Method for testing coupling characteristic of soil-rock interface soil body pore seepage and rock side wall seepage

Abstract

The invention discloses a soil-rock interface soil body pore seepage and rock side wall seepage coupling characteristic test method, which comprises the following steps: step 1) designing a soil-rock interface contact seepage visual test system, carrying out a visual test, and obtaining a propulsion process of a soil-rock interface seepage wetting peak; step 2): constructing a soil-rock interface contact seepage model, and calculating model parameters in a coupling process; 3, the apparent permeability of the soil-rock interface is calculated. According to the method, the coupling characteristic change rule of soil body pore seepage and rock side wall seepage of the soil-rock interface can be effectively obtained, and powerful support is provided for researching the dynamic change and mechanism of the seepage phenomenon of the soil-rock interface.

Description

Technical Field

[0001] The invention relates to the technical field of water conservancy engineering and geotechnical engineering, in particular to a method for testing coupling characteristics of soil pore seepage and rock side wall seepage at a soil-rock interface. Background Art

[0002] Accumulation layer landslide is the most common type of landslide in the reservoir area. The soil-rock interface provides a good seepage channel for water migration under the action of rainfall and reservoir water level changes, and is the key part of the accumulation body slope sliding instability. The soil-rock interface is composed of rock and soil. Its seepage mainly involves the coupling process of rock wall seepage and soil pore seepage. The permeability of the soil itself is not much different from the permeability of the soil-rock interface. Water will seep along the soil-rock contact surface and migrate in the pores inside the soil, making the soil-rock interface show complex and changeable seepage characteristics.

[0003] Existing methods for observing internal seepage in rock and soil are mainly divided into two categories: interventional and non-interventional. Interventional methods usually include embedded pressure sensors and humidity sensors, which are directly implanted into the rock and soil to obtain data. However, this method may cause irreversible disturbances to the internal pore structure of the rock and soil, thereby affecting the accuracy and reliability of the test results. Non-intrusive measurement techniques, such as CT scanning, nuclear magnetic resonance (NMR) and X-ray imaging, reveal the internal microscopic pore structure and water flow state of rock and soil through non-destructive means, and can obtain high-resolution internal structure images without disturbing the sample, providing detailed information on the internal moisture distribution and pore structure of the rock and soil. However, it is difficult for such methods to achieve continuous tracking and real-time observation of the seepage process, which limits the application of such methods in capturing and analyzing the dynamic evolution of seepage phenomena.

[0004] For complex and inhomogeneous materials such as geotechnical media, there is an urgent need to develop an experimental method that can be visualized and monitored in real time, which can be directly used for in-depth research on geotechnical seepage behavior, help to more comprehensively understand and describe the dynamic changes and mechanisms of seepage phenomena, and provide strong technical support for solving complex seepage problems in geotechnical engineering. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a testing method for the coupling characteristics of soil pore seepage and rock side wall seepage at the soil-rock interface, so as to obtain a more intuitive observation of the real-time advancement process of the wetting peak of the soil-rock interface seepage, obtain the dynamic evolution law of the coupling characteristics of soil pore seepage and rock side wall seepage, and provide strong technical support for the analysis and research of soil-rock interface seepage behavior.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for testing the coupling characteristics of soil pore seepage and rock wall seepage at a soil-rock interface, which comprises the following steps: Step 1): Design a soil-rock interface contact seepage visualization test system, carry out visualization tests, and obtain the advancement process of the soil-rock interface seepage wetting peak; Step 2): Construct a soil-rock interface contact seepage model and calculate the model parameters in the coupling process; Step 3): Calculate the apparent permeability of the soil-rock interface.

[0007] Preferably, the step 1) specifically includes the following steps: Step 1.1): Construct a soil-rock interface contact seepage visualization test system; Step 1.2): Conduct a soil-rock interface contact seepage visualization test and use a CCD camera to capture the seepage process; Step 1.3): Use Matlab image acquisition tools to obtain the seepage wetting front morphology diagram of the soil-rock interface at each moment.

[0008] More preferably, the soil-rock interface contact seepage visualization test system constructed in the step 1.1) includes a seepage main body test device and an image acquisition device, the seepage main body test device includes a model box, one side of the model box is connected to the inlet pipeline, and the other side is connected to the outlet pipeline, the inlet pipeline is sequentially provided with a water tank, a water pump and a pressure measuring tube, a collecting beaker is provided at the end of the outlet pipeline, the collecting beaker is provided on an electronic balance, the water pump is connected to a DC power supply, and the image acquisition device includes a computer and a CCD camera arranged on the front of the model box.

[0009] More preferably, the model box includes a slow flow chamber, a seepage chamber and a liquid collecting chamber which are combined in sequence, a water inlet is arranged on one side of the slow flow chamber, a water outlet is arranged on one side of the liquid collecting chamber, a step is arranged between the slow flow chamber and the seepage chamber, a gap is left at the connection, a porous partition and a step are arranged between the seepage chamber and the liquid collecting chamber, and a layer of filter net is attached to the porous partition.

[0010] More preferably, the step 1.2) is specifically as follows: Test preparation: Arrange the test equipment, prepare transparent soil materials with different particle sizes and organic glass plates, prepare soil-rock interface samples, load the samples, and perform sealing treatment; Start seepage: turn on the DC power supply, adjust the voltage, control the flow rate, turn on the water pump, and the liquid in the water tank enters the slow flow chamber on the left side of the model box from the water inlet through the water pump, penetrates into the seepage chamber through the gap, and after the infiltration, enters the liquid collecting chamber through the porous partition, and finally flows out through the water outlet into the collection beaker; Data collection: After the seepage stabilizes, the water head value of the piezometer is recorded, and the weight change data obtained by the electronic balance is used to determine the flow through the soil-rock interface. The front CCD camera is used to capture the movement of the seepage wetting front at the soil-rock interface at each moment, and the results are fed back to the computer; End of the test: organize and collect test data, make relevant test records, and clean up the test site.

[0011] More preferably, the step 1.3) is specifically as follows: Step 1.3.1): Screen the images and select images at the same interval within the seepage time period; Step 1.3.2): Use Matlab software to identify the RGB values ​​of different color gamuts in the image, and numerically calibrate the percolation state of the color image into two areas; Step 1.3.3): Normalize the color gamut value of the original color image to grayscale value; Step 1.3.4): Through the grayscale histogram, use the formula: I = grayscale value / 255 to accurately divide the seepage area; Step 1.3.5): After the critical I value is normalized and the partition is simplified, a black and white highlight binary image is obtained; Step 1.3.6): Use secondary layer overlay rendering to process the image.

[0012] Preferably, the step 2) is specifically as follows: Step 2.1) Determine the peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time relationship; Step 2.2) Calculate the thickness of the soil pore seepage layer Equivalent seepage layer thickness to rock wall .

[0013] More preferably, the step 2.1) is specifically as follows: The wetting peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time The relationship is: ; The wetting peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time The relationship is: ; The wetting peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time The relationship is: ; Where: is the initial infiltration velocity, It is the moment when water begins to infiltrate into the pore seepage layer of the soil. For the thickness The time required for the soil pore seepage layer to diffuse.

[0014] More preferably, the step 2.2) is specifically as follows: The moment when water begins to infiltrate into the pore seepage layer of the soil Equivalent seepage layer thickness to rock wall The relationship is: ; In thickness The time required for the diffusion of the soil pore seepage layer The thickness of the soil pore seepage layer The relationship is: ; Where: is the diffusion coefficient of the soil pore seepage layer, is the saturation of the equivalent seepage layer of the rock wall, is the soil porosity, is the initial saturation of the soil pore seepage layer.

[0015] Preferably, the step 3) is specifically as follows: the apparent permeability of the soil-rock interface is calculated from the permeability of the equivalent seepage layer of the rock wall and the seepage layer of the soil pores: ; Where: is the permeability of the equivalent seepage layer of the rock wall, is the permeability of the soil, is the soil layer thickness, is the equivalent seepage layer thickness of the rock wall, is the thickness of the soil pore seepage layer.

[0016] Beneficial effects of the present invention: 1) It overcomes the non-transparency problem of rock and soil media, realizes intuitive visualization observation of the water flow state inside the soil-rock interface, can obtain the continuous and complete water flow movement process inside the soil-rock interface, and can obtain a more intuitive observation of the real-time advancement process of the wetting peak of soil-rock interface seepage; 2) Through the coupling model of soil pore seepage and rock wall seepage at the soil-rock interface, the correlation between the wetting peak advancement process at the soil-rock interface and the coupling of soil pore seepage and rock wall seepage was established, and the experimental test of the coupling characteristics of soil pore seepage and rock wall seepage at the soil-rock interface was realized; 3) It can effectively obtain the dynamic evolution law of the coupling characteristics of soil pore seepage and rock wall seepage at the soil-rock interface, provide strong support for studying the dynamic changes and mechanisms of soil-rock interface seepage phenomena, and provide strong technical support for analyzing and studying soil-rock interface seepage behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of the testing method of the present invention; Figure 2 It is a structural schematic diagram of the soil-rock interface contact seepage visualization test system of the present invention; Figure 3 is the movement process of the seepage wetting front at the soil-rock interface at each moment in the embodiment; Figure 4 It is the relationship between the wetting peak infiltration distance and the infiltration time in the embodiment. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0019] Example 1: Figure 1 As shown, a method for testing the coupling characteristics of soil pore seepage and rock wall seepage at a soil-rock interface includes the following steps: Step 1): Design a soil-rock interface contact seepage visualization test system, carry out visualization tests, and obtain the advancement process of the soil-rock interface seepage wetting peak; Step 1.1): Construct a soil-rock interface contact seepage visualization test system; Figure 2 As shown, the soil-rock interface contact seepage visualization test system constructed in the step 1.1) includes a seepage main body test device and an image acquisition device, the seepage main body test device includes a model box, one side of the model box is connected to the inlet pipeline, and the other side is connected to the outlet pipeline, the inlet pipeline is sequentially provided with a water tank 9, a water pump 8 and a pressure measuring tube 10, a collecting beaker 13 is provided at the end of the outlet pipeline, the collecting beaker 13 is arranged on an electronic balance 15, the water pump 8 is connected to a DC power supply 14, and the image acquisition device includes a computer 11 and a CCD camera 12 arranged on the front of the model box.

[0020] The model box includes a slow flow chamber 1, a seepage chamber 2 and a liquid collecting chamber 3 which are combined in sequence. A water inlet 4 is arranged on one side of the slow flow chamber 1, and a water outlet 5 is arranged on one side of the liquid collecting chamber 3. A step is arranged between the slow flow chamber 1 and the seepage chamber 2, and a gap is left at the connection. A porous partition 7 and a step are arranged between the seepage chamber 2 and the liquid collecting chamber 3, and a layer of filter screen 6 is attached to the porous partition 7.

[0021] In this embodiment, a test model box is designed and processed, and the size of the model box is 20cm×10cm×10cm (length×width×height); a porous partition 7 is provided between the seepage chamber 2 and the liquid collecting chamber 3 of the model box, and a layer of fine filter mesh 6 is attached to the porous partition 7 to prevent soil particles from being lost along with the water; the water inlet 4 is connected to the pressure measuring tube 10 for measuring the water head; the water pump 8 is connected to a DC power supply 14; a CCD camera 12 is arranged on the front of the model box and connected to a computer 11 to record the morphology of the seepage wetting front of the soil-rock interface at each moment.

[0022] Step 1.2): Conduct a soil-rock interface contact seepage visualization test and use a CCD camera to capture the seepage process; specifically: Test preparation: arrange the test equipment, prepare transparent soil materials and organic glass plates with different particle sizes, prepare soil-rock interface samples, fill the samples, and perform sealing treatment; in this embodiment, prepare transparent soil materials and organic glass plates with a particle size of 0.5-1 mm, prepare soil-rock interface samples, fill the samples with a thickness of 1.5 cm, and perform sealing treatment; Start seepage: turn on the DC power supply 14, adjust the voltage, control the flow rate, turn on the water pump 8, and the liquid in the water tank 9 enters the slow flow chamber 1 on the left side of the model box from the water inlet 4 through the water pump 8, penetrates into the seepage chamber 2 through the gap, and after the infiltration, enters the liquid collection chamber 3 through the porous partition 7, and finally flows out through the water outlet 5 into the collection beaker 13; in this embodiment, the voltage is adjusted to 8V and the flow rate is controlled to 2.3cm 3 / s; Data collection: After the seepage is stable, the water head value of the pressure gauge 10 is recorded (in this embodiment, the water head value of the pressure gauge is 12.78 cm after the seepage is stable), the weight change data obtained by the electronic balance 15 is used to determine the flow through the soil-rock interface, and the front CCD camera 12 is used to capture the movement of the seepage wetting front at the soil-rock interface at each moment (such as Figure 3 As shown), and the result is fed back to the computer 11; End of the test: organize and collect test data, make relevant test records, and clean up the test site.

[0023] Step 1.3): Use Matlab image acquisition tools to obtain the seepage wetting front morphology of the soil-rock interface at each moment. Specifically: Step 1.3.1): Screen the images and select 100 images at the same interval within the seepage time period; Step 1.3.2): Use Matlab software to identify the RGB values ​​of different color gamuts in the image, and numerically calibrate the percolation state of the color image into two areas; Step 1.3.3): Normalize the color gamut value of the original color image to grayscale value; Step 1.3.4): Through the grayscale histogram, use the formula: I = grayscale value / 255 to accurately divide the seepage area; Step 1.3.5): After the critical I value is normalized and the partition is simplified, a black and white highlight binary image is obtained; Step 1.3.6): Use secondary layer overlay rendering to process the image.

[0024] Step 2): Construct a soil-rock interface contact seepage model and calculate the model parameters in the coupling process; Step 2.1) Determine the peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time relationship (such as Figure 4 Specifically: The wetting peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time The relationship is: ; The wetting peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time The relationship is: ; The wetting peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time The relationship is: ; Where: is the initial infiltration velocity, It is the moment when water begins to infiltrate into the pore seepage layer of the soil. For the thickness The time required for the soil pore seepage layer to diffuse. , ; Step 2.2) Calculate the thickness of the soil pore seepage layer Equivalent seepage layer thickness to rock wall Specifically: The moment when water begins to infiltrate into the pore seepage layer of the soil Equivalent seepage layer thickness to rock wall The relationship is: ; In thickness The time required for the diffusion of the soil pore seepage layer The thickness of the soil pore seepage layer The relationship is: ; Where: is the diffusion coefficient of the soil pore seepage layer, is the saturation of the equivalent seepage layer of the rock wall, is the soil porosity, is the initial saturation of the soil pore seepage layer. In this embodiment, is the equivalent seepage layer thickness of the rock wall, is the thickness of the soil pore seepage layer, calculated , ; Step 3): Calculate the apparent permeability of the soil-rock interface. Specifically, the apparent permeability of the soil-rock interface is calculated from the permeability of the equivalent seepage layer of the rock wall and the seepage layer of the soil pores: ; Where: is the permeability of the equivalent seepage layer of the rock wall, is the permeability of the soil, is the soil layer thickness, is the equivalent seepage layer thickness of the rock wall, is the thickness of the soil pore seepage layer. In this embodiment, the calculation results are ; The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for testing the coupling characteristics of soil pore seepage and rock wall seepage at a soil-rock interface, characterized in that: It includes the following steps: step 1): Design a soil-rock interface contact seepage visualization test system, carry out visualization tests, and obtain the advancement process of the soil-rock interface seepage wetting peak; Step 2): Construct a soil-rock interface contact seepage model and calculate the model parameters in the coupling process; Step 3): Calculate the apparent permeability of the soil-rock interface.

2. The method for testing the coupled characteristics of soil pore seepage and rock wall seepage at a soil-rock interface according to claim 1, characterized in that: The step 1) specifically includes the following steps: Step 1.1): Construct a soil-rock interface contact seepage visualization test system; Step 1.2): Conduct a soil-rock interface contact seepage visualization test and use a CCD camera to capture the seepage process; Step 1.3): Use Matlab image acquisition tools to obtain the seepage wetting front morphology diagram of the soil-rock interface at each moment.

3. The method for testing the coupled characteristics of soil pore seepage and rock wall seepage at a soil-rock interface according to claim 2, characterized in that: The soil-rock interface contact seepage visualization test system constructed in step 1.1) comprises a seepage main body test device and an image acquisition device. The seepage main body test device comprises a model box, one side of the model box is connected to an inlet pipeline, and the other side is connected to an outlet pipeline. The inlet pipeline is provided with a water tank (9), a water pump (8) and a pressure measuring tube (10) in sequence. A collecting beaker (13) is provided at the end of the outlet pipeline. The collecting beaker (13) is arranged on an electronic balance (15). The water pump (8) is connected to a direct current power supply (14). The image acquisition device comprises a computer (11) and a CCD camera (12) arranged on the front of the model box.

4. The method for testing the coupled characteristics of soil pore seepage and rock wall seepage at a soil-rock interface according to claim 3, characterized in that: The model box comprises a slow flow chamber (1), a seepage chamber (2) and a liquid collecting chamber (3) which are sequentially combined together; a water inlet (4) is arranged on one side of the slow flow chamber (1); a water outlet (5) is arranged on one side of the liquid collecting chamber (3); a step is arranged between the slow flow chamber (1) and the seepage chamber (2); a gap is left at the connection; a porous partition (7) and a step are arranged between the seepage chamber (2) and the liquid collecting chamber (3); and a layer of filter screen (6) is attached to the porous partition (7).

5. The method for testing the coupled process of soil pore seepage and rock wall seepage at the soil-rock interface according to claim 2, characterized in that: The step 1.2) is specifically as follows: Test preparation: Arrange the test equipment, prepare transparent soil materials with different particle sizes and organic glass plates, prepare soil-rock interface samples, load the samples, and perform sealing treatment; Start seepage: turn on the DC power supply (14), adjust the voltage, control the flow rate, turn on the water pump (8), and the liquid in the water tank (9) enters the slow flow chamber (1) on the left side of the model box from the water inlet (4) through the water pump (8), penetrates through the gap into the seepage chamber (2), and after the infiltration, enters the liquid collection chamber (3) through the porous partition (7), and finally flows out through the water outlet (5) into the collection beaker (13); Data collection: After the seepage stabilizes, the water head value of the pressure measuring tube (10) is recorded, and the weight change data obtained by the electronic balance (15) is used to determine the flow rate through the soil-rock interface. The front CCD camera (12) is used to photograph the movement of the seepage wetting front at the soil-rock interface at each moment, and the results are fed back to the computer (11); End of the test: organize and collect test data, make relevant test records, and clean up the test site.

6. The method for testing the coupled characteristics of soil pore seepage and rock wall seepage at a soil-rock interface according to claim 2, characterized in that: The step 1.3) is specifically as follows: Step 1.3.1): Screen the images and select images at the same interval within the seepage time period; Step 1.3.2): Use Matlab software to identify the RGB values ​​of different color gamuts in the image, and numerically calibrate the percolation state of the color image into two areas; Step 1.3.3): Normalize the color gamut value of the original color image to grayscale value; Step 1.3.4): Through the grayscale histogram, use the formula: I = grayscale value / 255 to accurately divide the seepage area; Step 1.3.5): After the critical I value is normalized and the partition is simplified, a black and white highlight binary image is obtained; Step 1.3.6): Use secondary layer overlay rendering to process the image.

7. The method for testing the coupled characteristics of soil pore seepage and rock wall seepage at a soil-rock interface according to claim 1, characterized in that: The step 2) is specifically as follows: Step 2.1) Determine the peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time relationship; Step 2.2) Calculate the thickness of the soil pore seepage layer Equivalent seepage layer thickness to rock wall .

8. The method for testing the coupled characteristics of soil pore seepage and rock wall seepage at a soil-rock interface according to claim 7, characterized in that: The step 2.1) is specifically as follows: The wetting peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time The relationship is: ； The wetting peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time The relationship is: ； The wetting peak infiltration distance of water in the equivalent seepage layer of the rock wall Infiltration time The relationship is: ； Where: is the initial infiltration velocity, It is the moment when water begins to infiltrate into the pore seepage layer of the soil. For the thickness The time required for the soil pore seepage layer to diffuse.

9. The method for testing the coupled characteristics of soil pore seepage and rock wall seepage at a soil-rock interface according to claim 7, characterized in that: The step 2.2) is specifically as follows: The moment when water begins to infiltrate into the pore seepage layer of the soil Equivalent seepage layer thickness to rock wall The relationship is: ； In thickness The time required for the diffusion of the soil pore seepage layer The thickness of the soil pore seepage layer The relationship is: ； Where: is the diffusion coefficient of the soil pore seepage layer, is the saturation of the equivalent seepage layer of the rock wall, is the soil porosity, is the initial saturation of the soil pore seepage layer.

10. The method for testing the coupled characteristics of soil pore seepage and rock wall seepage at a soil-rock interface according to claim 1, characterized in that: The step 3) is specifically as follows: the apparent permeability of the soil-rock interface is calculated from the permeability of the equivalent seepage layer of the rock wall and the seepage layer of the soil pores: ； Where: is the permeability of the equivalent seepage layer of the rock wall, is the permeability of the soil, is the soil layer thickness, is the equivalent seepage layer thickness of the rock wall, is the thickness of the soil pore seepage layer.

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