Research device and method for rock surface flow scouring erosion in karst rocky desertification area

Abstract

The invention discloses a research device and method for rock surface flow scouring erosion in a karst rocky desertification region, and belongs to the technical field of soil erosion and water and soil conservation research, and the research device comprises a surface runoff-sediment collection mechanism which is used for collecting runoff flowing along the surface and sediment carried by the runoff; the rock-soil interface flow-sediment collecting mechanism is used for collecting runoff flowing along the rock-soil interface and sediment carried by the runoff; and the simulated rock surface flow scouring mechanism is used for providing stable and controllable water flow for the test area. According to the invention, the surface runoff-sediment collection mechanism and the rock-soil interface flow-sediment collection mechanism are respectively arranged in the test area, so that the surface runoff formed in the scouring process and the runoff flowing along the rock-soil contact interface form an independent collection and drainage path in space; separation and collection of different runoff channels and sediment carried by the runoff channels are achieved, and interference to test results caused by mixing of runoff and sediment from different sources is avoided.

Description

Technical Field

[0001] This invention belongs to the field of soil erosion and water and soil conservation research technology, and in particular relates to a research device and method for rock surface erosion in karst rocky desertification areas. Background Technology

[0002] Karst regions, with their well-developed karst landforms, shallow soil layers, and extremely uneven spatial distribution, are highly susceptible to soil erosion under heavy rainfall, leading to desertification. Exposed rock surfaces and rock-soil mosaic structures are typical surface features of karst desertification areas. Runoff from the rock surface during rainfall not only directly participates in surface erosion but also generates hidden runoff along the rock-soil interface, significantly impacting soil stability and sediment transport. Therefore, research on the mechanisms of rock surface runoff erosion is crucial for revealing the formation and evolution of karst desertification and guiding regional soil and water conservation measures.

[0003] Existing research on slope erosion and runoff scour is mostly based on indoor artificial slope tests or overall slope simulation tests. The research subjects are usually assumed to be continuous and homogeneous soil layers, which makes it difficult to truly reflect the complex underlying surface conditions in karst areas where exposed rock surfaces and shallow overburden layers coexist. Some studies have used artificial rainfall simulation devices or slope runoff test devices to conduct scour tests on rock surfaces or soil-covered slopes, but these studies mostly focus on single surface runoff processes and fail to effectively distinguish the interaction relationships between rock surface runoff, surface runoff, and rock-soil interface runoff.

[0004] Furthermore, current technologies for collecting runoff and sediment typically involve either overall collection or single-point collection at the slope toe, lacking diversion and independent collection structures for different runoff channels. This results in mixed sources of runoff and sediment in the collection results, making it difficult to achieve quantitative analysis of rock-soil interface flow and its carried sediment. Simultaneously, some in-situ field test devices are structurally complex, difficult to construct, or cause significant disturbance to the test site, which is detrimental to maintaining the original state of the karst rock-soil structure, thus affecting the accuracy and repeatability of the test results. Summary of the Invention

[0005] The purpose of this invention is to provide a research device and method for studying rock surface erosion in karst rocky desertification areas, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: The present invention provides a research apparatus for rock surface flow erosion in karst rocky desertification areas, comprising: A surface runoff-sediment collection mechanism is installed in the surface soil layer below the test area to collect runoff flowing along the surface and the sediment it carries. The surface runoff-sediment collection mechanism includes a first guide section installed below the test area, and the first guide section is connected to a first sediment runoff collection trough. A rock-soil interface flow-sediment collection mechanism is installed at the bottom of the test area and close to the rock wall to collect runoff flowing along the rock-soil interface and the sediment it carries. The rock-soil interface flow-sediment collection mechanism includes a second guide section installed below the test area, and the second guide section is connected to a second sediment runoff collection trough. A simulated rock surface flow scouring mechanism is installed above the test area to provide a stable and controllable water flow to the test area.

[0007] Optionally, the first flow guide includes flat baffles disposed on both sides of the bottom of the test area. A V-shaped baffle is fixedly connected to the side of the flat baffle away from the test area. A first fixed connection structure is fixedly connected between the two V-shaped baffles. A first PVC drainage pipe is connected to the side of the first fixed connection structure away from the flat baffle. The first PVC drainage pipe is connected to the first sediment runoff collection trough.

[0008] Optionally, the side of the planar baffle closest to the rock surface is in contact with the rock surface.

[0009] Optionally, the bottom of the planar baffle is located below the surface soil layer.

[0010] Optionally, a rock-soil interface flow collection space is set below the surface soil layer near the rock wall. The second diversion part is located in the rock-soil interface flow collection space. The second diversion part includes a runoff collection trough set in the rock-soil interface flow collection space. Runoff diversion troughs are fixedly connected to both sides of the runoff collection trough. A second fixed connection structure is fixedly connected to the side of the runoff diversion trough away from the rock wall. One end of the second fixed connection structure is connected to the second PVC diversion pipe. The other end of the second PVC diversion pipe is connected to the second sediment runoff collection trough.

[0011] Optionally, the simulated rock surface flow scouring mechanism includes a water tank located above the test area. The water tank has a second outlet hose connected to its outlet end. The end of the second outlet hose away from the water tank is connected to a rotor flow meter. The outlet end of the rotor flow meter is connected to a first outlet hose. The end of the first outlet hose away from the rotor flow meter is connected to an outlet flow stabilizer located above the test area.

[0012] Optionally, the top of the water outlet stabilizer is provided with multiple water outlet holes at equal intervals.

[0013] Optionally, the water outlet height of the first water outlet hose is lower than that of the water outlet hole.

[0014] A research method for studying rock surface flow erosion in karst rocky desertification areas includes the following steps: S1. Select the test area. In the karst rocky desertification area, select an area with exposed bedrock and adjacent shallow overburden as the test object. The selected area should be able to reflect the natural distribution characteristics of the rock surface, soil and rock-soil contact interface, and the boundary of the test area should be defined. S2. Experimental variable design and replication settings: The rock surface flow scour test in the field used rock surface flow input and rock surface dip angle as the main control variables, and set different levels of rock surface flow input and different gradients of rock surface dip angle combination. S3. Soil initial condition treatment: Before the scour test, the soil sample at the rock-soil interface is pretreated. S4. Rock surface flow scour test implementation and sample collection: According to the pre-designed rock surface flow input, water is supplied to the test area through a simulated rock surface flow scour device to carry out the rock surface flow scour test, and runoff-sediment mixture samples are collected. S5. Runoff volume, sediment volume measurement and index calculation: After completing the rock surface flow scour test, the collected surface runoff and rock-soil interface flow samples are measured and calculated.

[0015] Optionally, the pretreatment described in step S3 involves using a water sprayer to uniformly wet the surface of the soil sample at the rock-soil interface until flow begins to occur below, then stopping the water supply and allowing the soil sample to settle and stabilize naturally.

[0016] This invention discloses the following technical effects: By separately setting up surface runoff-sediment collection mechanisms and rock-soil interface flow-sediment collection mechanisms within the test area, the surface runoff formed during the scouring process and the runoff flowing along the rock-soil interface form independent collection and diversion paths in space, achieving separate collection of different runoff channels and their carried sediment, avoiding interference with the test results caused by the mixing of runoff and sediment from different sources; by setting up a simulated rock surface flow scouring mechanism with flow stabilization function and continuously and gradedly adjustable flow rate above the test area, the rock surface runoff scouring process of different intensities is simulated under in-situ conditions, making the test water supply stable and uniform, and improving the controllability and repeatability of the rock surface runoff scouring test conditions; by setting up a first guide section and a second guide section close to the exposed rock surface at the bottom of the test area, the system achieves the collection of surface runoff and runoff at different intensities under the premise of minimizing damage to the in-situ rock-soil structure. Effective interception and diversion of rock-soil interface flow, ensuring the stable and complete collection of the flow and its carried sediment, is a key technical means for conducting quantitative research on interface runoff. By setting up scour test areas in exposed rock surfaces and adjacent shallow overburden layers with typical karst desertification characteristics, and defining the boundaries of these test areas, the experiment aims to minimize disturbance to the in-situ rock-soil structure and natural slope morphology while ensuring experimental independence. This allows the test results to accurately reflect the scour and erosion characteristics of rock surface runoff in karst desertification areas. Based on the test results of separate collection of surface runoff and rock-soil interface flow, multiple evaluation indicators and their calculation methods are proposed, including runoff volume, sediment load, runoff yield, sediment yield, and erosion resistance coefficient. This enables quantitative analysis of the scour and erosion characteristics of different runoff channels, providing a reliable data foundation for revealing the scour and erosion mechanism of rock surface runoff in karst desertification areas. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the research device for studying rock surface erosion in karst rocky desertification areas according to the present invention. Figure 2 This is a schematic diagram of the surface runoff-sediment collection mechanism of the present invention; Figure 3 This is a schematic diagram of the rock-soil interface flow-sediment collection mechanism of the present invention; Figure 4 This is a schematic diagram of the structure of the simulated rock surface scouring mechanism of the present invention.

[0018] Figure label: 2. Surface runoff-sediment collection mechanism; 3. Rock-soil interface flow-sediment collection mechanism; 4. Simulated rock surface flow scouring mechanism; 5. Planar baffle; 6. V-shaped baffle; 7. First PVC diversion pipe; 8. First fixed connection structure; 9. First sediment runoff collection trough; 10. Runoff collection trough; 11. Runoff diversion trough; 12. Second PVC diversion pipe; 13. Second fixed connection structure; 14. Second sediment runoff collection trough; 15. Outlet flow stabilizer; 16. First outlet hose; 17. Rotor flow meter; 18. Second outlet hose; 19. Water tank. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Reference Figures 1 to 4 As shown, this embodiment provides a research device for studying rock surface flow erosion in karst rocky desertification areas, comprising: The surface runoff-sediment collection mechanism 2 is installed in the surface soil layer below the test area to collect the runoff flowing along the surface and the sediment it carries. The surface runoff-sediment collection mechanism 2 includes a first guide section installed below the test area, and the first guide section is connected to a first sediment runoff collection trough 9. The rock-soil interface flow-sediment collection mechanism 3 is set at the bottom of the test area and close to the rock wall to collect the runoff flowing along the rock-soil interface and the sediment it carries. The rock-soil interface flow-sediment collection mechanism 3 includes a second guide section set below the test area, and the second guide section is connected to a second sediment runoff collection trough 14. The simulated rock surface flow scouring mechanism 4 is set above the test area to provide a stable and controllable water flow to the test area.

[0022] This invention establishes separate collection mechanisms for surface runoff and sediment (2) and rock-soil interface flow and sediment (3) within the test area. This allows the surface runoff generated during scouring and the runoff flowing along the rock-soil interface to form independent collection and diversion paths in space, achieving separate collection of different runoff channels and their carried sediment. This avoids interference with the test results caused by the mixing of runoff and sediment from different sources. Furthermore, by installing a simulated rock surface flow scouring mechanism (4) above the test area, which has a flow stabilization function and allows for continuous and graded flow adjustment, the invention simulates rock surface runoff scouring processes of varying intensities under in-situ conditions. This ensures stable and uniform water supply, improving the controllability and repeatability of the rock surface runoff scouring test conditions. Finally, by installing a first and second diversion section close to the exposed rock surface at the bottom of the test area, the invention achieves effective collection of the rock-soil interface without significantly damaging the in-situ rock-soil structure. Effective interception and diversion of runoff, ensuring the stable and complete collection of rock-soil interface flow and its carried sediment, is a key technical means for conducting quantitative research on interface runoff. By setting up scour test areas in exposed rock surfaces and adjacent shallow overburden layers with typical karst desertification characteristics, and defining the boundaries of the test areas, the experiment aims to minimize disturbance to the in-situ rock-soil structure and natural slope morphology while ensuring experimental independence. This allows the test results to truly reflect the scour and erosion characteristics of rock surface runoff in karst desertification areas. Based on the test results of separate collection of surface runoff and rock-soil interface flow, multiple evaluation indicators and their calculation methods are proposed, including runoff volume, sediment load, runoff yield ratio, sediment yield ratio, and erosion resistance coefficient. This enables quantitative analysis of the scour and erosion characteristics of different runoff channels, providing a reliable data foundation for revealing the scour and erosion mechanism of rock surface runoff in karst desertification areas.

[0023] The scheme is further optimized. The first diversion part includes a flat baffle 5 set on both sides of the bottom of the test area. A V-shaped baffle 6 is fixedly connected to the side of the flat baffle 5 away from the test area. A first fixed connection structure 8 is fixedly connected between the two V-shaped baffles 6. A first PVC drainage pipe 7 is connected to the side of the first fixed connection structure 8 away from the flat baffle 5. The first PVC drainage pipe 7 is connected to the first sediment runoff collection tank 9.

[0024] The design was further optimized so that the side of the flat baffle 5 closest to the rock surface fits into the rock surface.

[0025] The design was further optimized so that the bottom of the planar baffle 5 is located below the surface soil layer.

[0026] Baffles are installed along the boundary of the scour test area and embedded approximately 5 cm below the surface soil layer to enclose the test area and prevent surface runoff from escaping outwards. The side of the baffle that contacts the rock surface is designed with an inclined structure approximately at the same angle as the rock surface, allowing the baffle to fit tightly against the rock surface shape and reducing leakage or turbulence of surface runoff at the boundary. V-shaped baffles 6 are installed in the direction of surface runoff convergence, arranged in a V-shape, to concentrate and collect surface runoff and its carried sediment during the scour process, guiding it into the subsequent diversion structure. The V-shaped structure effectively improves the collection efficiency of runoff and sediment, reducing losses during the collection process. One end of the first PVC drainage pipe 7 is connected to the baffle through quick-drying cement to form a first fixed connection structure 8. The other end of the first PVC drainage pipe 7 is connected to the first sediment runoff collection trough 9 through quick-drying cement, thereby forming a drainage channel for surface runoff and sediment, so that surface runoff and the sediment it carries can be stably and continuously transported to the first sediment runoff collection trough 9 for quantitative collection.

[0027] To further optimize the scheme, a rock-soil interface flow collection space is set up below the surface soil layer near the rock wall. The second diversion part is located in the rock-soil interface flow collection space. The second diversion part includes a runoff collection trough 10 set in the rock-soil interface flow collection space. Runoff diversion troughs 11 are fixedly connected to both sides of the runoff collection trough 10. A second fixed connection structure 13 is fixedly connected to the side of the runoff diversion trough 11 away from the rock wall. The second fixed connection structure 13 is connected to one end of a second PVC diversion pipe 12. The other end of the second PVC diversion pipe 12 is connected to a second sediment runoff collection trough 14.

[0028] The rock-soil interface flow-sediment collection mechanism 3 is used to collect the runoff and its carried sediment flowing along the rock-soil interface. A rock-soil interface flow collection space is formed by excavation on the exposed rock side of the scour test area, with an excavation depth of about 50 cm. The original soil layer within 0 to 15 cm from the surface is retained, and the remaining soil layer is completely removed. The removal extends about 30 cm towards the rock to ensure that the width of the rock-soil interface flow collection space is consistent with the width of the scour test area.

[0029] The runoff collection trough 10 and the runoff diversion trough 11 are constructed with quick-drying cement at the bottom of the scour test area, closely attached to the rock wall. They are used to collect runoff flowing along the rock-soil interface and its carried sediment without damaging the in-situ rock-soil interface structure, and then guide it into the interface runoff diversion trough 11. One end of the second PVC diversion pipe 12 is connected to the interface runoff diversion trough 11 with quick-drying cement to form a second fixed connection structure 13. The other end of the second PVC diversion pipe 12 is connected to the second sediment runoff collection trough 14 with quick-drying cement, thereby stably diverting the rock-soil interface flow and its sediment into the second sediment runoff collection trough 14, achieving separate collection of the rock-soil interface flow and surface runoff.

[0030] Further optimization of the scheme: the simulated rock surface flow scouring mechanism 4 includes a water tank 19, which is located above the test area. The water tank 19 is connected to a second water outlet hose 18 at its outlet end. The end of the second water outlet hose 18 away from the water tank 19 is connected to a rotor flow meter 17. The water outlet end of the rotor flow meter 17 is connected to a first water outlet hose 16. The end of the first water outlet hose 16 away from the rotor flow meter 17 is connected to a water outlet stabilizer 15, which is located above the test area.

[0031] The design has been further optimized by providing multiple water outlet holes at equal intervals on the top of the water outlet stabilizer 15.

[0032] The design was further optimized so that the water outlet height of the first water outlet hose 16 is lower than that of the water outlet hole.

[0033] Water tank 19 is used to store test water. The outlet of water tank 19 is connected to the inlet of rotor flowmeter 17 through the second outlet hose 18. Rotor flowmeter 17 is used to precisely adjust the water supply flow. The outlet of rotor flowmeter 17 is connected to outlet flow stabilizer 15 through the first outlet hose 16. By adjusting the regulating valve on rotor flowmeter 17, continuous and graded flow control from small to large can be achieved to meet the test requirements of different scouring intensities.

[0034] The water flow stabilizer 15 is positioned above the scouring test area, and has multiple water outlets above it to evenly distribute the water flow. The outlet height of the first water outlet hose 16 is lower than the multiple water outlets of the water flow stabilizer 15 to prevent water from preferentially flowing out from individual outlets, thereby achieving the effect of stabilizing and uniformly distributing the flow. This makes the water flow entering the scouring test area more uniform and stable, ensuring the consistency and repeatability of the scouring test conditions.

[0035] During the experiment, the simulated rock surface flow erosion mechanism 4 provides a stable and controllable water flow to the test area. The test water flow rate is regulated by the rotor flowmeter 17 and then evenly dispersed by the outlet flow stabilizer 15, acting on the exposed rock surface and adjacent soil-covered areas to simulate the rock surface runoff erosion process under different intensity conditions. After the water flow acts, surface runoff is formed on the ground surface. Under the constraint of the baffles, it is collected by the V-shaped baffle 6 and transported to the first runoff sediment collection trough via the first PVC diversion pipe 7. Simultaneously, some water flows along the rock-soil interface to form a rock-soil interface flow, which is intercepted by the runoff collection trough 10 and guided into the second runoff sediment collection trough via the interface runoff diversion trough 11 and the second PVC diversion pipe 12. Through the synergistic effect of the above structures, the surface runoff and the rock-soil interface flow and their carried sediment are separated and collected, thus completing the study of the rock surface flow erosion process.

[0036] A research method for studying rock surface flow erosion in karst rocky desertification areas includes the following steps: S1. Select the test area: In the karst rocky desertification area, select an area with exposed bedrock and adjacent shallow overburden as the test object. The selected area should reflect the natural distribution characteristics of the rock surface, soil, and rock-soil interface. Set up a scour test area within the selected area to conduct rock surface runoff scour and erosion tests under in-situ conditions. The planar dimensions of the scour test area are 30cm × 30cm, and its range covers the exposed rock surface and its overlying or adjacent shallow soil, so that the runoff generated during the test can act on the rock surface, soil, and rock-soil interface simultaneously. Before the test, set a boundary limiting structure at the boundary of the test area to define the test area, so that the test area is relatively isolated from the surrounding undisturbed area. While ensuring the independence of the test process, minimize the disturbance to the in-situ rock-soil structure and natural slope morphology, so as to maintain the original rock-soil spatial structure characteristics of the test area and improve the authenticity and representativeness of the test results. S2. Experimental variable design and replication settings: The field rock surface flow scour test uses rock surface flow input and rock surface dip angle as the main control variables. Different levels of rock surface flow input and different gradients of rock surface dip angle combinations are set. Within each rock surface dip angle combination, multiple repeated tests are set for each rock surface dip angle. Multiple bedrock outcrops that meet the conditions are selected as test objects in the test area to ensure the reliability and comparability of the experimental results. S3. Initial soil condition treatment: Before the scour test, the soil sample at the rock-soil interface was pretreated. The surface of the soil sample at the rock-soil interface was uniformly moistened with a water sprayer until flow began to occur below. Then, the water supply was stopped and the sample was allowed to settle and stabilize naturally. Through the above moistening treatment, the initial soil moisture content in the test area was made as close as possible to the same level, thereby eliminating the potential impact of differences in initial soil moisture content on the scour test results and ensuring the comparability of test data under different test conditions. S4. Rock Surface Flow Scour Test Implementation and Sample Collection: Water was supplied to the test area through a simulated rock surface flow scour device according to the pre-designed rock surface flow input rate to conduct the rock surface flow scour test. Collection troughs were set up at the outlets of surface runoff and rock-soil interface flow to collect runoff-sediment mixture samples. During each scour test, timing was started immediately after the surface runoff and rock-soil interface flow began to generate flow. Turbid water samples were collected once every 1 minute during the first 3 minutes of the initial scour. Subsequently, turbid water samples were collected once every 4 minutes during the scour process. The entire rock surface flow scour test lasted until 21 minutes. Water supply was stopped immediately after the test ended. At this time, the rock surface flow stopped scouring the soil around the rock. After the water supply was stopped, the sampling container was immediately replaced, and the flow rates of surface runoff and rock-soil interface flow were collected at 1-minute intervals until the flow completely stopped. After the flow stopped, the sample was left to stand for 30 minutes. Then, at the same test location, the next level of rock surface flow input was carried out in sequence from small to large. S5. Runoff and Sediment Measurement and Calculation: After completing the rock surface flow scour test, the collected surface runoff and rock-soil interface flow samples were measured and calculated. Specifically, the following indicators were included: Runoff Measurement Runoff includes surface runoff and rock-soil interface flow. During the scour test, sample collection containers were placed at the outlets of both surface runoff and rock-soil interface flow. The volume of runoff collected at each time point was measured in-situ using a graduated cylinder, and the volumes were summed to obtain the total runoff for the entire scour test. The surface runoff and rock-soil interface flow are denoted as follows: The sum of the yields of surface runoff and rock-soil interface flow during rock surface flow scouring is denoted as All units are .

[0037] Sediment volume Measurement Sediment quantity includes surface sediment and sediment at the rock-soil interface. For the collected turbid water samples, a 30mm aperture was used. μm Qualitative filter paper was used to filter the water sample to separate sediment particles. The filtered sediment sample was then placed in an oven and dried at 105℃ for at least 5 hours. After the sample mass stabilized, it was weighed. The amount of surface sediment and the amount of sediment at the rock-soil interface were recorded as follows: S i The sum of surface sediment and sediment at the rock-soil interface during rock surface erosion is denoted as . S The unit is g .

[0038] Further optimization of the plan, the calculation of the indicators in step S5 includes the proportion of production flow. The runoff share is used to characterize the contribution of different runoff channels to the total runoff, and its calculation formula is as follows: ; In the formula: For the proportion of production flow ( % ); Surface runoff or rock-soil interface flow ( ); The sum of surface runoff and rock-soil interface flow during rock surface erosion ( ); Sand production ratio The sediment yield percentage is used to characterize the contribution of different runoff channels to the total sediment yield, and its calculation formula is as follows: ; In the formula: The proportion of sand production ( % ); Surface sediment or rock-soil interface sediment content ( g ); It is the sum of the amount of surface sediment and the amount of sediment at the rock-soil interface during the rock surface flow erosion process. g ); Impact coefficient The erosion resistance coefficient is used to characterize the soil's resistance to erosion. It is defined as the amount of water required to wash away a unit mass of soil. The calculation formula is as follows: ; In the formula: Impact resistance coefficient ( L / g ); To flush out the flow ( L / min ); For flushing time ( min ); The mass of sediment collected and dried under the corresponding experimental conditions ( g ).

[0039] Under the condition of exposed rock surface-soil combination in a typical karst rocky desertification area, with a fixed rock surface dip angle and rock surface flow input, this invention's rock surface runoff erosion research device is used. Based on measured data, the runoff and sediment yield indices of surface runoff and rock-soil interface flow are calculated to conduct a research method for rock surface flow erosion in karst rocky desertification areas. The method includes the following steps: S1. In a typical karst rocky desertification area, a concave bedrock outcrop with direct contact with the surrounding soil, a continuous and intact rock-soil interface, and a rock surface conducive to the formation of stable surface runoff was selected as the test object. The dip angle of the rock surface was measured on-site, and in this embodiment, a rock surface dip angle of 60° was selected as the fixed dip angle condition. At the same time, the surface runoff input rate was selected as 1.00 L·min. - ¹As a condition for a fixed flushing flow rate; S2. Set up a scour test area in the rock-soil combination area near the lower edge of the selected exposed rock. The test area has a planar dimension of 30cm×30cm. Set up a boundary limiting structure at the boundary of the test area and embed it about 5cm below the soil layer to limit the outflow of surface runoff. Set up a V-shaped collection structure at the lower end of the slope to collect surface runoff. Set up a rock-soil interface flow collection and diversion structure at the bottom of the test area close to the rock wall so that the rock-soil interface flow can be intercepted and diverted to an independent collection trough. S3. Before the formal flushing, use a watering can to evenly wet the surface of the soil sample at the rock-soil interface until flow begins to appear below. Then stop the water supply and let it settle to ensure that the initial moisture content of the test soil is as consistent as possible. S4. Start the simulated rock surface flow flushing mechanism, and stabilize the rock surface flow input at 1.00 L·min using the rotor flowmeter 17. - ¹, to allow the rock surface flow to form stably along the rock surface and enter the test area; timing begins immediately after the two outlets at the surface and rock-soil interface start producing flow; S5. During the flushing phase, runoff-sediment mixture samples were collected from the surface water outlet and the rock-soil interface water outlet, respectively. Samples were taken every 1 minute for the first 3 minutes after the flushing started, and then every 4 minutes thereafter. The flushing phase lasted until 21 minutes, after which the water supply was immediately stopped. S6. Immediately after stopping the water supply, replace the sample container and measure the outflow volume of surface runoff and rock-soil interface flow at 1-minute intervals until both streams completely stop. Add up the outflow volumes of the flushing stage and the replenishment stage to obtain the two stream flow rates for the entire test. S7. Use a graduated cylinder to measure the volume of the two outflowing water streams in the field to obtain the surface runoff. Flow rate at the rock-soil interface (Unit: L); and calculate the total production flow: ; This embodiment can be recorded. =6.30L, =3.7L, then =10.00L; S8. Sediment quantity determination and total sediment yield calculation: The collected turbid water samples were analyzed using a 30mm aperture... μm Qualitative filter paper was used to separate sediment. The sediment samples were dried at 105℃ for no less than 5 hours until the mass was constant, and then weighed to obtain the amount of surface sediment. Sediment content at the rock-soil interface (unit: g And calculate the total sediment yield: ; available =42.0g, =18.0g, then =60.0g; S9. Calculation of runoff share: Calculate the surface runoff share and the rock-soil interface runoff share separately. ; when =6.30L, =3.70L, =10.00L, therefore... =63%, =37%; S10. Calculation of sediment yield ratio: Calculate the surface sediment yield ratio and the rock-soil interface sediment yield ratio separately. ; S11, Calculation of scour resistance coefficient, based on scour flow rate （ unit: L / min ), flushing time (unit: min (and the mass of the sediment collected and dried under the corresponding test conditions) (unit: g Calculate the impact resistance coefficient: ; exist =1.00L / min-1 =21min Under the condition of 60.0g, we can obtain =0.35L / g.

[0040] The independent data collection and calculation results from the surface and rock-soil interface show that, under the selected fixed operating conditions, surface runoff is the main runoff channel, while rock-soil interface flow accounts for a certain proportion; the proportion of surface sediment yield is higher than that of rock-soil interface sediment yield. This demonstrates that the device of this invention can achieve separate collection of the two types of runoff and their sediments, and the method of this invention can obtain repeatable quantitative calculation results based on measurable parameters and well-defined formulas.

[0041] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0042] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A research device for studying surface erosion by rock flow in karst rocky desertification areas, characterized in that, include: The surface runoff-sediment collection mechanism (2) is set in the surface soil layer below the test area to collect the runoff flowing along the surface and the sediment it carries; the surface runoff-sediment collection mechanism (2) includes a first guide section set below the test area, and the first guide section is connected to a first sediment runoff collection trough (9). The rock-soil interface flow-sediment collection mechanism (3) is set at the bottom of the test area and close to the rock wall to collect the runoff flowing along the rock-soil interface and the sediment it carries; the rock-soil interface flow-sediment collection mechanism (3) includes a second guide section set below the test area, and the second guide section is connected to a second sediment runoff collection trough (14). A simulated rock surface flow scouring mechanism (4) is installed above the test area to provide a stable and controllable water flow to the test area.

2. The research device for rock surface erosion in karst rocky desertification areas according to claim 1, characterized in that: The first flow guide includes a flat baffle (5) disposed on both sides of the bottom of the test area. A V-shaped baffle (6) is fixedly connected to the side of the flat baffle (5) away from the test area. A first fixed connection structure (8) is fixedly connected between the two V-shaped baffles (6). A first PVC drainage pipe (7) is connected to the side of the first fixed connection structure (8) away from the flat baffle (5). The first PVC drainage pipe (7) is connected to the first sediment runoff collection trough (9).

3. The research device for rock surface erosion in karst rocky desertification areas according to claim 2, characterized in that: The side of the flat baffle (5) closest to the rock surface is in contact with the rock surface.

4. The research device for rock surface erosion in karst rocky desertification areas according to claim 2, characterized in that: The bottom of the planar baffle (5) is located below the surface soil layer.

5. The research device for rock surface erosion in karst rocky desertification areas according to claim 1, characterized in that: A rock-soil interface flow collection space is set below the surface soil layer near the rock wall. The second flow guide is located in the rock-soil interface flow collection space. The second flow guide includes a runoff collection trough (10) set in the rock-soil interface flow collection space. Runoff diversion troughs (11) are fixedly connected to both sides of the runoff collection trough (10). A second fixed connection structure (13) is fixedly connected to the side of the runoff diversion trough (11) away from the rock wall. The second fixed connection structure (13) is connected to one end of a second PVC diversion pipe (12). The other end of the second PVC diversion pipe (12) is connected to the second sediment runoff collection trough (14).

6. The research device for rock surface flow erosion in karst rocky desertification areas according to claim 1, characterized in that: The simulated rock surface flow scouring mechanism (4) includes a water tank (19) located above the test area. The water tank (19) has a second water outlet hose (18) connected to its outlet end. The end of the second water outlet hose (18) away from the water tank (19) is connected to a rotor flow meter (17). The outlet end of the rotor flow meter (17) is connected to a first water outlet hose (16). The end of the first water outlet hose (16) away from the rotor flow meter (17) is connected to a water outlet stabilizer (15). The water outlet stabilizer (15) is located above the test area.

7. The research device for rock surface erosion in karst rocky desertification areas according to claim 6, characterized in that: The top of the water outlet stabilizer (15) is provided with multiple water outlet holes at equal intervals.

8. The research device for rock surface flow erosion in karst rocky desertification areas according to claim 7, characterized in that: The water outlet height of the first water outlet hose (16) is lower than that of the water outlet hole.

9. A method for studying surface erosion in karst rocky desertification areas, based on the research apparatus for surface erosion in karst rocky desertification areas as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Select the test area. In the karst rocky desertification area, select an area with exposed bedrock and adjacent shallow overburden as the test object. The selected area should be able to reflect the natural distribution characteristics of the rock surface, soil and rock-soil contact interface, and the boundary of the test area should be defined. S2. Experimental variable design and replication settings: The rock surface flow scour test in the field used rock surface flow input and rock surface dip angle as the main control variables, and set different levels of rock surface flow input and different gradients of rock surface dip angle combination. S3. Initial soil condition treatment: Before the scour test, the soil sample at the rock-soil interface is pretreated. S4. Rock surface flow scour test implementation and sample collection: According to the pre-designed rock surface flow input, water is supplied to the test area through a simulated rock surface flow scour device to carry out the rock surface flow scour test, and runoff-sediment mixture samples are collected. S5. Runoff volume, sediment volume measurement and index calculation: After completing the rock surface flow scour test, the collected surface runoff and rock-soil interface flow samples are measured and calculated.

10. The research method for rock surface flow erosion in karst rocky desertification areas according to claim 9, characterized in that: The pretreatment described in step S3 involves using a water sprayer to uniformly wet the surface of the soil sample at the rock-soil interface until flow begins to occur below. Then, the water supply is stopped and the sample is left to settle and stabilize naturally.

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