A simulation experiment system and method for blockage-opening of mid-flow in hillside rainstorm soil

Abstract

The present invention relates to a simulation experimental system and method for the blockage and opening of a mid-flow in a hillside rainstorm soil, which integrates an artificial rainfall device, a layered soil simulation device, a drainage and water collection device, and a video monitoring device. The layered soil simulation device is sequentially buried with clay, loam, and sandy soil layers from bottom to top. The preferential flow path is simulated by artificial or natural means such as inserting a steel needle into the soil and then pulling it out, cultivating earthworms to form caves, etc.; by laying loose materials such as pollen, catkins, and artificial particles on the soil surface, the materials scattered on the soil surface in nature that can block the preferential flow path are simulated; by simulating the process of "opening-blocking-opening" of the preferential flow path, the state transition conditions of the blockage or opening of the preferential flow path in the soil are explored. The present invention collects and analyzes the layered runoff on the hillside by simulating hydrological processes such as rainfall, infiltration, and runoff generation, explores the excitation conditions of the mid-flow in a rainstorm soil, and supports further exploration of the key mechanism and constitutive relationship of flash flood formation.

Description

Technical Field

[0001] The invention relates to the technical field of soil water movement, and in particular to a hillside rainstorm soil mid-flow blocking-opening simulation experiment system and a simulation experiment method. Background Art

[0002] Preferential flow refers to a fast soil flow that flows across most of the soil volume and along pores, cracks and other preferential flow paths. It is a common form of soil water movement. Preferential flow will advance the peak time of flash floods.

[0003] In recent years, although there have been artificial rainfall runoff soil water movement simulation experiments, such as the publication number CN108801589A, named two-dimensional slope soil, surface, and groundwater movement simulation experiment system, etc., they are limited to simulating rainfall intensity, slope inclination, layered soil, etc., and cannot simulate the blockage or open state of the preferential flow path in the soil. Moreover, for soil preferential flow, currently, usually only the simulation of water flow path and movement process is focused on, and there is a lack of research on the conditions for the transition of the preferential flow path from blockage to open state.

[0004] From the above, it can be seen that at present, there is a lack of portable and flexible soil moisture stratified runoff simulation experimental equipment that can support the exploration of the conditions for the transition from blockage or open state of preferential flow paths, and further explore the midflow mechanism of rainstorm soil in mountainous areas. Summary of the invention

[0005] In response to the above problems, a simulation experimental system and method for blockage-opening of midflow in rainstorm soil on hillside are provided, which aims to simulate the rainfall and stratified runoff process on hillsides, support the exploration of the state transition conditions of blockage or opening of preferential flow paths and identify the excitation conditions of midflow in rainstorm soil, which is helpful to explore the key mechanism and constitutive relationship of flash flood formation.

[0006] The beneficial effects of the above scheme are:

[0007] 1) The experimental system provided in this application can simulate the surface and soil layered runoff process under different rainfall intensities and different slope inclinations;

[0008] 2) The experimental system provided in this application can simulate the blockage or open state of the preferential flow path, and explore the state transition conditions of the blockage or open state of the preferential flow path in the soil, thereby helping to explore the key mechanism and constitutive relationship of flash flood formation;

[0009] 3) The structure of the present invention is relatively complete and has strong scalability. Each device of this experimental system is relatively independent and can be upgraded on this basis to explore other influencing factors. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic diagram of the structure of a simulation experiment system provided in an embodiment of the present invention;

[0011] Figure 2 It is a cross-sectional schematic diagram of the soil layer in an embodiment of the present invention.

[0012] In the attached figure: 1. support frame; 2. soil box; 3. first clay layer; 4. first loam layer; 5. first sand layer; 6. second sand layer; 7. third sand layer; 8. fourth sand layer; 9. rotating nozzle; 10. water supply pump; 11. regulating valve; 12. flow meter; 13. camera equipment; 14. particulate matter. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0015] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0016] like Figure 1 , Figure 2 As shown, the experimental system provided in the embodiment of the present invention includes a soil box device, an artificial rainfall device, a water collection device, a monitoring device and a data analysis device; the soil box device includes a support frame 1 for simulating and changing the inclination of the soil layer and a soil box 2 installed on the support frame 1, soil layers are laid in the soil box 2, and the soil layers include a first clay layer 3, a first loam layer 4, and a first sand layer 5 from bottom to top, a second sand layer 6 is buried in the first clay layer 3, and the second sand layer 6 forms an angle with the bottom surface of the soil box 2 to simulate the conditions for the generation of funnel flow, a third sand layer 7 and a fourth sand layer 8 are buried in the first loam layer 4, and the third sand layer 5 is buried in the first loam layer 4. Layer 7 and the fourth sandy soil layer 8 are parallel to the bottom surface of the soil box 2 to simulate the conditions for the generation of finger flow. The inner wall of the soil box 2 is provided with sensor monitoring points, in which sensor monitoring probes are buried to measure and collect the moisture content, temperature and matrix potential of the stratified soil. Large soil pores are simulated in the soil layer; the artificial rainfall device includes a raindrop forming device and a water supply device thereof; the water collection device includes a diversion pipe buried in each soil layer and a filter screen correspondingly arranged in the diversion pipe; the monitoring device is used to monitor the change process of the water level line in the soil box 2; the data analysis device is used to collect the drainage process of each layer of soil and analyze and calculate the flow generation process of each layer of soil.

[0017] The raindrop forming device in the present invention is a rotating nozzle 9, which is correspondingly installed at the four corners of the top of the soil box 2 to overlap and superimpose to form a rainfall area with uniform rainfall intensity; the water supply device is a flow-controllable water supply pump 10, which is connected to the rotating nozzle 9 through a water supply pipe. The water supply pipe is also equipped with a regulating valve 11 and a flow meter 12 to simulate rainfall of different rainfall intensities.

[0018] In the present invention, the macroporous structure in the soil can be simulated by inserting a steel needle into the soil and then pulling it out, or cultivating earthworms to form caves, or cultivating vegetation to form roots and then pulling the vegetation out.

[0019] The simulation experiment method of the present invention using the above-mentioned hillside rainstorm soil mid-flow blocking-opening simulation experiment system is as follows:

[0020] S1, laying layered soil in soil box 2;

[0021] S2, adjusting the support frame 1 to simulate the inclination angle of the soil layer on the hillside;

[0022] S3, using a water supply device to supply water to the raindrop forming device, adjusting the flow of the water supply device, and performing sufficient artificial rainfall through the raindrop forming device so that a preferential flow path in the soil is opened;

[0023] S4, adjusting the flow of the water supply device to reduce the rainfall intensity, and then laying artificial particles 14 on the surface of the soil layer to simulate the process in nature where pollen, catkins, etc. are scattered on the soil surface and blocked by the slow water flow and other external forces.

[0024] S5. Use a data analysis device to analyze the outflow process line of the soil, identify the moment when the priority flow path is blocked, and record the blockage time t from "open" to "blocked" 1 , precipitation accumulation P acc1 , precipitation intensity P t1 , slope inclination θ, water level process line l 1 , obstruction volume V, preferential flow path ratio φ;

[0025] S6. Adjust the flow of the water supply device to increase the rainfall intensity to simulate the process of opening the soil preferential flow path when heavy rainfall occurs in nature, observe the soil outflow process line, identify the moment when the preferential flow path is opened, and record the opening time t from "blocking" to "opening" 2 , precipitation accumulation P acc2 , precipitation intensity P t2 , water level process line 2 , obstruction volume V, preferential flow path ratio φ;

[0026] S7. Change the rainfall intensity and tilt angle, repeat the above steps S2-S7, record multiple sets of experimental data, and explore the state transition conditions of the preferential flow path being blocked or open.

[0027] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A simulation experimental method for blockage and opening of midstream flow in hillside rainstorm soil, It is characterized in that A simulation experiment was conducted using a hillside rainstorm soil mid-flow blockage-opening simulation experiment system, which includes a soil box device, an artificial rainfall device, a water collection device, a monitoring device, and a data analysis device; the soil box device includes a support frame for simulating and changing the inclination of a soil layer and a soil box installed on the support frame, wherein soil layers are laid in the soil box, and the soil layers include a first clay layer, a first loam layer, and a first sandy soil layer from bottom to top, a second sandy soil layer is buried in the first clay layer, and the second sandy soil layer forms an angle with the bottom surface of the soil box to simulate the conditions for generating a funnel flow, and a third sandy soil layer and a fourth sandy soil layer are buried in the first loam layer. The third sand layer and the fourth sand layer are parallel to the bottom surface of the soil box to simulate the conditions for the generation of finger flow. The inner wall of the soil box is provided with sensor monitoring points, and the sensor monitoring points are buried with sensor monitoring probes to measure and collect the moisture content, temperature and matrix potential of the layered soil. The soil layer is simulated with soil macropores; the artificial rainfall device includes a raindrop forming device and a water supply device thereof; the water collection device includes a diversion pipe buried in each soil layer and a filter screen correspondingly arranged in the diversion pipe; the monitoring device is used to monitor the change process of the water level line in the soil box; the data analysis device is used to collect the drainage process of each layer of soil and analyze and calculate the flow generation process of each layer of soil; The simulation experiment method comprises the following steps: S1. Laying the layered soil in a soil box; S2, adjust the support frame to simulate the inclination angle of the soil layer on the hillside; S3, using a water supply device to supply water to the raindrop forming device, adjusting the flow of the water supply device, and performing sufficient artificial rainfall through the raindrop forming device so that a preferential flow path in the soil is opened; S4. Adjust the flow of the water supply device to reduce the rainfall intensity, and then lay artificial particles on the surface of the soil layer to simulate the process in nature where pollen and catkins float on the soil surface and block the preferential flow path under the influence of slow water flow and other external forces; S5. Use the data analysis device to analyze the soil outflow process line, identify the moment when the priority flow path is blocked, and record the blockage time t from "open" to "blocked" 1 , precipitation accumulation P acc1 , precipitation intensity P t1 , slope inclination θ, water level process line l 1 , obstruction volume V, preferential flow path ratio φ; S6. Adjust the flow of the water supply device to increase the rainfall intensity to simulate the process of opening the soil preferential flow path when heavy rainfall occurs in nature, observe the soil outflow process line, identify the moment when the preferential flow path is opened, and record the opening time t from "blocking" to "opening" 2 , precipitation accumulation P acc2 , precipitation intensity P t2 , water level process line 2 , obstruction volume V, preferential flow path ratio φ; S7. Change the rainfall intensity and tilt angle, repeat the above steps S2-S6, record multiple sets of experimental data, and explore the state transition conditions of the preferential flow path being blocked or open.

2. The method for simulating the blockage and opening of flow in rainstorm soil on a hillside according to claim 1, It is characterized in that The raindrop forming device is a rotating nozzle, which is correspondingly installed at the four corners of the top of the soil box. The water supply device is a flow-controllable water supply pump, which is connected to the rotating nozzle through a water supply pipe.

3. The method for simulating the blockage and opening of flow in rainstorm soil on a hillside according to claim 2, It is characterized in that A regulating valve and a flow meter are also installed on the water supply pipe.

4. The method for simulating the blockage and opening of flow in rainstorm soil on a hillside according to claim 1, It is characterized in that The monitoring device is a camera device.

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