Testing device and testing method for positioning soil slope slip plane based on acoustic emission

Abstract

The invention discloses a test device for positioning a soil slope slip plane based on acoustic emission, the test device comprises a simulation unit, a test unit and a signal acquisition and analysis unit, the simulation unit encloses a simulation cavity, and the simulation cavity can accommodate a landslide mass geotechnical material and is provided with a waveguide tube and a granular material; normal pressure is applied to the simulation unit by using the first loading mechanism, and acting force is applied to the lower-layer shear box by using the second loading mechanism. An acoustic emission sensor of the signal acquisition and analysis unit is used for acquiring acoustic emission signals, and a signal analysis module can analyze the acoustic emission signals generated in the shear test process. In the test process, particle materials with different particle sizes are replaced, loading conditions of the test unit are adjusted, acoustic emission spectrum characteristics of the particle materials with different particle sizes are analyzed, changes of the particle materials with different particle sizes in different shear speeds and stress states are analyzed, and an accurate slip plane positioning basis is provided. The invention further provides a test method for positioning the soil slope slip plane based on acoustic emission.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a test device and a test method for locating a sliding surface of a soil slope based on acoustic emission. Background Art

[0002] Landslide disaster is a common and extremely destructive geological disaster, usually triggered by factors such as rainfall. Especially in the case of continuous rainfall, the moisture in the soil increases rapidly, reducing the cohesion and stability of the soil. When the soil cannot withstand the force of gravity, a landslide will occur. Landslide disasters directly threaten the lives and safety of people living in mountainous and hilly areas, and will also cause serious damage to important infrastructure such as roads, bridges, tunnels, and power transmission lines. With climate change and the increase in extreme weather events, the frequency and intensity of landslide disasters are also on the rise. Therefore, strengthening the monitoring, early warning and prevention and control measures of landslide disasters has become a top priority in the prevention and control of geological disasters.

[0003] At present, the main technical means for monitoring landslide deformation include GNSS, remote sensing, etc. However, these technologies are limited in practical application, are easily affected by climatic conditions, and have relatively low sensitivity, making it difficult to achieve rapid early warning of landslide deformation. Although inclinometers, array displacement meters (SAA) and other equipment have high accuracy in deformation monitoring, their high cost and complex maintenance requirements make it difficult for these devices to be widely promoted and applied.

[0004] During the deformation and destruction of landslides, a series of complex interactions such as friction, collision and micro-fracture will occur between rock and soil particles. These interactions will release some energy, which will be converted into acoustic emission elastic waves and produce continuous acoustic emission signals. Acoustic emission technology can effectively detect the extremely slow deformation of landslides due to its high sensitivity to small changes in early displacement and velocity of the slope. Therefore, acoustic emission technology has been considered as one of the powerful tools for monitoring slope deformation status.

[0005] At present, common active waveguide systems have been widely used in landslide monitoring. These systems place metal waveguide rods in geological boreholes and fill them with discrete granular materials. When the landslide rock and soil squeeze the waveguide rods, the discrete granular materials will generate acoustic emission signals. By analyzing these signals, the deformation process of the landslide can be effectively captured. This active waveguide system has gradually developed into an applicable landslide monitoring method due to its high time resolution, high sensitivity and low cost.

[0006] Another simple active waveguide system directly fills discrete granular materials in a metal waveguide rod and drives the waveguide rod into the ground. When landslide deformation occurs, the metal waveguide rod is squeezed and deformed, and the granular materials inside also generate acoustic emission signals. This simple system has the advantages of simple structure and low cost, and is suitable for promotion and use in areas without complex monitoring conditions.

[0007] The acoustic emission signal characteristics generated by granular materials of different particle sizes during shearing are different. Therefore, by filling granular materials of different particle sizes at different depths in geological boreholes and performing spectrum analysis on the acoustic emission signals generated during landslide deformation, the particle size characteristics of the backfill granular materials can be identified based on the frequency characteristics of the signal, thereby achieving accurate positioning of the slip surface. However, there is currently no special experimental device for studying the differences in the spectral characteristics of acoustic emission signals generated by backfill granular materials of different particle sizes during landslide deformation. Research in this field is still in the exploratory stage, and it is urgent to develop corresponding experimental devices to further promote the development of related technologies. Summary of the invention

[0008] The purpose of the present invention is to provide a test device and a test method for locating the slip surface of a soil slope based on acoustic emission, so as to solve the problems existing in the above-mentioned related technologies, simulate the acoustic emission characteristics under different rock and soil bodies, active waveguide systems, granular materials, stress states and shear rates, thereby providing a test basis for locating the slip surface of a soil slope based on active waveguide acoustic emission technology, and thus improving the accuracy and reliability of landslide monitoring.

[0009] To achieve the above object, the present invention provides the following solutions:

[0010] The present invention provides a test device for locating the sliding surface of a soil slope based on acoustic emission, comprising:

[0011] A simulation unit, the simulation unit comprises an upper shear box and a lower shear box arranged at the bottom of the upper shear box, the upper shear box and the lower shear box are detachably connected and enclose a simulation cavity, the top of the simulation cavity is open, the simulation cavity can accommodate landslide rock and soil materials, and a waveguide and granular materials are arranged in the simulation cavity, the waveguide is arranged in a vertical direction, the granular materials are filled in the inside of the waveguide or arranged around the waveguide, during the shear test, the landslide rock and soil materials are deformed, and the granular materials can generate acoustic emission signals;

[0012] A test unit, the test unit comprising a first loading mechanism and a second loading mechanism, the first loading mechanism being located at the top of the upper shear box and being capable of applying a normal pressure to the simulation unit, the second loading mechanism being located at one side of the simulation unit and being capable of applying a force to the lower shear box in a horizontal direction;

[0013] A signal acquisition and analysis unit, the signal acquisition and analysis unit comprises an acoustic emission sensor and a signal analysis module, the acoustic emission sensor is communicatively connected with the waveguide and is used to acquire acoustic emission signals, and the signal analysis module can analyze the acoustic emission signals generated during the shear test.

[0014] Preferably, the test unit also includes a cover plate and a support frame, the cover plate can cover the top of the landslide body rock and soil material in the simulation cavity, the first loading mechanism includes a force-applying pressure rod and a pressure rod support foot, one end of the force-applying pressure rod is hinged to the support frame, and the hinge axis of the two is parallel to the horizontal direction, the pressure rod support foot is arranged at the bottom of the force-applying pressure rod, and the force-applying pressure rod is abutted against the cover plate, and a force is applied to the end of the force-applying pressure rod away from the support frame, so as to realize the application of normal pressure to the landslide body rock and soil material in the simulation cavity and the waveguide tube through the pressure rod support foot; the upper shear box is detachably connected to the support frame.

[0015] Preferably, the pressure rod support foot is an inverted T-shaped structure, and the pressure rod support foot comprises a connecting rod and a transverse pressure plate, the connecting rod connects the force-applying pressure rod and the transverse pressure plate, and the transverse pressure plate can be abutted against the cover plate.

[0016] Preferably, one end of the force-applying pressure rod away from the support frame is connected to a counterweight tray, and the counterweight tray can accommodate a counterweight object.

[0017] Preferably, there are multiple groups of force-applying pressure rods, which are arranged at equal intervals along the direction in which the second loading mechanism applies force to the lower shear box, and the pressure rod legs and the counterweight tray correspond one-to-one to the force-applying pressure rods.

[0018] Preferably, the second loading mechanism includes a driver and a shear rod, the driver is arranged on the support frame, the output end of the driver is transmission-connected to one end of the shear rod, the other end of the shear rod is connected to the lower shear box, and the driver can drive the shear rod to move in the horizontal direction.

[0019] Preferably, the second loading mechanism also includes a transmission screw and a slider nut, the output end of the driver is connected to the transmission screw, the transmission screw is rotatably connected to the support frame, the slider nut is threadedly connected to the transmission screw, and the slider nut is connected to the shear rod.

[0020] Preferably, the support frame has a mounting plate, one end of the transmission screw away from the driver is rotatably connected to the mounting plate, and the shear rod is connected to the lower shear box after sliding through the mounting plate;

[0021] The second loading mechanism further includes a tension sensor and a distance measuring element. The tension sensor is arranged between the shear rod and the support frame. The distance measuring element is connected to the slider nut to monitor the displacement of the slider nut.

[0022] Preferably, the cover plate has a through hole matched with the waveguide tube; when the granular material is filled in the interior of the waveguide tube, the cover plate also has a pressure cap matched with the inner diameter of the waveguide tube.

[0023] Preferably, the signal acquisition and analysis unit also includes an amplifier and a signal acquisition card, wherein the amplifier is communicatively connected to the acoustic emission sensor to enhance the strength of the acoustic emission signal, and the amplifier is also communicatively connected to the signal acquisition card, and the signal acquisition card is used to convert the acoustic emission signal into a digital signal, and the signal acquisition card can also transmit the converted digital signal to the signal analysis module.

[0024] Preferably, the signal analysis module is a computer, which performs time domain and frequency domain analysis on the collected acoustic emission signals through MATLAB professional software, studies the acoustic emission rates of different granular materials under various stress states and shear rate conditions, and obtains the main frequency range of acoustic emission of granular materials through spectrum analysis, providing key data support for related engineering applications.

[0025] The present invention also provides a test method for locating the slip surface of a soil slope based on acoustic emission. The test device for locating the slip surface of a soil slope based on acoustic emission comprises the following steps: filling the simulation cavity with landslide rock and soil materials, connecting the waveguide tube with the acoustic emission sensor, applying normal pressure to the simulation unit using the first loading mechanism, applying force to the lower shear box in a horizontal direction using the second loading mechanism, deforming the landslide rock and soil materials in the simulation cavity under the action of shear force, generating acoustic emission signals from the granular materials, and collecting and analyzing the acoustic emission signals during the loading process to analyze and locate the slip surface.

[0026] Compared with the related art, the present invention has achieved the following technical effects:

[0027] 1. The present invention can conduct an in-depth analysis of the spectrum characteristics of acoustic emission signals generated by granular materials of different particle sizes during landslides, and provide a scientific theoretical basis for the positioning of the sliding surface.

[0028] 2. The present invention fills granular materials inside or outside the waveguide to simulate the response characteristics of a simple active waveguide system and a typical active waveguide system during a landslide, which is suitable for various test needs and improves the flexibility and adaptability of the test device.

[0029] 3. The present invention can simulate the landslide process under different stress states and shear speeds, and improve the flexibility of the test. By studying the differences in acoustic emission signals under different landslide rates and stress conditions, it is helpful to gain a deeper understanding of the landslide mechanism and further improve the accuracy and reliability of landslide warning.

[0030] 4. The present invention can also simulate the influence of factors such as the shape and moisture content of granular materials on the acoustic emission signal, thereby comprehensively analyzing the acoustic emission behavior of granular materials during landslides in multiple dimensions, and providing scientific basis and technical support for landslide early warning and prevention based on acoustic emission. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of the principle of using a typical active waveguide in a simulation unit of a test device for locating a soil slope sliding surface based on acoustic emission provided by an embodiment of the present invention;

[0033] Figure 2 for Figure 1 A schematic diagram of the enlarged structure at A in the middle;

[0034] Figure 3 A schematic diagram of the principle of using a simple active waveguide in a simulation unit of a test device for locating a soil slope sliding surface based on acoustic emission provided by an embodiment of the present invention;

[0035] Figure 4 for Figure 3 A schematic diagram of the enlarged structure at B in the middle;

[0036] Figure 5 A schematic diagram of a structure in which a simulation unit of a test device for locating a soil slope sliding surface based on acoustic emission provided by an embodiment of the present invention adopts a typical active waveguide;

[0037] Figure 6 A schematic diagram of the structure of a simulation unit of a test device for locating a soil slope sliding surface based on acoustic emission provided by an embodiment of the present invention using a simple active waveguide;

[0038] Figure 7 A schematic diagram of the structure of a test device for locating the sliding surface of a soil slope based on acoustic emission provided in an embodiment of the present invention;

[0039] Figure 8 A schematic diagram of the principle of a signal acquisition and analysis unit of a test device for locating a soil slope sliding surface based on acoustic emission provided in an embodiment of the present invention.

[0040] In the figure: 100, a test device for locating the sliding surface of a soil slope based on acoustic emission; 200, a signal acquisition and analysis unit;

[0041] 1. Upper shear box; 2. Lower shear box; 3. Landslide rock and soil materials; 4. Waveguide tube; 5. Granular material; 6. Cover plate; 7. Support frame; 8. Force rod; 9. Rod support foot; 10. Counterweight tray; 11. Driver; 12. Shear rod; 13. Transmission screw; 14. Slider nut; 15. Mounting plate; 16. Tension sensor; 17. Distance measuring element; 18. Acoustic emission sensor; 19. Amplifier; 20. Signal acquisition card; 21. Signal analysis module; 22. Pressure cover. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The purpose of the present invention is to provide a test device and a test method for locating the slip surface of a soil slope based on acoustic emission, so as to solve the problems existing in the above-mentioned related technologies, simulate the acoustic emission characteristics under different rock and soil bodies, active waveguide systems, granular materials, stress states and shear rates, thereby providing a test basis for locating the slip surface of a soil slope based on active waveguide acoustic emission technology, and thus improving the accuracy and reliability of landslide monitoring.

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] Embodiment 1

[0046] This embodiment provides a test device 100 for locating the sliding surface of a soil slope based on acoustic emission. Figure 1-Figure 8, including a simulation unit, a test unit and a signal acquisition and analysis unit 200, the simulation unit includes an upper shear box 1 and a lower shear box 2 arranged at the bottom of the upper shear box 1, the upper shear box 1 and the lower shear box 2 can be detachably connected and surrounded by a simulation cavity, the top of the simulation cavity is open, the simulation cavity can accommodate landslide rock and soil materials 3, and a waveguide 4 and granular material 5 are arranged in the simulation cavity, the waveguide 4 is arranged in a vertical direction, and the waveguide 4 can be connected to the acoustic emission sensor 18, the granular material 5 is filled in the waveguide 4 or arranged around the waveguide 4, during the shear test, the landslide rock and soil materials Deformation, the granular material 5 can generate an acoustic emission signal; the test unit includes a first loading mechanism and a second loading mechanism, the first loading mechanism is located at the top of the upper shear box 1, the first loading mechanism can apply a normal pressure to the simulation unit, the second loading mechanism is located on one side of the simulation unit, the second loading mechanism can apply a force to the lower shear box 2 in a horizontal direction; the signal acquisition and analysis unit 200 includes an acoustic emission sensor 18 and a signal analysis module 21, the acoustic emission sensor 18 is communicatively connected to the waveguide 4 for collecting acoustic emission signals, and the signal analysis module 21 can analyze the acoustic emission signals generated during the shear test.

[0047] The test device 100 for locating the sliding surface of soil slope based on acoustic emission of the present invention, the upper shear box 1 and the lower shear box 2 of the simulation unit enclose a simulation cavity, and the landslide rock material 3 is filled in the simulation cavity to simulate the rock and soil environment around the landslide body. During the test, the first loading mechanism of the test unit can be used to apply normal pressure to the simulation unit; the second loading mechanism can also be used to apply force to the lower shear box 2 to transfer shear force to the landslide rock material 3 in the simulation cavity to simulate the landslide conditions under different stress states. In practical applications, the method of filling granular material 5 inside or outside the waveguide 4 is adopted to realize a simple active waveguide or a typical active waveguide design, and the waveguide 4 can be connected to the acoustic emission sensor 18. During the test, the landslide rock material 3 is deformed, and the granular material 5 generates an acoustic emission signal. The waveguide 4 transmits the acoustic emission signal to the acoustic emission sensor 18, which is convenient for the test personnel to use the signal acquisition and analysis unit 200 to monitor, record and analyze in time, thereby analyzing and locating the sliding surface. During the test, the granular materials 5 of different particle sizes are replaced, the loading conditions of the test unit are adjusted, the acoustic emission spectrum characteristics of the granular materials 5 of different particle sizes are analyzed, and their changes under different shear speeds and stress states are analyzed, so as to provide accurate basis for positioning the sliding surface. The test device 100 for positioning the sliding surface of soil slopes based on acoustic emission of the present invention can also simulate the influence of factors such as the shape and moisture content of the granular material 5 on the acoustic emission signal, so as to comprehensively analyze the physical behavior of the granular material 5 during the landslide process, and provide multi-dimensional support for landslide early warning and prevention and control measures; in addition, it can also simulate the landslide process under different stress states and shear speeds, improve the flexibility of the test, and conduct a study on the difference of acoustic emission signals under different landslide rates and stress states, which is helpful to further understand the mechanism of landslide occurrence and improve the accuracy and reliability of landslide early warning. The present invention can simulate the deformation process of landslides under typical and simple active waveguide technology conditions. The test personnel can provide theoretical references for the optimization design of landslide early warning systems in practical applications by comparing the differences in acoustic emission signal parameters generated by different systems.

[0048] It should be noted that the test unit also includes a cover plate 6 and a support frame 7. The cover plate 6 can cover the top of the landslide body geotechnical material 3 in the simulation cavity, so as to facilitate the first loading mechanism to load the simulation unit. Among them, the first loading mechanism includes a force-applying pressure rod 8 and a pressure rod support foot 9. One end of the force-applying pressure rod 8 is hinged to the support frame 7, and the hinge axis of the two is parallel to the horizontal direction. The pressure rod support foot 9 is arranged at the bottom of the force-applying pressure rod 8, and the force-applying pressure rod 8 is in contact with the cover plate 6. The pressure rod support foot 9 is located between the hinge end and the free end of the force-applying pressure rod 8 and the support frame 7, and a force is applied to the end of the force-applying pressure rod 8 away from the support frame 7 (i.e., the free end of the force-applying pressure rod 8), so as to realize the application of normal pressure to the landslide body geotechnical material 3 and the waveguide 4 in the simulation cavity through the pressure rod support foot 9, so as to simulate the landslide conditions under different stress states. At the same time, the upper shear box 1 and the support frame 7 are detachably connected. When the first loading mechanism is used to apply normal pressure to the simulation unit, the upper shear box 1 can be connected to the support frame 7 to ensure the structural stability of the upper shear box 1 during the loading process. The upper shear box 1 and the support frame 7 can be connected by a latch, and the disassembly and assembly operation is convenient. Similarly, the upper shear box 1 and the lower shear box 2 can also be connected by a latch, which is convenient for filling the landslide rock material 3 into the simulation cavity; when a force is applied to the lower shear box 2 to cause it to displace, the latch between the upper shear box 1 and the lower shear box 2 can be opened in advance to allow the lower shear box 2 to displace smoothly. In addition, in actual applications, the first loading mechanism can also use other loading devices to achieve normal loading.

[0049] In this specific embodiment, the pressure rod support foot 9 is an inverted T-shaped structure, and the pressure rod support foot 9 includes a connecting rod and a transverse pressure plate. The connecting rod connects the force pressure rod 8 and the transverse pressure plate. The transverse pressure plate can be abutted against the cover plate 6. The arrangement of the pressure rod support foot 9 facilitates the force pressure rod 8 to load the simulation unit. The inverted T-shaped structure of the pressure rod support foot 9 is beneficial to further improve the loading uniformity and stability.

[0050] In order to facilitate loading and adjusting the loading force, the end of the force-applying pressure rod 8 away from the support frame 7 is connected to a counterweight tray 10, which can accommodate a counterweight object. By adjusting the counterweight object in the counterweight tray 10, the normal stress applied by the first loading mechanism to the simulation unit can be adjusted, thereby improving the convenience of operation of the device. The counterweight tray 10 is hinged to the force-applying pressure rod 8 so that the force applied by the counterweight tray 10 and the counterweight object to the force-applying pressure rod 8 is always parallel to the vertical direction.

[0051] In practical applications, the number of force-applying pressure rods 8 can be multiple groups, and the force-applying pressure rods 8 are arranged at equal intervals along the direction in which the second loading mechanism applies force to the lower shear box 2 to ensure loading stability and loading uniformity, and the pressure rod support feet 9 and the counterweight tray 10 correspond to the force-applying pressure rods 8 one by one. In addition, the number and distribution of the force-applying pressure rods 8 can also be adjusted according to actual test requirements to meet different simulation conditions and improve the flexibility and adaptability of the device.

[0052] Specifically, the second loading mechanism includes a driver 11 and a shear rod 12. The driver 11 is arranged on the support frame 7. The output end of the driver 11 is connected to one end of the shear rod 12 by transmission. The other end of the shear rod 12 is connected to the lower shear box 2. The driver 11 can drive the shear rod 12 to move in the horizontal direction. The driver 11 uses the shear rod 12 to drive the lower shear box 2 to move and generate lateral displacement to simulate the landslide process and control the displacement speed, so as to simulate the deformation rate in the landslide process. The driver 11 can use a servo motor, which is convenient to operate and control.

[0053] In order to ensure the smooth transmission of the output power of the driver 11, the second loading mechanism also includes a transmission screw 13 and a slider nut 14. The output end of the driver 11 is connected to the transmission screw 13, the transmission screw 13 is rotatably connected to the support frame 7, the slider nut 14 is threadedly connected to the transmission screw 13, and the slider nut 14 is connected to the shear rod 12. The driver 11 drives the transmission screw 13 to rotate, and the transmission screw 13 and the slider nut 14 are threadedly connected to form a screw transmission mechanism, so that the transmission screw 13 drives the slider nut 14 to slide in the horizontal direction, and then drives the shear rod 12 and the lower shear box 2 to move. The screw transmission mechanism is adopted, and the transmission is stable and reliable, which ensures the loading stability and reliability of the second loading mechanism. In other specific embodiments that can be realized by the present invention, other transmission structures can also be adopted, such as a gear rack transmission structure, a chain transmission structure, etc., to improve the flexibility and adaptability of the device.

[0054] More specifically, the support frame 7 has a mounting plate 15, and the end of the transmission screw 13 away from the driver 11 is rotatably connected to the mounting plate 15. The mounting plate 15 provides stable support for the transmission screw 13. The shear rod 12 slides through the mounting plate 15 and is connected to the lower shear box 2. The mounting plate 15 also provides a guide for the shear rod 12 to make sliding movements.

[0055] In this specific embodiment, the second loading mechanism also includes a tension sensor 16 and a distance measuring element 17. The tension sensor 16 is arranged between the shear rod 12 and the support frame 7 to monitor the shear force applied by the second loading mechanism to the simulation unit, which is convenient for the test personnel to operate. The distance measuring element 17 is connected to the slider nut 14 to monitor the displacement of the slider nut 14, further improving the convenience of operation of the device. In practical applications, the distance measuring element 17 can select a caliper, and a scale mark is set at the corresponding position of the mounting plate 15. The caliper slides with the slider nut 14 and produces a relative displacement with the scale mark to measure the displacement of the lower shear box 2. The structure is simple and easy to use.

[0056] It should also be noted that the cover plate 6 has a through hole adapted to the waveguide tube 4 to prevent the waveguide tube 4 from affecting the loading; when the granular material 5 is filled in the interior of the waveguide tube 4, the cover plate 6 also has a pressure cap 22 adapted to the inner diameter of the waveguide tube 4 to ensure that the granular material 5 in the waveguide tube 4 is subjected to appropriate pressure.

[0057] Furthermore, in the test device 100 for locating the sliding surface of a soil slope based on acoustic emission of the present invention, the signal acquisition and analysis unit 200 is used to capture and analyze the acoustic emission signal generated during the shear test, including an acoustic emission sensor 18, an amplifier 19, and a signal acquisition card 20. In practical applications, the acoustic emission sensor 18 can be installed on the outer wall of the upper end of the waveguide 4, and the acoustic emission signal generated by the granular material 5 can be detected in real time. The amplifier 19 is used to enhance the intensity of the acoustic emission signal to ensure the accuracy of subsequent signal processing. The signal acquisition card 20 is responsible for converting the acoustic emission signal into a digital signal and transmitting it to the signal analysis module 21 for subsequent analysis. The signal analysis module 21 performs time domain and frequency domain analysis on the collected acoustic emission signal through professional software such as MATLAB, and studies the acoustic emission signal characteristics of different granular materials 5 under different stress states and shear speeds. Through spectrum analysis, the main frequency range of the acoustic emission of the granular material 5 can be obtained, providing a theoretical basis for further locating the sliding surface.

[0058] Embodiment 2

[0059] The present embodiment provides a test method for locating the slip surface of a soil slope based on acoustic emission. The test device 100 for locating the slip surface of a soil slope based on acoustic emission of the first embodiment includes the following steps: filling a landslide rock material 3 in a simulation cavity, connecting a waveguide tube 4 to an acoustic emission sensor 18, applying normal pressure to the simulation unit by a first loading mechanism, applying a force to the lower shear box 2 in a horizontal direction by a second loading mechanism, deforming the landslide rock material 3 in the simulation cavity under the action of shear force, generating an acoustic emission signal in the granular material 5, transmitting the acoustic emission signal to the acoustic emission sensor 18, and collecting and analyzing the signal acquisition and analysis unit 200 to analyze and locate the slip surface.

[0060] The test method for locating the slip surface of a soil slope based on acoustic emission of the present invention simulates the acoustic emission characteristics of the backfill granular material 5 under different shear speeds and stress states during the landslide process, and analyzes the position of the slip surface accordingly.

[0061] In practical applications, the test method for locating the slip surface of a soil slope based on acoustic emission of the present invention, using the test device 100 for locating the slip surface of a soil slope based on acoustic emission of the first embodiment, may include the following operating steps:

[0062] 1. No-load test

[0063] Before the shear test, the device is first run without load. This step is intended to measure the background noise in the test environment, including mechanical noise, electromagnetic interference, etc. The frequency distribution and signal amplitude of the background noise are recorded by the signal acquisition and analysis unit 200, and the appropriate filter frequency range and threshold voltage are determined. These parameters are used for noise filtering in subsequent tests to ensure that the acoustic emission signal collected in the test can accurately reflect the shear characteristics of the granular material 5, rather than the environmental noise.

[0064] 2. Sample preparation

[0065] The outer walls of the upper shear box 1 and the lower shear box 2 are fixed to ensure the stability of the device during the experiment. The waveguide 4 is placed in the simulation cavity, and then the soil is filled in the simulation cavity and compacted to simulate the soil state under actual landslide conditions.

[0066] Simple active waveguide system: In this system, quartz sand of a specific particle size is selected to fill the interior of the waveguide 4. During the shearing process, the quartz sand will be affected by the deformation of the waveguide 4 and generate an acoustic emission signal.

[0067] A typical active waveguide system is as follows: the selected quartz sand is filled into the outside of the waveguide tube 4 so that the quartz sand is arranged around the waveguide tube 4 to simulate the shearing effect of the soil on the waveguide tube 4. The acoustic emission signal is generated by the interaction of the granular material 5 outside the waveguide tube 4.

[0068] Place the filled simulation unit into the test unit and fix the connection position between the upper shear box and the test unit by means of latches to ensure that the simulation unit remains stable during the test.

[0069] 3. Apply normal pressure

[0070] The way of applying the normal pressure varies according to the design of the active waveguide system.

[0071] Simple active waveguide system: A square cover plate 6 needs to be placed on the soil, and a circular pressure cover 22 needs to be placed on the granular material 5 inside the waveguide 4 to ensure that the granular material 5 is subjected to appropriate pressure.

[0072] Typical active waveguide system: only a square cover plate 6 needs to be placed on the soil and the outer granular material 5, and a circular pressure cover 22 is not required.

[0073] The force-applying pressure rod 8 is used to apply normal pressure. One end of the force-applying pressure rod 8 is connected to the counterweight tray 10. The specific mass of the counterweight is determined by calculating the lever ratio and the required normal pressure. The applied pressure simulates the normal stress state of the actual soil and waveguide system during the landslide process.

[0074] 4. Install the acoustic emission sensor 18

[0075] The acoustic emission sensor 18 is firmly bonded to the outer wall of the waveguide 4 to ensure that it is tightly coupled with the waveguide 4 to improve the accuracy of signal acquisition. The acoustic emission sensor 18 is connected to the amplifier 19 and the signal acquisition card 20 through a signal line. The amplifier 19 is used to enhance the weak acoustic emission signal, and the signal acquisition card 20 converts the amplified analog signal into a digital format for subsequent signal analysis module 21 to analyze.

[0076] 5. Determine the shear rate

[0077] According to the test requirements, first determine the relationship between the servo motor speed and the moving speed of the lower shear box 2. Set the servo motor to run at a fixed speed until the displacement of the lower shear box 2 reaches 50mm, and calculate the shear speed corresponding to this displacement. Adjust the servo motor speed through repeated tests to ensure the accuracy of the shear speed.

[0078] According to the classification standard of landslide velocity in the Code for Monitoring Collapse, Landslide and Debris Flow (DZ / T 0221-2006), the setting values ​​of different shear velocities are determined to simulate the influence of different deformation rates on the acoustic emission signal during the landslide process.

[0079] 6. Acquisition and processing of acoustic emission signals

[0080] The signal acquisition and analysis unit 200 is started to record the acoustic emission signal generated during the shearing process. The acoustic emission signal is amplified by the amplifier 19 and transmitted to the signal analysis module 21 through the signal acquisition card 20 for digital processing.

[0081] Filtering: Based on the noise analysis results of the no-load test, filtering is performed to remove high-frequency and low-frequency noise and only retain valid signals within the medium frequency range.

[0082] Threshold voltage setting: according to the statistical characteristics of the noise amplitude, the threshold voltage is set to filter out invalid signals with smaller amplitudes, thereby ensuring that the retained acoustic emission signals are mainly generated by the granular material 5 during the shearing process.

[0083] Time domain and frequency domain analysis: Perform time domain analysis on the collected signals to calculate the occurrence rate of acoustic emission events, i.e., the acoustic emission rate. Then perform frequency domain analysis to calculate the spectrum of the signal, identify the amplitude and phase of each frequency component, and finally determine the main frequency of the acoustic emission signal. If necessary, wavelet transform can be used for time-frequency analysis to generate a time-frequency diagram to reveal the frequency change characteristics of the signal in different time periods.

[0084] 7. Statistics and analysis of test results

[0085] According to the predetermined test plan, the granular materials 5 of different particle sizes are replaced, the weight of the counterweight of the second loading mechanism is adjusted, and the shear speed is changed, and the above test steps are repeated. After each round of test, the acoustic emission rate and spectrum distribution of the granular materials 5 of each diameter grade under different normal pressures and shear speeds are recorded and counted.

[0086] Through comprehensive analysis of the test results, the acoustic emission characteristics of granular materials 5 with different particle sizes under different stress states are studied, with a focus on analyzing the range of their main frequency changes. In the test results, if the range of changes of the main frequency of acoustic emission of granular materials 5 with different particle sizes under different conditions does not intersect with each other, the type of backfill granular material 5 on the sliding surface can be identified based on the main frequency of the acoustic emission signal, thereby achieving accurate positioning of the sliding surface.

[0087] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A test device for locating the sliding surface of soil slope based on acoustic emission, characterized in that: include: A simulation unit, the simulation unit comprises an upper shear box and a lower shear box arranged at the bottom of the upper shear box, the upper shear box and the lower shear box are detachably connected and enclose a simulation cavity, the top of the simulation cavity is open, the simulation cavity can accommodate landslide rock and soil materials, and a waveguide and granular materials are arranged in the simulation cavity, the waveguide is arranged in a vertical direction, the granular materials are filled in the inside of the waveguide or arranged around the waveguide, during the shear test, the landslide rock and soil materials are deformed, and the granular materials can generate acoustic emission signals; A test unit, the test unit comprising a first loading mechanism and a second loading mechanism, the first loading mechanism being located at the top of the upper shear box and being capable of applying a normal pressure to the simulation unit, the second loading mechanism being located at one side of the simulation unit and being capable of applying a force to the lower shear box in a horizontal direction; A signal acquisition and analysis unit, the signal acquisition and analysis unit comprises an acoustic emission sensor and a signal analysis module, the acoustic emission sensor is communicatively connected with the waveguide and is used to acquire acoustic emission signals, and the signal analysis module can analyze the acoustic emission signals generated during the shear test.

2. The test device for locating the sliding surface of soil slope based on acoustic emission according to claim 1 is characterized in that: The test unit also includes a cover plate and a support frame, the cover plate can cover the top of the landslide rock material in the simulation cavity, the first loading mechanism includes a force-applying pressure rod and a pressure rod support foot, one end of the force-applying pressure rod is hinged to the support frame, and the hinge axis of the two is parallel to the horizontal direction, the pressure rod support foot is arranged at the bottom of the force-applying pressure rod, and the force-applying pressure rod is abutted against the cover plate, and a force is applied to the end of the force-applying pressure rod away from the support frame, so as to realize the application of normal pressure to the landslide rock material in the simulation cavity and the waveguide tube through the pressure rod support foot; the upper shear box is detachably connected to the support frame.

3. The test device for locating the sliding surface of soil slope based on acoustic emission according to claim 2 is characterized by: The pressure rod support foot is an inverted T-shaped structure, and the pressure rod support foot includes a connecting rod and a transverse pressure plate, the connecting rod connects the force-applying pressure rod and the transverse pressure plate, and the transverse pressure plate can abut against the cover plate; One end of the force-applying pressure rod away from the support frame is connected to a counterweight tray, and the counterweight tray can accommodate a counterweight object.

4. The test device for locating the sliding surface of soil slope based on acoustic emission according to claim 3 is characterized in that: The number of the force-applying pressure rods is multiple groups, and the force-applying pressure rods are arranged at equal intervals along the direction in which the second loading mechanism applies a force to the lower shear box, and the pressure rod legs and the counterweight tray correspond to the force-applying pressure rods one by one.

5. The test device for locating the sliding surface of soil slope based on acoustic emission according to claim 2 is characterized in that: The second loading mechanism includes a driver and a shear rod. The driver is arranged on the support frame. The output end of the driver is transmission-connected to one end of the shear rod. The other end of the shear rod is connected to the lower shear box. The driver can drive the shear rod to move in the horizontal direction.

6. The test device for locating the sliding surface of soil slope based on acoustic emission according to claim 5 is characterized by: The second loading mechanism also includes a transmission screw and a slider nut. The output end of the driver is connected to the transmission screw, the transmission screw is rotatably connected to the support frame, the slider nut is threadedly connected to the transmission screw, and the slider nut is connected to the shear rod.

7. The test device for locating the sliding surface of soil slope based on acoustic emission according to claim 6 is characterized by: The support frame has a mounting plate, one end of the transmission screw rod away from the driver is rotatably connected to the mounting plate, and the shear rod is connected to the lower shear box after sliding through the mounting plate; The second loading mechanism further includes a tension sensor and a distance measuring element. The tension sensor is arranged between the shear rod and the support frame. The distance measuring element is connected to the slider nut to monitor the displacement of the slider nut.

8. The test device for locating the sliding surface of soil slope based on acoustic emission according to claim 2 is characterized by: The cover plate has a through hole matched with the waveguide tube; when the granular material is filled in the interior of the waveguide tube, the cover plate also has a pressure cap matched with the inner diameter of the waveguide tube.

9. The test device for locating the sliding surface of soil slope based on acoustic emission according to any one of claims 1 to 8, characterized in that: The signal acquisition and analysis unit also includes an amplifier and a signal acquisition card. The amplifier is communicatively connected to the acoustic emission sensor to enhance the strength of the acoustic emission signal. The amplifier is also communicatively connected to the signal acquisition card. The signal acquisition card is used to convert the acoustic emission signal into a digital signal. The signal acquisition card can also transmit the converted digital signal to the signal analysis module.

10. A test method for locating the sliding surface of soil slope based on acoustic emission, characterized in that: The test device for locating the slip surface of a soil slope based on acoustic emission according to any one of claims 1 to 9 comprises the following steps: filling the simulation cavity with landslide rock and soil materials, connecting the waveguide tube with the acoustic emission signal sensor, applying normal pressure to the simulation unit using the first loading mechanism, applying force to the lower shear box in the horizontal direction using the second loading mechanism, the landslide rock and soil materials in the simulation cavity deform under the action of shear force, the granular material generates an acoustic emission signal, and the signal acquisition and analysis unit acquires and analyzes the acoustic emission signals during the loading process to analyze and locate the slip surface.

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