A direct shear model device for monitoring the shear deformation of slopes

Abstract

The present invention relates to the field of engineering technology, and discloses a direct shear model device for monitoring slope shear deformation, which includes a shear box, a loading system, a DIC monitoring system, a data acquisition system and a fixing device. In order to characterize the shear process of soil mass and summarize the shear failure mode of soil mass in the direct shear model test, a tempered glass structure is constructed. It is mainly composed of two shear boxes with dimensions of 2*1*0.5 (length, width, height) cubic meters and one shear box with dimensions of 2*1*1 (length, width, height) cubic meters. The large shear box on the left is connected to the middle shear box by a rotatable shaft, and a detachable baffle is provided at the bottom. A buckle is provided at the bottom of the shear box for fixing the fiber optic sensor used for testing. The direct shear model device for monitoring slope shear deformation provided by the present invention provides a new idea for solving the needs of research on the initiation and expansion of shear bands in slope soil.

Description

Technical Field

[0001] The present invention relates to the field of engineering technology, particularly to the field of laboratory simulation research, and more particularly to a direct shear model device for monitoring the shear deformation of slopes. Background Art

[0002] Slope disasters are sudden and highly destructive. When severe, they can interrupt traffic and destroy buildings, causing huge property losses to human society and even more seriously, casualties. Among slope movements, landslide disasters are the most difficult to predict. Landslide movements are mainly controlled by the shear deformation behavior in the sliding area. Deeply understanding the deformation of the sliding surface is of great significance for slope stability assessment and landslide event early warning.

[0003] In recent years, fiber optic sensing technology has been widely applied in slope stability monitoring. In particular, the fiber Bragg grating (FBG) has shown great application potential and excellent performance in slope stability monitoring. The fiber Bragg grating (FBG) is an optical device that uses the grating structure in the optical fiber to reflect and transmit light. When a broadband optical signal is input into the optical fiber, only light of a specific wavelength will be reflected back by the FBG, while light of other wavelengths will be transmitted through. This specific wavelength is called the Bragg wavelength, which is related to the strain and temperature changes in the optical fiber. It has the advantages of good economic efficiency, high measurement accuracy, quasi-distributed measurement, and real-time monitoring. It is a low-cost and high-performance alternative to a variety of commercial distributed fiber optic sensors. It is widely used in monitoring parameters such as strain, temperature, and vibration of large buildings such as bridges and tunnels. It plays a very important role in slope stability monitoring and is often used to monitor the deformation and displacement of slope disasters. By analyzing data, it can timely warn of the potential occurrence of disasters and ensure the safety of people's lives and property. Determining the relationship between the FBG strain measurement value and the soil shear displacement is a difficult problem that must be solved for the development of an FBG-based slope deformation monitoring system.

[0004] It is difficult to establish a full-range real-time monitoring of slope disasters in the field, and monitoring the deformation of the shear zone of slopes is crucial for understanding the dynamic process of slope evolution and evaluating slope stability.

[0005] Therefore, the present invention proposes a direct shear model device for monitoring the shear deformation of slopes, which is used to simulate the actual state of slopes in the field. By conducting direct shear model experiments, it studies the initial state and development process of the shear zone in the soil, and has a very important impact on slope stability monitoring. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a direct shear model device for monitoring the shear deformation of slopes, to meet the need for determining the relationship between the FBG strain measurement value and the soil shear displacement for the development of an FBG-based slope deformation monitoring system.

[0007] The direct shear model device for monitoring slope shear deformation provided by the present invention includes a shear box, a loading system, a DIC monitoring system, a data acquisition system, and a fixing device: among them, the shear box is used to simulate the shear state that the soil mass may encounter in actual situations; the loading system is used to apply vertical stress and horizontal shear force; the DIC monitoring system is used to monitor and capture the dynamic process of subtle displacement changes in real time; the data acquisition system is used to measure the shear displacement and record and analyze the data.

[0008] Preferably, three shear boxes are used in the device, two of which have the same size. One is fixed by a fixing device, and the other can slide along the sliding groove under the influence of shear force to achieve the effect of simulating the shear displacement of the slope; the size of the third shear box is different from the previous two in height and is equipped with a removable baffle, which is connected to the fixed shear box by a rotatable shaft. When it rotates clockwise to a certain angle, it can simulate a slope model with an inclination angle. When the two shear boxes overlap, the baffle is removed and a shear force is applied to synchronously monitor the deep displacement; the shear joints located above, below, left, and right can well simulate the shear movement of the soil sample along this joint during this process.

[0009] Preferably, the loading system consists of a loading device and a cylinder: the loading device realizes the vertical stress received in the actual process through an external force, and the pressure size is controlled by the cylinder, and a pressure sensor is equipped to control the size of the vertical stress; the cylinder at the shear box position is used to provide horizontal shear force to simulate the shear movement of the soil sample after applying the horizontal shear force.

[0010] Preferably, the DIC monitoring system is connected to the computer terminal by a digital camera and a high-resolution motion camera in a network communication manner and uses professional software for data processing. The DIC technology is based on the principle of image correlation and can monitor and capture the dynamic process of subtle displacement changes in real time. It is very suitable for non-contact measurement of the strain and displacement of the entire experimental area.

[0011] Preferably, the data acquisition system includes a laser displacement meter and a computer terminal: the laser displacement meter is an instrument that uses laser technology to measure the distance between the surface of an object and the laser source. It is commonly used for non-contact measurement. It has high stability, strong anti-interference ability, can respond quickly, and is suitable for dynamic monitoring. In this device, the laser displacement meter is used to measure the shear displacement; the computer terminal integrates data recording and data analysis, and verifies the experimental results of the fiber optic sensor in the experimental process by analyzing and processing the data of the DIC and the laser displacement meter.

[0012] Preferably, the fixing device consists of a steel structure bracket and a buckle: the steel structure bracket is stable and firm and can play a supporting role; the buckle is placed at the bottom of the shear box to fix the optical fiber for testing and avoid interference from other factors to the experimental results.

[0013] Preferably, the device is applied to systematic and simulated experiments on the fiber optic sensors to be tested. By adjusting the inclination of the large shear box on the left, a slope model can be simulated. When the inclination is 90 degrees, the detachable baffle can be removed to simulate the shear force on the sensing optical fiber at different depths in the vertical state. When the middle shear box and the right shear box are joined together, there is a shear gap in the middle. By fixing the middle shear box and applying a horizontal shear force to the right shear box through a cylinder, the shear force on the fiber optic sensor in the horizontal state can be simulated. The DIC monitoring system and the data acquisition system process the collected data, and the strain values measured by the fiber optic sensors are compared with the shear displacement of the soil through conversion to further verify that the studied fiber optic sensors can achieve the required accuracy and functions.

[0014] Compared with the related technologies, the direct shear model device for monitoring slope shear deformation provided by the present invention has the following beneficial effects:

[0015] 1. The direct shear model device for monitoring slope shear deformation provided by the present invention can help researchers more efficiently understand the initiation and expansion of shear zones in slope soil, and can provide technical support for the detection and early warning of slope stability.

[0016] 2. The direct shear model device is an important experimental device, which plays an important role in slope research and prevention; the direct shear model experiment can be carried out in the laboratory, and the experimental conditions can be precisely controlled, solving the problems of difficult detection and too many uncontrollable factors under field conditions; and the device is simple and easy to operate, the experimental process can be repeated, the test cost is low, and it can be combined with other slope experiments; this device has the advantages of simplicity, economy and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a direct shear model device for monitoring slope shear deformation provided by the present invention;

[0018] Figure 2 is a schematic plan view of the direct shear model in Embodiment 1;

[0019] Figure 3 is a schematic structural diagram of the DIC device in Embodiment 2;

[0020] Figure 4 is a schematic block diagram of the principle of strain and displacement measurement realized by DIC in Embodiment 2;

[0021] Figure 5 is a schematic diagram of the laser displacement meter in Embodiment 2;

[0022] Figure 6 is a schematic block diagram of the principle of the laser displacement meter in Embodiment 2.

[0023] Reference numerals: 1, fixing device; 2, loading device; 3, laser displacement meter; 4, detachable baffle; 5, cylinder; 6, rotatable shaft; 7, DIC system; 8, shear seam; 9, buckle; 10, DIC device; 11, card slot; 12, laser emitter; 13, receiver; 14, signal processor; 15, output device. Detailed implementation manners

[0024] The present invention will be further described below in conjunction with the accompanying drawings and implementation manners.

[0025] The direct shear model device for monitoring the shear deformation of a slope provided by the present invention includes a shear box, a loading system, a DIC monitoring system, a data acquisition system, and a fixing device, wherein:

[0026] (1) The shear box is a key component in the experimental device. Its design can simulate the shear state that the soil may encounter in actual situations. A total of 3 shear boxes are used in this device. Two of the shear boxes have the same size (length, width, and height are 2 m, 1 m, and 0.5 m respectively), and one is fixed by a fixing device, and the other can slide along the sliding groove under the influence of shear force to achieve the effect of simulating the shear displacement of the slope. The third shear box has a different height from the previous two (length, width, and height are 2 m, 1 m, and 1 m respectively), and is equipped with a detachable baffle, which is connected to the fixed shear box by a rotatable shaft. When it rotates clockwise to a certain angle, it can simulate a slope model with an inclination angle. When the two shear boxes overlap, the baffle is removed and a shear force is applied, and the deep displacement can be monitored synchronously. The shear box is composed of tempered glass, and marking points and scales are arranged on the outside for visual observation. The tempered glass is transparent, has high strength and high safety. The bottom is made of steel structure and is equipped with a grille to increase friction. The types of shear boxes include standard and specially designed shear boxes. For special experimental requirements, specially shaped shear boxes can be designed. Its design and manufacturing quality directly affect the accuracy and reliability of the experimental results. Therefore, when designing and using the shear box, it is necessary to strictly follow the experimental standards and operating procedures.

[0027] (2) The loading system consists of a vertical loading device and a cylinder, which simulates the vertical stress that the soil is subjected to in actual engineering, usually by applying a certain pressure to simulate the self-weight of the soil or external loads. The cylinder provides a horizontal shear force, and an automatic control module can be added later.

[0028] (3) The DIC monitoring system is composed of a digital camera and a high-resolution motion camera connected to a computer terminal in a network communication manner and uses professional software for data processing. Modern cameras and image acquisition devices have high parameters, which can meet the recording of the rapid deformation process and can be quickly calculated by professional software. The DIC technology can measure the deformation and displacement fields of the entire object surface, including parameters such as deformation gradient and strain, and rich test data can be obtained.

[0029] (4) The data acquisition system consists of a laser displacement meter and a computer terminal. The laser displacement meter has strong anti-interference ability, high precision, and is less affected in extreme environments. The working principle of the laser displacement meter is based on laser ranging technology. The laser emitter emits a beam of laser, which is reflected after hitting the object surface. The reflected laser is captured by the receiver and converted into an electrical signal. By measuring the time difference or phase difference between the laser emission and reception, the distance between the laser beam and the object surface can be calculated. The computer terminal performs data integration and processing.

[0030] (5) The fixing device consists of a steel structure bracket and a buckle. The steel structure has good plasticity, can be processed and formed according to needs, meets various design requirements, and has high strength, which can play a good supporting role. The buckle is made of plastic, light in weight, corrosion-resistant, simple and easy to operate, and can be recycled, greatly reducing the impact on the experimental results.

[0031] Example 1:

[0032] Taking the direct shear model experiment as an example.

[0033] In the direct shear model experiment device, the shear box is a key component of the experimental device. Its design can simulate the shear state that the soil mass may encounter in actual situations. The function of the shear box is to accommodate the soil sample and ensure a closed shear environment during the experiment. A total of three shear boxes are used in this device, with buckles at the bottom. The plan view is as Figure 2 shown. Two of the shear boxes have the same size, and one is fixed with a fixing device, while the other can slide along the sliding groove under the influence of the shear force to achieve the effect of simulating the shear displacement of the slope. The size of the third shear box is different from the previous two in height and is equipped with a removable baffle, which is connected to the fixed shear box by a rotatable shaft. When it is rotated clockwise to a certain angle, it can simulate a slope model with an inclination angle. When the two shear boxes overlap, the baffle is removed and the shear force is applied, and the deep displacement can be monitored synchronously. The experimental process is as follows: Prepare the soil sample, fill it evenly, and avoid being too dry or wet to meet the experimental requirements. Calibrate the equipment, adjust the three shear boxes to the angles that meet the experimental conditions, ensure that the DIC monitoring system, the loading device, and the data acquisition system are operating normally. The loading system applies vertical pressure to avoid uneven compaction of the soil sample, which may affect the experimental results. The cylinder applies horizontal shear force, and the shear rate is constant. Pay attention to safety during the operation, and operate strictly in accordance with the experimental steps. To ensure the reliability of the experiment, multiple tests should be carried out, and at the same time, pay attention to the temperature and humidity of the experimental environment to reduce the impact on the experimental results. Follow the above experimental steps and precautions to ensure the accuracy and reliability of the experiment, thereby providing effective data.

[0034] Example 2:

[0035] Take the DIC monitoring system and the laser displacement meter as examples.

[0036] For the structural diagram of the expected designed DIC monitoring system, see Figure 3 , this system connects a digital camera and a high-resolution motion camera to a computer terminal through network communication for data processing. DIC technology is an advanced non-contact full-field deformation measurement technology, with advantages such as non-contact measurement, full-field measurement, high precision, high resolution, and wide application range. DIC realizes displacement and strain measurement through the following steps. The principle block diagram is as Figure 4 shown. Before the experiment starts, the equipment is debugged. The digital camera and the high-resolution motion camera are used to capture the surface images of the slope soil deformation before and after. The captured images are preprocessed, such as denoising, enhancing, and classifying, to improve the quality. Feature points are set and marked in advance before the experiment, and the corresponding positions of these feature points are searched after deformation. Through correlation function calculation, the position changes of the feature points before and after deformation are determined. Based on the displacement of the feature points, the displacement field and strain field of the entire test area are calculated. Through the DIC monitoring system, the deformation of the test area can be monitored in real time, and the observation of the dynamic process can be realized. The fiber Bragg grating (FBG) is tested through a direct shear model device. By comparing the DIC and the strain measurement values of the fiber Bragg grating (FBG), they can verify each other. It can greatly improve the efficiency.

[0037] It should be noted that the laser displacement meter is an instrument that uses laser technology to measure the distance or displacement between the surface of an object and the laser source. As Figure 5 shown, it is used to measure shear displacement and is a tool that can measure without contacting the surface of the object, with the advantages of high precision, real-time measurement, and strong anti-interference performance. Its measurement principle is as Figure 6 shown. In engineering applications, it is often used to study the deformation behavior of materials under force or temperature changes. Before use, calibration should be carried out to ensure the measurement accuracy. At the same time, attention should be paid to the installation position of the laser displacement meter to avoid the installation position of the laser displacement meter affecting the experimental results.

[0038] The above are only embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent structural or equivalent process transformations made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are equally included in the patent protection scope of the present invention.

Claims

1. A direct shear model device for monitoring slope shear deformation, characterized in that: Includes shear box, loading system, DIC monitoring system, data acquisition system and fixture: Wherein, the shear box is used to simulate the shear state encountered by the soil in actual situations; The loading system is used to apply vertical stress and horizontal shear force; The DIC monitoring system is used to monitor and capture the dynamic process of subtle displacement changes in real time; The data acquisition system is used to measure shear displacement and record and analyze data; Three shear boxes are used in the device, two of which have the same size, and one is fixed by a fixing device, and the other slides along the sliding groove under the influence of shear force to achieve the effect of simulating shear displacement of the slope; the size of the third shear box is different from the first two in height, and is equipped with a detachable baffle, which is connected to the fixed shear box with a rotatable shaft, and when it is rotated clockwise to a certain angle, it simulates a slope model with an inclined angle. When the two shear boxes overlap, the baffle is removed, the shear force is applied, and the deep displacement is monitored synchronously; the shear joints located above and below and left and right are used to simulate the shear movement of the soil sample along the joint during this process.

2. The direct shear model device for monitoring slope shear deformation according to claim 1, characterized in that: The loading system consists of a loading device and a cylinder: the loading device realizes the vertical stress in the actual process through external force, the pressure is controlled by the cylinder, and a pressure sensor is equipped to control the magnitude of the vertical stress; the cylinder at the shear box position is used to provide horizontal shear force to simulate the shear movement of the soil sample after the horizontal shear force is applied.

3. The direct shear model device for monitoring slope shear deformation according to claim 1, characterized in that: The DIC monitoring system is composed of a digital camera and a high-resolution motion camera connected to a computer via network communication and using professional software for data processing. DIC technology is based on the principle of image correlation, real-time monitoring, and capturing the dynamic process of subtle displacement changes. It is suitable for non-contact measurement of strain and displacement of the entire experimental area.

4. The direct shear model device for monitoring slope shear deformation according to claim 1, characterized in that: The data acquisition system includes a laser displacement meter and a computer terminal: the laser displacement meter is used to measure shear displacement; the computer terminal integrates data recording and data analysis, and verifies the experimental results of the optical fiber sensor in the experimental process by analyzing and processing the data of DIC and laser displacement meter.

5. The direct shear model device for monitoring slope shear deformation according to claim 1, characterized in that: The fixing device is composed of a steel structure bracket and a buckle: the steel structure bracket is stable and strong and can play a supporting role; the buckle is placed at the bottom of the shear box and is used to fix the optical fiber used for testing to prevent other factors from interfering with the experimental results.

6. The direct shear model device for monitoring slope shear deformation according to claim 1, characterized in that: The device is used to conduct systematic and simulated experiments on the optical fiber sensor required to be tested. The slope model is simulated by adjusting the inclination of the large shear box on the left. When the inclination is 90 degrees, the disassembly baffle is removed to simulate the shear force on the sensing optical fiber at different depths in a vertical state. When the middle shear box and the right shear box are spliced, a shear gap is left in the middle. By fixing the middle shear box, a horizontal shear force is applied to the right shear box through a cylinder to simulate the shear force on the optical fiber sensor in a horizontal state. The DIC monitoring system and data acquisition system process the collected data and compare the strain value measured by the fiber optic sensor with the shear displacement of the soil through conversion, further verifying that the fiber optic sensor under study can achieve the required accuracy and function.

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