An experimental device and method for simulating the combined driving of soil particle loss by reciprocating seepage and dry-wet cycles

Abstract

The present invention provides an experimental device and method for simulating the loss of soil particles driven by reciprocating seepage and dry-wet cycle. The device includes a water supply and drainage system, a sample chamber, an air drying system and a measurement system. The sample chamber is used to hold samples required for the experiment. The sample chamber is connected to the water supply and drainage system for water supply and drainage. The top of the sample chamber is provided with an air drying system for air drying. The air drying system is equipped with a measurement system for measurement. The device can fully simulate the mass loss, crack development, surface depression degree and other conditions of the bank slope soil under the action of periodic fluctuations of water levels and natural air drying. The specific data of soil mass loss driven by reciprocating seepage and dry-wet cycle and the real-time changes of cracks on the sample surface can be accurately grasped. The device has a simple structure and is convenient and quick to use.

Description

Technical Field

[0001] The invention relates to the field of water conservancy and rock and soil experiments, in particular to an experimental device and method for simulating particle loss in bank slope soil under the condition of river and reservoir water level fluctuation. Background Art

[0002] my country has built more than 100,000 reservoirs and dams of various sizes, of which nearly 20,000 are over 15 meters high. There are also many lakes and water systems of various types, including more than 2,800 natural lakes with an area of ​​more than 1 square kilometer. For gravel soil slopes, when the water level of rivers and reservoirs rises, the water flows into the slope, and when the water level drops, the groundwater in the slope will flow out of the slope, forming a periodic back-and-forth seepage effect. The loss of fine particles in the soil under the seepage effect will reduce the plasticity and viscosity of the soil and increase the degree of crack development; on the other hand, the fluctuation of water levels causes the slope soil to experience dry-wet cycles, which will lead to the development of micro-cracks in the soil, and will inevitably accelerate the stripping of fine particles and increase their loss channels. The combined driving effect of back-and-forth seepage and dry-wet cycles will cause the soil microstructure and mechanical properties to deteriorate, which will lead to a decrease in the stability of the slope, causing potential harm and adverse effects on the country's economic development, residents' daily life, and natural environmental protection. Exploring and studying the loss of fine particles, crack development, and performance degradation in slope soil has always been an important research topic in the fields of civil engineering, water conservancy engineering, and environmental engineering. According to the current situation analysis, there are mainly the following deficiencies:

[0003] (1) The seepage erosion experiment only studies the effect of water flow in a single direction on soil particle loss, and does not simulate the round-trip seepage caused by the rise and fall of reservoir water;

[0004] (ii) The combined driving effect of round-trip seepage and wetting-drying cycles on the loss of soil fine particles is not considered;

[0005] (III) There is no quantitative description of the process of fine particle loss in the soil and the development of cracks on the soil surface as the number of combined actions increases. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an experimental device and method for simulating the loss of soil particles driven by the combined action of reciprocating seepage and wet-dry cycles. The device can fully simulate the mass loss, crack development, surface depression degree, etc. of the slope soil under the action of periodic fluctuations in water levels and natural wind drying, and can accurately grasp the specific data of soil mass loss under the combined action of reciprocating seepage and wet-dry cycles and the real-time changes of cracks on the sample surface. The device has a simple structure and is quick and convenient to use.

[0007] In order to realize the above technical features, the object of the present invention is achieved as follows: an experimental device for simulating the loss of soil particles driven by round-trip seepage and dry-wet cycles, characterized in that it includes a water supply and drainage system, a sample chamber, an air drying system and a measurement system;

[0008] The sample chamber is used to hold samples required for the experiment;

[0009] The sample chamber is connected to a water supply and drainage system for water supply and drainage;

[0010] The top of the sample chamber is provided with an air drying system for air drying;

[0011] The air drying system is equipped with a measuring system for measuring.

[0012] The sample chamber comprises a transparent cylinder, the bottom layer of which is paved with a gravel buffer layer, the upper layer of which is paved with permeable stones, and a filter screen for filtering is arranged at the center of the bottom end of the transparent cylinder; the sample is arranged on the top layer of the permeable stones.

[0013] The water supply and drainage system includes a water storage tank, which is connected to the upper side wall of the transparent cylinder through a water pipe and a flush valve; the water storage tank is connected to the filter screen at the bottom of the sample chamber through a water pipe and a water inlet valve; the filter screen is connected to a drainage pipe through a three-way pipe, and a drainage valve is installed on the drainage pipe;

[0014] The upper outer side wall of the transparent cylinder is connected with a sand discharge pipe.

[0015] The air drying system comprises a fixed bracket, which is provided with a plurality of warm fans for air drying; the fixed bracket is arranged at the top of the transparent cylinder of the sample chamber;

[0016] The invention also comprises a heating tube which is arranged inside the transparent cylinder of the sample chamber.

[0017] The measuring system includes a camera and a fine particle collection cylinder;

[0018] The camera is arranged at the bottom center of the fixed bracket of the air drying system;

[0019] The fine particle collection cylinder is connected to the sand discharge pipe of the water supply and drainage system.

[0020] The water tank and the water inlet valve are used to control the upward seepage of water from the water pipe so that the fine particles in the sample migrate to the upper surface, and the flushing valve is used to allow the turbid water containing fine particles to enter the sand discharge pipe. When the water inlet valve and the flushing valve are closed, the drainage valve is opened to allow the free water in the sample to flow slowly downward, thereby realizing the round-trip seepage process and simulating the movement environment of groundwater on the slope when the water level rises and falls.

[0021] After the free water is discharged, the sample is dried evenly and quickly through the heating tubes evenly distributed in the sample room and the warm fan placed on the fixed bracket, so as to fully simulate the field environment where the soil is exposed to wind and sun; and the steps of water intake-drainage-air drying are repeated to simulate the combined driving effect of round-trip seepage and dry-wet cycle.

[0022] The camera placed in the fixed bracket directly above the soil sample can clearly record the development of cracks on the surface of the sample and the degree of soil surface depression during the entire test. The fine particle collection tube connected to the sand discharge pipe can collect fine particles lost by the sample under the combined drive of reciprocating seepage and dry-wet cycles.

[0023] The method for conducting an experiment using the experimental device for simulating reciprocating seepage and dry-wet cycle combined driving soil particle loss comprises the following steps:

[0024] Step 1: Set up the water tank to the preset height and check whether the water pipes, heating pipes, cameras and electric heater components in the experimental device can be used normally;

[0025] Step 2: Evenly lay a gravel buffer layer on the bottom layer of the transparent cylinder, then apply vaseline on the upper and lower sides of the permeable stone and place it on top of the gravel buffer layer;

[0026] Step 3: Place the prepared sample on the upper layer of the permeable stone padded with filter paper, and ensure that the sample is even and flat;

[0027] Step 4: Adjust the position between the sand discharge pipe and the fine particle collection tube, connect the data transmission and start the camera, then open the water inlet valve to simulate the penetration of the upward water flow on the sample, and the fine particles gradually migrate upward to the surface of the sample;

[0028] Step 5: Open the flush valve to allow the suspended particles on the surface of the sample to flow into the fine particle collection tube through the sand discharge pipe. When there are no obvious particles in the upper water layer, close the water inlet valve and flush valve;

[0029] Step 6: Open the drain valve to allow the free water in the transparent cylinder to drain slowly from the bottom;

[0030] Step 7: After adjusting the position of the fixed bracket, turn on the heating tube and the warm fan to start drying the sample;

[0031] Step 8: Observe the development of cracks on the surface of the sample. When the cracks develop stably, turn off the heating tube, the fan, and the camera, and calculate the surface crack area ratio c1 through image processing software;

[0032] Step 9: Remove the fine particle collection cylinder and dry the liquid in the cylinder, and weigh the dry mass of the fine particles as m1;

[0033] Step 10: Repeat the above steps 4 to 9, complete the infiltration-drainage-drying process n times, and measure the mass m of the lost fine particles. n and surface crack rate c n , and data analysis was performed to determine the evolution of fine particle loss mass and surface crack rate with the number of combined driving actions.

[0034] The present invention has the following beneficial effects:

[0035] 1. The specific scheme of the present invention reveals the development law of fine particle loss process of bank slope soil under the action of periodic fluctuation of river water level;

[0036] 2. Change the seepage water pressure by adjusting the height of the water storage tank and analyze the effect of the water level drop rate on the loss of fine particles;

[0037] 3. Reveal the evolution law of crack development on the soil surface caused by dry-wet cycles;

[0038] 4. Explore the mutual promotion of soil microcrack development and fine particle loss;

[0039] 5. The same experiment can be carried out on soil samples with different particle gradations and densities to explore the influence of the initial state of the soil on the process of fine particle loss and the law of microcrack development;

[0040] 6. The development law of sample density, water content and porosity with the number of combined driving times can be calculated through the loss of fine particles and the overall volume change of the sample; BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0042] Figure 1 This is a three-dimensional diagram from the first perspective of the present invention.

[0043] Figure 2 This is a three-dimensional diagram from the second viewing angle of the present invention.

[0044] Figure 3 This is a three-dimensional diagram from the third viewing angle of the present invention.

[0045] Figure 4 It is a cross-sectional view of the interior of the transparent cylinder of the present invention.

[0046] In the figure: water tank 1, water inlet valve 2, flushing valve 3, water pipe 4, sand discharge pipe 5, drain valve 6, filter 7, transparent cylinder 8, gravel buffer layer 9, permeable stone 10, sample 11, heating tube 12, heating fan 13, fixing bracket 14, camera 15, fine particle collection tube 16. DETAILED DESCRIPTION

[0047] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0048] Embodiment 1:

[0049] Experimental preparation:

[0050] See also Figure 1-4, Experimental equipment: water tank, water valve, water pipe, filter, Φ40cm*10cm transparent cylinder, buffer gravel, permeable stone, heating tube, 200W*4 warm fan, fixed bracket, high-definition camera, fine particle collection tube, etc.

[0051] Soil samples: fixed volume, saturated mass, density, particle size distribution, moisture content and other related information.

[0052] Heating tube and heating fan: connect to 220V power supply.

[0053] Oven and balance: used to weigh the mass of solid particles in the fine particle collection tube after drying.

[0054] Embodiment 2:

[0055] like Figure 1-4 As shown, an experimental device for simulating reciprocating seepage and dry-wet cycle to drive soil particle loss, which includes a water supply and drainage system simulating the reciprocating seepage and an air drying system simulating the dehydration and drying process of the sample; a sample chamber connected to the water supply and drainage system for placing the experimental soil; and a measurement system connected to the sample chamber for measuring and recording the experimental process.

[0056] Furthermore, the water supply and drainage system mainly includes a water tank 1 with adjustable height, a water inlet valve 2, a flushing valve 3, a water pipe 4 connected to the water tank, and a drain valve 6 and a sand discharge pipe 5 connected to the sample chamber; by adopting the above-mentioned water supply and drainage system, the reciprocating seepage effect of water on the sample is realized.

[0057] Furthermore, the sample chamber includes a transparent cylinder 8 connected to the water supply and drainage system; a filter screen 7, a crushed stone buffer layer 9, a permeable stone 10, and a sample are placed in the cylinder from bottom to top, which can achieve the effect of uniformly acting the infiltration water flow and water pressure on the soil.

[0058] Furthermore, the air-drying system includes a heating tube 12 located in the transparent cylinder 8 and a warm fan 13 located above the sample and its fixing bracket 14; the above-mentioned air-drying system can be used to accelerate the drying process of the sample and simulate the effects of wind and sun after the free water in the soil is discharged.

[0059] Furthermore, the measurement system mainly includes a camera 15 installed above the sample and a fine particle collection tube 16 connected to the sand discharge pipe 5; the camera 15 is used to monitor the phenomenon of fine particle loss during seepage, and record images and videos of the occurrence and development of cracks on the surface of the soil sample during the drying process; the fine particle collection tube 16 is used to collect fine particles migrated from the sample, and after deposition, drying and weighing, to achieve accurate measurement of the data of the mass of fine particle loss of the sample.

[0060] Embodiment 3:

[0061] The experimental method for simulating the loss of soil particles by combining the back-and-forth seepage and the dry-wet cycle using the experimental device includes the following steps:

[0062] Step 1: Erect the water tank 1 to a preset height, and check whether the water pipe 4, heating pipe 12, camera 15 and electric heater 13 components in the experimental device can be used normally;

[0063] Step 2: Evenly lay a gravel buffer layer 9 on the bottom layer of the transparent cylinder 8, and then apply vaseline on the upper and lower sides of the permeable stone 10, and then place it on top of the gravel buffer layer 9;

[0064] Step 3: Place the prepared sample on the upper layer of the permeable stone 10 padded with filter paper, and ensure that the sample is even and flat;

[0065] Step 4: Adjust the position between the sand discharge pipe 5 and the fine particle collection tube 16, connect the data transmission and start the camera 15, then open the water inlet valve 2 to simulate the penetration of the upward water flow on the sample, and the fine particles gradually migrate upward to the surface of the sample;

[0066] Step 5: Open the flush valve 2 to allow the suspended particles on the surface of the sample to flow into the fine particle collection tube 16 through the sand discharge pipe 5. When there are no obvious particles in the upper water layer, close the water inlet valve 2 and the flush valve 3;

[0067] Step 6: Open the drain valve 6 to allow the free water in the transparent cylinder 8 to drain slowly from the bottom;

[0068] Step 7: After adjusting the position of the fixed bracket 14, turn on the heating tube 12 and the warm fan 13 to start drying the sample;

[0069] Step 8: Observe the development of cracks on the surface of the sample. After the cracks develop stably, turn off the heating tube 12, the warm fan 13, and the camera 15, and calculate the surface crack area ratio c1 through image processing software;

[0070] Step 9: Remove the fine particle collection cylinder 16 and dry the liquid in the cylinder, and weigh the dry mass of the fine particles as m1;

[0071] Step 10: Repeat the above steps 4 to 9, complete the infiltration-drainage-drying process n times, and measure the mass m of the lost fine particles. n and surface crack rate c n , record the data as shown in the following table and perform data analysis to determine the evolution law of fine particle loss mass and surface crack rate with the number of combined driving actions.

[0072] Experimental process data information table

[0073]

[0074] Embodiment 4:

[0075] The experimental method of simulating the loss of soil particles driven by reciprocating seepage alone using the experimental device, that is, not considering the effect of dry-wet cycle, includes the following steps:

[0076] Step 1: Erect the water tank 1 to a preset height;

[0077] Step 2: Evenly lay a gravel buffer layer 9 on the bottom layer of the transparent cylinder 8, and then apply vaseline on the upper and lower sides of the permeable stone 10, and then place it on top of the gravel buffer layer 9;

[0078] Step 3: Place the prepared sample on the permeable stone 10 padded with filter paper, and ensure that the sample is even and flat;

[0079] Step 4: Adjust the position between the sand discharge pipe 5 and the fine particle collection tube 16, connect the data transmission and start the camera 15, then open the water inlet valve 2 to simulate the penetration of the upward water flow on the sample, and the fine particles gradually migrate upward to the surface of the sample;

[0080] Step 5: Open the flush valve 2 to allow the suspended particles on the surface of the sample to flow into the fine particle collection tube 16 through the sand discharge pipe 5. When there are no obvious particles in the upper water layer, close the water inlet valve 2 and the flush valve 3;

[0081] Step 6: Open the drain valve 6 to allow the free water in the transparent cylinder 8 to slowly drain from the bottom, simulating downward seepage;

[0082] Step 7: Remove the fine particle collection cylinder 16 and dry the liquid in the cylinder, and weigh the dry mass of the fine particles as m1;

[0083] Step 8: Repeat the above steps 4 to 7, complete the infiltration-drainage-drying process n times, and measure the mass m of the lost fine particles. n , and conduct data analysis.

Claims

1. An experimental device for simulating the combined driving of soil particle loss by reciprocating seepage and dry-wet cycles, characterized in that: It includes water supply and drainage system, sample room, air drying system and measurement system; The sample chamber is used to hold samples required for the experiment; The sample chamber is connected to a water supply and drainage system for water supply and drainage; The top of the sample chamber is provided with an air drying system for air drying; The air-drying system is equipped with a measuring system for measuring; The sample chamber comprises a transparent cylinder (8), the bottom layer of the transparent cylinder (8) is paved with a gravel buffer layer (9), the upper layer of the gravel buffer layer (9) is paved with permeable stones (10), and a filter screen (7) for filtering is arranged at the center of the bottom end of the transparent cylinder (8); the sample is arranged on the top layer of the permeable stones (10); The water supply and drainage system comprises a water storage tank (1), the water storage tank (1) being connected to the upper side wall of the transparent cylinder (8) via a water pipe and a flushing valve (3); the water storage tank (1) being connected to a filter screen (7) at the bottom of the sample chamber via a water pipe and a water inlet valve (2); the filter screen (7) being connected to a drainage pipe via a three-way pipe, and a drainage valve (6) being installed on the drainage pipe; A sand discharge pipe (5) is connected to the upper outer wall of the transparent cylinder (8); The water is controlled to flow upward from the water pipe (4) through the water storage tank (1) and the water inlet valve (2) so that fine particles in the sample migrate to the upper surface, and the turbid water containing fine particles is allowed to enter the sand discharge pipe (5) by using the flushing valve (3); when the water inlet valve (2) and the flushing valve (3) are closed, the drainage valve (6) is opened to allow the free water in the sample to flow slowly downward, thereby realizing a reciprocating seepage process and simulating the movement environment of groundwater on the bank slope when the water level rises and falls; After the free water is discharged, the sample is dried uniformly and quickly through the heating pipes (12) evenly distributed in the sample chamber and the warm fan (13) placed on the fixed bracket (14), thereby fully simulating the field environment where the soil is exposed to wind and sun; and the steps of water intake-drainage-air drying are repeated to simulate the combined driving effect of reciprocating seepage and dry-wet cycle.

2. The experimental device for simulating the loss of soil particles by combined driving of reciprocating seepage and dry-wet cycles according to claim 1, characterized in that: The air drying system comprises a fixed support (14), the fixed support (14) being provided with a plurality of warm fans (13) for air drying; the fixed support (14) being arranged at the top end of the transparent cylinder (8) of the sample chamber; It also includes a heating tube (12) arranged inside the transparent cylinder (8) of the sample chamber.

3. The experimental device for simulating the loss of soil particles by combined driving of reciprocating seepage and dry-wet cycles according to claim 2, characterized in that: The measuring system comprises a camera (15) and a fine particle collection cylinder (16); The camera (15) is arranged at the bottom center of the fixed bracket (14) of the air drying system; The fine particle collection cylinder (16) is connected to the sand discharge pipe (5) of the water supply and drainage system.

4. The experimental device for simulating the loss of soil particles by combined driving of reciprocating seepage and dry-wet cycles according to claim 3, characterized in that: The camera (15) placed in the fixed bracket (14) directly above the soil sample can clearly record the development of cracks on the surface of the sample and the degree of soil surface depression during the entire test period. The fine particle collection tube (16) connected to the sand discharge pipe (5) can collect fine particles lost by the sample under the combined drive of reciprocating seepage and dry-wet cycles.

5. A method for conducting an experiment using the experimental device for simulating reciprocating seepage and dry-wet cycle combined driving soil particle loss as described in claim 4, characterized in that: The following steps are involved: Step 1: Erect the water storage tank (1) to a preset height, and check whether the water pipe (4), heating pipe (12), camera (15) and heating fan (13) components in the experimental device can be used normally; Step 2: Evenly lay a gravel buffer layer (9) on the bottom layer of the transparent cylinder (8), then apply vaseline on the upper and lower sides of the permeable stone (10), and then place it on top of the gravel buffer layer (9); Step 3: Place the prepared sample on the upper layer of the permeable stone (10) lined with filter paper, and ensure that the sample is even and flat; Step 4: After adjusting the position between the sand discharge pipe (5) and the fine particle collection tube (16), connecting the data transmission and starting the camera (15), the water inlet valve (2) is opened to simulate the penetration effect of the upward water flow on the sample, and the fine particles gradually migrate upward to the surface of the sample; Step 5: Open the flushing valve (3) to allow the suspended particles on the surface of the sample to flow into the fine particle collection tube (16) through the sand discharge pipe (5). When there are no obvious particles in the upper water layer, close the water inlet valve (2) and the flushing valve (3); Step 6: Open the drain valve (6) to allow the free water in the transparent cylinder (8) to slowly drain from the bottom; Step 7: After adjusting the position of the fixed bracket (14), turn on the heating tube (12) and the warm fan (13) to start drying the sample; Step 8: Observe the development of cracks on the surface of the sample. When the cracks develop stably, turn off the heating tube (12), the warm fan (13), and the camera (15), and calculate the surface crack area ratio through image processing software. c 1; Step 9: Remove the fine particle collection cylinder (16) and dry the liquid in the cylinder. Weigh the dry mass of the fine particles. m 1; Step 10: Repeat steps 4 to 9 to complete n After the first infiltration-drainage-drying process, the mass of lost fine particles is measured m n and surface crack rate c n , and data analysis was performed to determine the evolution of fine particle loss mass and surface crack rate with the number of combined driving actions.

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