Ground fissure and land subsidence test device and method for simulating multilayer groundwater level change

Abstract

The application discloses a kind of ground fissure and ground subsidence test device and method simulating multilayer groundwater level change, including box, fixed platform and liftable platform are arranged in the box, the fixed platform and the liftable platform are together with the box is divided into two parts space, space for laying test soil layer is located on the upper surface of the fixed platform and the liftable platform;Several water pipe groups are buried in the test soil layer along the height direction, a main opening and several water holes are formed on each water pipe group, a water supply pipe is connected to the main opening of each water pipe group, each water supply pipe is connected to water supply assembly, each water supply pipe is branched and connected with drain pipe, each drain pipe is connected to pumping equipment, first valve is arranged between water supply assembly and drain pipe on each water supply pipe, second valve is arranged on each drain pipe.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ground fissure and land subsidence simulation test, and particularly relates to a ground fissure and land subsidence test device and method for simulating multi-layer groundwater level changes. BACKGROUND

[0002] In the fields of geology and environmental science, studying the impact of groundwater activity on the stability of geological structures, especially the mechanism of ground fissure and land subsidence caused by groundwater, has always been the focus of scientists. However, there is still a lack of a comprehensive and accurate simulation test system platform to simulate and analyze ground fissure and land subsidence phenomena under multi-layer groundwater conditions. The complexity of multi-layer groundwater systems, including the distribution of different aquifers, the difference in permeability, and the dynamic changes of water flow, all pose challenges to simulation tests.

[0003] Although some experimental devices have been proposed, such as the ground fissure test device and method for simulating fault movement and groundwater changes disclosed in patent application CN110954680A, the test device mainly uses a water tank as a water injection system, utilizes the gravitational potential energy of water, and controls the water injection process of the test model tank through a water supply valve. However, this water injection method and related structural design are relatively simple and do not fully consider the uneven permeability characteristics of water in complex geological structures. In addition, the test device does not consider the specific arrangement of water distribution pipes and water inlet pipes, and the drainage device is too simple, with only one drainage port. Since the flow and discharge of groundwater in multi-layer aquifers is a complex process, the design of a single drainage port obviously cannot fully simulate this process, thus limiting the application effect of the device in simulating ground fissure and land subsidence under multi-layer groundwater conditions, and easily causing uneven drainage problems, affecting the accuracy of test results. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a ground fissure and land subsidence test device and method for simulating multi-layer groundwater level changes, which aims to solve the above problems.

[0005] To solve the above technical problems, the present application is implemented by the following technical solutions:

[0006] The utility model provides a kind of ground fissure and ground subsidence test device simulating multilayer groundwater level change, including box, fixed platform and liftable platform are provided in the box, the fixed platform and the liftable platform jointly divide the box into two parts space, the space on the upper surface of the fixed platform and the liftable platform is used to lay test soil layer;Several water seepage pipe groups are buried in the test soil layer along the height direction, a main opening and several water seepage holes are opened on each water seepage pipe group, a water supply pipe is connected to the main opening of each water seepage pipe group, each water supply pipe is connected to water supply assembly, each water supply pipe is branched and connected with drain pipe, each drain pipe is connected to pumping equipment, first valve is provided between water supply assembly and drain pipe on each water supply pipe, second valve is provided on each drain pipe.

[0007] Further, the water supply assembly includes a water supply device, a water tank support, and a water tank disposed on the water tank support. The water supply device is connected to the water inlet of the water tank through a first pipeline. The bottom water outlet of the water tank is vertically connected with a second pipeline. Each water supply pipe is connected to the second pipeline.

[0008] Further, the bottom of the water tank support is provided with moving wheels.

[0009] Further, the water seepage pipe group is formed by at least two water seepage pipes connected in a loop. Each water seepage pipe is provided with a plurality of water seepage holes.

[0010] Further, the bottom of the liftable platform is provided with a plurality of jacks. A limit link mechanism is hingedly connected between the liftable platform and the bottom of the box.

[0011] Further, the test device further includes an anti-overturning device located on one side of the box. The anti-overturning device includes a support frame. A plurality of inclined supports inclined towards the box are arranged in the support frame. A sliding block is arranged on each inclined support. A connecting frame is connected between the sliding block on each inclined support and the box.

[0012] Further, the top of the box is provided with a soil material transportation device.

[0013] Further, the soil material transportation device includes triangular supports arranged on both sides of the top of the box. Horizontal sliding rails are arranged on the triangular supports. A sliding vehicle is arranged on the horizontal sliding rails. A lifting hook is arranged on the sliding vehicle.

[0014] Further, the test soil layer is alternately arranged by sand layer and silty clay layer from bottom to top. The water seepage pipe groups are buried in the corresponding sand layers.

[0015] The application discloses a test method for simulating ground fissure and ground subsidence caused by multilayer underground water level change.

[0016] The test soil layer is paved on the upper surfaces of the fixed platform and the liftable platform, a plurality of water seepage pipe groups are buried in the test soil layer along the height direction, a first detection sensor is buried in the test soil layer, and a second detection sensor is arranged above the box body and used for detecting ground subsidence.

[0017] The first valve is opened, the second valve is closed, the water supply assembly and the water supply pipe are used to supply water to the water seepage pipe groups for ground fissure simulation, and the first detection sensor and the second detection sensor are used to detect data in real time.

[0018] The first valve is closed, the second valve is opened, the water pumping equipment and the water drainage pipe are used to pump out water in the soil layer, and the first detection sensor and the second detection sensor are used to detect data in real time.

[0019] Compared with the prior art, the application has at least the following beneficial effects:

[0020] The application provides a test device for simulating ground fissure and ground subsidence caused by multilayer underground water level change, a plurality of water seepage pipe groups are buried in the test soil layer along the height direction, each water seepage pipe group can be independently controlled to supply water and drain water, the accurate simulation of multilayer underground water level change is realized, the uneven permeation characteristics of underground water in complex geological structures are fully considered, and the simulation test is closer to the actual situation. Each water seepage pipe group is equipped with a water supply pipe, a water drainage pipe and a corresponding valve, the process of water supply and water drainage can be accurately controlled, the change conditions of ground fissure and ground subsidence can be monitored in real time, and therefore the accuracy of test results is greatly improved. The lifting of the liftable platform can be controlled, the generation and expansion process of ground fissure can be flexibly simulated, and the influence of underground water activity on ground subsidence can be further simulated in combination with the water supply and water drainage operations. The device has reasonable structure design, the connection between components is close and easy to operate. During the test, the water supply and water drainage control can be realized by only opening or closing the corresponding valves, and the operation is simple and fast.

[0021] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the following preferred embodiments are specifically described below, and the accompanying drawings are referred to. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application, the drawings needed to be used in the specific embodiment description will be briefly introduced as follows. Obviously, the drawings described below are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0023] Figure 1 Figure is a schematic diagram of a test device for simulating the change of ground fissure and ground subsidence of multi-layer underground water level according to the present application;

[0024] Figure 2 Figure is a schematic diagram of a test coating;

[0025] Figure 3 Figure is a schematic diagram of the layout of a laser displacement meter (ground surface displacement meter) in the embodiment;

[0026] Figure 4 Figure is a schematic diagram of the layout of a soil pressure sensor (pressure cell) in the embodiment;

[0027] Figure 5 Figure is a schematic diagram of the layout of an optical fiber (with a soil pressure cell) in the embodiment;

[0028] Figure 6 、 Figure 7 and Figure 8 Figure is a schematic diagram of the layout of a pore pressure sensor and a water distributor at different depths in the embodiment.

[0029] In the figure: 1-box; 2-fixed platform; 3-liftable platform; 4-test soil layer; 40-sand layer; 41-silty clay layer; 5-seepage pipe group; 6-water supply pipe; 7-water supply assembly; 70-water supply equipment; 71-water tank support; 72-water tank; 73-first pipeline; 74-second pipeline; 75-moving wheel; 8-drainage pipe; 9-pumping equipment; 10-first valve; 11-second valve; 12-jack; 13-limiting connecting rod mechanism; 14-anti-overturning device; 140-supporting frame; 141-inclined support; 142-sliding block; 143-connecting frame; 15-soil material transportation equipment; 150-triangular support; 151-horizontal sliding rail; 152-sliding vehicle; 153-lifting hook. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the present application will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are some embodiments of the present application, and for those skilled in the art, all other embodiments obtained without creative labor on the basis of these embodiments also belong to the scope of protection of the present application.

[0031] As Figure 1 and Figure 2 The embodiment of the present application provides a kind of ground fissure and ground subsidence test device for simulating multilayer groundwater level change, including box 1, fixed platform 2 and liftable platform 3 are arranged in box 1, fixed platform 2 and liftable platform 3 are separated into two parts space, the space on the upper surface of fixed platform 2 and liftable platform 3 is used to lay test soil layer 4;Test soil layer 4 is buried with several water pipe groups 5 along the height direction, a main opening and several water holes are opened in each water pipe group 5, the main opening of each water pipe group 5 is connected with water supply pipe 6, each water supply pipe 6 is connected to water supply assembly 7, each water supply pipe 6 is branched and connected with drain pipe 8, each drain pipe 8 is connected to pumping equipment 9, first valve 10 is provided between water supply assembly 7 and drain pipe 8 on each water supply pipe 6, second valve 11 is provided on each drain pipe 8.

[0032] Specifically, the box 1 is made of high-strength, corrosion-resistant material to ensure durability during long-term testing. The box 1 is made of transparent material for easy observation. The size of the box 1 is designed according to the needs of the simulation test to accommodate enough test soil layer 4 and allow enough space for observation and measurement. The fixed platform 2 is located near the bottom of the box 1 and is a non-movable structure for supporting the test soil layer 4 and the seepage pipe group 5. The surface of the fixed platform 2 is flat to ensure uniform laying of the test soil layer 4. The liftable platform 3 is installed near the bottom of the box 1 by a mechanical lifting mechanism and can be adjusted in height according to the test requirements to simulate the process of ground fissure generation. It should be noted that the height of the liftable platform 3 is not higher than the height of the fixed platform 2. The test soil layer 4 is mixed according to the geological structure characteristics of the research area using different types of soil materials (such as sand, clay, etc.) in a certain proportion to simulate the real geological layer. The test soil layer 4 is layered on the fixed platform 2 and the liftable platform 3. Each seepage pipe group 5 is composed of multiple slender seepage pipes connected in parallel, and each pipe is uniformly distributed with seepage holes for simulating the seepage process of groundwater in the soil. The main opening of the seepage pipe group 5 is connected to the water supply assembly 7 through the water supply pipe 6 to realize water quantity control. It should be noted that the arrangement of the seepage pipe group 5 in the test soil layer 4 should consider the distribution and permeability difference of the water-bearing layer in the actual geological structure to achieve a more realistic simulation effect. The water supply assembly 7 is composed of a water pump and a control system, which can adjust the water supply quantity and rate according to the test requirements. The water supply assembly 7 is connected to the main opening of each seepage pipe group 5 through the water supply pipe 6 to ensure that the water flow can be uniformly distributed to different depths and positions of the test soil layer 4. The first valve 10 provided on the water supply pipe 6 is used to control the water supply to the seepage pipe group 5, and the second valve 11 on the drain pipe 8 is used to adjust the drainage quantity, which together constitute a water flow control system. By adjusting the opening and closing states of the first valve 10 and the second valve 11, the flow and discharge processes of groundwater in different water-bearing layers can be simulated, including seepage, accumulation and discharge, etc. The water pumping device 9 is used to pump out water from the seepage pipe group 5 when needed to simulate the process of groundwater level decline.

[0033] The embodiment is a method for simulating ground fissure and land subsidence caused by changes in multi-layer groundwater level, which specifically comprises:

[0034] According to the test requirements, the test soil layer 4 is laid on the surface of the fixed platform 2 and the liftable platform 3, and a plurality of seepage pipe groups 5 are buried in the soil layer along the height direction. At the same time, the first detection sensor is buried in the test soil layer 4, and the second detection sensor is arranged above the box 1.

[0035] Water injection stage, open the first valve 10, close the second valve 11, start the water supply assembly 7, through the water supply pipe 6 to the soil layer where the water pipe group 5 is injected. The first detection sensor and the second detection sensor are used to detect the soil moisture change, the ground fissure development and the ground subsidence in real time. According to the detection result, the water injection speed and pressure are adjusted to simulate the underground water activity under different conditions.

[0036] Ground fissure simulation stage, after the water injection reaches the predetermined condition, the lifting platform 3 is controlled to descend a certain height to simulate the formation process of the ground fissure. At the same time, the first detection sensor and the second detection sensor are used to detect the data in real time to observe the development of the ground fissure and the change of the ground subsidence.

[0037] Drainage stage, close the first valve 10, open the second valve 11, start the water pumping device 9, through the drainage pipe 8 to extract the water in the soil layer. The first detection sensor and the second detection sensor are used to detect the soil moisture change, the ground fissure closure and the ground subsidence recovery in real time. According to the detection result, the water pumping speed and duration are adjusted to simulate the underground water level decline process under different conditions. The water pumping device 9 is a water pump.

[0038] Finally, the data of the first detection sensor and the second detection sensor in the test process are collected and arranged, the influence mechanism of the underground water activity on the geological structure stability is analyzed, and the cause mechanism of the ground fissure and the ground subsidence is analyzed.

[0039] In one implementation manner, the water supply assembly 7 includes a water supply device 70, a water tank support 71 and a water tank 72 arranged on the water tank support 71, the water supply device 70 is connected with the water inlet of the water tank 72 through the first pipeline 73, the bottom water outlet of the water tank 72 is vertically connected with the second pipeline 74, and each water supply pipe 6 is connected with the second pipeline 74.

[0040] Specifically, the water supply assembly 7 is used to provide stable water flow to the water infiltration pipe group 5 to simulate underground water activities under different conditions. The assembly includes a water supply device 70, a water tank support 71, and a water tank 72 arranged on the water tank support 71. The water supply device 70 is a power device that provides a water source, which can be a water pump, a booster pump, etc., and its function is to inject water into the water tank 72 and maintain a certain water pressure to ensure that the water flow can smoothly enter the water infiltration pipe group 5. The water tank support 71 is a structural member that supports the water tank 72, ensuring that the water tank 72 remains stable during the test process to avoid affecting the water supply effect due to shaking or tilting. The water tank 72 is a container for storing and regulating water flow, such as stainless steel, glass steel, etc. The capacity of the water tank 72 is selected according to the test requirements to ensure that sufficient water can be provided during long-term testing. The water inlet of the water tank 72 is connected to the water supply device 70 through the first pipeline 73 for receiving water flow from the water supply device 70. The bottom water outlet of the water tank 72 is vertically connected to the second pipeline 74 for delivering water flow to each water supply pipe 6. The first pipeline 73 is a pipeline connecting the water supply device 70 and the water tank 72 to ensure that the water flow can smoothly enter the water tank 72. Valves or flow meters and other accessories can be installed on the first pipeline 73 to regulate and control the flow and pressure of the water flow. The second pipeline 74 is a pipeline connecting the water tank 72 and each water supply pipe 6 to ensure that the water flow can be evenly distributed to each water supply pipe 6. Water distributors or flow valves and other accessories can be installed on the second pipeline 74 to evenly distribute water flow to each water infiltration pipe group 5.

[0041] Before the test starts, first start the water supply device 70 to inject water into the water tank 72. When the water level in the water tank 72 reaches the predetermined height, the water supply device 70 stops working. Then, open the first valve 10 and close the second valve 11, the water in the water tank 72 enters each water supply pipe 6 through the second pipeline 74, and then penetrates into the test soil layer 4 through the water infiltration holes on the water infiltration pipe group 5. By adjusting the working state of the water supply device 70 and the valve on the first pipeline 73, the flow and pressure of the water flow can be controlled to simulate underground water activities under different conditions. During the test, the working state of the water supply device 70 and the water level in the water tank 72 can be adjusted as needed to simulate changes in different underground water levels. At the same time, by observing the data changes of the first detection sensor and the second detection sensor, the soil moisture changes, the development of ground fissures, and the ground subsidence are monitored in real time, so as to analyze the influence mechanism of underground water activities on the stability of geological structure.

[0042] In an implementation, the bottom of the water tank support 71 is provided with mobile wheels 75, which enable the entire water supply assembly 7 to be easily moved and adjusted in position. The material of the mobile wheels 75 is wear-resistant and corrosion-resistant rubber or plastic to ensure good durability during long-term use. To facilitate the fixing of the position of the water tank support 71 during the test, the mobile wheels 75 are equipped with locking functions. When it is necessary to fix the water tank support 71, the mobile wheels 75 can be locked to prevent them from sliding or moving. To meet the needs of moving the water tank support 71 in different directions, some of the mobile wheels 75 are designed to be steerable, i.e., they can rotate 360 degrees or turn within a certain angle.

[0043] In an implementation, the water infiltration pipe group 5 is formed by at least two water infiltration pipes connected in a loop, and a plurality of water infiltration holes are formed on each water infiltration pipe. The water infiltration pipe group 5 is used to simulate the infiltration process of groundwater in soil. That is, the water infiltration pipe is the basic unit of the water infiltration pipe group 5 and is made of corrosion-resistant and high-pressure-resistant materials such as stainless steel and PE pipe. The length and diameter of the water infiltration pipe are selected according to the test requirements to ensure that it can cover the test area and meet the requirements of seepage simulation. The water infiltration pipes in the water infiltration pipe group 5 are connected in parallel to form a loop, which improves the uniformity and stability of seepage. A plurality of water infiltration holes are formed on each water infiltration pipe to uniformly infiltrate water flow into the test soil layer. The size, number, and distribution of the water infiltration holes are designed according to the test requirements to ensure that the water flow can infiltrate at the predetermined speed and direction. The shape of the water infiltration hole can be circular, oval, or other shapes to adapt to different infiltration modes and soil conditions.

[0044] During the test, the water flow provided by the water supply assembly 7 enters the water infiltration pipe group 5 through the second pipe 74. When the water flow flows in the water infiltration pipe, it infiltrates into the test soil layer 4 through the water infiltration holes, simulating the infiltration process of groundwater in soil. Since the water infiltration pipe group 5 adopts a parallel loop design, the water flow can be uniformly distributed on each water infiltration pipe, thereby improving the uniformity and stability of seepage.

[0045] In an implementation, the bottom of the liftable platform 3 is provided with a plurality of jacks 12, and a limiting linkage mechanism 13 is hinged between the liftable platform 3 and the bottom of the box 1. Specifically, the jack 12 is a key component installed at the bottom of the liftable platform 3, which is used to realize the lifting function of the platform. The number and layout of the jacks 12 are designed according to the size and weight of the liftable platform 3 to ensure stability during lifting. Exemplarily, the type of the jack 12 can be hydraulic, mechanical or electric. During lifting, the jacks 12 are controlled synchronously to ensure that the liftable platform 3 rises or falls smoothly and uniformly. The limiting linkage mechanism 13 is a hinged mechanism connected between the liftable platform 3 and the bottom of the box 1, which is used to limit the lifting range of the liftable platform 3 and prevent it from tilting excessively. The limiting linkage mechanism 13 is composed of a plurality of connecting rods and hinge points. During lifting, the limiting linkage mechanism 13 plays a guiding and limiting role to ensure that the liftable platform 3 moves smoothly within the predetermined trajectory.

[0046] In an implementation, the test device further includes an anti-overturning device 14 located on one side of the box 1. The anti-overturning device 14 includes a support frame 140, a plurality of inclined supports 141 are arranged in the support frame 140 and inclined towards the box 1, a sliding block 142 is arranged on each inclined support 141, and a connecting frame 143 is connected between the sliding block 142 on each inclined support 141 and the box 1. The anti-overturning device 14 is used to prevent the box 1 from overturning or being unstable during the test due to various reasons such as sudden changes in underground water level and uneven settlement of soil.

[0047] Specifically, the support frame 140 is the main structure of the anti-overturning device 14, which is used to support and fix the inclined supports 141. The support frame 140 is made of metal material such as steel or aluminum alloy to ensure that it has sufficient strength. The shape and size of the support frame 140 are designed according to the size and shape of the box 1 to ensure that it can closely fit and effectively support the box 1. The inclined supports 141 are connected to the support frame 140 to provide inclined support force towards the box 1. The number and layout of the inclined supports 141 are designed according to the weight and stability requirements of the box 1 to ensure that sufficient support force can be provided during the test. The inclined supports 141 are designed to be adjustable to adjust according to different test conditions and the inclination of the box 1. The sliding block 142 is a moving part arranged on the inclined support 141, which is used to cooperate with the connecting frame 143 to realize flexible connection between the box 1 and the anti-overturning device 14. The connecting frame 143 is a bridge connecting the sliding block 142 and the box 1, which is used to transmit the support force of the anti-overturning device 14 to the box 1. The connecting frame 143 is made of metal material to ensure that it has sufficient strength.

[0048] During the experiment, when the box 1 is affected by external factors such as groundwater activity and soil settlement, the anti-overturning device 14 begins to work. The inclined support 141 provides an inclined support force to the box 1 through the sliding block 142 and the connecting frame 143, preventing it from overturning or becoming unstable. At the same time, due to the adjustable design of the sliding block 142 and the connecting frame 143, it can be adjusted according to different experimental conditions and the inclination of the box 1 to ensure that the anti-overturning device 14 can always provide effective support. The anti-overturning device 14 prevents the box 1 from overturning or becoming unstable during the experiment, ensuring the smooth progress of the experiment and the safety of personnel and equipment.

[0049] In one implementation, the top of the box 1 is provided with a soil transportation device 15. The soil transportation device 15 is used to transport soil or test material to the top of the box 1, thereby facilitating loading into the box 1. During the experiment, the soil transportation device 15 begins to work, transporting soil from the ground or a low place to the top of the box 1, improving the operating efficiency of the test device and reducing the labor intensity of the operator.

[0050] In one implementation, the soil transportation device 15 includes triangular supports 150 arranged on both sides of the top of the box 1, horizontal sliding rails 151 arranged on the triangular supports 150, and sliding cars 152 arranged on the horizontal sliding rails 151, and hooks 153 arranged on the sliding cars 152.

[0051] Specifically, the triangular supports 150 are the support structure of the soil transportation device 15 and are arranged on both sides of the top of the box 1. The triangular supports 150 adopt the principle of triangular stability to ensure the stability and load-bearing capacity of the structure. The horizontal sliding rails 151 are arranged on the triangular supports 150 to support and guide the movement of the sliding cars 152. The sliding cars 152 are moving platforms arranged on the horizontal sliding rails 151 to carry and transport soil. For example, the bottom of the sliding car 152 is provided with rollers or sliding blocks matched with the horizontal sliding rails 151, so that it can slide smoothly during movement. The hooks 153 are arranged on the sliding cars 152 and are used to suspend and lift the soil.

[0052] During the experiment, the operator first places the soil on the hooks 153, then moves the sliding cars 152 on the horizontal sliding rails 151 by operating them, and transports the soil above the box 1. Then, the operator adjusts the height and position of the hooks 153 to put the soil into the box 1. Throughout the process, the triangular supports 150 provide stable support to ensure the stability of the soil transportation device 15.

[0053] The soil transportation device 15 can continuously and efficiently transport soil, greatly improving the efficiency of the experiment. The automatic operation of the soil transportation device 15 greatly reduces the labor intensity of the operator and improves the comfort of the experiment.

[0054] In an implementation manner, the test soil layer 4 is alternately arranged from bottom to top by the sand layer 40 and the silty clay layer 41, and the water infiltration pipe group 5 is buried in the corresponding sand layer 40. Specifically, the test soil layer 4 is alternately arranged from bottom to top by the sand layer 40 and the silty clay layer 41, simulating the common multilayer geological structure in nature, and studying the response characteristics of different soil layers under the change of the underground water level. The water infiltration pipe group 5 is buried in the corresponding sand layer 40. Since the sand layer 40 has good water permeability, the water infiltration pipe group 5 can more effectively introduce or discharge water into or out of the test soil layer.

[0055] It can be seen that the test device provided by the above embodiment can not only perform a test without a preset crack (fracture), but also can set a preset crack to simulate the influence of the change of the multilayer underground confined water level on the crack expansion characteristics of the ground crack and the ground subsidence. The test device is mainly used for simulating the evolution process of the ground crack and the ground subsidence when the underground aquifer occurs drainage seepage in the natural environment; and simulating the crack expansion and ground subsidence deformation evolution process of the underground water level under the action of natural seepage supply (drainage) or human extraction (recharge) of underground water.

[0056] The application provides a test method for simulating the ground crack and the ground subsidence caused by the change of the multilayer underground water level, and specifically as follows.

[0057] The test device for simulating the ground crack and the ground subsidence caused by the change of the multilayer underground water level is built, and the fixed platform 2 and the liftable platform 3 are stably installed in the box 1. The test soil layer 4 is laid on the upper surfaces of the fixed platform 2 and the liftable platform 3, and the multilayer geological structure is simulated in the manner that the sand layer 40 and the silty clay layer 41 are alternately arranged. A plurality of water infiltration pipe groups 5 are buried in the test soil layer 4 along the height direction, and the main openings of the water infiltration pipe groups 5 are connected to the water supply pipe 6, and the water supply pipe 6 is connected to the water supply assembly 7. A first detection sensor is buried in the test soil layer 4 and used for monitoring the stress, strain and pore water pressure in the soil layer. A second detection sensor is arranged above the box 1 and used for detecting the ground subsidence.

[0058] The water injection stage: the first valve 10 is opened, and the second valve 11 is closed. The water supply assembly 7 and the water supply pipe 6 are used for injecting water into the soil layer where the water infiltration pipe group 5 is located, so as to simulate the rise of the underground water level. The data of the first detection sensor and the second detection sensor are observed and recorded in real time, and the stress, strain and pore water pressure changes in the soil layer and the ground subsidence are analyzed.

[0059] The ground crack simulation stage: after the water injection stage ends, the liftable platform 3 is controlled to descend, so as to simulate the ground crack caused by the stratum subsidence. The data of the first detection sensor and the second detection sensor are observed and recorded in real time, and the stress and strain changes in the soil layer and the ground subsidence during the formation of the ground crack are analyzed.

[0060] Drainage stage: close the first valve 10, open the second valve 11. Use the water pumping device 9 and the drainage pipe 8 to pump out the water in the soil layer, simulate the decline of the underground water level. Real-time observation and record the data of the first detection sensor and the second detection sensor, analyze the stress, strain, pore water pressure recovery and ground subsidence recovery in the soil layer during the drainage process.

[0061] Arrange and analyze the data of the first detection sensor and the second detection sensor in the water injection stage, ground fissure simulation stage and drainage stage. According to the data analysis results, study the stress, strain, pore water pressure change and ground subsidence of the soil layer under different underground water level change conditions. Analyze the change of the internal mechanical properties of the soil layer during the formation and recovery process of the ground fissure.

[0062] In an embodiment, as shown in Figure 3 , the laser displacement meter is symmetrically arranged along the middle axis of the box body, and 4 monitoring displacement lines are arranged. The middle axis is also arranged with monitoring displacement lines, which are uniformly arranged at a distance of 0.4 m. Each monitoring line is arranged with 11 laser displacement meters, a total of 55. The laser monitoring points extend along the top middle axis. The distance between the monitoring line at the middle axis and the adjacent monitoring lines above and below is 0.2 m. The adjacent distance between the upper and lower two side lines is 0.4 m.

[0063] In an embodiment, as shown in Figure 4 , when burying the soil pressure sensor, first compact and flatten the hole bottom, and then lay a layer of fine sand selected by screening on the hole bottom to ensure uniform stress of the soil pressure sensor during the crack activity. When placing, the front of the soil pressure sensor measuring vertical pressure is upward and horizontally placed, and the front of the soil pressure sensor measuring horizontal pressure is toward the preset crack direction and vertically placed. Finally, fine sand selected by screening is laid around the pressure box and compacted to ensure uniform pressure on the surface of the pressure box and avoid reading fluctuation of the pressure box. At this time, the burying work of the soil pressure sensor is completed.

[0064] In an embodiment, as shown in Figure 5 , the burying of the optical fiber is similar to the pressure box. A channel is excavated along the length direction of the box body to the predetermined buried stratum height. The soil tank is as straight as possible to avoid distortion. At the same time, a mixture of kaolin and fine sand is spread on the bottom of the optical fiber to flatten the bottom and increase the coupling between the soil body and the optical fiber and the sensitivity of the optical fiber deformation. At the same time, the positions of the preset crack projection and other fixed points are recorded for easy comparison and analysis of the strain change of the optical fiber in the later stage. Then, the optical fiber is fixed by the acrylic plate and the soil layer in sections. The optical fiber is buried by winding a PVC pipe with a diameter of 15 cm to realize the conversion of the burying direction and the pre-tension of the optical fiber.

[0065] In an embodiment, as shown in Figure 6 ,Figure 7 and Figure 8 As shown in the figure, the pore pressure sensor and the moisture meter: adopt the ring cutter to punch and bury, adopt the ring cutter to press and punch at the burying point, after reaching the required depth or elevation, first fill part of clean sand at the bottom of the hole, then put the probe into the hole, then fill sand around the probe, finally seal the upper part of the drill hole with expandable clay ball or dry clay ball, so that the probe measures the pore water pressure of the soil layer at the elevation. The technical key of the pore water pressure probe burying is to first ensure that the sand around the probe is permeable, and second to cut off the downward seepage of the upper part of the drill hole. The pore pressure sensor is arranged at the center of the silty clay water-resisting layer and near the top and bottom of the water-bearing layer.

[0066] The above-mentioned embodiment adopts a physical model test for simulating the coupling of fault dislocation and multi-layer groundwater level change to induce the expansion of ground fissures and ground subsidence. Different monitoring instruments, multi-layer, multi-array, and different arrangement modes are used to reproduce the formation, expansion, and evolution process of ground fissures and ground subsidence, and the width development of the ground fissures and ground subsidence in the simulated stratum, the simulated ground subsidence amount, the simulated stress, strain, and pore water pressure in the simulated stratum are obtained, thereby providing analysis basis and physical model support for the formation mechanism and activity expansion analysis of ground fissures and ground subsidence.

[0067] In the description of the present application, it should be understood that the terms "upper", "lower", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0068] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0069] In the present application, unless otherwise specifically specified and limited, the terms "connected", "connected" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or in communication with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication or interaction relationship of two elements, unless otherwise specifically limited. For ordinary skilled persons in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0070] In the present application, unless otherwise explicitly specified and limited, a first feature is "on" or "under" a second feature can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature is "over", "above" and "on top of" the second feature can mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. The first feature is "under", "below" and "underneath" the second feature can mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0071] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the skilled person in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples, without contradiction.

[0072] Finally, it should be noted that the above-described embodiments are merely specific embodiments of the present application, which are used to illustrate the technical solutions of the present application, and are not limiting. The protection scope of the present application is not limited thereto, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily think of changes to the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some technical features thereof; and these modifications, changes or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A test device for simulating ground fissures and ground settlement by simulating changes in groundwater levels across multiple layers, characterized in that, The test soil layer (4) includes a housing (1), which is equipped with a fixed platform (2) and a liftable platform (3). The fixed platform (2) and the liftable platform (3) together divide the housing (1) into two spaces. The space on the upper surface of the fixed platform (2) and the liftable platform (3) is used to lay the test soil layer (4). Several water seepage pipe groups (5) are buried in the test soil layer (4) along the height direction. Each water seepage pipe group (5) has a main opening and several water seepage holes. A water supply pipe (6) is connected to the main opening of each water seepage pipe group (5). Each water supply pipe (6) is connected to a water supply component (7). Each water supply pipe (6) is branched and connected to a drain pipe (8). Each drain pipe (8) is connected to a pumping device (9). A first valve (10) is provided on each water supply pipe (6) between the water supply component (7) and the drain pipe (8). A second valve (11) is provided on each drain pipe (8). The seepage pipe group (5) consists of at least two seepage pipes connected in parallel to form a loop, and each seepage pipe has several seepage holes. The test soil layer (4) consists of alternating layers of sand (40) and silty clay (41) from bottom to top, and the permeable pipe group (5) is buried in the corresponding sand layer (40).

2. The experimental device for simulating multi-layer groundwater level changes and ground subsidence according to claim 1, characterized in that, The water supply assembly (7) includes a water supply device (70), a water tank bracket (71), and a water tank (72) mounted on the water tank bracket (71). The water supply device (70) is connected to the water inlet of the water tank (72) via a first pipe (73). The bottom outlet of the water tank (72) is vertically connected to a second pipe (74). Each water supply pipe (6) is connected to the second pipe (74).

3. The experimental device for simulating multi-layer groundwater level changes and ground subsidence according to claim 2, characterized in that, The bottom of the water tank support (71) is provided with casters (75).

4. The experimental device for simulating multi-layer groundwater level changes and ground subsidence according to claim 1, characterized in that, The bottom of the liftable platform (3) is provided with several jacks (12), and the liftable platform (3) and the bottom of the box (1) are hinged to a limit linkage mechanism (13).

5. The experimental device for simulating multi-layer groundwater level changes and ground subsidence according to claim 1, characterized in that, The test apparatus also includes an anti-tipping device (14) located on one side of the box (1). The anti-tipping device (14) includes a support frame (140). The support frame (140) is provided with a plurality of inclined supports (141) inclined towards the box (1). Each inclined support (141) is provided with a slider (142). A connecting frame (143) is connected between the slider (142) on each inclined support (141) and the box (1).

6. The experimental device for simulating multi-layer groundwater level changes and ground subsidence according to claim 1, characterized in that, The top of the box (1) is equipped with soil transport equipment (15).

7. The experimental device for simulating multi-layer groundwater level changes and ground subsidence according to claim 6, characterized in that, The soil transport equipment (15) includes triangular brackets (150) set on both sides of the top of the box (1), a horizontal slide rail (151) is set on the triangular brackets (150), a sliding trolley (152) is set on the horizontal slide rail (151), and a hook (153) is set on the sliding trolley (152).

8. A test method for simulating ground fissures and ground settlement by measuring changes in groundwater levels across multiple layers, characterized in that, The test apparatus for simulating multi-layer groundwater level changes and ground subsidence according to any one of claims 1 to 7 comprises: A test soil layer (4) is laid on the upper surface of the fixed platform (2) and the liftable platform (3), and several of the seepage pipe groups (5) are buried in the test soil layer (4) along the height direction. A first detection sensor is buried in the test soil layer (4), and a second detection sensor is arranged above the box (1). The second detection sensor is used to detect ground settlement. Open the first valve (10), close the second valve (11), inject water into the soil layer where the seepage pipe group (5) is located using the water supply component (7) and the water supply pipe (6), and use the first detection sensor and the second detection sensor to detect the data in real time; The lifting platform (3) is controlled to descend to simulate ground fissures, and the data is detected in real time using the first and second detection sensors. Close the first valve (10), open the second valve (11), use the pumping equipment (9) and the drainage pipe (8) to pump out the water from the soil layer, and use the first detection sensor and the second detection sensor to detect the data in real time.

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