A multi-modal rainfall simulation and slope scouring dynamic monitoring integrated test device

Abstract

This invention provides a simulation test device and method for erosion of surface-solidified soil based on multimodal rainfall, variable slope, and other factors. The main body of the test device includes a support frame, a variable-angle sample box, a servo push rod system, a rainfall simulation device, a weighing sensor, an image monitoring system, a runoff collection device, and a base. The variable-angle sample box has an open top structure and is movably hinged to the support frame, forming the erosion test area for surface-solidified soil specimens. A rainfall simulation device corresponding to the erosion test area is horizontally installed above the support frame, serving as an independent variable-pressure nozzle array to realize multimodal rainfall. The bottom of the variable-angle sample box has a high-precision weighing sensor and bottom drainage channels. The slope toe of the variable-angle sample box has a runoff guide channel and a sediment collection channel. This invention aims to accurately reproduce complex rainfall and slope conditions, achieve multi-factor variable control during erosion tests, realize dynamic high-precision monitoring of runoff and sediment production and surface erosion evolution, and make the device suitable for quantitatively evaluating the erosion resistance of novel ecological soil-stabilizing materials such as EICP.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering testing equipment, and in particular to a comprehensive testing device for simulating the characteristics of soil erosion on the surface of soil under different rainfall durations and scouring conditions. Background Technology

[0002] Soil erosion and slope instability are major ecological and geotechnical engineering problems facing the world. Particularly in the Yellow River basin and Loess Plateau region of my country, silty loess and Yellow River sediment are widely distributed. These soils possess engineering characteristics such as high porosity, high water sensitivity, low structural strength, and a tendency for shear strength to decrease sharply with increasing water content. Under natural rainfall, especially extreme rainstorm conditions, slope soils are highly susceptible to soil erosion disasters such as splash erosion, surface erosion, gully erosion, and even shallow landslides. This not only seriously threatens the safe operation of transportation infrastructure (such as highway and railway subgrade slopes) but also leads to the discharge of large amounts of sediment, exacerbating river siltation and ecological degradation. Therefore, adopting effective slope surface protection and soil stabilization measures, and elucidating the erosion resistance evolution mechanism under complex rainfall conditions, has become a common issue urgently needing to be addressed in the interdisciplinary fields of geotechnical engineering and soil and water conservation.

[0003] Traditional slope surface protection often employs hardening techniques such as concrete revetment, masonry, or chemical grouting. While these methods offer high short-term mechanical strength, they suffer from drawbacks including high carbon emissions, damage to existing ecosystems, and a high risk of structural cracking leading to soil erosion. These methods fail to meet the demands of modern major engineering projects for ecological ethics and a green, low-carbon transformation. In recent years, biogeotechnologies based on biogeochemical processes have attracted widespread attention. A representative example is enzyme-induced calcium carbonate precipitation (EICP), which uses urease extracted from soybeans for soil reinforcement—specifically, soybean urease-induced calcium carbonate precipitation (SICP). This technology utilizes free urease to catalyze the hydrolysis of urea, generating calcium carbonate crystals in the presence of a calcium source. These calcium carbonate crystals effectively cement soil particles and fill pores, significantly improving the unconfined compressive strength and weathering resistance of the soil.

[0004] Applying SICP technology to the surface solidification of Yellow River sediment or loess slopes can form an "ecological hard shell" with a certain strength and permeability on the soil surface. However, the durability, permeability changes, and eventual erosion failure modes (such as microcrack initiation, block spalling, and gully incision) of this new type of solidified shell under the impact of rainfall kinetic energy and surface runoff shear force are fundamentally different from those of traditional pure soil or concrete. In order to accurately and quantitatively evaluate the erosion resistance of SICP and other new surface-solidified soils, it is necessary to rely on scientific and precise indoor erosion simulation test equipment.

[0005] Existing rainfall devices often only allow for setting a constant rainfall intensity, or require manual shutdown and nozzle replacement to change the rainfall intensity. Real natural rainfall is typically characterized by "multimodal, intermittent, and variable rainfall patterns." Current equipment cannot achieve smooth, stepless adjustment of rainfall intensity or programmed automatic pressure control, resulting in significant deviations in raindrop size distribution and rainfall kinetic energy from real natural rainfall. This makes it impossible to accurately simulate the fatigue damage process of soil-stabilizing materials under extreme and variable climate conditions.

[0006] The slope gradient is a key boundary condition affecting surface runoff velocity and scour shear force. Traditional sample chambers often use mechanical pins or jacks for stepped adjustment, which is not only cumbersome and inaccurate, but also unable to simulate slope changes caused by ground settlement or dynamic topographic changes at the toe without shutting down the machine. In addition, existing devices are mostly simple one-way tests of "rainfall-sediment production," lacking multi-field coupled testing interfaces for soil internal conditions (such as pore water pressure, moisture content changes, and temperature field distribution), making it difficult to deeply reveal the fluid-structure interaction instability mechanism of "rainfall infiltration-soil softening-runoff scour."

[0007] In traditional scour tests, data collection on runoff and sediment yield mainly relies on manually placing water collection tanks at the toe of the slope and collecting sediment and turbid water at fixed time intervals (e.g., every 5 minutes). The sediment loss is then estimated by allowing the water to settle, dry, and weigh the samples. This "discrete, post-hoc" measurement method has significant time lag and human error, making it impossible to capture the transient peak characteristics of sediment loss, let alone reflect the dramatic collapse or erosion of the soil surface at any given moment.

[0008] For surface solidification technologies such as SICP, the microscopic damage morphology of the solidified layer has a decisive impact on its overall erosion resistance. Existing equipment typically only focuses on the final "total weight of sediment loss," lacking a high-definition image acquisition and processing system based on computer vision. Researchers cannot dynamically track the occurrence time, development path, and evolution of spatial geometry (depth, width, and length) of erosion cracks, resulting in a lack of intuitive morphological evidence to explain the failure mechanism of novel soil-stabilizing materials.

[0009] To overcome the limitations of traditional testing methods and accurately evaluate the soil and water conservation effectiveness of SICP reinforcement technology under complex climate and terrain conditions, there is an urgent need in this field to develop a new type of comprehensive testing device. This device should be able to highly integrate multimodal dynamic rainfall simulation, high-precision servo slope control, and a dynamic sensing and monitoring system that integrates "microscopic image tracking, macroscopic real-time weighing, and precise runoff collection," thereby achieving continuous, dynamic, automated, and high-precision measurement of the soil surface erosion evolution process. Summary of the Invention

[0010] The purpose of this invention is to address the shortcomings of existing technologies by proposing a tunnel road surface garbage cleaning vehicle for civil engineering.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] An integrated experimental device for multimodal rainfall simulation and dynamic monitoring of slope erosion includes a support frame system, a multimodal rainfall simulation system, a variable angle sample box assembly, a dynamic sensing and monitoring system, and a runoff collection system.

[0013] The support frame system includes a base and columns vertically mounted on the base; the multimodal rainfall simulation system is suspended on top of the columns and includes a support grid and an array of variable pressure nozzles mounted on the support grid, used to provide simulated rainfall with multi-level variable intensity downwards.

[0014] The variable angle sample box assembly is located directly below the rainfall simulation system. One end of the assembly is hinged to the support frame system, and the other end is connected to a servo push rod device fixed on the base. The servo push rod device is used to steplessly adjust the tilt angle of the sample box assembly. The variable angle sample box assembly forms an erosion test area to accommodate the test soil.

[0015] The dynamic sensing and monitoring system includes a high-precision weighing module and a high-definition image acquisition module. The high-precision weighing module is embedded between the bottom bearing surface of the variable angle sample box assembly and the scour test area to acquire soil mass loss data in real time. The high-definition image acquisition module is set above and to the side of the test area to continuously track the scour erosion morphology of the soil surface.

[0016] The runoff collection system is located at the lowest end of the slope foot of the variable angle sample box assembly when it is tilted, and includes a guide channel and a sediment settling and separation box below it.

[0017] The multimodal rainfall simulation system also includes a water supply tank, a variable frequency high-pressure water pump, and a control solenoid valve group. Each variable pressure nozzle branch is independently controlled by the solenoid valve group to achieve dynamic switching of different rainfall intensities.

[0018] The variable angle sample box assembly includes an outer box and a sample-containing inner liner nested therein; the high-precision weighing module is a multi-point force sensor installed between the bottom plate of the outer box and the bottom surface of the sample-containing inner liner, which suspends and lifts the entire sample-containing inner liner to achieve accurate weighing.

[0019] The bottom of the variable angle sample box is sequentially covered with a permeable plate and a filter layer, and a drainage hole connected to the outside is opened at the bottom to simulate the permeable boundary conditions of a natural slope.

[0020] A high-precision tilt sensor is installed at the movable hinge, and it is connected to the control host together with the servo push rod device to form a closed-loop control circuit. Attached Figure Description

[0021] Figure 1 This is a cross-sectional structural schematic diagram of an integrated experimental device for multimodal rainfall simulation and dynamic monitoring of slope erosion proposed in this invention;

[0022] Figure 2 This is a technical diagram of the rainfall system of an integrated experimental device for multimodal rainfall simulation and dynamic monitoring of slope erosion proposed in this invention.

[0023] In the diagram: 1. Support frame; 2. Rain collector; 3. Variable angle test chamber; 4. Dynamic monitor; 5. Scour collector. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] Based on the previously described structural diagram, the main assembly relationship of the integrated testing device provided in this embodiment is as follows: The support frame system serves as the overall foundation, and its base is movably connected to the front end (lower end) of the variable angle sample box assembly via heavy-duty hinges. A servo push rod device is hinged to the bottom of the rear end (higher end) of the variable angle sample box assembly. The servo push rod is connected in a closed loop with a high-precision tilt sensor installed at the hinge axis. The operator can input the target slope (e.g., 30°) through the integrated control cabinet, and the servo push rod will automatically extend or retract, precisely lifting the box to the set angle and locking it.

[0026] The variable-angle sample box assembly adopts a "box-within-a-box" structure. Drainage holes are provided at the bottom of the outer box, and four cantilever beam force sensors with waterproof flexible sleeves (forming a high-precision weighing module) are mounted in a rectangular array on its inner bottom surface. The sample-holding liner is placed on top of these four sensors, maintaining a 5mm frictionless gap between it and the inner wall of the outer box. This suspended liner design eliminates interference from sidewall friction, allowing any minute mass loss of the soil during scouring to be captured by the bottom sensors in real time and at high frequency.

[0027] Above the sample chamber, the support frame of the multimodal rainfall simulation system is suspended from the top of the column. The evenly distributed variable-pressure nozzles on the frame are divided into two paths, A and B. Path A consists of large-aperture storm nozzles, and path B consists of atomizing light rain nozzles. Both nozzle paths are connected to a variable-frequency high-pressure water pump via a control solenoid valve assembly.

[0028] The specific implementation steps for dynamically evaluating the scour resistance performance of slopes using the above-mentioned device are as follows:

[0029] 1. Sample preparation and loading

[0030] (1) Lift the inner container of the sample container out of the outer box. Lay permeable plates and geotextiles at its bottom in sequence to simulate the bottom permeable boundary of the natural stratum.

[0031] (2) Fill and compact the test soil in layers in the inner liner to a predetermined height from the upper edge of the inner liner.

[0032] (3) Reinforce the surface soil.

[0033] (4) The entire sample container, after curing, is hoisted back into the outer casing and placed stably on the high-precision weighing module at the bottom.

[0034] 2. Initial State Setting and System Calibration

[0035] (1) Open the integrated control cabinet and perform initial tare and zeroing operation on the high-precision weighing module.

[0036] (2) Drive the servo push rod through the control panel to smoothly adjust the variable angle sample box to the preset test slope.

[0037] (3) Turn on the shadowless supplementary lights around the support grid, and adjust the focal length of the top global camera and the side macro camera to ensure that the soil surface is clear and without blind spots in the monitoring screen.

[0038] 3. Dynamic simulation of multimodal rainfall and scour

[0039] (1) Set the rainfall program in the control system.

[0040] (2) Initiating rainfall. Raindrops hit the solidified layer on the soil surface, and surface runoff begins to occur. The slope runoff that has not penetrated into the soil carries eroded sediment and flows down the slope into the runoff collection trough at the bottom, eventually converging into the sediment settling and separation box.

[0041] 4. Real-time acquisition of multi-source data and analysis of erosion evolution

[0042] (1) During rainfall, the high-precision weighing module at the bottom transmits the total weight of the inner liner to the data acquisition instrument at a frequency of 10Hz. The system automatically plots the "time-mass loss curve" to accurately capture the peak value of instantaneous sediment loss caused by the sudden rupture of the surface solidified shell.

[0043] (2) A high-definition camera records the video throughout the process and extracts soil surface images at regular intervals through a visual recognition algorithm to record the initiation location of surface microcracks, the blocky peeling process of solidified crust, and the downcutting topological evolution of fine groove network.

[0044] (3) After the predetermined rainfall duration is reached, the system will automatically shut down. Collect the sediment in the separation chamber for final drying and verification, and remove the inner liner for cleaning, in preparation for the next set of variable tests.

Claims

1. An integrated experimental device for multimodal rainfall simulation and dynamic monitoring of slope erosion, characterized in that: It includes a support frame system (1), a multimodal rainfall simulation system (2), a variable angle sample box assembly (3), a dynamic sensing and monitoring system (4), and a runoff collection system (5).

2. The experimental apparatus according to claim 1, characterized in that, The multimodal rainfall simulation system also includes a water supply tank, a variable frequency high-pressure water pump, a pipeline system, and a control solenoid valve group; the variable pressure nozzle group includes at least two independent nozzle branches with different orifice diameters or different atomization angles; each nozzle branch is independently controlled by the control solenoid valve group and connected to the variable frequency high-pressure water pump, which is used to realize the dynamic simulation of light rain, moderate rain, heavy rain and their alternating evolution process in nature by switching branches and adjusting pump pressure.

3. The experimental apparatus according to claim 1, characterized in that, The bottom bearing surface inside the variable angle sample box assembly is sequentially covered with a permeable plate and a filter screen layer. The bottom of the bottom bearing surface is provided with a bottom seepage drainage hole that connects to the outside. The permeable plate and filter screen layer are used to simulate the permeable boundary conditions of natural loess or silt slopes and separate surface runoff from soil flow (infiltration water).

4. The experimental apparatus according to claim 1, characterized in that, A high-precision tilt sensor is installed at the movable hinge or on the side wall of the variable angle sample box assembly; the telescopic end of the servo push rod device is connected to the bottom of the variable angle sample box assembly through a U-shaped universal joint or pulley track; the tilt sensor is electrically connected to the servo push rod device to form a closed-loop servo control circuit, realizing continuous stepless slope change within the range of 0° to 60°.

5. The experimental apparatus according to claim 1, characterized in that, The variable angle sample box assembly includes an outer box and a sample-holding liner nested therein, with the scouring test area located in the sample-holding liner; the high-precision weighing module is a multi-point, matrix-distributed spoke-type or cantilever beam-type force sensor, installed between the bottom plate of the outer box and the bottom surface of the sample-holding liner, supporting the entire sample-holding liner; the force sensors are all covered with a waterproof and mud-proof flexible protective sleeve.

6. The experimental apparatus according to claim 1, characterized in that, The high-definition image acquisition module includes a global top-view camera installed at the center or side of the support frame, and a macro side-view camera installed at an angle on both sides of the variable angle sample box assembly; the support frame is also equipped with a waterproof shadowless supplementary light array to eliminate shadows caused by rainfall and slope obstruction, and to ensure high-contrast acquisition of images of soil surface cracks and gully evolution.

7. The experimental apparatus according to claim 1, characterized in that, The runoff collection system has a funnel-shaped water collection structure with a wide front end and a narrow end, and a sediment settling and separation box is connected to the end of the funnel. A micro flow meter or water level gauge is installed inside the funnel, and a turbidity sensor is installed at the overflow port of the sediment settling and separation box to calculate the instantaneous sediment content of the surface runoff in real time.

8. The testing apparatus according to any one of claims 1 to 7, characterized in that, It also includes an integrated control cabinet; the control cabinet integrates a PLC controller and a data acquisition instrument. The variable frequency high-pressure water pump, solenoid valve group, servo push rod device, high-precision weighing module, high-definition image acquisition module and tilt sensor are all connected to the integrated control cabinet to realize the synchronous acquisition and timestamp alignment of rainfall parameter setting, slope change execution and multi-source erosion data.

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