A small physical model experimental device and method for reservoir landslide with detachable sliding body

Abstract

The present invention provides a small-scale physical model experimental device and method for a detachable sliding body reservoir landslide, the device comprises a slope adjustment platform, a first box, and a second box arranged in the first box; the first box is fixedly arranged on the slope adjustment platform, and the inclination of the two boxes can be adjusted by the slope adjustment platform to simulate different reservoir foot conditions, and a water inlet is provided on one side of the first box and a rainfall component is provided on the top to simulate the reservoir water and rainfall conditions in actual working conditions; at the same time, the method of the present invention is simple and easy to implement, and more importantly, the first box and the second box in the present invention are located in the same seepage field, which can better simulate the conditions in the actual reservoir, and the second box can be separated from the first box, which reduces the amount of rock and soil filling engineering during the test, and has high repeatability. The present invention has a simple structure, and can simulate reservoir landslides under different slopes and working conditions according to the needs of the test, so as to better explore the formation mechanism of reservoir landslides.

Description

Technical Field

[0001] The invention relates to the technical field of geological disasters and prevention and control, and in particular to a small-scale physical model experimental device and method for a reservoir landslide with a detachable sliding body. Background Art

[0002] Landslide geological disasters are natural disasters. In order to reduce the losses and threats caused by them, it is particularly important to explore the formation mechanism of reservoir landslides and provide instability warnings for reservoir landslides. This can not only provide quantitative data for the prediction and risk assessment of reservoir landslides, but also artificially influence the development process of reservoir landslides through effective prevention and control projects, ultimately achieving the purpose of preventing, avoiding and reducing landslide disasters.

[0003] In the existing research on the formation mechanism of reservoir landslides, scholars mostly use methods such as landslide geological environment research, on-site multi-field monitoring, model tests and numerical simulation. Among them, the two methods of landslide geological environment investigation and research and on-site multi-field monitoring are relatively abundant, but there are relatively few model test studies on landslides. For example, using centrifuge model tests to simulate landslides, the stress state of the landslide body is good and the stress path is consistent. However, when it comes to reservoir landslides, the pore water pressure is often not dissipated in time, making the model easy to be destroyed and the test success rate is low. In addition, for on-site in-situ model tests, it has the advantages of high accuracy and consistent stress conditions, but it is often difficult to achieve due to limited site conditions, high cost, long time, and many uncontrollable safety factors. Based on this, many laboratory-sized indoor model tests have been carried out to improve the above problems. However, judging from most test results, the failure mode of the reservoir landslide accumulation body is often due to the collapse caused by long-term immersion in water, which is disconnected from the typical working condition of reservoir water circulation rise and fall. Moreover, for some reservoir slopes with typical sliding belts, indoor model tests often ignore the typical factor of sliding belt soil, and often use the overall accumulation to build the slope as a model of reservoir landslide. At the same time, large-scale model tests have the disadvantages of large rock and soil volume, inconvenient sliding belt stacking, difficult and time-consuming sensor deployment, high cost, difficult operation due to water influence, poor visibility of experimental results, etc. Moreover, after completing a set of working conditions, the overall model is greatly disturbed, and the rock and soil on the slope surface is often severely damaged and cannot be repeated, which often makes the model unable to be tested under typical working conditions, and has certain limitations.

[0004] Based on this, the present invention proposes a small-scale physical model experimental device and method for reservoir landslides with detachable sliding bodies, in order to address the problems of reservoir landslides being affected by the rise and fall of reservoir water and the defects of traditional large-scale model test devices, such as large rock and soil volume, inconvenient and non-repeatable stacking of sliding belts, difficulty and time-consuming sensor deployment, high cost, and incomplete working conditions. This is of great significance to the study of the formation mechanism of reservoir landslides. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a small-scale physical model experimental device and method for a reservoir landslide with a detachable sliding body.

[0006] An embodiment of the present invention provides a small-scale physical model experimental device for a reservoir landslide with a detachable sliding body, comprising:

[0007] A slope adjustment platform, comprising a platform body, a rotating plate and a telescopic push rod, wherein one end of the rotating plate is rotatably connected to the upper surface of the platform body, and the other end is connected to the telescopic end of the telescopic push rod;

[0008] A first box body is arranged on the upper surface of the rotating plate, the top of which is provided with a rainfall component, and the upper surface of the bottom is paved with simulated bedrock, the simulated bedrock is provided with a sliding belt, and the sliding belt is embedded with a sensor component;

[0009] And a second box body arranged in the first box body, a simulated slide body is arranged inside the second box body, the sensor assembly is buried in the simulated slide body, the second box body is placed on the slide belt and does not contact the first box body, and a plurality of seepage holes are arranged on the bottom surface and one side surface of the second box body.

[0010] Furthermore, the first box body has no cover on the top, and its length direction is consistent with the length direction of the rotating plate. The bottom of the first box body is fixedly connected to the rotating plate through a locking piece. The first box body has a water inlet at the upper end of a side away from the telescopic push rod and a drain at the lower end.

[0011] Furthermore, the second box body has no cover on the top, and its length direction is consistent with that of the first box body. A plurality of seepage holes are provided on a side surface of the second box body away from the telescopic push rod, and a mesh is provided on the inner side of the side surface.

[0012] Furthermore, a displacement sensor is provided on one side surface of the top of the second box body, a plurality of anti-slip parts are pasted on the lower surface of the bottom of the second box body, and the simulated sliding body is arranged on the upper surface of the bottom of the second box body.

[0013] Furthermore, the rainfall component is relatively located above the second box body, and the rainfall component includes a V-shaped support plate and a plurality of nozzles, wherein the V-shaped support plate is erected on the top of the first box body, and each of the nozzles is arranged on the inner side of the V-shaped support plate to simulate rainfall into the second box body.

[0014] Furthermore, the anti-slip part is pasted on the upper surface of the simulated bedrock, and the sliding belt is laid on the anti-slip part on the simulated bedrock, and the simulated bedrock is made of bricks.

[0015] Furthermore, each of the anti-slip parts is artificial gravel, the first box body and the second box body are both made of acrylic plates, and the sensor assembly includes a pore water pressure sensor and a soil pressure sensor.

[0016] Furthermore, it also includes a water pump, a monitor, a power supply, and a data acquisition analyzer, wherein the water pump is used to inject water into the first box through the water inlet, the monitor is used to record the test process, the power supply is used to supply power to the electrical equipment, and the data acquisition analyzer is respectively communicated with each of the pore water pressure sensors, each of the soil pressure sensors and the displacement sensor to obtain data.

[0017] The above-mentioned small-scale physical model experimental device of a reservoir landslide with detachable sliding body also includes a test method of a test method, which includes the following steps:

[0018] S1, placing the first box on the upper surface of the rotating plate, and then laying the simulated bedrock and the anti-slip member on the upper surface of the bottom of the first box in sequence;

[0019] S2, laying the sliding belt on the simulated bedrock and installing the corresponding sensor assembly;

[0020] S3, pasting the anti-slip part on the lower surface of the bottom of the second box, filling the simulated sliding body in the box, then burying the corresponding sensor assembly in the simulated sliding body, and then placing the second box on the sliding belt, and ensuring that the second box does not contact the first box;

[0021] S4, according to the set working condition requirements, injecting water into the first box and the second box through the water pump and the rainfall component or simulating rainfall;

[0022] S5. Collect the data of each sensor in real time through the data acquisition and analysis instrument, and observe the sliding of the second box in real time until the sliding belt is cut. The test ends here, and then take out the second box to observe the shearing condition of the sliding belt.

[0023] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention are:

[0024] First, the present invention is aimed at the indoor test of reservoir landslide model. The model size is small in scale, less rock and soil mass needs to be piled up, the operation is simple, the results are simple, the design is reasonable, and time and labor are saved;

[0025] Second, the present invention arranges the simulated sliding body in the second box so that the two form a whole. At the same time, the overall displacement can be measured by the displacement sensor, which is convenient for overall analysis. Moreover, the second box can be taken out from the first box, which is convenient for repeated tests.

[0026] Thirdly, the present invention is aimed at reservoir landslides, and has an obvious structure. The sliding belt is provided at the simulated bedrock in the second box and the first box, and sensors can be arranged in a targeted manner to study the stress and strain of the sliding belt. The second box can be taken out, and the failure surface of the sliding belt can be visually analyzed.

[0027] Fourthly, in the present invention, in terms of sensor layout, since the overall model is small and there is no large amount of rock and soil connected between the second box, the sliding belt and the simulated bedrock, the layout is convenient, thus ensuring the monitoring accuracy;

[0028] Fifth, in the present invention, a plurality of seepage holes are provided on the second box body, so as to ensure that the first box body and the second box body are located in the same seepage field during the test, thereby ensuring the accuracy of the test;

[0029] Sixth, the simulation device in the present invention is relatively small, which avoids a lot of filling and cleaning work, has adjustable slope, flexible working condition setting, high operability, and repeatable tests, thus ensuring work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of a small-scale physical model experimental device for reservoir landslide with detachable sliding body according to the present invention;

[0031] Figure 2 yes Figure 1 Structural schematic diagram of the medium slope adjustment platform;

[0032] Figure 3 yes Figure 1 A schematic diagram of the structure of the first box;

[0033] Figure 4 yes Figure 1 Schematic diagram of the structure of the middle sliding belt;

[0034] Figure 5 yes Figure 1 A schematic diagram of the structure of the second box;

[0035] Figure 6 The present invention discloses a flow chart of a test method of a small-scale physical model test device for a reservoir landslide with a detachable sliding body.

[0036] In the figure: 1-slope adjustment platform, 2-first box, 3-second box, 4-simulated bedrock, 5-slide belt, 6-water pump, 7-monitor, 8-power supply, 9-data acquisition analyzer, 10-platform, 11-support leg, 12-rotating plate, 13-telescopic push rod, 14-locking member, 15-controller, 16-water inlet, 17-drainage outlet, 18-V-type support plate, 19-sprinkler, 20-anti-slip member, 21-pore water pressure sensor, 22-soil pressure sensor, 23-simulated sliding body, 24-displacement sensor, 25-permeability hole, 26-mesh. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0038] Please refer to Figure 1 An embodiment of the present invention provides a small-scale physical model experimental device for a reservoir landslide with a detachable sliding body, which includes a slope adjustment platform 1, a first box body 2, and a second box body 3.

[0039] Please refer to Figure 2 The slope adjustment platform 1 includes a platform body 10, a rotating plate 12, and a telescopic push rod member 13, wherein the length direction of the rotating plate 12 is consistent with the length direction of the platform body 10, one end of the rotating plate 12 is rotatably connected to the upper surface of the platform body through a hinge, and the other end is connected to the telescopic end of the telescopic push rod member 13; a detachable supporting leg 11 is provided on the lower surface of the platform body 10, and the platform body 10 is placed on a horizontal plane through the supporting leg 11, and the telescopic push rod member 13 is fixedly arranged on the supporting leg 11, and the telescopic end of the telescopic push rod member 13 faces upward and is hinged to the lower surface of the rotating plate 12, so that the inclination of the rotating plate 12 can be adjusted by the telescopic push rod member 13.

[0040] It should be noted here that since the telescopic push rod is a relatively common prior art in the prior art, it will not be described in detail here; at the same time, in the present embodiment, the telescopic push rod member 13 is equipped with a controller 15, and the controller 15 is used to control the telescopic amount of the telescopic push rod member 13, so as to control the inclination of the rotating plate 12; and in the present embodiment, the maximum thrust of the telescopic push rod member 13 is 500N, and its telescopic accuracy is 0.1㎜ / s, which is mainly to more accurately control the inclination of the rotating plate 12.

[0041] Please refer to Figure 1 , Figure 3 and Figure 4The first box body 2 is arranged on the upper surface of the rotating plate 12, and the length direction of the first box body 2 is consistent with the length direction of the rotating plate 12. The first box body 2 is fixedly connected to the upper surface of the rotating plate 12 through a locking member 14, so that when the inclination of the rotating plate 12 is adjusted, the slope of the first box body 2 can be adjusted.

[0042] The first box body 2 is a box body without a top cover. In this embodiment, the first box body 2 is made of acrylic plate material, so that it is convenient to observe the situation inside the first box body 2 during the test; the first box body 2 is provided with a simulated bedrock 4 and a sliding belt 5 inside, and the simulated bedrock 4 is laid on the upper surface of the bottom of the first box body 2. In this embodiment, the simulated bedrock 4 is made of bricks with good water permeability, and a plurality of anti-slip parts 20 are evenly pasted on the upper surface of the simulated bedrock 4. The sliding belt 5 is laid on the upper surface of the simulated bedrock 4, and each of the anti-slip parts 20 on the simulated bedrock 4 is located at Between the simulated bedrock 4 and the sliding belt 5, in this embodiment, the anti-slip parts 20 on the simulated bedrock 4 are artificial gravel, and the sliding belt 5 is made of rock and soil, so that it can ensure that the lower surface of the sliding belt 5 is in non-smooth contact with the upper surface of the simulated bedrock 4, so as to better simulate the conditions of the reservoir base in actual working conditions; at the same time, a sensor assembly is buried inside the sliding belt 5. In this embodiment, the sensor assembly buried inside the sliding belt 5 includes a pore water pressure sensor 21 and a soil pressure sensor 22, which are mainly used to measure the pore water pressure and soil pressure of the sliding belt 5 during the test.

[0043] A water inlet 16 is provided at the upper end of a side surface of the first box body 2 away from the telescopic push rod member 13, and a drain outlet 17 is provided at the lower end, and control valves are provided on the water inlet 16 and the drain outlet 17; a small physical model experimental device of a detachable reservoir landslide in this embodiment also includes a water pump 6, and the water pump 6 is connected to the water inlet 16 through a conduit to inject water into the first box body 2 when the test requires, so as to simulate the water in the reservoir under actual working conditions.

[0044] A rainfall component is provided at the top of the first box body 2, and the rainfall component is used to simulate rainfall on rainy days in actual working conditions, so as to simulate the impact of rainwater on the reservoir in actual working conditions; in this embodiment, the rainfall component includes a V-shaped support plate 18 and a plurality of nozzles 19, wherein the concave surface of the V-shaped support plate 18 is inside and faces the first box body 2, and the V-shaped support plate 18 is detachably mounted on the top of the first box body 2, and each of the nozzles 19 is evenly arranged on the inner side of the V-shaped support plate 18. In this embodiment, the number of the nozzles 19 is two, and each of the nozzles 19 is connected to an external water source.

[0045] Please refer to Figure 1 and Figure 5 The second box body 3 is arranged inside the first box body 2, and the second box body 3 does not contact the first box body 2. The second box body 3 is a box body without a top cover. In this embodiment, the second box body 3 is made of an acrylic plate material, so that it is convenient to observe the situation inside the second box body 3 during the test; a plurality of the anti-slip members 20 are evenly pasted on the lower surface of the bottom of the second box body 3, as shown in the attached Figure 5 (c) The second box body 3 is placed on the upper surface of the sliding belt 5, and the anti-slip parts 20 on the second box body 3 are located between the sliding belt 5 and the second box body 3. In this embodiment, the anti-slip parts 20 on the second box body 3 are artificial gravel, so as to ensure that there is non-smooth contact between the upper surface of the sliding belt 5 and the lower surface of the bottom of the second box body 3, so as to better simulate the situation of the reservoir base in actual working conditions.

[0046] A simulated sliding body 23 is provided inside the second box body 3, and the simulated sliding body 23 is formed by layered filling of rock and soil. The sensor assembly is buried inside the simulated sliding body 23. Similarly, the sensor assembly in the simulated sliding body 23 includes the pore water pressure sensor 21 and the soil pressure sensor 22, which are mainly used to measure the pore water pressure and soil pressure of the simulated sliding body 23 during the test; in this embodiment, the simulated sliding body 23 and the second box body 3 are used to simulate the reservoir dam in actual working conditions.

[0047] In this embodiment, the length direction of the second box body 3 is consistent with the length direction of the first box body 2. A displacement sensor 24 is provided on one side surface of the top of the second box body 3. The displacement sensor 24 is used to monitor the displacement of the second box body 3 and the simulated slide 23 during the test. In this embodiment, the displacement sensor 24 is a laser displacement sensor.

[0048] A plurality of seepage holes 25 are provided on one side of the second box body 3 away from the telescopic push rod 13. Figure 5 (b) In this embodiment, the second box body 3 is provided with the seepage holes 25 on the left side, and a mesh 26 is also attached to the left side of the second box body 3, and the mesh 26 is used to prevent the sand particles formed after the simulated sliding body 23 is soaked in water from flowing out from the seepage holes 25 on the left side of the second box body 3; please refer to the attached Figure 5 (c) A plurality of seepage holes 25 are also provided on the bottom plate of the second box body 3. It should be noted that the seepage holes 25 on the second box body 3 are mainly used to make the interior of the second box body 3 and the interior of the first box body 2 in the same seepage field.

[0049] A small-scale physical model experimental device for a reservoir landslide with a detachable sliding body in this embodiment also includes a monitor 7, a power supply 8, and a data acquisition analyzer 9, wherein the monitor 7 is used to monitor the entire test process, the power supply 8 is used to power the electrical equipment in the test device, and the data acquisition analyzer 9 is respectively communicated with each of the pore water pressure sensors 21, each of the soil pressure sensors 22, and the displacement sensor to obtain the data measured by each sensor during the test in real time and display it.

[0050] The small-scale physical model experimental device of a reservoir landslide with a detachable sliding body in this embodiment also includes a test method, which includes the following steps:

[0051] S1. Place the first box 2 on the upper surface of the rotating plate 12, and then lay the simulated bedrock 4 and the anti-slip member 20 on the upper surface of the bottom of the first box 2 in sequence.

[0052] Specifically, the first box body 2 is fixedly arranged on the upper surface of the rotating plate 12 , and then the simulated bedrock 4 is laid on the bottom upper surface of the first box body 2 , and then the anti-slip member 20 is pasted on the simulated bedrock 4 .

[0053] S2. Laying the sliding belt 5 on the simulated bedrock 4 and installing the corresponding sensor components.

[0054] S3. Paste the anti-slip part 20 on the bottom lower surface of the second box body 3, fill the simulated slide 23 in the box, and then bury the corresponding sensor component in the simulated slide 23. Then, place the second box body 3 on the sliding belt 5, and ensure that the second box body 3 does not contact the first box body 2.

[0055] Specifically, the anti-slip part 20 is pasted on the lower surface of the bottom of the second box body 3, and then the simulated sliding body 23 is filled in the second box body 3 as required, with the thicker end of the simulated sliding body 23 close to the telescopic push rod 13, and the thinner end close to the left side surface where the penetration hole 25 is provided. At the same time, the corresponding sensor component is buried when filling the simulated sliding body 23. Finally, the second box body 3 is placed on the upper surface of the sliding belt 5, and then matched with the simulated bedrock 4, so that the upper and lower surfaces of the sliding belt 5 have the anti-slip part 20, and when placing the second box body 3, it is necessary to ensure that it does not contact the inner wall of the first box body 2.

[0056] S4. In accordance with the set working condition requirements, water is injected into the first box body 2 and the second box body 3 through the water pump 6 and the rainfall component or rainfall is simulated.

[0057] Specifically, the water pump 6 is turned on to inject water into the first box 2 to simulate the water body in the reservoir. While injecting water, the drain port 17 is opened to simulate the rise and fall of reservoir water in actual working conditions, and the rate of rise and fall of reservoir water in the simulation device is controlled according to the test requirements. At the same time, the rainfall component is started to simulate the impact of rainy weather on the reservoir in actual working conditions, and the rainfall is also controlled according to the test requirements.

[0058] S5. Collect the data of each sensor in real time through the data acquisition analyzer 9, and observe the sliding of the second box 3 and the simulated sliding body 23 in real time until the sliding belt 5 is cut. The test is ended here, and then take out the second box 3 to observe the shearing condition of the sliding belt 5.

[0059] In this document, the directional words such as front, back, top, and bottom are defined by the positions of the components in the drawings and the positions of the components relative to each other, and are only for the sake of clarity and convenience in expressing the technical solution. It should be understood that the use of the directional words should not limit the scope of protection claimed in this application.

[0060] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A small physical model experimental device for reservoir landslide with detachable sliding body, characterized in that: include: A slope adjustment platform, comprising a platform body, a rotating plate and a telescopic push rod, wherein one end of the rotating plate is rotatably connected to the upper surface of the platform body, and the other end is connected to the telescopic end of the telescopic push rod; A first box body is arranged on the upper surface of the rotating plate, the top of which is provided with a rainfall component, and the upper surface of the bottom is paved with simulated bedrock, the simulated bedrock is provided with a sliding belt, and the sliding belt is embedded with a sensor component; And a second box body arranged in the first box body, a simulated slide body is arranged inside the second box body, the sensor assembly is buried in the simulated slide body, the second box body is placed on the slide belt and does not contact the first box body, and a plurality of seepage holes are arranged on the bottom surface and one side surface of the second box body.

2. A small-scale physical model experimental device for reservoir landslide with detachable sliding body as claimed in claim 1, characterized in that: The first box body has no cover on the top, and its length direction is consistent with the length direction of the rotating plate. The bottom of the first box body is fixedly connected to the rotating plate through a locking piece. The first box body has a water inlet at the upper end of a side away from the telescopic push rod and a drain at the lower end.

3. A small-scale physical model experimental device for reservoir landslide with detachable sliding body as claimed in claim 1, characterized in that: The second box body has no cover on the top, and its length direction is consistent with that of the first box body. A plurality of seepage holes are arranged on a side surface of the second box body away from the telescopic push rod, and a mesh is arranged on the inner side of the side surface.

4. A small-scale physical model experimental device for reservoir landslide with detachable sliding body as claimed in claim 2, characterized in that: A displacement sensor is provided on one side surface of the top of the second box body, a plurality of anti-slip parts are pasted on the lower surface of the bottom of the second box body, and the simulated sliding body is arranged on the upper surface of the bottom of the second box body.

5. The small-scale physical model experimental device for reservoir landslide with detachable sliding body according to claim 1, characterized in that: The rainfall component is relatively located above the second box body, and includes a V-shaped support plate and a plurality of nozzles, wherein the V-shaped support plate is erected on the top of the first box body, and each nozzle is arranged on the inner side of the V-shaped support plate to simulate rainfall into the second box body.

6. A small-scale physical model experimental device for reservoir landslide with detachable sliding body as claimed in claim 4, characterized in that: The anti-slip part is pasted on the upper surface of the simulated bedrock, and the sliding belt is laid on the anti-slip part on the simulated bedrock. The simulated bedrock is made of bricks.

7. A small-scale physical model experimental device for reservoir landslide with detachable sliding body as claimed in claim 4, characterized in that: Each of the anti-slip parts is artificial gravel, the first box body and the second box body are both made of acrylic plates, and the sensor assembly includes a pore water pressure sensor and a soil pressure sensor.

8. A small-scale physical model experimental device for reservoir landslide with detachable sliding body as claimed in claim 7, characterized in that: It also includes a water pump, a monitor, a power supply, and a data acquisition analyzer, wherein the water pump is used to inject water into the first box through the water inlet, the monitor is used to record the test process, the power supply is used to supply power to the electrical equipment, and the data acquisition analyzer is respectively communicated with each of the pore water pressure sensors, each of the soil pressure sensors and the displacement sensor to obtain data.

9. The test method of a small-scale physical model experimental device for a reservoir landslide with a detachable sliding body as claimed in claim 8, characterized in that: The following steps are involved: S1, placing the first box on the upper surface of the rotating plate, and then laying the simulated bedrock and the anti-slip member on the upper surface of the bottom of the first box in sequence; S2, laying the sliding belt on the simulated bedrock and installing the corresponding sensor assembly; S3, pasting the anti-slip part on the lower surface of the bottom of the second box, filling the simulated sliding body in the box, then burying the corresponding sensor assembly in the simulated sliding body, and then placing the second box on the sliding belt, and ensuring that the second box does not contact the first box; S4, according to the set working condition requirements, injecting water into the first box and the second box through the water pump and the rainfall component or simulating rainfall; S5. Collect the data of each sensor in real time through the data acquisition analyzer, and observe the sliding of the second box and the simulated sliding body in real time until the sliding belt is cut. The test is ended here, and then take out the second box to observe the shearing condition of the sliding belt.

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