soil pressure and three-dimensional soil failure mode on the shield tunnel face under different construction environments.

[0056] It should be understood that the examples and implementation modes described herein are for illustrative purposes only and are not intended to limit the present invention. Those skilled in the art may make various modifications or changes based on the examples and implementation modes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The test device for the failure mode of shield tunnel face in water-rich and complex strata is characterized by: It includes a model assembly unit (1), an upper loading unit (2) and a shield driving unit (3); The model assembly unit (1) comprises a test box model (6) and a tunnel model (7). The test box model (6) is a box structure with an open top and a rectangular cross section, which is formed by closely assembling a plurality of transparent glass plates (602). The lower and upper parts of the test box model (6) are filled with muddy siltstone layers (10) and gravel sand layers (9) in sequence. A semicircular excavation entrance (603) is provided on one side of the test box model (6) and close to the back. The tunnel model (7) is a semi-enclosed arc-shaped arch plate structure with a semicircular cross section. The tunnel model (7) is placed in the test box model (6) and is located at the boundary between the gravel sand layer (9) and the muddy siltstone layer (10). The side end of the tunnel model (7) is welded to the excavation entrance (603), and the open end of the tunnel model (7) contacts the transparent glass plate (602) at the back. The upper loading unit (2) comprises a horizontal loading beam (13), an earth pressure jack (14) and a concrete pressure layer (15); the concrete pressure layer (15) is pressed on the top of the gravel sand layer (9); a plurality of water injection holes (1501) for injecting a test liquid containing a colored fluorescent agent are evenly opened on the concrete pressure layer (15); the earth pressure jack (14) is fixed to the bottom of the horizontal loading beam (13) and pressed against the concrete pressure layer (15); The shield driving unit (3) is installed on a side of the test box model (6) where the excavation entrance (603) is provided, and is pushed through the excavation entrance (603) into the tunnel model (7); The model group unit (1) also includes an injection pipe (8) and a slag improvement layer (11). The slag improvement layer (11) is preset at a position near the excavation entrance (603) in the tunnel model (7). The excavation baffle (20) pushes the slag improvement layer (11) inward along the tunnel model (7) to advance the gravel sand layer (9) and the mud siltstone layer (10) in the tunnel model (7) forward by shield excavation. The cross section of the slag improvement layer (11) is consistent with the cross section of the excavation baffle (20). A plurality of water permeable holes (2003) are evenly spaced along the outer arc edge of the excavation baffle (20). The injection pipe (8) passes through any of the water permeable holes (2003) and is inserted into the slag improvement layer (11) to inject soil improver into the slag improvement layer (11); The test unit (5) further comprises a test unit (5), the test unit (5) comprising a camera module (25), an ultraviolet module (26), a floodlight (27) and a computer (28); the camera module (25) and the ultraviolet module (26) are arranged side by side on the back of the test box model (6) and both face the soil layer in the test box model (6) and the tunnel model (7); the floodlight (27) is arranged behind the camera module (25) and the ultraviolet module (26) and faces the test box model (6); the camera module (25) and the ultraviolet module (26) are respectively connected to the computer (28) via data transmission lines; and the wireless acquisition unit (4) is wirelessly connected to the computer (28).

2. The shield tunnel face failure mode test device in water-rich complex strata according to claim 1, characterized in that: The upper loading unit (2) further comprises a linear guide column (12), wherein the linear guide column (12) comprises a plurality of columns, each of which is respectively disposed at the four corners of the test box model (6); the horizontal loading beam (13) is located above the test box model (6); the horizontal loading beam (13) is slidably assembled with the linear guide column (12); and the earth pressure jack (14) comprises a plurality of columns, each of which is evenly fixed at the bottom of the horizontal loading beam (13) in an array structure.

3. The shield tunnel face failure mode test device in water-rich complex strata according to claim 1, characterized in that: The transparent glass plates (602) are made of organic anti-corrosion material, and angle steel edging (601) is fixed at the joint position of two adjacent transparent glass plates (602). A sealing plate (604) matching the excavation entrance (603) is detachably mounted on the side of the transparent glass plates (602). The tunnel model (7) is made of stainless steel. The opening of the tunnel model (7) faces the back of the test box model (6), and the arch of the tunnel model (7) faces the front of the test box model (6). The cross-sectional length of the tunnel model (7) is smaller than the cross-sectional length of the test box model (6).

4. The test device for the failure mode of shield tunnel face in water-rich complex strata according to claim 1, characterized in that: The shield driving unit (3) comprises a reaction frame (16), a horizontal jack (17), a support frame (18), a jacking rod (19) and an excavation baffle (20). The reaction frame (16) stands on the side end of the test box model (6) and is maintained on the same horizontal line as the tunnel model (7). The horizontal jack (17) has a plurality of jacks, which are respectively transversely fixed between the reaction frame (16) and the support frame (18). The jacking rod (19) is transversely fixed on the support frame (18) and the top is inserted into the top support groove (2002) of the excavation baffle (20). The excavation baffle (20) can pass through the excavation entrance (603) and be jacked into the tunnel model (7).

5. The shield tunnel face failure mode test device in water-rich complex strata according to claim 4, characterized in that: The excavation baffle (20) is a transparent organic glass plate with a semicircular cross section. A sealing rubber ring (2004) is provided around the outer ring of the excavation baffle (20). A waterproof sealing layer (701) is fixedly attached to the inner wall surface of the tunnel model (7). The excavation baffle (20) and the tunnel model (7) are slidably matched.

6. The device for testing the failure mode of shield tunnel face in water-rich complex strata according to claim 4, characterized in that: It also comprises a wireless acquisition unit (4), the wireless acquisition unit (4) comprising a displacement sensor (21), an earth pressure sensor (22) and a pore water pressure sensor (23), wherein a plurality of the displacement sensors (21), earth pressure sensors (22) and pore water pressure sensors (23) are respectively buried in the gravel sand layer (9) and the mud siltstone layer (10) at intervals.

7. The device for testing the failure mode of shield tunnel face in water-rich complex strata according to claim 6, characterized in that: The wireless acquisition unit (4) further comprises an earth pressure box (24), wherein the earth pressure box (24) is installed in a mounting groove (2001) located on the front side of the excavation baffle (20), and the tunnel model (7) is not provided with the displacement sensor (21) or the earth pressure sensor (22) or the pore water pressure sensor (23).

8. A method for testing the failure mode of a tunnel face in a water-rich complex stratum shield tunnel, which is implemented by using a test device for the failure mode of a tunnel face in a water-rich complex stratum shield tunnel as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Arrange the model group unit (1): the soil sample in the test box model (6) is divided according to different proportions of the soil layer of the excavation surface of the tunnel model (7), the lower part is filled with the muddy siltstone layer (10), the upper part is filled with the gravel sand layer (9), and the slag improvement layer (11) is pre-filled inside the tunnel model (7) and close to the excavation entrance (603). At the same time, a plurality of displacement sensors (21), earth pressure sensors (22) and pore water pressure sensors (23) which are all wirelessly connected to the computer (28) are pre-buried in the gravel sand layer (9) and the muddy siltstone layer (10) around the tunnel model (7), and the sensors on the same section are kept spaced apart; S2: Arranging an upper loading unit (2), a shield driving unit (3) and a test unit (5) in sequence on the upper side, the side and the back of the test box model (6) in accordance with the requirements of the above-mentioned test device; S3: starting the horizontal jack (17), driving the excavation baffle (20) to be pushed from the excavation entrance (603) into the tunnel model (7) via the jacking rod (19), simulating shield excavation in the tunnel model (7), and changing the magnitude of the jacking force through adjustment. At the same time, during the excavation process, the soil improvement agent is added to the slag improvement layer (11) through the injection pipe (8); S4: starting the electric linear guide module on the linear guide column (12), driving the horizontal loading beam (13) to press down the earth pressure jack (14), and the earth pressure jack (14) simultaneously pushes down the concrete pressure layer (15), simulating applying pressure to the soil in the test box model (6) or unloading pressure, and changing the load pressure of the soil by adjusting; S5: injecting a test liquid containing a colored fluorescent agent from the water injection hole (1501) into the soil in the test box model (6), and irradiating the soil with the ultraviolet module (26). At the same time, the camera module (25) starts recording and photographing from the moment the excavation baffle (20) is pushed into the tunnel model (7). The soil damage mode in the test box model (6) and the tunnel model (7) and the flow direction of the test liquid containing a colored fluorescent agent are automatically photographed, and the video data is uploaded to the computer (28) for PIV image analysis. On the one hand, the degree of active damage to the tunnel face of the tunnel model (7) caused by the shield drive unit (3) and the degree of passive damage to the upper loading unit (2) are observed and detected. On the other hand, the content of the fluorescent agent at different positions in the soil is observed and detected to determine the seepage direction and flow rate of the test liquid. S6: As the upper loading unit (2) performs downward pressing operations and the shield driving unit (3) performs excavation operations, the displacement sensor (21), the earth pressure sensor (22), the pore water pressure sensor (23) and the earth pressure box (24) respectively collect and transmit the measured test data to the computer (28) in real time. The computer (28) performs simulation comparison and analysis processing in combination with the video data to obtain a displacement-load curve variation law diagram of the tunnel face of the tunnel model (7) and determine the ultimate support force of the tunnel face. S7: When the excavation baffle (20) is excavated to a preset position in the tunnel model (7), the upper loading unit (2) and the shield driving unit (3) are stopped, the layout in the test box model (6) is reset, and the above S1-S6 are repeated to obtain accurate and reliable test results, truly and comprehensively simulating the influence of water and soil pressure on the shield tunnel face and the three-dimensional soil failure mode under different construction environments.

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