Critical pore size measuring device for rock and soil and critical seepage path reconstruction method

Abstract

The present invention belongs to the field of geotechnical engineering technology, and relates to a device for measuring the critical pore size of a rock and soil body and a method for reconstructing a critical seepage path, comprising: 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 walls and the 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 walls of the sample container are made of a transparent material; the gas output port of the air pressure controller is connected to the air inlet; the shooting direction of the digital camera is from top to bottom facing the top opening of the sample container, and the air pressure controller and the digital camera are electrically connected to the computer respectively; when reconstructing the critical seepage path of the rock and soil body, the present invention overcomes the defects of the traditional method of being rough, destructive, and inaccurate in path judgment, and realizes the visual representation of the critical seepage path of the harmless soil sample.

Description

Technical Field

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

[0002] With the rapid development of geotechnical engineering in my country, research on the seepage characteristics of special soils, such as rock and soil, is becoming increasingly important. In various engineering projects, many infrastructure projects (such as slopes, tunnels, and dams) place stringent requirements on soil seepage stability. Inaccurate seepage parameters can seriously impact project safety assessments and design optimization. Most geotechnical projects require precise determination of critical seepage parameters to guide construction and maintenance.

[0003] However, the existing rock and soil seepage parameter testing methods are complex, destructive, and random, and the existing methods cannot efficiently meet the critical seepage parameter measurement needs in different engineering scenarios.

[0004] Therefore, how to build an accurate and efficient critical seepage pore size testing system is an urgent problem that needs to be solved in the 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 rock and soil based on air pressure control, which combines stepped air pressure loading with image acquisition to meet the needs of critical seepage pore size measurement in different engineering scenarios; at the same time, by combining the pore size and position coordinate set obtained by three-dimensional scanning with the measured critical seepage pore size, theoretical reconstruction of the seepage path is realized within a blank three-dimensional model, thereby greatly improving the accuracy and efficiency of rock and soil seepage path measurement.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a device for measuring the critical pore size of rock and soil, 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 walls 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 walls of the sample container are made of transparent material.

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

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

[0009] Preferably, the sample container comprises a top plate, a cylinder, and a bottom plate. The cylinder is a straight cylinder with upper and lower openings. The top plate is provided with an opening, which has the same shape and size as the inner cylinder opening of the cylinder.

[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 adopts 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, gas does not flow out, and the internal pressure of the sample is balanced with the atmospheric pressure, where ΔP represents the real-time pressure.

[0022] Phase 2: Boost phase, 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. 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 from the top opening. At this time, the sealing system still maintains peripheral airtightness and only allows the gas to escape from the designed opening at the top.

[0024] Preferably, in step 3, during data collection, ΔP is triggered by step-by-step pressure increase. break , simultaneously record the theoretical calculated value of critical pore size When reconstructing the 3D network, the pore size and position coordinate sets of the 3D scan are arranged into sets from large to small. ; When the path is rebuilt, the collection Reconstruct the 3D blank model from large to small pore size, and rearrange the critical pore size The first connected seepage path is obtained, namely the critical seepage path.

[0025] Preferably, in step 1, saturating the rock and soil sample and placing it in a sample container specifically includes the following steps:

[0026] Select natural rock and soil that meets the test requirements, crush and screen them to remove impurities and large particles to ensure the uniformity of the soil samples.

[0027] Subsequently, the treated rock and soil are saturated using the vacuum saturation method. The rock and soil are placed in a sealed container, vacuumed to a certain negative pressure and maintained for a period of time, and then airless water is slowly injected to allow the water to fully penetrate the pores of the soil sample until the soil sample is completely saturated.

[0028] More preferably, in step 1, the saturated rock and soil sample needs to be tested within a specified time to prevent water loss from affecting the test results.

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

[0030] The present invention overcomes the defects of the traditional method of roughness, destruction and inaccurate path judgment when reconstructing the critical seepage path of rock and soil, and realizes the visualization representation of the critical seepage path for harmless soil samples. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0033] Figure 3 The present invention Figure 2 AA cross-section of

[0034] Figure 4 It is a schematic diagram of the three stages of the experiment of the present invention;

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

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

[0037] Figure 7 The three-dimensional pore reconstruction of the present invention is Front schematic diagram;

[0038] Figure 8 The three-dimensional pore reconstruction of the present invention is Schematic diagram;

[0039] Figure 9 Schematic diagram of the three-dimensional critical seepage path (dashed line) of the present invention.

[0040] In the figure, 1. air pressure controller; 2. sample container; 3. digital camera; 4. computer; 5. air inlet; 6. barometer; 21. top plate; 22. cylinder; 23. bottom plate; 24. opening; 25. sealing ring; 26. fastener. DETAILED DESCRIPTION

[0041] The following will provide a clear and complete description of the relevant technologies in the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

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

[0043] The air pressure control module, located next to the sample sealing module, includes an air pressure controller 1 equipped with a high-precision pressure sensor for real-time air pressure monitoring. A high-pressure-resistant air pipe is connected to the output end of the air pressure controller 1, the other end of which is connected to the bottom of the sample container 2, applying air pressure to the saturated rock and soil sample. The air pressure controller 1 is equipped with a multi-stage pressure adjustment knob that can be adjusted manually or program-controlled via a connection to a computer 4, achieving a step-by-step increase in air pressure ΔP to the saturated rock and soil sample. The air pressure controller 1 also has a built-in voltage stabilization circuit module to ensure the stability of the output air pressure, with a pressure regulation accuracy of up to ±0.1 kPa.

[0044] The sample sealing module consists of a sample holder, a sample container 2 composed of a transparent, pressure-resistant resin sheet, and an O-ring 25. A circular opening is located at the top of the sample container 2 for accommodating saturated rock and soil samples. The transparent, pressure-resistant resin sheet ensures clear observation of the sample's state during air pressure loading and withstands high pressures. The O-ring 25, made of fluororubber, is installed at the interface between the cylinder 22 and the base plate 23 of the sample container 2. It has a pressure tolerance range of 0-500 kPa. When the air pressure controller 1 applies a stepped, increasing air pressure ΔP to the sample, it effectively seals the sample on all sides, allowing gas to escape only from the top opening, ensuring the accuracy and reliability of the test data.

[0045] Saturated rock and soil samples are cylindrical, 20 mm in diameter and 40 mm in height, precisely fitting within sample container 2. During preparation, natural rock and soil meeting the test requirements are first selected and crushed and sieved to remove impurities and large particles, ensuring uniformity. The treated rock and soil are then saturated using a vacuum saturation method. The rock and soil are placed in a sealed container, evacuated to a certain negative pressure and maintained for a period of time. Then, airless water is slowly injected to allow the water to fully penetrate the soil pores until the sample is completely saturated. The saturated rock and soil sample must be tested within the specified time to prevent water loss from affecting the test results. The saturated state ensures that the pore water pressure changes and gas evolution characteristics are accurately captured during the stepwise application of increasing air pressure ΔP by the air pressure controller 1, providing a reliable test subject for determining critical pore size and reconstructing seepage paths.

[0046] The external terminal consists of a digital camera 3 and a computer 4, which are the core components for realizing data acquisition, transmission and processing. The digital camera 3 is equipped with a high-resolution lens, which is precisely aligned with the top surface of the sample container 2. It has a high-speed shooting frame rate of 1000fps and an autofocus function. It can continuously shoot images of bubbles overflowing from the top surface of the sample at a time interval of 0.001s while the air pressure controller 1 applies air pressure to the saturated rock and soil sample. 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, and on the other hand, it synchronously obtains the air pressure data ΔP output by the air pressure controller 1. The computer 4 has built-in dedicated data processing software to correspond the air pressure change curve with the image sequence, and based on the capillary equation r c =ΔP break / (2γcosθ) (where γ is the surface tension and θ is the contact angle) to automatically calculate the critical pore size.

[0047] Furthermore, the air pressure control module includes a multi-stage buffer air chamber, and its unique structure and working principle can effectively alleviate pressure mutations and ensure that the pressure fluctuation during step-by-step pressurization is ≤±0.5kPa.

[0048] Furthermore, the digital camera 3 includes a high-speed image acquisition function, which automatically takes pictures at intervals of 0.001s when the test starts, thereby reducing errors caused by a large time span of image shooting.

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

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

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

[0052] The accurate determination of the critical state of seepage in rock and soil is achieved, and the ΔP is improved through the synergy of stepped air pressure loading and high frame rate image acquisition. break The measurement accuracy can be improved to obtain a more accurate critical seepage pore size.

[0053] The present invention also discloses a method for reconstructing the critical seepage path of rock and soil, which includes three-dimensional pore data acquisition, three-dimensional pore set reconstruction, and path reconstruction. This method can achieve high-precision visual reconstruction of the seepage process.

[0054] Three-dimensional pore data acquisition uses micro-CT scanning equipment to rotate the saturated rock and soil sample 360 ​​degrees to obtain the sample image, thereby realizing the microscopic data acquisition of the overall pore structure of the sample.

[0055] The reconstruction of 3D pore set is to import the pore size and spatial coordinates obtained from 3D pore data into professional 3D modeling software. The pore information set is constructed by arranging the pores from large to small according to their size. , the set contains the critical pore sizes measured using the above device .

[0056] Path reconstruction is to accurately locate the pore position in the three-dimensional blank space based on the spatial coordinates of each pore in the set, and then combine the pore size data to restore the pore shape one by one by size from large to small through geometric modeling. Theoretically, the first connected pore channel will appear, that is, the critical seepage path is obtained.

[0057] Furthermore, the three-dimensional pore data is collected by using a micro CT scanning device to scan the soil sample 360 ​​degrees, and the data collection accuracy is high.

[0058] Furthermore, the three-dimensional pore set reconstruction process can utilize professional software to more efficiently sort and construct sets of pore size and coordinate information, thereby ensuring the accuracy and completeness of the set data.

[0059] Furthermore, during the path reconstruction stage, a more optimized geometric modeling algorithm can be used for three-dimensional spatial positioning and pore morphology restoration to more accurately determine the critical seepage path.

[0060] Example

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

[0062] The cylinder 22 of the sample container 2 is made of a transparent pressure-resistant sealing resin plate, and is a hollow cylinder with an inner diameter of 20 mm, an outer diameter of 30 mm, and a height of 40 mm. It is sealed all around to prevent gas leakage from the sides and ensure the accuracy of the test results. 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, precisely aligned with the top surface of the sample container 2. During installation, the camera's position and angle must be adjusted to ensure the image capture fully covers the top surface of the sample container. The camera has a high-speed frame rate of 1000 fps and autofocus. Computer 4 establishes a bidirectional communication connection with the digital camera 3 and the air pressure controller 1 via a high-speed data transmission line. During the connection process, check that the data transmission line is properly plugged in and that the software is properly identifying the device.

[0068] According to this device, accurate measurement of critical pore size of rock and soil can be achieved: in the initial stage, the air pressure controller 1 outputs air pressure ΔP=0, the air pressure inside the sample is balanced with the atmospheric pressure, and the gas does not flow out; in the pressurization stage, the air pressure controller performs step-by-step pressurization at 0.1kPa / step. During this process, the sealing system maintains a leakage rate of ≤0.1kPa / min, and the gas has not yet broken through the pores of the sample; until the critical stage, when the air pressure reaches the critical value ΔP=ΔP break When the test is complete, the gas will escape from the top opening of the specimen. The sealing system will maintain airtightness around the specimen, allowing the gas to escape only from the designed opening at the top. This allows for accurate measurement of the critical pore size of the soil and rock mass. After the test, the modules of the device can be easily disassembled for cleaning and storage.

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

[0070] Step 1: Device construction and sample preparation

[0071] After the air pressure controller 1 is connected to the bottom of the sample container 2 and the connection is secure, an air tightness testing device is used to test the connection to ensure that there is no air pressure leakage.

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

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

[0074] Step 2: Air pressure control and data acquisition preparation

[0075] On computer 4, open the control software for air pressure controller 1 and set the air pressure adjustment range to 0-200 kPa, the pressure adjustment accuracy to ±0.1 kPa, and the stepped pressure mode with a pressure increment of 0.1 kPa. Turn on the voltage stabilization circuit module of air pressure controller 1 to ensure stable output pressure. In the settings menu of digital camera 3, turn on the autofocus function and set the exposure mode to automatic exposure. Set the image data storage path to a designated folder on computer 4 to ensure that images can be transmitted and saved in real time.

[0076] Step 3: Critical pore size determination

[0077] Start air pressure controller 1 and begin step-by-step pressurization of the saturated rock and soil sample. Starting from 0 kPa, gradually increase the air pressure in 0.1 kPa increments. Maintain the pressure steady for 10 seconds after each pressure increase to allow digital camera 3 to capture an image of the sample in a stable state.

[0078] Closely observe the image of the sample top surface taken by the digital camera 3, select the image when the bubble first appears, and record the pressure value output by the air pressure controller 1 at this time, which is the critical pressure ΔPbreak. c =ΔP break / (2γcosθ), the recorded ΔP break Substitute the value into the equation and calculate the critical seepage pore size r c and stores the calculation results in the database of computer 4.

[0079] Step 4: Reconstruction of critical seepage path of rock and soil

[0080] 1. 3D pore data collection

[0081] The saturated rock and soil sample that has completed the critical pore size determination is scanned 360° using a micro-CT scanner. The scanning resolution is set to 0.01mm to ensure that detailed pore structure information inside the sample can be obtained. After the scan is completed, the obtained sample pore image data is imported into professional 3D modeling software, such as Figure 5 , where the cylinders are the pores.

[0082] (2) Three-dimensional pore set reconstruction

[0083] The imported pore size and spatial coordinates are processed in the 3D modeling software. Pore size is arranged in descending order to construct a pore information set. This set includes the critical pore size measured using the aforementioned device to ensure data integrity.

[0084] (3) Path reconstruction

[0085] Based on the spatial coordinates of each pore in the collection, the pore position is precisely located in a three-dimensional blank space. Combined with the pore size data, geometric modeling is used to reconstruct the pore morphology by arranging them one by one from largest to smallest. During the arrangement process, when the first connected pore channel appears, the critical seepage path is obtained. The software's visualization function displays the reconstructed critical seepage path in three dimensions, allowing the morphology and direction of the seepage path to be observed from different angles.

[0086] To facilitate the description of the reconstruction method, the pores are colored in descending order. Figure 6 This is the result of staining all the pores in the soil. Fill the pores into the blank three-dimensional space step by step from large to small. The previous image is Figure 7 , in the three-dimensional pore reconstruction to Image such as Figure 8 , then theoretically a connected path can be seen, which is the critical seepage path, such as Figure 9 .

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

[0088] The rock and soil critical pore size measuring device and critical seepage path reconstruction method of this embodiment can effectively realize the accurate measurement of the critical pore size of rock and soil and the visual representation of the critical seepage path, providing a reliable technical means for the study of rock and soil seepage characteristics.

[0089] In summary, the present invention overcomes the defects of the traditional method of roughness, destruction and inaccurate path judgment when reconstructing the critical seepage path of rock and soil, and realizes the visualization representation of the critical seepage path for harmless soil samples.

[0090] It should be emphasized that the above are only preferred embodiments of the present invention and do not constitute any form of limitation to the present invention. Any simple modifications made to the above embodiments based on the technical essence of the present invention also fall within the scope of protection of the present invention. Other equivalent changes and modifications still fall within the scope of the technical solution of the present invention.

Claims

1. A device for measuring critical pore size of rock and soil, characterized in that: include: An air pressure controller (1), a sample container (2), a digital camera (3), and a computer (4); the sample container (2) is in the shape of a straight cylinder with an open top, the side walls and the bottom of the sample container (2) are sealed inside and outside, an air inlet (5) is provided at the bottom of the sample container (2), and the side walls of the sample container (2) are made of a transparent material; The gas output port of the air pressure controller (1) is connected to the air inlet (5); the shooting direction of the digital camera (3) is from top to bottom facing the top opening of the sample container (2); the air pressure controller (1) and the digital camera (3) are electrically connected to the computer (4) respectively; Also provided is a method for reconstructing a critical seepage path of a rock mass, the method comprising the following steps: Step 1: Device construction and sample preparation: connect the air pressure controller (1) to the bottom air inlet (5) of the sample container (2), select a saturated rock and soil sample and place it in the sample container (2), and connect the digital camera (3), air pressure controller (1) and computer (4); Step 2: Air pressure control and data acquisition preparation: set the air pressure controller (1) parameters and start the digital camera (3); Step 3, critical pore size determination data collection; stepwise pressurization of the saturated rock and soil sample in the sample container (2) by the air pressure controller (1); When the critical pressure ΔP is reached break Then turn off the device; use the capillary equation r based on the recorded data c =ΔP break / (2γcosθ) Calculate the theoretical value of critical pore size r c and record, where γ represents surface tension and θ represents contact angle; In step 3, the stepped supercharging includes three stages: Stage 1: Initial stage, ΔP=0, gas does not flow out, and the internal pressure of the sample is balanced with the atmospheric pressure, where ΔP represents the real-time pressure; Phase 2: Boost phase, ΔP<ΔP break , the air pressure controller increases the pressure in steps, the sealing system maintains a leakage rate of ≤0.1kPa / min, and the gas still does not break through the pores of the sample; Stage 3: Critical stage, ΔP=ΔP break When the air pressure reaches the critical value, the gas will overflow from the top opening. At this time, the sealing system still maintains the peripheral airtightness and only allows the gas to escape from the designed opening at the top. In step 3, during data collection, ΔP is triggered by step-by-step pressure increase. break , simultaneously record the theoretical calculated value of critical pore size When reconstructing the 3D network, the pore size and position coordinate sets of the 3D scan are arranged into sets from large to small. ; When the path is rebuilt, the set Reconstruct the 3D blank model from large to small pore size, and rearrange the critical pore size The first connected seepage path is obtained, namely the critical seepage path.

2. The rock and soil critical pore size measuring device according to claim 1, characterized in that: The air inlet (5) is located at the geometric center of the bottom of the sample container (2), and the air pressure controller (1) is provided with an air pressure gauge (6).

3. The rock and soil critical pore size measuring device according to claim 1, characterized in that: The sample container (2) comprises: a top plate (21), a cylinder (22), and a bottom plate (23); the cylinder (22) is a straight cylinder with upper and lower openings; an opening (24) is provided on the top plate (21); the opening (24) is of the same shape and size as the inner cylinder opening of the cylinder (22); The top plate (21) covers the edge of the upper opening of the cylinder (22) from top to bottom, and the bottom plate (23) supports the lower opening of the cylinder (22) from bottom to top.

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

5. The device for measuring critical pore size of rock and soil according to claim 1, characterized in that: The straight cylindrical shape of the sample container (2) includes: a circular cylindrical shape, an elliptical cylindrical shape, a rhombus cylindrical shape, and a regular polygonal cylindrical shape.

6. The rock and soil critical pore size measuring device according to claim 1, characterized in that: In step 1, the saturated rock and soil sample is placed in the sample container (2) and specifically includes the following steps: Select natural rock and soil that meets the test requirements, crush and sieve them to remove impurities and large particles to ensure the uniformity of the soil sample; Subsequently, the treated rock and soil were saturated using the vacuum saturation method. The rock and soil were placed in a sealed container, vacuumed to negative pressure and maintained for a period of time, and then airless water was slowly injected to allow the water to fully penetrate the pores of the soil sample until the soil sample was completely saturated.

7. The rock and soil critical pore size measuring device according to claim 6, characterized in that: In step 1, the saturated rock and soil sample needs to be tested within a specified time to prevent water loss from affecting the test results.

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