Visual test system and method for compaction transparency of soil-rock mixed filler

Abstract

The invention discloses a soil-rock mixed filler compaction transparency visual test system and method, and relates to the technical field of civil engineering test equipment. In order to solve the problem that the movement and deformation of soil particles in the soil-rock mixed filler cannot be observed and recorded in the compaction process, the following technical scheme is provided: the device comprises a reaction frame and a model groove formed in the inner side of the reaction frame, an actuator is arranged at the top of the reaction frame, a double-track ball screw transmission mechanism is arranged between the reaction frame and the actuator, and the double-track ball screw transmission mechanism is arranged in the model groove. A pressure sensor is arranged at the bottom of the actuator, and the bottom of the pressure sensor compacts the transparent soil in the model groove through a roller; a laser is arranged at the side end of the model groove and irradiates the transparent soil in the model groove to present a speckle field plane, and an industrial camera is fixed right behind the model groove and collects speckle field pictures generated in the compaction process. According to the invention, visual monitoring and analysis of the compaction process of the soil-rock mixed filler can be comprehensively and accurately realized.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering test equipment, and in particular to a soil-rock mixed filler compaction transparent visualization test system and method. Background Art

[0002] In recent years, my country's highway and railway construction has rapidly expanded, and soil-rock fill materials are increasingly being used as roadbed fill materials in more and more projects. However, current research on roadbed fill materials is primarily based on homogeneous soil or rock fill. Research on the compaction of soil-rock fill materials is relatively scarce, and the compaction characteristics of heterogeneous soil-rock fill materials are still underdeveloped. The compaction quality of soil-rock fill materials is crucial to the stability and durability of engineering structures. Even the slightest inaccuracy during construction can easily lead to quality problems. Therefore, it is necessary to study the compaction characteristics of heterogeneous soil-rock fill materials.

[0003] Currently, the main compaction methods for roadbed soil-rock mixtures include vibration compaction, static compaction, impact compaction, and dynamic tamping. However, these traditional compaction test methods make it difficult to visually observe the movement and deformation of soil particles, hindering a deep understanding of the compaction mechanism. Furthermore, the use of invasive instruments for measurements at specific locations not only fails to capture continuity but also affects the degree of soil compaction due to the instrument's involvement. Therefore, the development of a compaction test system that enables transparent visualization is of great significance.

[0004] Transparent soil materials can be used to measure the displacement of the soil inside the filler and observe its deformation process using a non-embedded method for compacted soil-rock mixtures. In addition, combined with PIV image processing technology, the displacement cloud map and compaction degree changes of the filler during the compaction process can be continuously collected and analyzed. The preparation principle of transparent soil is to mix transparent granular solids with transparent liquids of the same refractive index, allowing the transparent liquid to fill the voids in the transparent material particles to obtain a transparent mixture to simulate saturated soil, thereby enabling the displacement field changes of the particles inside the soil to be collected. The preparation of transparent soil must fully consider the similarity between transparent soil and natural soil, and at the same time ensure that the transparency of the prepared soil meets certain requirements to ensure the rationality of the model test. Summary of the Invention

[0005] The purpose of the present invention is to provide a soil-rock mixed filler compaction transparent visualization test system and method to solve the problem that the movement and deformation of internal soil particles in the existing soil-rock mixed filler cannot be observed and recorded during the compaction process.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] A soil-rock mixed filler compaction transparent visualization test system includes: a reaction frame and a model tank arranged inside the reaction frame, an actuator is provided on the top of the reaction frame, a double-track ball screw transmission mechanism is provided between the reaction frame and the actuator, a pressure sensor is provided at the bottom of the actuator, and the bottom of the pressure sensor compacts the transparent soil in the model tank through a roller;

[0008] A laser is installed at the side of the model trough. The laser illuminates the transparent soil in the model trough to present a speckle field plane. An industrial camera is fixed directly behind the model trough to collect the speckle field images generated during the compaction process.

[0009] Furthermore, a slide groove is provided at the center line of the bottom plate of the double-track ball screw transmission mechanism, and the pressure sensor is connected to the roller through the slide groove.

[0010] Furthermore, a high-definition camera is provided in front of the model tank to capture the displacement and deformation of the dyed characteristic particles during the compaction of the transparent soil in the model tank, as well as the differences in the movement trajectories of particles of different sizes.

[0011] A test method using a soil-rock mixed filler compaction transparent visualization test system comprises the following steps:

[0012] S1. Equipment assembly and fixation: Fix the actuator to the double-track ball screw transmission mechanism, install the actuator and the double-track ball screw transmission mechanism on the reaction frame, and install a pressure sensor on the lower part of the actuator; connect the pressure sensor to the roller through the bottom plate slide of the transmission mechanism; fix the laser on one side of the model slot, and adjust its position so that the sheet laser surface generated by the laser fully covers the model slot; fix the industrial camera directly behind the model slot, calibrate the camera angle and position so that only the front of the model slot is shown in the picture; fix the high-definition camera directly in front of the model slot, adjust the camera parameters so that only the front of the model slot appears in the picture and focuses on the characteristic dyed particles in the soil-rock mixed filler; embed a fiber Bragg grating sensor array FBG in the side wall of the model slot, integrate a MEMS micro-vibration sensor on the surface of the roller, and transmit the sensor data to the control terminal in real time through a wireless transmission module;

[0013] S2. Prepare transparent soil-stone mixed filler:

[0014] S21. Determine the test temperature and infiltration treatment: Determine the test temperature of the compaction process, and infiltrate the fused silica particles with white oil having a refractive index of 1.4580±0.005;

[0015] S22. Select and dye fused quartz particles: Based on the gradation range of the selected embankment fill gravel, select fused quartz particles with a characteristic particle size that is recognizable in the speckle field, perform fluorescent dyeing on them, and implement fluorescent dye coding on fused quartz sand of different particle sizes to ensure that the high-definition camera can track the dyed fused quartz sand of different particle sizes under the action of laser. The dyed fused quartz sand accounts for 1 / 4 of the mass of the transparent gravel.

[0016] S23. Preparing transparent clay: thoroughly mixing fumed silica powder with a mixed pore solution having the same refractive index, wherein the mixed pore solution is prepared by mixing white oil and n-dodecane in a specific ratio at a predetermined test temperature. During the preparation process, an appropriate amount of tracer particles is added, and the mixed solution, fumed silica, and tracer particles are uniformly stirred using a stirring device to prepare transparent clay;

[0017] S24, mixing transparent gravel and transparent clay: adding the prepared transparent gravel to the transparent clay according to a predetermined mass ratio, and thoroughly stirring and mixing using a stirring device to uniformly disperse the dyed fused quartz sand. After stirring, the soil-stone mixed filler is placed in a vacuum tank, and the air inside the soil is expelled by vacuuming to produce a transparent soil-stone mixed filler;

[0018] S3. Filling and consolidating transparent soil-rock mixed filler:

[0019] S31. Filling fillers in batches: Fill the transparent soil-rock mixed filler into the model tank in batches to ensure uniform filling and reduce the impact of air mixing on soil transparency;

[0020] S32, applying pressure in stages for consolidation: sequentially placing a qualitative filter paper with a pore size of 1.3 microns soaked with the mixed pore liquid and a perforated organic glass pressure plate on the slurry surface, gradually placing weights on the pressure cover plate, and applying pressure in stages to promote oil drainage and consolidation of the mixed slurry;

[0021] S4. Driving the roller to compact the soil: The actuator is controlled to input a specified downward pressure load, and at the same time, a reciprocating motion instruction within a specified range is input to the double-track ball screw transmission mechanism supporting the actuator, driving the roller to apply a stable reciprocating downward pressure load to the transparent soil. A vibration excitation module and an impact load device are installed in the double-track ball screw transmission mechanism, so that the roller can superimpose vibration frequency or impact energy while applying a static load, simulating various engineering compaction processes such as vibration compaction and dynamic tamping.

[0022] S5. Capturing speckle field images: The parameters of the industrial camera are adjusted according to the model groove size, laser irradiation angle, and soil optical properties. During the test, speckle field images are automatically captured at preset intervals to ensure that the speckle field images of the soil-rock mixed filler during the compaction process are fully captured and a high-quality image dataset is stored.

[0023] S6. Recording the changes in the dyed particles: A high-definition camera is set up in front of the model tank. The camera is focused on the characteristic dyed particles inside the soil-rock mixture filler of the model tank. The video function is immediately activated after the actuator applies a load for compaction. The video is continuously recorded until the entire compaction process is completed, and the video of the compaction process is stored.

[0024] S7. Collect and analyze data:

[0025] S71. Measure and calculate relative density: Measure the maximum dry density ρ of the soil-rock mixture before compaction d，max and the minimum dry density ρ d,min , after each compaction, the expression is:

[0026]

[0027] Calculate the relative density D of soil-rock mixed filling r ;

[0028] S72. Analyze displacement and acceleration vectors: Collect speckle field images captured by industrial cameras before and after each compaction stage. Combined with PIV image processing technology, calculate the displacement and acceleration vector size of the soil particles inside the soil-rock mixed filler. Draw a displacement cloud map of the soil-rock mixed filler during the compaction process. Analyze the displacement cloud map to obtain the volume change of the soil-rock mixed filler. Further calculate the density D of the soil-rock mixed filler at this compaction stage. r , and then analyze to get the relative density distribution map of the whole field;

[0029] S73. Tracking the movement trajectory of dyed particles: Analyze high-definition video footage of dyed fused quartz sand captured by a high-definition camera, use video processing software to track dyed particles with different fluorescence spectra, and analyze the displacement and deformation of characteristic dyed particles during the compaction process, as well as the differences in movement trajectories between particles of different particle sizes;

[0030] S74. Recording load and displacement values: Record the load applied by the actuator during the compaction process, control the downward pressure load to remain constant during each compaction stage, and record the displacement value fed back by the actuator in real time. When the displacement value remains constant during a compaction stage, the compaction stage is determined to be complete, and the downward pressure load is increased to enter the next compaction stage.

[0031] S8. Determine the degree of compaction: After all preset downward pressure loads are applied, the displacement information fed back by the actuator in the last compaction stage is observed to no longer change, and the compaction operation is terminated. The cone tip resistance and side wall friction resistance of the compacted soil-rock mixture are measured using a micro static penetration test to determine whether the compacted soil-rock mixture meets the compaction requirements.

[0032] Furthermore, in step S1, the fiber Bragg grating sensor array FBG is arranged in a distributed manner and evenly distributed along the height and width directions of the side wall of the model groove to more comprehensively monitor the stress changes of the soil-rock mixed filler at different positions.

[0033] Furthermore, in the step of preparing the transparent soil-rock mixed filler in step S2, the stirring device is a planetary stirrer, the stirring speed is set to 50-150 rpm, and the stirring time is 10-30 minutes to ensure that the mixed solution, fumed silica and tracer particles are fully mixed.

[0034] Furthermore, in the step of applying pressure and consolidating in step S3, the mass of the weights is increased in the order of 5 kg, 10 kg, 15 kg, and 20 kg. After each weight is applied, the pressure is maintained for 10-20 minutes to ensure that the mixed slurry is fully drained and consolidated.

[0035] Furthermore, in step S4, the vibration frequency of the vibration excitation module is adjusted to an accuracy of ±0.5 Hz, and the impact energy of the impact load device is adjusted to an accuracy of ±1 J, so as to accurately simulate different engineering compaction processes.

[0036] Furthermore, in step S5, the preset interval is 1-5 minutes, and the shooting frame rate of the industrial camera is 1-10 frames per second to ensure that the dynamic changes of the speckle field of the soil-rock mixed filler during the compaction process are captured.

[0037] Furthermore, in the step of tracking the movement trajectory of the dye particles in step S73, the video processing software uses an algorithm based on feature point matching to identify and track the dye particles with different fluorescence spectra, and its identification accuracy is not less than 95%.

[0038] The present invention has the following beneficial effects:

[0039] By focusing on characteristic dyed particles within the soil-rock mixture with a high-definition camera and capturing speckle field images with an industrial camera, the displacement and deformation of soil-rock particles during compaction, as well as the differences in motion trajectories between particles of different sizes, can be observed in real time and intuitively. For example, when simulating the compaction of soil-rock fillers in actual projects, one can clearly see how large gravel particles move and how small clay particles fill the voids. This is like observing the microscopic changes within the soil-rock filler through a "transparent window," providing an intuitive basis for in-depth research on compaction mechanisms.

[0040] The high-definition camera continuously records the changes in the soil-rock filler throughout the compaction process. This facilitates subsequent analysis and research of the compaction process, uncovering details and patterns that might otherwise be overlooked. For example, by replaying the video, it is possible to analyze the cause of sudden acceleration or deceleration of particle movement at a certain stage in the compaction process, thereby optimizing the compaction process parameters.

[0041] A vibration excitation module and impact load device are installed in the dual-track ball screw transmission mechanism, allowing the roller to superimpose different vibration frequencies (0-50Hz) or impact energy while applying a static load, accurately simulating various engineering compaction processes such as vibration compaction and dynamic tamping. This is like being able to "switch between" different engineering compaction scenarios on a single test platform, providing convenient conditions for studying the impact of different compaction processes on the compaction effect of soil-rock mixed fillers. By determining the test temperature of the compaction process, impregnating fused quartz particles with white oil of a specific refractive index, and preparing transparent clay with a mixed pore fluid with the same refractive index, a high degree of similarity between the test environment and the actual engineering environment in terms of optical properties is ensured. For example, when constructing embankments in different regions and seasons, factors such as ambient temperature and humidity will affect the compaction effect of the filler. This test method can improve the accuracy and reliability of the test results by controlling the test temperature to simulate the compaction process under different environmental conditions.

[0042] Using a variety of sensors (pressure sensors, fiber Bragg grating sensor arrays, and MEMS micro-vibration sensors) to collect real-time data on load, stress, vibration, and other aspects of the compaction process, combined with image and video data captured by industrial cameras and high-definition video cameras, this enables multi-dimensional, all-encompassing monitoring of the compaction process. This data, like a "code," comprehensively reflects the changes in the physical and mechanical state of the soil-rock mixture during compaction.

[0043] Using PIV image processing technology to analyze speckle field images, we determine the displacement and acceleration vectors of particles within the soil-rock filler, plotting displacement contours and calculating relative density distributions. Video processing software is used to track the motion of the dyed particles, analyzing their displacement, deformation, and the differences in motion between particles of different sizes. The load and displacement of the actuator are also recorded to determine the end point of the compaction phase. These analytical methods can provide insights into the inherent laws and mechanisms of the compaction process.

[0044] This test method greatly shortens the test cycle and improves test efficiency through automated equipment operation (such as actuator input of specified load, reciprocating motion of double-track ball screw transmission mechanism, automatic shooting of industrial cameras and high-definition cameras, etc.) and real-time data collection and analysis. Compared with traditional compaction test methods, this solution reduces the time of manual operation and data processing, allowing test personnel to obtain test results more quickly. Precise equipment assembly and fixation, strict control of test conditions (such as temperature, refractive index, etc.) and multi-dimensional, high-precision data collection and analysis ensure the accuracy and reliability of the test results. By using transparent soil-rock mixed fillers and advanced visual monitoring technology, the compaction process in actual engineering can be simulated more realistically, reducing errors caused by inaccurate test conditions or imperfect monitoring methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the overall structure of the compaction system of the present invention;

[0046] Figure 2 A top view of the double-track ball screw transmission mechanism of the present invention;

[0047] Figure 3 The overall front view and top view of the soil-rock mixed filler compaction transparent visualization test system of the present invention;

[0048] Figures 1 to 3 The reference numerals shown in the figure represent respectively: reaction frame 1, actuator 2, pressure sensor 3, double-track ball screw transmission mechanism 4, roller 5, model groove 6, laser 7, industrial camera 8, slide 9, high-definition camera 10. DETAILED DESCRIPTION

[0049] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0050] Please refer to Figure 1-3 , a test method of a soil-rock mixed filler compaction visualization test system

[0051] In the field of soil-rock mixed fill compaction engineering, visual monitoring and analysis of the compaction process is crucial for understanding the compaction characteristics of soil-rock mixed fill, optimizing the compaction process, and ensuring project quality. This specific embodiment details a test method for a soil-rock mixed fill compaction visualization test system, aiming to provide a comprehensive, accurate, and operational test solution for visual monitoring and in-depth analysis of the soil-rock mixed fill compaction process.

[0052] The assembly and fixation of the equipment in this test system is the basis of the entire test, and its accuracy directly affects the accuracy and reliability of subsequent test data. First, the actuator 2 is firmly fixed to the double-track ball screw transmission mechanism. During the fixation process, it is necessary to ensure that the connection between the actuator 2 and the double-track ball screw transmission mechanism is firm and tight to avoid loosening or shaking during subsequent tests. Specifically, high-strength bolts can be used to connect the mounting flange of the actuator 2 to the corresponding mounting part of the double-track ball screw transmission mechanism, and tighten them according to the specified torque value to ensure the reliability of the connection.

[0053] Secure the actuator 2 and the dual-track ball screw mechanism to the reaction frame 1. As the supporting structure for the entire test system, the reaction frame 1 must possess sufficient strength and rigidity to withstand the various forces generated during the test. During mounting, carefully adjust the position and level of the reaction frame 1 to align with the installation requirements of the actuator 2 and the dual-track ball screw mechanism. Use a spirit level to calibrate the level of the reaction frame 1, and ensure stability by adjusting the support feet at the bottom of the reaction frame 1.

[0054] Actuator 2 is connected to a pressure sensor 3 at its lower portion. The accuracy and sensitivity of pressure sensor 3 are crucial for accurately measuring load during compaction. During connection, ensure the contact surface between pressure sensor 3 and actuator 2 is flat and clean to avoid measurement errors caused by impurities or unevenness. A dedicated connector can be used to connect pressure sensor 3 to actuator 2, and sealant should be used to seal the connection to prevent external factors from interfering with the measurement results.

[0055] The pressure sensor 3 must be connected to the roller 5 through the chute 9 on the transmission mechanism's baseplate. During installation, ensure that the pressure sensor 3 can move smoothly within the chute 9 to accommodate the movement of the roller 5 during compaction. Also, be careful to avoid collision or friction between the pressure sensor 3 and the edges of the chute 9 to prevent damage. Apply a moderate amount of grease to the chute 9 to reduce frictional resistance, and use a limiter to limit the movement of the pressure sensor 3 to prevent it from exceeding a safe range.

[0056] Fix laser 7 to one side of model slot 6 so that the sheet laser surface covers the entire slot. The installation position and angle of laser 7 are crucial for forming a clear speckle field image. When fixing laser 7, use a dedicated laser bracket. Adjust the bracket's height, angle, and position to ensure that the laser beam evenly illuminates the surface of the soil-rock mixture filler in model slot 6. Use a laser rangefinder to accurately measure the distance between laser 7 and model slot 6. Based on the measurement results, adjust the installation parameters of laser 7 to ensure that the sheet laser surface completely covers model slot 6.

[0057] Industrial camera 8 is fixed directly behind model slot 6, so that only the front of the model slot appears in the image. The installation position and parameter settings of industrial camera 8 directly affect the quality of the captured speckle field image. When fixing industrial camera 8, a tripod or other stable support device should be used to ensure that the camera remains stable during the test. At the same time, the camera parameters such as focal length, aperture, and shutter speed should be adjusted to ensure a clear image with moderate brightness, and to capture only the front of the model slot 6. The industrial camera 8 can be calibrated using a calibration plate to eliminate image distortion and improve measurement accuracy.

[0058] The high-definition camera 10 is fixed in front of the model tank 6 so that only the front of the model tank appears in the picture and the focus is on the characteristic dyed particles in the soil-rock mixed filler. The focusing of the high-definition camera 10 is a key link, and it is necessary to ensure that the movement of the characteristic dyed particles can be clearly captured. When fixing the high-definition camera 10, a stable support device should also be used, and the lens position and focal length of the camera should be adjusted to make the characteristic dyed particles clearly visible in the picture. Manual focus or automatic focus function can be used, and selection should be made according to actual conditions. After focusing is completed, the focal length should be locked to avoid focus shift during shooting.

[0059] A fiber Bragg grating sensor array (FBG) is embedded in the sidewall of the model groove 6, and a MEMS micro-vibration sensor is integrated on the surface of the roller 5. The fiber Bragg grating sensor array (FBG) can monitor in real time the stress, strain and other parameters of the soil-rock mixed filler during the compaction process, while the MEMS micro-vibration sensor can sense the vibration of the roller 5 during the compaction process. When embedding the fiber Bragg grating sensor array (FBG), it is necessary to pre-groove the sidewall of the model groove 6, and carefully embed the sensor into the groove. Use special glue to fix it to ensure that the sensor fits tightly with the sidewall of the model groove 6 to ensure measurement accuracy. For the MEMS micro-vibration sensor integrated on the surface of the roller 5, a suitable installation position should be selected to prevent the sensor from being damaged by friction or collision during the rotation of the roller 5. The sensor can be fixed to the surface of the roller 5 by welding or gluing.

[0060] Sensor data is synchronized to the control terminal in real time via a wireless transmission module. The selection and configuration of the wireless transmission module is crucial for timely and accurate data transmission. The appropriate wireless transmission module, such as Wi-Fi, Bluetooth, or ZigBee, should be selected based on the test site environment and the volume of sensor data. When configuring the wireless transmission module, ensure that it matches the communication protocol between the sensor and the control terminal, and perform signal strength testing to ensure stable and reliable data transmission. Furthermore, encryption should be implemented within the wireless transmission module to prevent data leakage and interference.

[0061] The preparation of transparent soil-rock mixed filler is one of the core links of this test method, and its quality directly affects the accuracy and reliability of the test results.

[0062] Determine the test temperature for the compaction process and infiltrate the fused silica particles with white oil having a refractive index of 1.4580 (±0.005). The selection of the test temperature requires comprehensive consideration of the physical properties and chemical stability of the fused silica particles, the white oil, and any other additives. During the infiltration process, the fused silica particles should be placed in a container filled with white oil, ensuring that the oil completely covers the particles. A stirring device can be used to slowly agitate the mixture in the container to ensure that the white oil fully infiltrates the surface of the fused silica particles. The infiltration time can be adjusted based on actual conditions, but is generally at least 24 hours to ensure effective infiltration.

[0063] Based on the gradation of the selected embankment fill gravel, fused silica particles with a characteristic particle size that is recognizable in the speckle field are fluorescently dyed. Furthermore, fused silica sand of varying particle sizes is fluorescently dyed and coded. This allows a high-definition camera to track the dyed fused silica sand of varying particle sizes under laser illumination. The dyed fused silica sand accounts for one-quarter of the mass of the transparent gravel. When selecting the characteristic particle size, the clarity and resolution of the speckle field image, as well as the differences in the motion characteristics of particles of different sizes during compaction, must be considered. During the fluorescent dyeing process, an appropriate fluorescent dye should be selected and mixed with the fused silica sand in a specified ratio. Mechanical stirring or ultrasonic dispersion can be used to ensure uniform adhesion of the dye to the fused silica sand surface. When fluorescently coding fused silica sand of varying particle sizes, it is important to ensure distinct fluorescence spectra for accurate differentiation and tracking by the high-definition camera.

[0064] Fumed silica powder is thoroughly mixed with a mixed pore fluid with the same refractive index (approximately 1.46). The mixed pore fluid is prepared by mixing white oil and n-dodecane in a specific ratio at a predetermined test temperature. During the preparation process, an appropriate amount of tracer particles is added. A stirring device is used to evenly mix the mixed solution, fumed silica, and tracer particles to form a transparent clay. During the preparation of the mixed pore fluid, the ratio of white oil to n-dodecane must be precisely controlled. The two liquids can be accurately weighed using a weighing device and mixed in a clean container. The mixture is stirred using a stirring device, with the stirring speed and time adjusted according to the actual situation to ensure thorough mixing of the two liquids. When adding the fumed silica powder, sprinkle it in slowly and stir simultaneously to prevent powder clumping. During the stirring process, carefully observe the mixture until a uniform, viscous liquid is formed. The purpose of adding tracer particles is to more clearly observe the movement of soil particles in subsequent image processing. The selection of tracer particles should take into account their compatibility with the mixed pore fluid and their optical properties, and the amount added should be determined based on the test requirements.

[0065] Add the prepared transparent gravel to the transparent clay according to the predetermined mass ratio. Use a stirring device to mix the two thoroughly, ensuring that the dyed fused quartz sand is evenly distributed. After mixing is complete, place the soil-rock mixture into a vacuum tank and use vacuum to remove the air from the soil to produce the transparent soil-rock mixture. When mixing the transparent gravel and transparent clay, use a low-speed stirring method to avoid damaging the particles. The stirring time can be adjusted according to actual conditions, but it should generally be no less than 30 minutes to ensure thorough mixing. After mixing is complete, slowly pour the soil-rock mixture into the vacuum tank, taking care to avoid creating bubbles. Connect a vacuum pump and evacuate the tank. During the evacuation process, closely monitor the pressure inside the tank. Generally, the pressure should be reduced to below -0.09 MPa and maintained for a certain period of time (e.g., 24 hours) to ensure that the air inside the soil is fully expelled. After evacuation is complete, slowly open the valve of the vacuum tank to return the soil-rock mixture to ambient pressure. This results in the transparent soil-rock mixture.

[0066] The filling and consolidation process of transparent soil-rock mixed filler is crucial to ensure the initial state and compaction effect of the test soil sample.

[0067] The transparent soil-rock mixture filler is loaded into the model tank in batches to ensure uniform loading and reduce the amount of air mixed into the soil that affects its transparency. During the loading process, a layered loading method should be adopted. The thickness of each loading should not be too large, generally controlled at about 5-10 cm. Use a dedicated loading tool, such as a shovel or funnel, to slowly and evenly pour the soil-rock mixture filler into the model tank 6 to avoid local accumulation or voids. After each layer of loading, use a small vibrator or gently tap the side wall of the model tank 6 to initially compact the filler and reduce air mixing.

[0068] Sequentially place qualitative filter paper with a pore size of 1.3 microns soaked in mixed pore liquid and a perforated organic glass pressure plate on the slurry surface, place weights on the pressure cover plate one by one, and apply pressure in stages to drain the oil and consolidate the mixed slurry. When placing the qualitative filter paper, make sure that the filter paper completely covers the slurry surface and is free of wrinkles or damage. The perforated organic glass pressure plate should be placed stably and in close contact with the filter paper to ensure that the pressure can be evenly transmitted to the slurry. When placing weights on the pressure cover plate, it should be done according to the predetermined pressure grading scheme, which can generally be divided into 3-5 levels. The size of each level of pressure should be determined according to the test requirements and the properties of the soil. After applying each level of pressure, it needs to be maintained for a certain period of time (such as 24 hours) to allow the slurry to have enough time to drain the oil and consolidate until the predetermined consolidation degree is reached.

[0069] Actuator 2 is controlled to input a specified downward compressive load. Simultaneously, the dual-track ball screw drive mechanism 4 supporting actuator 2 is instructed to reciprocate within a specified range, causing the roller to apply a stable reciprocating downward compressive load to the transparent soil. When inputting the downward compressive load to actuator 2, the load magnitude and loading rate should be precisely set using a dedicated control system. The load magnitude should be determined based on the test objectives and the bearing capacity of the soil. The loading rate should be controlled within a reasonable range to avoid soil damage due to excessively fast loading or test efficiency being affected by excessively slow loading. When inputting the reciprocating motion command to the dual-track ball screw drive mechanism 4, appropriate reciprocating frequency, amplitude, and stroke should be set. The reciprocating frequency can be selected based on the compaction process being simulated. For example, a higher frequency (e.g., 30-50 Hz) can be selected for vibratory compaction, while a lower frequency (e.g., 5-10 Hz) can be selected for conventional compaction. The amplitude and stroke should be adjusted based on the dimensions of the model trough 6 and the soil compaction requirements to ensure uniform compaction of the soil by the roller.

[0070] A vibration excitation module and an impact load device are set in the double-track ball screw transmission mechanism 4, so that the roller can superimpose the vibration frequency (0-50Hz) or impact energy while applying a static load, simulating various engineering compaction processes such as vibration compaction and dynamic compaction. The parameter setting of the vibration excitation module should be able to accurately control the vibration frequency and amplitude, which can be achieved by adjusting the speed of the vibration motor or using a frequency converter. The impact load device should be able to generate impact loads of different energies, and the selection of impact energy should be determined according to the simulated dynamic compaction process and the properties of the soil. During the test, different compaction process modes can be flexibly switched according to needs, and the vibration excitation module and the impact load device can be independently controlled or jointly controlled by the control system to simulate the complex compaction conditions in actual engineering.

[0071] The industrial camera parameters were adjusted based on the size of the model trough 6, the laser irradiation angle, and the optical properties of the soil. During the experiment, speckle field images were automatically captured at preset intervals to ensure that the speckle field images of the soil-rock mixed filler during the compaction process were captured and a high-quality image data set was stored. When adjusting the industrial camera parameters, the appropriate focal length was first determined based on the size of the model trough 6 so that the entire front of the model trough 6 could be clearly imaged on the camera's photosensitive element. The camera's exposure time and aperture size were adjusted according to the laser irradiation angle to obtain appropriate image brightness and contrast. When choosing the exposure time, it is important to avoid image blurring due to too long an exposure time or image darkness due to too short an exposure time. The adjustment of the aperture size requires a comprehensive consideration of the depth of field and the amount of light entering, ensuring that a clear image can be obtained while maintaining sufficient depth of field.

[0072] Automatically capture speckle field images at preset intervals. This interval can be determined based on the speed of the compaction process and the level of detail required. For example, in the early stages of compaction, when changes are rapid, the capture interval can be set to a shorter time (e.g., every 10 seconds); in the later stages of compaction, when changes are slower, the capture interval can be appropriately extended (e.g., every 30 seconds). During the capture process, the camera's position and parameters should be kept stable to avoid degradation of image quality due to external factors. After capture, the captured images are screened and stored, retaining only high-quality image datasets to reduce the workload of subsequent data processing.

[0073] A high-definition camera is set up in front of the model tank 6. The camera focuses on the characteristic dyed particles inside the soil-rock mixture filler. When the actuator 2 applies a load for compaction, the video starts immediately. The video continues until the entire compaction process is completed, and the compaction process video is stored. The location of the high-definition camera should ensure that the characteristic dyed particles inside the soil-rock mixture filler in front of the model tank 6 can be clearly captured to avoid the situation where some particles cannot be captured due to viewing angle problems. When focusing, the camera's autofocus function can be used for preliminary focus, and then the focus can be manually fine-tuned to make the characteristic dyed particles appear clearest in the picture.

[0074] As actuator 2 begins applying load for compaction, immediately start recording with a high-definition camera. During recording, maintain a stable camera to avoid blurring caused by shaking. Also, ensure the camera's storage device has sufficient capacity to record the entire compaction process. After recording, securely store the video file for subsequent processing and analysis.

[0075] Before compaction, measure the maximum dry density and minimum dry density of the soil-rock mixture, and calculate the relative density of the soil-rock mixture after each compaction. The maximum dry density and minimum dry density can be measured using standard test methods, such as compaction test or vibration table test. During the measurement process, the test procedures must be strictly followed to ensure the accuracy of the measurement results. After each compaction, the mass and volume of the compacted soil-rock mixture are measured, its dry density is calculated, and compared with the maximum dry density and minimum dry density to obtain the relative density. The calculation formula for relative density is:

[0076]

[0077] Among them D r is the relative density, ρ d is the dry density of the soil-rock mixed filler after compaction, ρ d,min is the minimum dry density, ρ d，max is the maximum dry density.

[0078] By collecting speckle field images before and after each compaction stage using an industrial camera and combining them with PIV image processing technology, the displacement and acceleration vectors of soil particles within the soil-rock fill are determined. This generates a displacement nephogram of the soil-rock fill during compaction. Analysis of the displacement nephogram reveals the volume change of the soil-rock fill, which is then used to calculate the density of the fill at that compaction stage. This analysis then yields a relative density distribution map for the entire field. PIV image processing, based on image correlation analysis, tracks and analyzes the motion trajectories of particles in the speckle field images to determine their displacement and velocity. Processing speckle field images requires specialized PIV image processing software for pre-processing, correlation calculations, and post-processing. Analysis of the displacement nephogram allows for intuitive visualization of the volume change of the soil-rock fill during compaction, such as localized compression or expansion. Based on this volume change information and the initial volume of the soil-rock fill, the density at that compaction stage can be calculated. Further analysis of the density distribution in the entire model tank 6 can obtain a relative density distribution diagram of the entire field, providing a basis for optimizing the compaction process.

[0079] By analyzing high-definition video footage of dyed fused quartz sand captured by a high-definition camera and using video processing software to track dyed particles with different fluorescence spectra, the displacement and deformation of characteristic dyed particles during compaction, as well as the differences in motion trajectories between particles of different particle sizes, were analyzed. The video processing software should possess powerful image recognition and tracking capabilities, enabling accurate identification and tracking of dyed particles based on their fluorescence spectral characteristics. During the analysis, the motion trajectories of dyed particles of different particle sizes can be labeled and counted, allowing observation of their displacement direction, magnitude, and deformation during compaction. By comparing the differences in motion trajectories of particles of different particle sizes, a deeper understanding of the particle interaction mechanisms and compaction characteristics of soil-rock mixed fillers during compaction can be obtained.

[0080] Record the load size of actuator 2 during the compaction process, control the downward load of each compaction stage to remain unchanged, and record the displacement value fed back by actuator 2 at all times. When the displacement value of a certain compaction stage remains unchanged, it is considered that the compaction stage is over, and the downward load is increased to enter the next compaction stage. The recording of the load size can be achieved through a data acquisition system connected to actuator 2. The data acquisition system should have the characteristics of high precision and high sampling rate, and can accurately record the load changes in real time. The displacement value can be calculated by the signal fed back by the pressure sensor 3, or a displacement sensor can be installed on the roller 5 or the model trough 6 for direct measurement. In each compaction stage, the size and stability of the downward load must be strictly controlled to ensure the consistency of the test conditions. When the displacement value of a certain compaction stage remains unchanged, it means that the soil has reached a relatively stable compaction state under the action of this load. At this time, the downward load can be increased to enter the next compaction stage until all preset compaction stages are completed.

[0081] After all preset downward loads have been applied, compaction can be terminated when the displacement information reported by the actuator during the final compaction phase no longer changes. During the final compaction phase, pay close attention to the displacement information reported by the actuator. When the displacement remains stable for a long period of time (e.g., 30 minutes) and the change is minimal (e.g., less than 0.01 mm), the soil is considered to have reached maximum compaction and the compaction operation can be terminated.

[0082] After compaction, the cone tip resistance and side wall friction of the soil-rock mixture are measured using a micro-static penetration tester to determine whether the compacted soil-rock mixture meets the compaction requirements. The micro-static penetration tester should have an appropriate probe size and measurement accuracy to accurately measure the cone tip resistance and side wall friction of the soil. During the measurement process, the specified operating procedures must be followed to ensure the reliability of the measurement data. The measured cone tip resistance and side wall friction are compared with the pre-set compaction standards. If the standards are met, it means that the compacted soil-rock mixture meets the compaction requirements. If the standards are not met, the reasons need to be analyzed, such as unreasonable compaction process parameter settings, improper soil-rock mixture preparation, etc., and appropriate improvement measures should be taken, such as adjusting the compaction load, number of compactions, or re-preparing the soil-rock mixture, and the compaction test should be repeated until the compaction requirements are met.

[0083] Through the above-described specific implementation methods, this test method can comprehensively and accurately implement visual monitoring and analysis of the soil-rock mixture compaction process, providing strong technical support and scientific basis for soil-rock mixture compaction projects. During actual operation, testers should strictly follow the requirements of this implementation method to ensure the accuracy and reliability of test data. Furthermore, depending on the specific test objectives and requirements, some parameters and operating procedures can be appropriately adjusted and optimized to meet the needs of different engineering scenarios.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A soil-rock mixed filler compaction transparent visualization test system, characterized in that: include: A reaction frame (1) and a model groove (6) arranged inside the reaction frame (1); an actuator (2) is provided on the top of the reaction frame (1); a double-track ball screw transmission mechanism (4) is provided between the reaction frame (1) and the actuator (2); a pressure sensor (3) is provided at the bottom of the actuator (2); and the bottom of the pressure sensor (3) compacts the transparent soil in the model groove (6) through a roller (5); A laser (7) is provided at the side end of the model trough (6), and the laser (7) irradiates the transparent soil in the model trough (6) to present a speckle field plane. An industrial camera (8) is fixed directly behind the model trough (6) to collect speckle field images generated during the compaction process.

2. The soil-rock mixed filler compaction transparent visualization test system according to claim 1 is characterized in that: A slide groove (9) is provided at the center line of the bottom plate of the double-track ball screw transmission mechanism (4), and the pressure sensor (3) is connected to the roller (5) through the slide groove (9).

3. The soil-rock mixed filler compaction transparent visualization test system according to claim 1 is characterized in that: A high-definition camera (10) is provided directly in front of the model tank (6) for photographing the displacement and deformation of the dyed characteristic particles and the differences in movement trajectories of particles of different particle sizes during the compaction process of the transparent soil in the model tank (6).

4. A test method using the soil-rock mixed filler compaction transparent visualization test system according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Equipment assembly and fixation: fix the actuator (2) to the double-track ball screw transmission mechanism (4), install the actuator (2) and the double-track ball screw transmission mechanism (4) to the reaction frame (1), install the pressure sensor (3) at the bottom of the actuator (2); connect the pressure sensor (3) through the transmission mechanism bottom plate slide groove (9) to the roller (5); fix the laser (7) on one side of the model groove (6), adjust its position so that the sheet laser surface generated by the laser (7) fully covers the model groove (6); install the industrial camera ( 8) is fixed directly behind the model tank (6), and the camera angle and position are calibrated so that only the front of the model tank is shown in the picture; a high-definition camera (10) is fixed directly in front of the model tank (6), and the camera parameters are adjusted so that only the front of the model tank is shown in the picture and the focus is on the characteristic dyed particles in the soil-rock mixed filler; a fiber Bragg grating sensor array FBG is embedded in the side wall of the model tank (6), a MEMS micro-vibration sensor is integrated on the surface of the drum (5), and the sensor data is synchronously transmitted to the control terminal in real time through a wireless transmission module; S2. Prepare transparent soil-stone mixed filler: S21. Determine the test temperature and infiltration treatment: Determine the test temperature of the compaction process, and infiltrate the fused silica particles with white oil having a refractive index of 1.4580±0.005; S22. Select and dye fused quartz particles: Based on the gradation range of the selected embankment filler gravel, select fused quartz particles with characteristic particle sizes that are recognizable in the speckle field, perform fluorescent dyeing on them, and implement fluorescent dyeing coding on fused quartz sands of different particle sizes to ensure that the high-definition camera (8) can track the dyed fused quartz sands of different particle sizes under the action of laser, wherein the dyed fused quartz sand accounts for 1 / 4 of the mass of the transparent gravel; S23. Preparing transparent clay: thoroughly mixing fumed silica powder with a mixed pore solution having the same refractive index, wherein the mixed pore solution is prepared by mixing white oil and n-dodecane in a specific ratio at a predetermined test temperature. During the preparation process, an appropriate amount of tracer particles is added, and the mixed solution, fumed silica, and tracer particles are uniformly stirred using a stirring device to prepare transparent clay; S24, mixing transparent gravel and transparent clay: adding the prepared transparent gravel to the transparent clay according to a predetermined mass ratio, and thoroughly stirring and mixing using a stirring device to uniformly disperse the dyed fused quartz sand. After stirring, the soil-stone mixed filler is placed in a vacuum tank, and the air inside the soil is expelled by vacuuming to produce a transparent soil-stone mixed filler; S3. Filling and consolidating transparent soil-rock mixed filler: S31. Filling fillers in batches: Fill the transparent soil-rock mixed filler into the model tank in batches to ensure uniform filling and reduce the impact of air mixing on soil transparency; S32, applying pressure in stages for consolidation: sequentially placing a qualitative filter paper with a pore size of 1.3 microns soaked with the mixed pore liquid and a perforated organic glass pressure plate on the slurry surface, gradually placing weights on the pressure cover plate, and applying pressure in stages to promote oil drainage and consolidation of the mixed slurry; S4, driving the roller to compact the soil: controlling the actuator (2) to input a specified downward pressure load, and simultaneously inputting a reciprocating motion instruction within a specified range to the double-track ball screw transmission mechanism (4) supporting the actuator (2), driving the roller to apply a stable reciprocating downward pressure load to the transparent soil; setting a vibration excitation module and an impact load device in the double-track ball screw transmission mechanism (4), so that the roller can superimpose vibration frequency or impact energy while applying a static load, simulating various engineering compaction processes such as vibration compaction and dynamic tamping; S5. Capturing speckle field images: adjusting the parameters of the industrial camera (8) according to the size of the model trough (6), the laser irradiation angle, and the optical properties of the soil, and automatically capturing speckle field images at preset intervals during the test to ensure that the speckle field images of the soil-rock mixed filler during the compaction process are fully captured, and storing a high-quality image data set; S6. Shooting a video of the changes in the dyed particles: a high-definition camera (10) is set up in front of the model tank (6), and the high-definition camera (10) is focused on the characteristic dyed particles inside the soil-rock mixed filler in the model tank (6). When the actuator (2) applies a load for compaction, the video function is immediately started, and the video is continuously shot until the entire compaction process is completed, and the compaction process video is stored; S7. Collect and analyze data: S71. Measure and calculate relative density: Measure the maximum dry density ρ of the soil-rock mixture before compaction d，max and the minimum dry density ρ d,min , after each compaction, the expression is: Calculate the relative density D of soil-rock mixed filling r ρ d is the dry density of the soil-rock mixed filler after compaction; S72. Analyze displacement and acceleration vectors: Collect speckle field images captured by the industrial camera (8) before and after each compaction stage, and combine them with PIV image processing technology to calculate the displacement and acceleration vector size of the soil particles inside the soil-rock mixed filler. Draw the displacement cloud map of the soil-rock mixed filler during the compaction process, analyze the displacement cloud map to obtain the volume change of the soil-rock mixed filler, and further calculate the density D of the soil-rock mixed filler at this compaction stage. r , and then analyze to get the relative density distribution map of the whole field; S73, tracking the movement trajectory of dyed particles: analyzing the high-definition video of dyed fused quartz sand taken by a high-definition camera (10), using video processing software to track dyed particles with different fluorescence spectra, analyzing the displacement and deformation of characteristic dyed particles during the compaction process and the difference in movement trajectories between particles of different particle sizes; S74, recording load and displacement values: recording the load of the actuator (2) during the compaction process, controlling the downward pressure load in each compaction stage to remain unchanged, and recording the displacement value fed back by the actuator (2) in real time. When the displacement value in a certain compaction stage remains unchanged, the compaction stage is determined to be finished, and the downward pressure load is increased to enter the next compaction stage; S8. Determine the degree of compaction: After all preset downward pressure loads are applied, the displacement information fed back by the actuator (2) in the last compaction stage is observed to no longer change, and the compaction operation is terminated; the cone tip resistance and side wall friction resistance of the compacted soil-rock mixed filling are measured using a micro static penetration test to determine whether the compacted soil-rock mixed filling meets the compaction requirements.

5. The soil-rock mixed filler compaction transparent visualization test method according to claim 4 is characterized in that: In step S1, the fiber Bragg grating sensor array FBG is arranged in a distributed manner and is evenly distributed along the height direction and width direction of the side wall of the model groove (6) to more comprehensively monitor the stress changes of the soil-rock mixed filler at different positions.

6. The soil-rock mixed filler compaction transparent visualization test method according to claim 4, characterized in that: In the step of preparing the transparent soil-rock mixed filler in step S2, the stirring device is a planetary stirrer, the stirring speed is set to 50-150 rpm, and the stirring time is 10-30 minutes to ensure that the mixed solution, fumed silica and tracer particles are fully mixed.

7. The soil-rock mixed filler compaction transparent visualization test method according to claim 4, characterized in that: In the step of applying pressure and consolidating in step S3, the mass of the weights increases in the order of 5 kg, 10 kg, 15 kg, and 20 kg. The pressure is maintained for 10-20 minutes after each weight is applied to ensure that the mixed slurry is fully drained and consolidated.

8. The soil-rock mixed filler compaction transparent visualization test method according to claim 4, characterized in that: In step S4, the vibration frequency of the vibration excitation module is adjusted to an accuracy of ±0.5 Hz, and the impact energy of the impact load device is adjusted to an accuracy of ±1 J, so as to accurately simulate different engineering compaction processes.

9. The soil-rock mixed filler compaction transparent visualization test method according to claim 4, characterized in that: In step S5, the preset interval is 1-5 minutes, and the shooting frame rate of the industrial camera is 1-10 frames per second, so as to ensure that the dynamic changes of the speckle field of the soil-rock mixed filler during the compaction process are captured.

10. The soil-rock mixed filler compaction transparent visualization test method according to claim 4, characterized in that: In the step of tracking the movement trajectory of the dye particles in step S73, the video processing software uses an algorithm based on feature point matching to identify and track dye particles with different fluorescence spectra, and its identification accuracy is not less than 95%.

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