Rock-soil body critical pore size measuring device and critical seepage path reconstruction method

Abstract

The invention belongs to the technical field of geotechnical engineering, and relates to a rock-soil body critical pore size measuring device and a critical seepage path reconstruction method, the rock-soil body critical pore size measuring device comprises an air pressure controller, a sample container, a digital camera and a computer; the sample container is in a straight cylinder shape with an open top, the side wall and the bottom of the sample container are internally and externally sealed, an air inlet is formed in the bottom of the sample container, and the side wall of the sample container is made of a transparent material; a gas output port of the gas pressure controller is in gas communication with the gas inlet; the shooting direction of the digital camera is over against the top opening of the sample container from top to bottom; the air pressure controller and the digital camera are electrically connected to a computer respectively; when the rock-soil body critical seepage path is reconstructed, the defects of roughness, damage and inaccurate path judgment of a traditional method are overcome, and the harmless critical seepage path visual representation of the soil sample is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical engineering and relates to a device for measuring the critical pore size of geotechnical bodies and a method for reconstructing the critical seepage path. Background Art

[0002] With the rapid development of geotechnical engineering construction in China, the research on the seepage characteristics of special soil bodies such as geotechnical bodies has become increasingly important. In various engineering practices, many infrastructure facilities (such as slopes, tunnels, dams, etc.) have strict requirements for the seepage stability of soil bodies, and inaccurate seepage parameters will seriously affect the engineering safety assessment and design optimization. Most geotechnical engineering projects require accurate determination of critical seepage parameters to guide construction and maintenance.

[0003] However, the existing testing methods for geotechnical seepage parameters are complex, destructive, and random in the process, and the existing methods cannot efficiently meet the requirements for determining critical seepage parameters in different engineering scenarios.

[0004] Therefore, how to construct an accurate and efficient testing system for critical seepage pore size is an urgent problem to be solved in the current field of geotechnical engineering. Summary of the Invention

[0005] The present invention aims to provide a device for measuring the critical seepage pore size of geotechnical bodies based on air pressure control, which combines stepped air pressure loading with image acquisition to meet the requirements for determining critical seepage pore size in different engineering scenarios; at the same time, combining the pore size and position coordinate set obtained by three-dimensional scanning with the measured critical seepage pore size, the theoretical reconstruction of the seepage path is realized in a blank three-dimensional model, thereby greatly improving the accuracy and efficiency of geotechnical seepage path determination.

[0006] The technical solution adopted by the present invention to solve the technical problems is: a device for measuring the critical pore size of geotechnical bodies, including: an air pressure controller, a sample container, a digital camera, and a computer; the sample container is in the shape of a straight cylinder with an open top, the side wall and bottom of the sample container are sealed inside and outside, an air inlet is provided at the bottom of the sample container, and the side wall of the sample container is made of a transparent material.

[0007] The gas output port of the air pressure controller is gas-connected to the air inlet; the shooting direction of the digital camera is directly downward facing the open top of the sample container, and the air pressure controller and the digital camera are respectively electrically connected to the computer.

[0008] Preferably, the air inlet is located at the geometric center of the bottom of the sample container, and a pressure gauge is provided on the air pressure controller.

[0009] Preferably, the sample container includes a top plate, a cylinder body, and a bottom plate, the cylinder body is a straight cylinder with openings at both the top and bottom, and an opening is provided on the top plate, and the opening has the same shape and size as the inner cylinder opening of the cylinder body.

[0010] The top plate is buckled and covered on the edge of the upper tube opening of the cylinder from top to bottom, and the bottom plate supports the lower tube opening of the cylinder from bottom to top.

[0011] More preferably, a sealing ring is provided at the joint between the top plate and the cylinder, and at the joint between the bottom plate and the cylinder, respectively, and a fastener is provided between the top plate and the bottom plate.

[0012] Preferably, the straight cylindrical shape of the sample container includes: a circular cylinder, an elliptical cylinder, a rhombus cylinder, a regular polygonal cylinder, such as a square cylinder, a regular pentagonal cylinder, a regular hexagonal cylinder, and a regular octagonal cylinder.

[0013] The present invention also discloses a method for reconstructing a critical seepage path of a rock mass, which uses the above-mentioned rock mass critical pore size measuring device and comprises the following steps:

[0014] Step 1: Build the device and prepare the sample; connect the air pressure controller to the bottom air inlet of the sample container, ensuring that the connection is stable and airtight; select a saturated rock and soil sample and place it in the sample container, ensuring that the sample is adapted and sealed to prevent air pressure leakage; connect the digital camera, air pressure controller and computer, ensuring that data transmission between the two is normal, and that the camera shooting function and the computer data receiving and processing functions are all operating well.

[0015] Step 2: Prepare for air pressure control and data acquisition: Set the air pressure controller parameters on the computer so that its adjustment range is 0-200kPa and adopt high-precision air pressure control mode.

[0016] Turn on the digital camera and set the shooting parameters, such as resolution and frame rate, to ensure that the relevant changes of the sample can be clearly captured. At the same time, set the image data to be transmitted to the computer in real time.

[0017] Step 3: Data collection for critical pore size determination: The saturated rock and soil sample in the sample container is pressurized in a stepwise manner by using an air pressure controller, starting from 0 kPa and gradually increasing the air pressure according to the set pressure increment (0.1 kPa).

[0018] Closely observe the state of the sample, when it reaches the critical pressure ΔP break After the sample has cooled (bubbles begin to emerge steadily from the top of the sample), turn off the device.

[0019] Use the capillary equation r based on the relevant data recorded in the computer (the air pressure at the time the bubble emerges) c =ΔP break / (2γcosθ) Calculate the theoretical value of critical pore size r c And record, where γ represents the surface tension and θ represents the contact angle.

[0020] Preferably, in step 3, the stepped pressurization includes three stages:

[0021] Stage 1: Initial stage, ΔP = 0, the gas does not flow out, and the internal air pressure of the sample is balanced with the atmospheric pressure, where ΔP represents the real-time pressure.

[0022] Stage 2: Pressure increasing stage, ΔP < ΔP break , the air pressure controller increases the pressure in steps of 0.1 kPa / level, and the sealing system maintains a leakage rate of ≤0.1 kPa / min, and the gas still does not break through the pores of the sample.

[0023] Stage 3: Critical stage, ΔP = ΔP break , when the air pressure reaches the critical value, the gas overflows concentratedly from the top opening. At this time, the sealing system still maintains the airtightness around, and only allows the gas to escape from the designed opening at the top.

[0024] Preferably, in step 3, during data acquisition, ΔP is triggered by stepped pressure increase break , and the theoretical calculated value of the critical pore size is synchronously recorded ; during three-dimensional network reconstruction, the set of pore sizes and position coordinates scanned three-dimensionally is arranged in descending order of size as a set ; during path reconstruction, the set is reconstructed in the three-dimensional blank model in descending order of pore size, and the first connected seepage path, that is, the critical seepage path, is obtained when rearranging the critical pore size .

[0025] Preferably, in step 1, specifically including the following steps for saturating the geotechnical sample and placing it in the sample container:

[0026] Select natural geotechnical materials that meet the test requirements, crush and sieve them to remove impurities and large particle substances to ensure the uniformity of the soil sample.

[0027] Subsequently, the treated geotechnical materials are saturated by the vacuum saturation method. The geotechnical materials are loaded into a sealed container, evacuated to a certain negative pressure and maintained for a period of time, and then gas-free water is slowly injected to allow the water to fully penetrate into the pores of the soil sample until the soil sample is completely saturated.

[0028] More preferably, in step 1, the saturated geotechnical sample needs to be tested within a specified time to prevent the loss of moisture from affecting the test results.

[0029] The beneficial effects of the present invention are:

[0030] When reconstructing the critical seepage path of the geotechnical body, the present invention overcomes the defects of the traditional method being rough, destructive, and inaccurate in path judgment, and realizes the visualization characterization of the critical seepage path of the soil sample without harm. Description of the Drawings

[0031] Figure 1It is a schematic diagram of the device assembly of the device for measuring the critical pore size of rock and soil mass and the method for reconstructing the critical seepage path of the present invention;

[0032] Figure 2 It is a top view of the device for measuring the critical seepage pore size of rock and soil mass of the present invention;

[0033] Figure 3 It is of the present invention Figure 2 A - A sectional view;

[0034] Figure 4 It is a schematic diagram of the three - stage test of the present invention;

[0035] Figure 5 It is a schematic diagram of the three - dimensional pore scanning result of the present invention;

[0036] Figure 6 It is a schematic diagram of coloring the three - dimensional pore size of the present invention;

[0037] Figure 7 It is of the present invention for reconstructing the three - dimensional pore to front schematic diagram;

[0038] Figure 8 It is of the present invention for reconstructing the three - dimensional pore to schematic diagram;

[0039] Figure 9 It is a schematic diagram of the three - dimensional critical seepage path (dotted line) of the present invention.

[0040] In the figure, 1. air pressure controller; 2. specimen container; 3. digital camera; 4. computer; 5. air inlet; 6. pressure gauge; 21. top plate; 22. cylinder body; 23. bottom plate; 24. opening; 25. sealing ring; 26. fastener. Specific implementation mode

[0041] Next, the relevant technologies in the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0042] Refer to Figures 1 - 9 As shown, a device for measuring the critical seepage pore size of rock and soil mass based on air pressure control in this embodiment includes an air pressure control module, a specimen sealing module, and an external terminal, where:

[0043] The air pressure control module is located beside the specimen sealing module and includes an air pressure controller 1. A high-precision pressure sensor is configured on the air pressure controller 1 to monitor the air pressure in real time. A high-pressure resistant air pipe is connected to the output end of the air pressure controller 1, and the other end of the pipe is connected to the bottom of the specimen container 2 to apply air pressure to the saturated rock and soil specimen. The air pressure controller 1 is provided with multi-stage pressure adjustment knobs, which can be manually adjusted or can be program-controlled by connecting to a computer 4 to apply a stepped increasing air pressure ΔP to the saturated rock and soil specimen. The air pressure controller 1 also has a built-in voltage stabilizing circuit module to ensure the stability of the output air pressure, and the pressure adjustment accuracy can reach ±0.1 kPa.

[0044] The specimen sealing module consists of a specimen holder, a specimen container 2 made of a transparent pressure-resistant sealing resin plate, and an O-ring 25. A circular opening is provided at the top of the specimen container 2 for placing the saturated rock and soil specimen. The material of its transparent pressure-resistant sealing resin plate ensures that the specimen state can be clearly observed during the air pressure loading process and can withstand high pressure. The O-ring 25 is made of fluororubber and is installed at the contact between the cylinder body 22 and the bottom plate 23 of the specimen container 2. The pressure tolerance range is 0 - 500 kPa. When the air pressure controller 1 applies a stepped increasing air pressure ΔP to the specimen, it effectively ensures the sealing around the specimen, and only allows the gas to overflow from the top opening, ensuring the accuracy and reliability of the test data.

[0045] The saturated rock and soil specimen: It is a cylinder with a diameter of 20 mm and a height of 40 mm, and its size is precisely adapted to the specimen container 2. During the preparation process, first select natural rock and soil that meets the test requirements, and after crushing and sieving, remove impurities and large particle substances to ensure the uniformity of the soil sample. Subsequently, the vacuum saturation method is used to saturate the treated rock and soil. The rock and soil are loaded into a sealed container, evacuated to a certain negative pressure and maintained for a period of time, and then degassed water is slowly injected to allow the water to fully penetrate into the pores of the soil sample until the soil sample is completely saturated. The saturated rock and soil specimen needs to be tested within a specified time to prevent water loss from affecting the test results. Its saturated state ensures that during the process of the air pressure controller 1 applying a stepped increasing air pressure ΔP, the change in pore water pressure and the characteristics of gas escape can be accurately presented, providing a reliable test object for measuring the critical pore size and reconstructing the seepage path.

[0046] The external terminal consists of a digital camera 3 and a computer 4, which are the core components for data acquisition, transmission, and processing. The digital camera 3 is equipped with a high-resolution lens that is precisely aligned with the top surface of the specimen container 2. It has a high-speed shooting frame rate of 1000fps and an autofocus function. During the process of the air pressure controller 1 applying air pressure to the saturated rock and soil specimen, it can continuously capture images of the bubble overflow on the top surface of the specimen at time intervals of 0.001s. The computer 4 establishes a two-way communication connection with the digital camera 3 and the air pressure controller 1 through a high-speed data transmission line. On the one hand, it receives the image data transmitted by the digital camera 3 in real time. On the other hand, it synchronously obtains the air pressure data ΔP output by the air pressure controller 1. The computer 4 is built-in with dedicated data processing software, which correlates the air pressure change curve with the image sequence and automatically calculates the critical pore size based on the capillary equation r c =ΔP break / (2γcosθ) (where γ is the surface tension and θ is the contact angle).

[0047] Furthermore, the air pressure control module includes multiple-stage buffer air chambers. Its unique structure and working principle can effectively relieve sudden pressure changes and ensure that the pressure fluctuation during stepped pressure increase is ≤ ±0.5kPa.

[0048] Furthermore, the digital camera 3 includes a high-speed image acquisition function. When the test starts, it automatically takes pictures at intervals of 0.001s to reduce errors caused by too large a time span for image shooting.

[0049] Furthermore, the computer 4 is built-in with a data processing module: a pressure-image synchronous analysis unit, which aligns the ΔP curve with the seepage image sequence through the time term.

[0050] Furthermore, the test device adopts a modular structure design, separating functional components such as the air pressure control module, specimen sealing module, and external terminal into independent modules. If a certain module fails, it can be directly replaced.

[0051] By adopting the above technical solutions, the present invention has the following advantages:

[0052] The accurate determination of the critical state of rock and soil seepage is realized. Through the synergistic effect of stepped air pressure loading and high-frame-rate image acquisition, the measurement accuracy of ΔP break is improved, and thus a more accurate critical seepage pore size can be obtained.

[0053] The present invention also discloses a method for reconstructing the critical seepage path of rock and soil, including three-dimensional pore data acquisition, three-dimensional pore set reconstruction, and path reconstruction. Through this method, high-precision visual reconstruction of the seepage process is realized.

[0054] Three-dimensional pore data acquisition is to use a micro-CT scanning device to rotate the saturated geotechnical specimen 360° to obtain specimen images, so as to realize the acquisition of microscopic data of the overall pore structure of the specimen.

[0055] Three-dimensional pore set reconstruction is to import the pore size, spatial coordinates and other information obtained from three-dimensional pore data acquisition into professional three-dimensional modeling software. Arrange them in descending order of pore size to construct a pore information set. The set contains the critical pore size measured using the above device. .

[0056] Path reconstruction is to accurately locate the pore positions in the three-dimensional blank space according to the spatial coordinates of each pore in the set, and then combine the pore size data to restore the pore morphology one by one in descending order of size through geometric modeling. When arranging to , theoretically the first connected pore channel will appear, that is, the critical seepage path is obtained.

[0057] Furthermore, for the three-dimensional pore data acquisition, the micro-CT scanning device scans the soil sample 360°, and the data acquisition accuracy is high.

[0058] Furthermore, in the process of three-dimensional pore set reconstruction, professional software can be used to sort and construct the pore size and coordinate information more efficiently, ensuring the accuracy and integrity of the set data.

[0059] Furthermore, in the path reconstruction stage, when positioning in three-dimensional space and restoring the pore morphology, a more optimized geometric modeling algorithm can be used to more accurately determine the critical seepage path.

[0060] Embodiment

[0061] In this embodiment, the air pressure controller 1 is configured with a multi-stage pressure adjustment module for applying a stepped increasing air pressure ΔP to the soil sample in the sample container 3. The pressure adjustment accuracy of the air pressure controller 1 is ±0.1 kPa.

[0062] The cylinder body 22 of the sample container 2 is made of a transparent pressure-resistant sealing resin plate, and its size specification is a hollow cylinder with an inner diameter of 20 mm, an outer diameter of 30 mm, and a height of 40 mm. The surrounding is in a sealed environment to prevent gas leakage from the side and ensure the accuracy of the test results. When ΔP reaches the critical value ΔP breakWhen the top plate 21 is opened, bubbles appear on the top surface; a circular opening is provided, and a 1mm groove is provided at the contact point between the top plate 21 and the cylinder 22, and at the contact point between the bottom plate 23 and the cylinder 22 to facilitate the installation of the cylinder 22. O-rings 25 are provided at the upper and lower contact points. The fasteners 26 use four studs and four nuts to form upper and lower bolts to fasten the top plate 21 and the bottom plate 23. In addition, the size specification of the geotechnical sample is a cylinder with a diameter of 20 mm and a height of 40 mm. This standard size is suitable for the sample container 2, ensuring that the sample can be accurately placed in the container. The sealing ring 25 is made of fluororubber and can withstand a pressure range of 0-500kPa.

[0063] The air pressure controller 1 can establish a communication connection with the computer 4 and output the air pressure data ΔP in real time. break The value is transmitted to the computer 4 to realize the synchronous recording and processing of the air pressure data and the image data of the bubble overflow on the top surface of the soil sample taken by the digital camera 3, and the critical pore size r is calculated by the formula c =ΔP break / (2γcosθ).

[0064] The rock and soil critical pore size measurement device in this embodiment mainly includes an air pressure controller, a sample sealing module, and an external terminal. These components work together to accurately measure the critical seepage pore size of the rock and soil, where:

[0065] The air pressure controller 1 is tightly connected to the air inlet 5 at the bottom of the sample container 2 via a high-pressure-resistant air pipe. The connection is coated with petroleum jelly and wrapped with multiple layers of sealing tape to ensure a good airtightness. The main body of the air pressure controller 1 is equipped with a multi-stage pressure regulation module, which can be adjusted manually or program-controlled via a connection to a computer 4. It also has a built-in high-precision barometer 6 for real-time air pressure monitoring, with a pressure regulation accuracy of ±0.1 kPa.

[0066] refer to Figure 4 、 Figure 5 、 Figure 6 and Figure 7 The sample sealing module consists of a sample rack, a sample container 2 composed of a transparent pressure-resistant sealing resin plate, and an O-ring 25. A circular opening is provided on the top of the sample container 2 for placing saturated rock and soil samples. Its transparent material ensures that the sample state can be clearly observed during the air pressure loading process and can withstand high pressure. The O-ring 25 is made of fluororubber and is installed at the contact point between the container and the sample rack. It has a pressure tolerance range of 0-500kPa. During assembly, first place the sample rack on a stable operating table, connect the bottom of the cylinder 22 composed of the transparent pressure-resistant sealing resin plate with the bottom plate 23, evenly apply sealant at the contact point, and then install the O-ring 25 to ensure the sealing effect. Finally, tighten the fastener 26, that is, the fastening nut. In order to facilitate installation, 1mm step holes are designed at the upper and lower interfaces of the cylinder 22 and the top plate 21 and bottom plate 23.

[0067] The external terminal consists of a digital camera 3 and a computer 4. The digital camera 3 is equipped with a high-resolution lens, and the lens is accurately aligned with the top surface of the specimen container 2. When installing, the position and angle of the camera need to be adjusted to ensure that the captured image completely covers the top surface of the specimen container. The camera has a high-speed shooting frame rate of 1000fps and an autofocus function. The computer 4 establishes a two-way communication connection with the digital camera 3 and the air pressure controller 1 through a high-speed data transmission line. During the connection process, it is necessary to check whether the data transmission line is plugged in properly and whether the software can normally recognize the device.

[0068] According to this device, the accurate measurement of the critical pore size of the rock and soil mass can be realized: In the initial stage, the air pressure controller 1 outputs an air pressure of ΔP = 0, the air pressure inside the specimen is balanced with the atmospheric pressure, and the gas does not flow out; in the pressurization stage, the air pressure controller increases the pressure step by step at 0.1 kPa / level. During this process, the sealing system maintains a leakage rate of ≤0.1 kPa / min, and the gas has not yet broken through the pores of the specimen; until the critical stage, when the air pressure reaches the critical value ΔP = ΔP break , the gas overflows concentratedly from the top opening of the specimen. At this time, the sealing system still maintains the airtightness around the perimeter and only allows the gas to escape from the designed opening at the top, thus completing the accurate measurement of the critical pore size of the rock and soil mass. After the test, each module of this device is convenient for disassembly, cleaning, preservation and management.

[0069] The specific steps of the test method of the present invention are as follows:

[0070] Step 1: Device setup and specimen preparation

[0071] Connect the bottom of the specimen container 2 connected to the air pressure controller 1. After the connection is stable, use an airtightness detection device to detect the connection part to ensure no air pressure leakage.

[0072] Select a saturated rock and soil mass sample that meets the requirements, and use the vacuum saturation method to saturate the treated rock and soil mass. Place the rock and soil mass in a sealed container, evacuate it to a vacuum and maintain it for 2 hours, then slowly inject air-free water to make the water fully penetrate into the pores of the soil sample until the soil sample is completely saturated. Prepare a cylindrical saturated rock and soil mass specimen with a diameter of 20 mm and a height of 40 mm, place it in the specimen container 2 and place it in the specimen sealing module. Install an O-ring 25 at the interface and apply vaseline to ensure that the specimen is properly fitted and sealed.

[0073] Then correctly connect the digital camera 3 and the computer 4, turn on the relevant software of the digital camera 3 and the computer 4, and set the image parameters. Set the resolution of the digital camera 3 to 4000×3000 pixels and the frame rate to 1000fps to ensure that the relevant changes of the specimen can be clearly captured. At the same time, set the image data to be transmitted to the computer 4 in real time.

[0074] Step 2: Pneumatic Control and Data Acquisition Preparation

[0075] Open the control software of the pneumatic controller 1 on the computer 4, set the pneumatic adjustment range to 0 - 200 kPa, the pressure adjustment accuracy to ±0.1 kPa, select the stepped increasing pneumatic mode, and set the pressure increment to 0.1 kPa. Turn on the voltage stabilizing circuit module of the pneumatic controller 1 to ensure stable output pressure. In the settings menu of the digital camera 3, turn on the autofocus function and set the exposure mode to auto exposure. Set the image data storage path to a specified folder on the computer 4 to ensure real-time transmission and saving of images.

[0076] Step 3: Determination of Critical Pore Size

[0077] Start the pneumatic controller 1 and begin to stepwise increase the pressure on the saturated geotechnical specimen. Starting from 0 kPa, gradually increase the air pressure in accordance with the set pressure increment of 0.1 kPa. For each increase in pressure level, maintain the air pressure stable for 10 seconds so that the digital camera 3 can capture an image of the stable specimen state.

[0078] Closely observe the top surface image of the specimen taken by the digital camera 3, select the image when bubbles first appear, and record the air pressure value output by the pneumatic controller 1 at this time, which is the critical pressure ΔPbreak. According to the equation r c =ΔP break / (2γcosθ), substitute the recorded ΔP break value into the equation to calculate the critical seepage pore size r c , and store the calculation result in the database of the computer 4.

[0079] Step 4: Reconstruction of Critical Seepage Path of Geotechnical Body

[0080] (I) Three-dimensional Pore Data Acquisition

[0081] Use a micro-CT scanning device to perform a 360° rotational scan on the saturated geotechnical specimen after the critical pore size determination. Set the scanning resolution to 0.01 mm to ensure detailed pore structure information inside the specimen can be obtained. After the scan is completed, import the obtained pore image data of the specimen into professional 3D modeling software, such as Figure 5 , where the cylinders are pores.

[0082] (II) Reconstruction of Three-dimensional Pore Set

[0083] In the 3D modeling software, process the imported information such as pore size and spatial coordinates. Arrange them in descending order of pore size to construct a pore information set. The set contains the critical pore size measured using the above device to ensure data integrity.

[0084] (3) Path Reconstruction

[0085] Based on the spatial coordinates of each pore in the set, accurately locate the pore positions in the three-dimensional blank space. Then, combined with the pore size data, restore the pore morphology one by one from large to small by means of geometric modeling. During the arrangement process, when the first connected pore channel appears, the critical percolation path is obtained. Through the visualization function of the software, conduct a three-dimensional display of the reconstructed critical percolation path, and the morphology and trend of the percolation path can be observed from different angles.

[0086] For the convenience of illustrating the reconstruction method, dye the pores with different colors from large to small. Figure 6 That is the dyeing result of all the pores in the soil mass. Fill the pores into the blank three-dimensional space body step by step from large to small. Before the three-dimensional pore reconstruction reaches the previous image is as shown in Figure 7 . Before the three-dimensional pore reconstruction reaches the image is as shown in Figure 8 . At this time, a connected path can be theoretically seen, which is the critical percolation path, as shown in Figure 9 .

[0087] Data processing program: The data processing program is compiled based on the MATLAB image recognition toolbox, and it mainly includes two parts. The first part is the interface part, which is used to import the measured data. The second part is the formula calculation.

[0088] The device for measuring the critical pore size of geotechnical bodies and the method for reconstructing the critical percolation path in this embodiment can effectively achieve the accurate measurement of the critical pore size of geotechnical bodies and the visualization characterization of the critical percolation path, providing a reliable technical means for the study of the seepage characteristics of geotechnical bodies.

[0089] In summary, when reconstructing the critical percolation path of geotechnical bodies, the present invention overcomes the defects of the traditional method such as roughness, damage, and inaccurate path judgment, and realizes the visualization characterization of the critical percolation path of the soil sample without harm.

[0090] It should be emphasized that: The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Any simple modification made to the above embodiments based on the technical essence of the present invention also belongs to the protection scope of the present invention. Other equivalent changes and modifications still fall within the scope of the technical solution of the present invention.

Claims

1. Rock and soil critical pore size measurement device, characterized in that Comprising: A pneumatic controller (1), a specimen container (2), a digital camera (3), and a computer (4); the specimen container (2) is in the shape of a straight cylinder with an open top, the side wall and the bottom of the specimen container (2) are both sealed inside and outside, an air inlet (5) is provided at the bottom of the specimen container (2), and the side wall of the specimen container (2) is made of a transparent material; The gas output port of the pneumatic controller (1) is gas-connected to the air inlet (5); the shooting direction of the digital camera (3) is directly downward facing the open top of the specimen container (2), and the pneumatic controller (1) and the digital camera (3) are respectively electrically connected to the computer (4).

2. The device for measuring the critical pore size of rock and soil mass according to claim 1, wherein The air inlet (5) is located at the geometric center of the bottom of the specimen container (2), and a pressure gauge (6) is provided on the pneumatic controller (1).

3. The device for measuring the critical pore size of rock and soil mass according to claim 1, characterized in that The specimen container (2) includes: a top plate (21), a cylinder body (22), and a bottom plate (23), the cylinder body (22) is a straight cylinder with openings at both the top and the bottom, an opening (24) is provided on the top plate (21), and the opening (24) has the same shape and size as the inner opening of the cylinder body (22); The top plate (21) is buckled downward from above on the edge of the upper opening of the cylinder body (22), and the bottom plate (23) supports the lower opening of the cylinder body (22) upward from below.

4. The device for measuring the critical pore size of rock and soil mass according to claim 3, characterized in that A sealing ring (25) is provided at the joint of the bottom plate (23) and the cylinder body (22), and a fastening member (26) is provided between the top plate (21) and the bottom plate (23).

5. The device for measuring the critical pore size of rock and soil mass according to claim 1, characterized in that, The straight cylinder shape of the specimen container (2) includes: cylindrical shape, elliptical cylinder shape, rhombic cylinder shape, and regular polygon cylinder shape.

6. A method for reconstructing the critical seepage path of a geotechnical body, characterized in that, The method uses the device for measuring the critical pore size of rock and soil mass according to any one of claims 1 to 5, and the method includes the following steps: Step 1, Device setup and specimen preparation; Connect the pneumatic controller (1) to the bottom air inlet (5) of the specimen container (2), select a saturated rock and soil mass specimen and place it in the specimen container (2), and connect the digital camera (3), the pneumatic controller (1) and the computer (4); Step 2, Pneumatic control and data acquisition preparation; Set the parameters of the pneumatic controller (1) and turn on the digital camera (3); Step 3, Data acquisition for measuring the critical pore size; Carry out stepped pressurization on the saturated rock and soil mass specimen in the specimen container (2) through the pneumatic controller (X); When the critical pressure ΔP is reached break the device is turned off; using the capillary equation r c = ΔP break / (2γcosθ) to calculate the theoretical calculated value r of the critical pore size c and record it, where γ represents the surface tension and θ represents the contact angle.

7. A method for reconstructing the critical seepage path of a rock and soil mass according to claim 6, characterized in that, In step 3, the stepped pressurization includes three stages: Stage 1: Initial stage, ΔP = 0, no gas flows out, the internal air pressure of the specimen is balanced with the atmospheric pressure, where ΔP represents the real-time pressure; Stage 2: Pressure boosting stage, ΔP < ΔP break , the pressure controller boosts the pressure step by step, the sealing system maintains a leakage rate of ≤ 0.1 kPa / min, and the gas still does not break through the pores of the specimen; Stage Three: Critical Stage, ΔP = ΔP break , when the air pressure reaches the critical value, the gas overflows concentratedly from the top opening. At this time, the sealing system still maintains the airtightness around, and only allows the gas to escape from the designed opening at the top.

8. A method for reconstructing the critical seepage path of a geotechnical body according to claim 6, characterized in that, In the step 3, during data acquisition, ΔP is triggered by stepped pressurization break , and the theoretically calculated value of the critical pore size is synchronously recorded ; during three-dimensional network reconstruction, the pore size and position coordinate sets obtained by three-dimensional scanning are arranged in descending order of size to form a set ; during path reconstruction, the set is reconstructed in the three-dimensional blank model in descending order of pore size, and the first connected seepage path, i.e., the critical seepage path, is obtained when the critical pore sizes are rearranged .

9. A method for reconstructing the critical seepage path of a rock and soil mass according to claim 6, characterized in that, In step 1, the specific steps of placing the saturated rock and soil mass specimen in the specimen container (2) are as follows: Select a natural rock and soil mass that meets the test requirements, perform crushing and sieving treatments to remove impurities and large particle substances to ensure the uniformity of the soil sample; Subsequently, use the vacuum saturation method to saturate the treated rock and soil mass, load the rock and soil mass into a sealed container, evacuate to negative pressure and maintain for a period of time, and then slowly inject gas-free water to allow the water to fully penetrate into the pores of the soil sample until the soil sample is completely saturated.

10. A method for reconstructing the critical seepage path of a geotechnical body according to claim 9, characterized in that, In the above-mentioned step 1, the saturated rock and soil specimen needs to be tested within a specified time to prevent water loss from affecting the test results.

Images