Model test device and method for influence of static pressure construction on adjacent existing tunnel

Abstract

The present application relates to a kind of static pressure construction influence model test device and method of adjacent existing tunnel, by moving the transverse and longitudinal slide rail on propeller fixed frame propeller together with movement, can realize the pressure of pile foundation or steel sheet pile in different positions, propeller head can be adjusted to a certain constant speed under pressure, can study the influence of static pressure speed on adjacent existing tunnel, the electromagnet in the lower part of connecting device can realize the undisturbed separation of pile foundation or steel sheet pile and connecting device, test form is various, and the scope of application is extensive. Experimental data are obtained by imaging device, and the three-dimensional displacement field in soil body and the deformation of existing tunnel are obtained by processing through image processing software.The present application can reflect the stress characteristics and deformation law of existing tunnel under the action of static pressure construction such as pile foundation or steel sheet pile, and can also consider the influence of various factors such as static pressure structure size, static pressure position, static pressure speed on tunnel response, to provide scientific and accurate test data for tunnel protection.

Description

Technical Field

[0001] This invention relates to a model test device and method for the impact of static pressure construction on adjacent existing tunnels, which is suitable for studying the stress characteristics and deformation laws of existing tunnels under static pressure construction such as near-pile foundations and sheet piles. Background Technology

[0002] With the rapid development of society and the economy, subway construction is increasing. The opening of subways drives further development in the surrounding areas, and pile foundations, as a typical foundation for buildings, are widely used. Compared with hammer-driven piles, static pressure piles are widely used due to their lower noise and vibration. To reduce the impact of pile foundation construction on adjacent existing tunnels, steel sheet piles are usually driven between the tunnel and the pile foundation before pile foundation construction. Whether it's pile driving or steel sheet pile driving, the soil squeezing effect inevitably affects existing tunnels. Improper construction or inadequate control measures can easily damage existing subway tunnels. For such projects, the three-dimensional continuous medium finite element method is often used for analysis and calculation. However, finite element simulation has extremely high requirements for parameter selection and often requires model tests for verification. Since such model tests are relatively rare, in-depth research is necessary.

[0003] For the problem of soil-structure interaction, the most commonly used experimental methods include field tests, scaled-down model tests, and centrifuge model tests. Among these, field tests can reflect the true stress characteristics of soil, but they involve a large workload, are expensive, and the complex influencing factors make it difficult to analyze the underlying mechanisms of the test results.

[0004] While centrifuge model tests can realistically simulate the existence of a gravitational field and reproduce the actual stress state in engineering projects, the testing costs are also very high. Scale-down model tests, on the other hand, have more relaxed conditions and are much cheaper than the previous two types of tests, generally offering greater operability and economic benefits.

[0005] Traditional model tests cannot directly obtain the displacement field inside the soil; they can only study soil deformation on the surface or boundary. Furthermore, to obtain the internal deformation of the soil, sensors need to be embedded within the natural soil, which inevitably disturbs the soil and results in unsatisfactory measurement results. Therefore, there is an urgent need for a transparent soil test model that can directly obtain the internal displacement field of the soil. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a model test device and method for assessing the impact of static pressure construction on adjacent existing tunnels.

[0007] This model test device for the impact of static pressure construction on adjacent existing tunnels includes an optical platform, a transparent soil model box, a sliding rail device, an imaging device, a thruster, an existing tunnel model, a pile foundation model connection device, and a steel sheet pile model connection device.

[0008] The transparent soil model box is placed on an optical platform and contains transparent soil.

[0009] The slide rail device includes a thruster slide rail, a laser emitter slide rail, and a camera slide rail; the thruster slide rail includes a transverse slide rail and a longitudinal slide rail, with both ends of the transverse slide rail slidably connected to the longitudinal slide rail; the thruster is slidably connected to the transverse slide rail; the laser emitter slide rail and the camera slide rail are both fixed to the optical platform parallel to the side wall of the transparent soil model box;

[0010] The existing tunnel model is fixedly installed between the glass plates on opposite sides of the transparent soil model box; the transparent soil model box is also equipped with a pile foundation model or a steel sheet pile model; the top of the pile foundation model and the steel sheet pile model are respectively attached with lightweight circular iron sheets and lightweight strip iron sheets;

[0011] The pile foundation model connection device includes a first pusher head slot and a circular suction cup electromagnet; the sheet pile model connection device includes a second pusher head slot and a strip suction cup electromagnet.

[0012] Preferably: the optical platform is provided with a limiting slot, and the transparent soil model box is placed in the limiting slot of the optical platform; the bottom of the pusher slide rail is provided with a pusher fixing frame, and the pusher fixing frame is fixed to the optical platform by screws; both the transverse slide rail and the longitudinal slide rail are provided with scales; the imaging device includes a laser emitter and a camera; the laser emitter and the camera are slidably connected to the laser emitter slide rail and the camera slide rail, respectively; the laser emitter and the camera in the same group are located on opposite sides of the transparent soil model box; both the laser emitter and the camera are connected to a base through a telescopic rod, and the laser emitter and the camera are slidably connected to the laser emitter slide rail and the camera slide rail, respectively, through the base.

[0013] Preferably, the thruster includes a thruster body and a thruster head, wherein the first thruster head slot and the second thruster head slot are both matched with the size of the thruster head.

[0014] Preferably, the circular suction cup electromagnet and the strip suction cup electromagnet are each connected to a switch via wires. When the switch is closed, the circular suction cup electromagnet and the strip suction cup electromagnet are magnetic, and the circular suction cup electromagnet and the strip suction cup electromagnet are respectively attracted and connected to the lightweight circular iron sheet and the lightweight strip iron sheet.

[0015] Preferably, the transparent soil model box, the existing tunnel model, the pile foundation model, and the sheet pile model are all made of transparent material.

[0016] The test method for this model device of the impact of static pressure construction on adjacent existing tunnels includes the following steps:

[0017] Step 1: Place the transparent soil model box into the limiting slot of the optical platform, and set the laser emitter slide rail and camera slide rail;

[0018] Step 2: Secure the existing tunnel model between the opposite glass plates of the transparent soil model box, and then insert the transparent soil to the designed height.

[0019] Step 3: Install the thruster mounting bracket, thruster rail, and thruster on the optical platform; install the laser emitter and camera and slide and adjust them to form the initial displacement field.

[0020] Step 4: Securely connect the pile foundation model connection device to the pusher, and activate the circular suction cup electromagnet to attract the lightweight circular iron sheet.

[0021] Step 5: Adjust the longitudinal and lateral coordinates of the thruster via the thruster slide rail; start the thruster to statically press the pile foundation model into the transparent soil; after turning off the circular suction cup electromagnet, reset the thruster; use a camera to record the changes in the speckle field of the transparent soil; after the speckle field stabilizes, use a laser emitter to obtain cross-sectional images of the transparent soil at different locations;

[0022] Step 6: Obtain the three-dimensional displacement field inside the transparent soil and the deformation of the existing tunnel model.

[0023] As a preferred option, step two involves installing and securing the existing tunnel model between the glass plates on opposite sides of the transparent soil model box, pouring transparent soil into the transparent soil model box to a depth of 1-2 cm below the design height, and then using a dropper to drip the transparent soil to the design height. If there are air bubbles in the transparent soil, the bubbles should be allowed to stand for a period of time until they disappear or the air should be removed using a vacuum device.

[0024] Preferably, in step four, the pile foundation model connection device is fixedly connected to the pusher head through the first pusher head slot, the switch is closed to energize the wire, and the circular suction cup electromagnet attracts the lightweight circular iron sheet, thereby realizing the connection between the pile foundation model connection device and the pile foundation model.

[0025] Preferably, step five involves adjusting the longitudinal coordinates of the thruster by sliding the transverse slide along the longitudinal slide rail, and adjusting the transverse coordinates of the thruster by sliding the thruster along the transverse slide rail; after adjusting the thruster to the design position, starting the thruster and moving the thruster head downwards to statically press the pile foundation model into the transparent soil; de-energizing the circular suction cup electromagnet to separate the pile foundation model connection device from the pile foundation model; reversing and resetting the thruster head, and turning off the thruster; using a camera to record the changes in the speckle field of the transparent soil in real time; and after the speckle field in the transparent soil stabilizes, using a laser emitter to acquire cross-sectional images of the transparent soil at different locations.

[0026] Preferably, in steps four and five, the pile foundation model is replaced with a steel sheet pile model, and the pile foundation model connection device is replaced with a steel sheet pile model connection device to simulate and study the impact of static pressure construction of steel sheet piles on adjacent existing tunnels.

[0027] The beneficial effects of this invention are:

[0028] 1) The present invention can achieve undisturbed separation of the pile foundation model, the steel sheet pile model and the connection device by means of the suction cup electromagnet at the bottom of the pile foundation connection device and the steel sheet pile connection device, avoiding disturbance to the transparent soil during separation, minimizing test errors and making the test results more accurate.

[0029] 2) The pile foundation model in this invention can be replaced with a steel sheet pile model, the pile foundation model connection device can be replaced with a steel sheet pile model connection device, and the downward movement speed of the pusher head can be changed to simulate the influence of the static pressure speed of the pile foundation and steel sheet pile on the existing tunnel, satisfying the diversity of the test and having a wide range of applications.

[0030] 3) In this invention, the bottom optical platform of the transparent soil model box has a limiting slot, and the pusher fixing frame is fixed to the optical platform with screws, which effectively ensures the accuracy of the experiment. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure in one embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the thruster mounting bracket and upper structure in one embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of a transparent soil model box and its internal structure in one embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram showing the connection between the propeller, the pile foundation model connection device, and the pile foundation model in one embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of a pile foundation model connection device in one embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram showing the connection between the propeller, the sheet pile model connection device, and the sheet pile model in one embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram of a steel sheet pile model connection device in one embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram of a pile foundation model in one embodiment of the present invention;

[0039] Figure 9This is a schematic diagram of a steel sheet pile model in one embodiment of the present invention.

[0040] In the diagram: 1-Optical platform, 2-Transparent soil model box, 3-Thruster, 301-Thruster body, 302-Thruster head, 4-Existing tunnel model, 5-Pile foundation model, 6-Sheet pile model, 7-Pile foundation model connecting device, 701-First thruster head slot, 702-Circular suction cup electromagnet, 8-Sheet pile model connecting device, 801-Second thruster head slot, 802-Strip suction cup electromagnet, 9-Thruster slide rail, 901-Transverse slide rail, 902-Longitudinal slide rail, 10-Laser emitter slide rail, 11-Camera slide rail, 12-Laser emitter, 13-Camera, 14-Telescopic rod, 15-Base, 16-Lightweight circular iron sheet, 17-Lightweight strip iron sheet, 18-Thruster fixing frame, 19-Screw, 20-Limiting slot, 21-Transparent soil, 22-Wire, 23-Switch. Detailed Implementation

[0041] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0042] Example 1

[0043] As one example, such as Figures 1 to 9 As shown, a model test device for the impact of static pressure construction on adjacent existing tunnels is characterized by comprising a transparent soil model box 2, a sliding rail device, an imaging device, a thruster 3, an existing tunnel model 4, a pile foundation model 5, a sheet pile model 6, a pile foundation model connection device 7, and a sheet pile model connection device 8 arranged on an optical platform 1; wherein the transparent soil model box 2, the existing tunnel model 4, the pile foundation model 5, and the sheet pile model 6 are all made of transparent material.

[0044] The transparent soil model box 2 is placed in the limiting slot 20 on the optical platform 1, and the box contains transparent soil 21.

[0045] The slide rail device includes a thruster slide rail 9, a laser emitter slide rail 10, and a camera slide rail 11; the thruster slide rail 9 includes a graduated transverse slide rail 901 and a longitudinal slide rail 902, with both ends of the transverse slide rail 901 slidably connected to the longitudinal slide rail 902; the laser emitter slide rail 10 and the camera slide rail 11 are fixed on the optical platform 1 and arranged parallel to the side wall of the transparent soil model box 2; the thruster slide rail 9 is installed on the top of the thruster fixing frame 18, and the thruster fixing frame 18 is fixed on the optical platform 1 by screws 19.

[0046] The imaging device includes a laser emitter 12 and a camera 13 disposed on the outside of the transparent soil model box 2; the laser emitter 12 and camera 13 in the same group are located on opposite sides of the transparent soil model box 2; the laser emitter 12 and camera 13 are both connected to the base 15 via a telescopic rod 14, and the base 15 is slidably connected to the laser emitter slide rail 10 and the camera slide rail 11.

[0047] The thruster 3 includes a thruster body 301 and a thruster head 302, and the thruster 3 is slidably connected to the transverse slide rail 901.

[0048] The existing tunnel model 4 is securely installed between the opposite glass plates of the transparent soil model box 2;

[0049] The top of the pile foundation model 5 is covered with a layer of lightweight circular iron sheet 16, and the top of the steel sheet pile model 6 is covered with a layer of lightweight strip iron sheet 17.

[0050] The pile foundation model connection device 7 includes a first pusher head slot 701 and a circular suction cup electromagnet 702; the sheet pile model connection device 8 includes a second pusher head slot 801 and a strip suction cup electromagnet 802. Both the first pusher head slot 701 and the second pusher head slot 801 are matched to the dimensions of the pusher head 302. The circular suction cup electromagnet 702 and the strip suction cup electromagnet 802 are connected to a switch 23 via a wire 22. When the switch 23 is closed, the circular suction cup electromagnet 702 and the strip suction cup electromagnet 802 are magnetic, and they are respectively attracted and connected to the lightweight circular iron sheet 16 and the lightweight strip iron sheet 17.

[0051] Example 2

[0052] As another embodiment, the method of using the model test device for the impact of static pressure construction on adjacent existing tunnels in Embodiment 1 includes the following steps:

[0053] Step 1: Design and fabricate the transparent soil model box 2, the existing tunnel model 4, and the sheet pile model 6. The connections between the panels of the transparent soil model box 2 are sealed with glass glue, and the top is uncovered. Lightweight strip iron sheets 17 are attached to the top of the pre-designed sheet pile model 6. The burial depth of the existing tunnel model 4 and the height of the transparent soil 21 are determined according to the experimental requirements.

[0054] Clean and wipe the transparent soil model box 2 clean. Slowly pour clean water into the model box until it reaches the top edge. Check the airtightness of the transparent soil model box 2. After confirming that there is no problem, pour out the clean water and clean and wipe the transparent soil model box 2 again. Place it into the limiting slot 20 of the optical platform 1. Fix the laser emitter slide rail 10 and camera slide rail 11 to the optical platform 1 with screws. The slide rails are parallel to the four sides of the transparent soil model box 2.

[0055] Step 2: Secure the existing tunnel model 4 between the glass plates on opposite sides of the transparent soil model box 2. Slowly pour the prepared transparent soil 21 into the transparent soil model box 2 to a depth of 1-2 cm below the design height. Then, use a dropper to slowly drip the transparent soil 21 to the design height. If there are air bubbles in the transparent soil 21, let it stand for a period of time or use an air extraction device to remove the remaining air bubbles.

[0056] Step 3: Fix the thruster mounting bracket 18 at a suitable position on the optical platform 1 with screws. Then, install the thruster slide rail 9 at the top of the thruster mounting bracket 18. The two ends of the transverse slide rail 901 are slidably connected to the longitudinal slide rail 902. Finally, install the thruster 3 at the bottom of the transverse slide rail 901. The thruster 3 is slidably connected to the transverse slide rail 901.

[0057] Install laser emitter 12 and camera 13 so that the laser emitter 12 and camera 13 of the same group are located on opposite sides of the transparent soil model box 2. Adjust the telescopic rod 14 of laser emitter 12 and camera 13 to reach a suitable height. The base 15 is slidably connected to the laser emitter slide rail 10 and camera slide rail 11. Adjust the laser emitter 12 and camera 13 to a suitable position by sliding the laser emitter slide rail 10 and camera slide rail 11 as the initial displacement field.

[0058] Step 4: Secure the sheet pile model connection device 8 to the pusher head 302 via the second pusher head slot 801. Lay the wire 22 along the pusher slide rail 9. Turn on the switch 23 to activate the strip suction cup electromagnet 802 to attract the lightweight strip iron sheet 17, thereby connecting the sheet pile model connection device 8 to the sheet pile model 6.

[0059] Step 5: Slide the longitudinal slide rail 902 along the transverse slide rail 901 to adjust the longitudinal coordinate of the pusher 3, and slide the pusher 3 along the transverse slide rail 901 to adjust its transverse coordinate; after the pusher 3 is adjusted to the design position, start the pusher 3, and the pusher head 302 moves downward at a certain speed to statically press the steel sheet pile model 6 to the design depth in the transparent soil 21; disconnect the switch 23 and turn off the strip suction cup electromagnet 802 to achieve undisturbed separation between the steel sheet pile model connection device 8 and the steel sheet pile model 6; reverse the pusher head 302 to reset, and turn off the pusher 3.

[0060] During the simulated static pressure construction, the camera 13 records the changes in the speckle field of the transparent soil 21 in real time; after the speckle field in the transparent soil 21 stabilizes, the horizontal position and height of the laser emitter 12 are adjusted to obtain cross-sectional images of the transparent soil 21 at different locations.

[0061] Save the image obtained by camera 13, turn off laser emitter 12, and tidy up the experimental equipment.

[0062] The pile foundation model (5) can be replaced with the sheet pile model (6), and the pile foundation model connection device (7) can be replaced with the sheet pile model connection device (8) to simulate and study the impact of sheet pile static pressure construction on the adjacent existing tunnel.

[0063] Step 6: Use PIV technology to process the photos to obtain experimental data, and use image processing software to process the data to obtain the three-dimensional displacement field inside the transparent soil 21 and the deformation of the existing tunnel model 4.

Claims

1. A model test device for investigating the influence of static pressure construction on a nearby existing tunnel, characterized in that: The device comprises an optical platform (1), a transparent soil model box (2), a sliding rail device, an imaging device, a propeller (3), an existing tunnel model (4), a pile foundation model connecting device (7) and a steel sheet pile model connecting device (8); The transparent soil model box (2) is arranged on the optical platform (1), and the box is filled with transparent soil (21); The sliding rail device comprises a propeller sliding rail (9), a laser emitter sliding rail (10) and a camera sliding rail (11); the propeller sliding rail (9) comprises a transverse sliding rail (901) and a longitudinal sliding rail (902), and the two ends of the transverse sliding rail (901) are slidably connected with the longitudinal sliding rail (902); the propeller (3) is slidably connected with the transverse sliding rail (901); the laser emitter sliding rail (10) and the camera sliding rail (11) are both fixed on the optical platform (1) and parallel to the side wall of the transparent soil model box (2); The existing tunnel model (4) is clamped and fixed between the glass plates on the opposite sides of the transparent soil model box (2); the transparent soil model box (2) is further provided with a pile foundation model (5) or a steel sheet pile model (6); the top of the pile foundation model (5) and the steel sheet pile model (6) is respectively pasted with a light round iron sheet (16) and a light strip-shaped iron sheet (17); The pile foundation model connecting device (7) comprises a first propeller head clamping groove (701) and a circular suction disc type electromagnet (702); the steel sheet pile model connecting device (8) comprises a second propeller head clamping groove (801) and a strip-shaped suction disc type electromagnet (802); the propeller (3) comprises a propeller main body (301) and a propeller head (302), the first propeller head clamping groove (701) and the second propeller head clamping groove (801) are matched with the size of the propeller head (302); the circular suction disc type electromagnet (702) and the strip-shaped suction disc type electromagnet (802) are connected with switches (23) through wires (22) respectively, the circular suction disc type electromagnet (702) and the strip-shaped suction disc type electromagnet (802) have magnetism when the switches (23) are closed, and the circular suction disc type electromagnet (702) and the strip-shaped suction disc type electromagnet (802) are respectively adsorbed and connected with light circular iron sheets (16) and light strip-shaped iron sheets (17); a limiting clamping groove (20) is arranged on the optical platform (1), and the transparent soil model box (2) is arranged in the limiting clamping groove (20) on the optical platform (1); a propeller slide rail (9) is provided with a propeller fixing frame (18) at the bottom, and the propeller fixing frame (18) is fixed on the optical platform (1) through screws (19); scales are arranged on the transverse slide rail (901) and the longitudinal slide rail (902); the imaging device comprises a laser emitter (12) and a camera (13); the laser emitter (12) and the camera (13) are respectively connected with the laser emitter slide rail (10) and the camera slide rail (11) in a sliding mode; the laser emitter (12) and the camera (13) in the same group are located on opposite sides of the transparent soil model box (2); the laser emitter (12) and the camera (13) are connected with bases (15) through telescopic rods (14), and the laser emitter (12) and the camera (13) are respectively connected with the laser emitter slide rail (10) and the camera slide rail (11) in a sliding mode through the bases (15).

2. The model test device for the influence of static pressure construction on adjacent existing tunnels according to claim 1, characterized in that: The transparent soil model box (2), the existing tunnel model (4), the pile foundation model (5) and the steel sheet pile model (6) are all transparent materials.

3. The test method of the model test apparatus for influence of static pressure construction on a nearby existing tunnel according to any one of claims 1 to 2, characterized in that, The method comprises the following steps: Step one, place the transparent soil model box (2) into the limiting clamping groove (20) of the optical platform (1), and set the laser emitter slide rail (10) and the camera slide rail (11); Step two, install the existing tunnel model (4) between the glass plates on the opposite sides of the transparent soil model box (2), and design the height of the transparent soil (21); Step three, install the propeller fixing frame (18), the propeller slide rail (9) and the propeller (3) on the optical platform (1), install the laser emitter (12) and the camera (13) and adjust the initial displacement field by sliding; Step four, embed and fix the pile foundation model connecting device (7) with the propeller (3), and turn on the circular suction disc type electromagnet (702) to adsorb the light circular iron sheet (16); Step five, adjust the longitudinal coordinate and lateral coordinate of the pusher (3) through the pusher slide rail (9); start the pusher (3) to press the pile foundation model (5) into the transparent soil (21); reset the pusher (3) after closing the circular suction cup electromagnet (702); record the speckle field change of the transparent soil (21) by using the camera (13); after the speckle field is stable, use the laser emitter (12) to obtain the section images of the transparent soil (21) at different positions. Step six, obtain the three-dimensional displacement field inside the transparent soil (21) and the deformation of the existing tunnel model (4).

4. The test method of the model test apparatus for the influence of static pressure construction on a nearby existing tunnel according to claim 3, characterized in that: Step two is specifically to install the existing tunnel model (4) between the glass plates on the opposite side of the transparent soil model box (2), pour the transparent soil (21) into the transparent soil model box (2) to 1-2 centimeters below the design height, and then use a dropper to drop the transparent soil (21) to the design height; if there are bubbles in the transparent soil (21), wait for a period of time for the bubbles to disappear or use a vacuum device to remove the bubbles.

5. The test method of the model test apparatus for the influence of static pressure construction on a nearby existing tunnel according to claim 3, characterized in that: In step four, the pile foundation model connecting device (7) is embeddedly connected with the pusher head (302) through the first pusher head clamping groove (701), the switch (23) is closed to make the wire (22) conduct electricity, the circular suction cup electromagnet (702) adsorbs the light circular iron sheet (16), and the connection between the pile foundation model connecting device (7) and the pile foundation model (5) is realized.

6. The test method of the model test apparatus for influence of static pressure construction on adjacent existing tunnel according to claim 3, characterized in that: Step five is specifically to adjust the longitudinal coordinate of the pusher (3) by sliding the lateral slide rail (901) along the longitudinal slide rail (902), and adjust the lateral coordinate of the pusher (3) by sliding the pusher (3) along the lateral slide rail (901); after adjusting the pusher (3) to the designed position, start the pusher (3), the pusher head (302) moves downward, the pile foundation model (5) is pressed into the transparent soil (21), the circular suction cup electromagnet (702) is turned off, the pile foundation model connecting device (7) is separated from the pile foundation model (5), the pusher head (302) is reversely lifted and reset, and the pusher (3) is turned off; the speckle field change of the transparent soil (21) is recorded in real time by using the camera (13); after the speckle field in the transparent soil (21) is stable, the section images of the transparent soil (21) at different positions are obtained by using the laser emitter (12).

7. The test method of the model test apparatus for the influence of static pressure construction on a nearby existing tunnel according to claim 3, characterized in that: In steps four and five, the pile foundation model (5) is replaced by the steel sheet pile model (6), and the pile foundation model connecting device (7) is replaced by the steel sheet pile model connecting device (8), so as to simulate the influence of the steel sheet pile static pressure construction on the adjacent existing tunnel.

Images