Soft rock shield excavation model test device capable of adjusting water level, tunnel burial depth and inclination angle and test method thereof

Abstract

The invention belongs to the technical field of geotechnical engineering, and discloses a soft rock shield excavation model test device capable of adjusting the water level and the tunnel burial depth and dip angle and a test method thereof.The soft rock shield excavation model test device comprises a model box, a water level adjusting device, a tunnel posture adjusting device, a shield tunnel structure model and a measuring system; the tunnel posture adjusting device comprises two sliding grooves and two transparent baffles, the two sliding grooves are oppositely formed in the inner wall of the model box, and tunnel entrances and exits are formed in the transparent baffles; the shield tunnel structure model is mounted in the model box; the measuring system comprises a data acquisition instrument, a digital camera, a pore water pressure sensor, a soil pressure sensor, a displacement sensor and a stress strain gauge; and the digital camera is used for photographing the model box. The device realizes coupling effect analysis of the underground water level, the tunnel burial depth and the inclination angle, is simple in structure and convenient in test flow, and provides theoretical support for tunnel structure design in soft rock shield construction.

Description

Technical Field

[0001] This invention relates to a test device and test method for a soft rock shield tunneling model with adjustable water level, tunnel depth and inclination angle, belonging to the field of geotechnical engineering technology. Background Technology

[0002] Shield tunnels are widely used in highway and railway construction due to their advantages such as safety, efficiency, and low environmental disturbance. However, this also means that shield tunneling often faces complex geological environments. Areas with soft rock strata present geological problems such as low surrounding rock strength, softening of the surrounding rock upon contact with water, and high degrees of weathering and fragmentation. Furthermore, due to the periodic rise and fall of river water levels, the groundwater level in riverside areas experiences significant periodic fluctuations. During construction and operation, shield tunnels are prone to segment deformation and uneven settlement, which impacts project safety.

[0003] Current research on soft rock shield tunnels rarely considers the impact of periodic rises and falls in groundwater levels on soft rock strata and tunnel segments. Furthermore, due to the generally long tunnel routes and the various tunnel depths and dip angles along these routes, the coupled effects of these factors with groundwater level fluctuations have also not been fully investigated. Scaled-down physical model tests based on the principle of similarity can effectively simulate changes in groundwater level, tunnel depth, and tunnel dip angle. By considering the coupling effects between different factors through combinations of working conditions, the stress and deformation of the tunnel segments during shield tunnel construction and operation can be analyzed.

[0004] Therefore, there is an urgent need to develop a test device and test method for soft rock shield tunneling model that can adjust the water level, tunnel depth and inclination angle. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a soft rock shield tunneling model test device and its test method that allows for adjustment of water level, tunnel burial depth and inclination angle.

[0006] The technical solution provided by this invention to solve the above-mentioned technical problems is: a soft rock shield tunneling model test device with adjustable water level and tunnel burial depth and inclination angle, including a model box, a water level adjustment device, a tunnel attitude adjustment device, a shield tunnel structure model and a measurement system; The water level regulating device includes a water tank connected to the model box; the shield tunnel structure model includes a shield shell and segment models installed inside the shield shell. The tunnel attitude adjustment device includes two slides and two transparent baffles that are vertically slidably installed in the two slides. The two slides are arranged opposite each other on the inner wall of the model box, and the transparent baffles are provided with tunnel entrances and exits. The model box has two opposing square through holes; the shield tunnel structure model is installed inside the model box, with both ends passing through the tunnel entrance / exit and the square through holes and extending to the outside of the model box; the model box is filled with a soft rock-like material; The measurement system includes a data acquisition instrument, a digital camera, and a pore water pressure sensor, an earth pressure sensor, a stress strain gauge, and a displacement sensor connected to the data acquisition instrument. The pore water pressure sensor, earth pressure sensor, and stress strain gauge are all installed on the shield tunnel structure model. The displacement sensor is set inside the soft rock-like material. The digital camera takes pictures of the model box.

[0007] A further technical solution is that the segment model includes several single-ring segments and connecting bolts, and the several single-ring segments are connected by connecting bolts.

[0008] A further technical solution is that a lubricant is filled between the segment model and the outer shell of the shield.

[0009] A further technical solution is that the model box includes side wall I, side wall II, side wall III and side wall IV, inner wall V, inner wall VI and a bottom plate; the two opposite square through holes are respectively located on side wall I and side wall III, and the inner wall V and inner wall VI are each provided with a number of inner wall through holes; the inner wall V and inner wall VI are arranged opposite to each other between side wall II and side wall IV, and are parallel to side wall II and side wall IV.

[0010] A further technical solution is that reinforcing plates are provided on the outer sides of both sidewall I and sidewall III.

[0011] A further technical solution is that the inner wall V and inner wall VI are covered with permeable geotextile on the side near the inside of the box.

[0012] A further technical solution is that the slide is provided with positioning bolts for adjusting the height of the transparent baffle.

[0013] A further technical solution is that a water-stop rubber strip is provided at the connection between the shield tunnel structure model and the transparent baffle.

[0014] A further technical solution is that a connecting pipe and a connecting hose are provided between the model box and the water tank. One side of the connecting pipe is connected to the water tank through the connecting hose, and the other side is connected to the model box through the connecting hose.

[0015] A test method for a soft rock shield tunneling model includes the following steps: 1) Determine the design thickness of the soft rock similar material, the burial depth and inclination angle of the shield tunnel structural model, the design water level height, and the water level variation height; 2) Lay permeable geotextile on the inner wall V and inner wall VI near the inside of the box to prevent soft rock material from being lost through the inner wall openings; 3) Based on the embedment depth and inclination angle of the shield tunnel structure model, fix the positions of the two positioning bolts on the chute, and slide the two transparent baffles into the chute respectively, pressing them onto the two positioning bolts; install the shield tunnel structure model, and attach stress strain gauges, pore water pressure sensors, soil pressure sensors, and displacement sensors. 4) Fill the model box with soft rock similar material according to the designed thickness, place the displacement sensor in the soft rock similar material, and compact it; 5) Adjust the water level in the water tank to control the water level in the model box to the designed height; 6) After a certain period of time, record the initial readings of each sensor, then slowly pull out the outer shell of the shield body, and continue to let the model stand for the designed time. 7) Record sensor data during the extraction process and subsequent static placement process, and analyze the stress and displacement changes in the shield tunnel and soft rock strata.

[0016] The present invention has the following beneficial effects: 1. The main structure of the model box of this invention is enclosed with stainless steel plates, which has good sealing performance and durability, effectively avoiding water leakage and steel plate corrosion problems, and ensuring reliable test results. At the same time, the transparent acrylic baffle provides a clear view for observing tunnel and stratum deformation, improves the convenience of data acquisition, and helps researchers to better understand the experimental phenomena.

[0017] 2. This invention, through a water level adjustment device and a tunnel attitude adjustment device, can effectively control the groundwater level, tunnel depth, and inclination angle of the tunnel. By combining working conditions, it can study the coupling effect between different factors and analyze the stress and deformation laws of the tunnel segment structure during the construction and operation of shield tunnels. Furthermore, the device of this invention is simple, the experimental procedure is convenient, the conclusions are reliable, and it has strong applicability and repeatability. It is not only suitable for soft rock shield tunnels but also for tunnel excavation research under other geological types. Attached Figure Description

[0018] Figure 1 A model test device for soft rock tunnel excavation; Figure 2 This is a schematic diagram of the model box structure; Figure 3 This is a schematic diagram of a water level regulating device; Figure 4 This is a schematic diagram of a tunnel attitude adjustment device. Figure 5 This is a schematic diagram of a shield tunnel structure.

[0019] The diagram shows: 1-Model box; 101-Side wall through hole; 102-Side wall water valve; 103-Inner wall through hole; 104-Square through hole; 105-Reinforcing plate; 2-Water level regulating device; 201-Water tank; 2011-Water tank through hole; 2012-Water tank water valve; 202-Connecting pipe; 203-Connecting hose; 3-Tunnel attitude adjusting device; 301-Slide groove; 3011-Positioning hole; 302-Transparent baffle; 3021-Tunnel entrance and exit; 303-Positioning bolt; 4-Shield tunnel structure model; 401-Segment model; 4011-Single ring segment; 40111-Connecting hole; 4012-Connecting bolt; 402-Shield shell. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figures 1-5 As shown, the present invention provides a soft rock shield tunneling model test device with adjustable water level, tunnel burial depth and inclination angle, comprising a model box 1, a water level adjustment device 2, a tunnel attitude adjustment device 3, a shield tunnel structure model 4 and a measurement system. The shield tunnel structure model 4 is a hollow cylindrical structure with open ends; the water level regulating device 2 includes a water tank 201 connected to the model box 1; the shield tunnel structure model 4 includes a shield shell 402 and a segment model 401 installed inside the shield shell 402. The tunnel attitude adjustment device 3 includes two slides 301 and two transparent baffles 302 that are vertically slidably installed in the slides 301. The two slides 301 are arranged opposite to each other on the inner wall of the model box 1. The transparent baffles 302 are provided with tunnel entrances and exits 3021. The model box 1 has two opposing square through holes 104; the shield tunnel structure model 4 is installed inside the model box 1, with both ends passing through the tunnel entrance / exit 3021 and the square through holes 104 respectively and extending to the outside of the model box 1; the model box 1 is filled with a soft rock-like material; The measurement system includes a data acquisition instrument, a digital camera, and a pore water pressure sensor, an earth pressure sensor, a stress strain gauge, and a displacement sensor connected to the data acquisition instrument. The pore water pressure sensor, earth pressure sensor, and stress strain gauge are all installed on the shield tunnel structure model 4. The displacement sensor is set inside the soft rock-like material. The digital camera takes pictures of the model box 1.

[0022] In this embodiment, during the experiment, water tank 201 was filled with laboratory water; at the same time, the diameter and strength of the shield tunnel structure model 4 were selected based on the similarity criteria between the prototype tunnel and the model tunnel, and were installed in the model box 1. The model box 1 was filled with soft rock similar material and compacted; then the water level in the model box 1 was controlled to the design height by water tank 201, and finally the shield shell 402 was slowly pulled out; the measurement system recorded the stress and deformation state of the tunnel segments in real time through force and displacement sensors, revealing the tunnel-soil interaction mechanism.

[0023] like Figure 5 As shown, in the embodiment, the segment model 401 includes a plurality of single-ring segments 4011 and connecting bolts 4012; the single-ring segments 4011 are provided with connecting holes 40111; the connecting bolts 4012 are installed in the connecting holes 40111, and the plurality of single-ring segments 4011 are connected in series to form the segment model 401.

[0024] The shield shell 402 and connecting bolts 4012 are made of stainless steel, and their diameter and strength are selected based on the similarity criteria between the prototype tunnel and the model tunnel. Lubricant is filled between the segment model 401 and the shield shell 402.

[0025] like Figure 2 As shown, in this embodiment, the model box 1 includes sidewalls I, II, III, and IV, inner wall V, inner wall VI, and a bottom plate. Sidewalls I, II, III, and IV are sequentially connected and fixed to the bottom plate to form a box with an open top. The two opposing square through holes 104 are located on sidewalls I and III, respectively. Inner wall V and inner wall VI are each provided with several inner wall through holes 103. Inner wall V and inner wall VI are arranged opposite to sidewalls II and IV, parallel to sidewalls II and IV, and located on both sides of the shield tunnel structure model 4.

[0026] like Figure 2 As shown, in this embodiment, in order to improve the strength of the model box 1, a preferred embodiment is that the outer sides of the side walls I and III are provided with reinforcing plates 105; the reinforcing plates 105 are H-beams and are welded to the outer sides of the side walls I and III.

[0027] In this embodiment, in order to prevent soft rock-like materials from being lost through the inner wall through holes 103 on inner wall V and inner wall VI, permeable geotextile is laid on the side of inner wall V and inner wall VI near the inside of the box.

[0028] like Figure 4As shown, in this embodiment, in order to adjust the burial depth and inclination angle of the shield tunnel structure model 4, the slide 301 is provided with positioning bolts 303 for adjusting the height of the transparent baffle 302. The slide 301 is provided with a number of positioning holes 3011. The positioning bolts 303 are installed in the positioning holes 3011 at different positions, and the bottom of the transparent baffle 302 is pressed on the positioning bolts 303. This achieves the purpose of adjusting the height of the transparent baffle 302.

[0029] The chute 301 is made of angle steel and is welded to the inner sides of sidewall I and sidewall III; the transparent baffle 302 is made of transparent acrylic sheet; the positioning bolt 303 is made of high-strength stainless steel; the transparent baffle 302 can move freely in the vertical direction within the chute 301; the two ends of the shield tunnel structure model 4 pass through tunnel entrances and exits 3021 opened on the two transparent baffles 302 respectively, and their outer diameter is consistent with the diameter of the tunnel entrances and exits 3021; ​​thus, by inserting the positioning bolt 303 into different positioning holes 3011, the position of the transparent baffles 302 at both ends of the shield tunnel structure model 4 in the vertical direction can be changed, that is, the burial depth and inclination angle of the shield tunnel structure model 4 can be adjusted.

[0030] In this embodiment, to prevent water in the model box 1 from flowing out from the connection, the preferred embodiment is that a water-stop rubber strip is provided at the connection between the shield tunnel structure model 4 and the tunnel inlet / outlet 3021 of the transparent baffle 302.

[0031] like Figure 2 and Figure 3 As shown, in this embodiment, in order to form a communicating device between the water tank 201 and the model box 1, so that the water level in the model box 1 can be controlled by adjusting the water level in the water tank 201, a preferred embodiment is provided with a connecting pipe 202 and a connecting hose 203 between the model box 1 and the water tank 201. A water tank through hole 2011 is opened at the bottom of the side wall of the water tank 201, and a water tank water valve 201 is provided in the water tank through hole 2011. Two side wall through holes 101 are opened at the lower position of side wall II and side wall IV, and a side wall water valve 102 is provided in the side wall through hole 101. One side of the connecting pipe 202 is connected to the water tank water valve 201 of the water tank 201 through the connecting hose 203, and the other side is connected to the side wall water valve 102 of the model box 1 through the connecting hose 203.

[0032] The specific experimental method of the above embodiments includes the following steps: 1) Determine the design thickness of the soft rock similar material, the burial depth and inclination angle of the shield tunnel structural model 4, the design water level height, and the water level change height; 2) Lay permeable geotextile on the inner wall V and inner wall VI near the inside of the box to prevent soft rock material from being lost through the inner wall through hole 103; 3) Fix the positions of two positioning bolts 303 on the slide 301 according to the embedment depth and inclination angle of the shield tunnel structure model 4, and slide two transparent baffles 302 in the slide 301 respectively and press them on the two positioning bolts 303; install the shield tunnel structure model 4, and attach stress strain gauges, pore water pressure sensors, soil pressure sensors and displacement sensors. 4) Fill the model box 1 with soft rock similar material according to the designed thickness, place the displacement sensor in the soft rock similar material, and compact it; 5) Adjust the water level in water tank 201 to control the water level in model box 1 to the designed height; 6) After a certain period of time, record the initial readings of each sensor, then slowly pull out the outer shell 402 of the shield body, and continue to let the model stand for the designed time. 7) Record sensor data during the extraction process and subsequent static placement process, and analyze the stress and displacement changes in the shield tunnel and soft rock strata.

[0033] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall fall within the scope of the present invention.

Claims

1. A test device for soft rock shield tunneling model with adjustable water level, tunnel depth, and inclination angle, characterized in that, It includes a model box (1), a water level regulating device (2), a tunnel attitude regulating device (3), a shield tunnel structure model (4), and a measurement system; The water level regulating device (2) includes a water tank (201) connected to the model box (1); the shield tunnel structure model (4) includes a shield shell (402) and a segment model (401) installed inside the shield shell (402). The tunnel attitude adjustment device (3) includes two slides (301) and two transparent baffles (302) that are vertically slidably installed in the two slides (301). The two slides (301) are arranged opposite to each other on the inner wall of the model box (1). The transparent baffles (302) are provided with tunnel entrances and exits (3021). The model box (1) is provided with two opposite square through holes (104); the shield tunnel structure model (4) is installed in the model box (1), and its two ends pass through the tunnel entrance / exit (3021) and the square through holes (104) respectively and extend to the outside of the model box (1); the model box (1) is filled with soft rock-like material; The measurement system includes a data acquisition instrument, a digital camera, and a pore water pressure sensor, an earth pressure sensor, a stress strain gauge, and a displacement sensor connected to the data acquisition instrument. The pore water pressure sensor, earth pressure sensor, and stress strain gauge are all installed on the shield tunnel structure model (4). The displacement sensor is set inside the soft rock similar material. The digital camera takes pictures of the model box (1).

2. The soft rock shield tunneling model test device with adjustable water level and tunnel depth and inclination angle according to claim 1, characterized in that, The segment model (401) includes several single-ring segments (4011) and connecting bolts (4012), and the several single-ring segments (4011) are connected by connecting bolts (4012).

3. The soft rock shield tunneling model test device with adjustable water level and tunnel depth and inclination angle according to claim 2, characterized in that, Lubricant is filled between the segment model (401) and the shield shell (402).

4. The soft rock shield tunneling model test device with adjustable water level and tunnel depth and inclination angle according to claim 1, characterized in that, The model box (1) includes side wall I, side wall II, side wall III and side wall IV, inner wall V, inner wall VI and a bottom plate; the two opposite square through holes (104) are located on side wall I and side wall III respectively, and the inner wall V and inner wall VI are provided with a number of inner wall through holes (103); the inner wall V and inner wall VI are arranged opposite to each other between side wall II and side wall IV, and are parallel to side wall II and side wall IV.

5. The soft rock shield tunneling model test device with adjustable water level and tunnel depth and inclination angle according to claim 4, characterized in that, Both sidewalls I and III are provided with reinforcing plates (105) on their outer sides.

6. The soft rock shield tunneling model test device with adjustable water level and tunnel depth and inclination angle according to claim 4, characterized in that, The inner walls V and VI are lined with permeable geotextile on the side closest to the inside of the box.

7. The soft rock shield tunneling model test device with adjustable water level and tunnel depth and inclination angle according to claim 1, characterized in that, The slide (301) is provided with a positioning bolt (303) for adjusting the height of the transparent baffle (302).

8. The soft rock shield tunneling model test device with adjustable water level and tunnel depth and inclination angle according to claim 1, characterized in that, A water-stop rubber strip is provided at the connection between the shield tunnel structure model (4) and the transparent baffle (302).

9. The soft rock shield tunneling model test device with adjustable water level and tunnel depth and inclination angle according to claim 1, characterized in that, A connecting pipe (202) and a connecting hose (203) are provided between the model box (1) and the water tank (201). One side of the connecting pipe (202) is connected to the water tank (201) through the connecting hose (203), and the other side is connected to the model box (1) through the connecting hose (203).

10. A test method using the apparatus according to any one of claims 1-9, characterized in that, Includes the following steps: 1) Determine the design thickness of the soft rock similar material, the burial depth and inclination angle of the shield tunnel structural model (4), the design height of the water level and the height of water level change; 2) Lay permeable geotextile on the inner wall V and inner wall VI near the inside of the box; 3) Fix the positions of two positioning bolts (303) on the slide (301) according to the embedment depth and inclination angle of the shield tunnel structure model (4), and slide two transparent baffles (302) in the slide (301) respectively, and press them on the two positioning bolts (303); install the shield tunnel structure model (4), and attach stress strain gauges, pore water pressure sensors, soil pressure sensors, and displacement sensors; 4) Fill the model box (1) with soft rock similar material according to the designed thickness, place the displacement sensor in the soft rock similar material, and compact it; 5) Adjust the water level in the water tank (201) to control the water level in the model box (1) to the designed height; 6) After a certain period of time, record the initial readings of each sensor, then slowly pull out the outer shell of the shield (402), and continue to let the model stand for the designed time. 7) Record sensor data during the extraction process and subsequent static placement process, and analyze the stress and displacement changes in the shield tunnel and soft rock strata.

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