A slope protection system based on intelligent drainage and multi-layer capillary barrier structure and its construction method

Abstract

This invention relates to the field of slope protection technology, specifically to a slope protection system and its construction method based on intelligent drainage and a multi-layer capillary barrier structure. It includes a multi-layer capillary barrier unit composed of a fine-grained soil layer, a medium-grained soil layer, and a coarse-grained soil layer arranged sequentially, and an intelligent drainage device. The intelligent drainage device includes a immersion zone connecting the boundaries of the coarse-grained and medium-grained soil layers and the boundary of the medium-grained and fine-grained soil layers, as well as a drainage channel communicating with the immersion zone. This system not only extends the infiltration length of rainwater through the multi-layer capillary barrier structure, optimizing the stratified management and rapid discharge of rainwater, but also introduces an intelligent drainage device to ensure the stability of the slope under extreme weather conditions and further optimize rainwater management.

Description

Technical Field

[0001] This invention relates to the field of slope protection technology, specifically to a slope protection system and its construction method based on intelligent drainage and multi-layer capillary barrier structure, which is applicable to slope stability and rainwater management under rainfall conditions. Background Technology

[0002] Existing slope protection technologies mainly include traditional GeoBarrier Systems (GBS), capillary barrier structures, and other slope reinforcement methods. While these technologies can protect slopes to a certain extent, they still have some shortcomings when facing complex and variable engineering conditions. Capillary barrier (CB) systems are widely used to control rainwater infiltration and enhance slope stability. Traditional capillary barrier systems typically employ a single-layer structure, relying primarily on the permeability difference between fine-grained and coarse-grained soils to intercept rainwater and guide it outwards along the slope. For example, the capillary barrier conduction length prediction formula proposed by Steenhuis et al., based on the difference in permeability and water retention between fine sand and gravel layers, can effectively predict the ultimate length of rainwater infiltration.

[0003] GBS (Gas Barrier System) is a slope protection structure that incorporates a capillary barrier system. It utilizes the capillary action principle by setting a capillary barrier layer on the slope to control rainwater infiltration and flow, thereby reducing water pressure on the slope and improving its stability. Specific steps include: laying geotextile or geogrid on the slope, then filling it with fine or coarse soil to form a capillary barrier layer; planting vegetation on top of the capillary barrier layer to increase the slope's green coverage. While GBS effectively reduces rainwater erosion and improves slope stability, it also improves the ecological environment. However, traditional GBS and capillary barrier slope protection primarily use a single capillary barrier layer, which limits its protective effect. Under conditions of steep slopes or high rainfall intensity, a single capillary barrier layer is easily eroded and damaged by rainwater, failing to effectively prevent rapid rainwater infiltration, leading to increased water pressure inside the slope and ultimately causing its protective function to fail.

[0004] Slope capillary barrier protection systems are a new technology, and the installation of drainage channels is often overlooked. This invention reveals that existing slope capillary barrier protection systems can cause rainwater to backflow into the slope during periods of excessive rainfall, exacerbating slope instability and significantly hindering the effectiveness of the capillary barrier system. Summary of the Invention

[0005] To overcome these shortcomings, this invention proposes a slope protection system and its construction method based on intelligent drainage and a multi-layer capillary barrier structure. This system not only extends the infiltration length of rainwater through the multi-layer capillary barrier structure, optimizing the stratified management and rapid discharge of rainwater, but also introduces an intelligent drainage device. This device can automatically drain water from the flooded area, ensuring the stability of the slope under extreme weather conditions. Furthermore, this invention incorporates a humidity-responsive material, poly(N-isopropylacrylamide) (PNIPAM), into the geotextile bags, which can automatically adjust permeability according to humidity changes, further optimizing rainwater management.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a slope protection system based on intelligent drainage and multi-layer capillary barrier structure, comprising a multi-layer capillary barrier unit consisting of a fine-grained soil layer, a medium-grained soil layer, and a coarse-grained soil layer arranged sequentially, and an intelligent drainage device located at the bottom of the slope; the intelligent drainage device includes a immersion zone connecting the junction of the coarse-grained soil layer and the medium-grained soil layer and the junction of the medium-grained soil layer and the fine-grained soil layer, and a drainage ditch connected to the immersion zone.

[0007] When the flow path is limited by the capillary gradient at a single interface, it often breaks through locally during extreme rainfall. This invention employs a multi-layered capillary barrier unit consisting of a fine-grained soil layer, a medium-grained soil layer, and a coarse-grained soil layer arranged sequentially. The flow path changes from a single transverse flow through a single capillary barrier layer to multiple zigzag flows, significantly increasing the total flow path length. The medium-grained soil layer serves as a transition layer, mitigating the abrupt change in permeability at the fine-to-coarse interface and reducing the risk of breakthrough under extreme rainfall.

[0008] A first water pump is installed at the bottom of the immersion zone to pump water from the immersion zone to a drainage ditch to prevent water from flowing back into the fine-grained soil layer, medium-grained soil layer and coarse-grained soil layer.

[0009] The drainage trough is equipped with a float, a laser emitter, and a laser receiver. The float is fixed in the drainage trough by a rope, and the laser emitter and laser receiver are installed on both sides of the drainage trough.

[0010] The permeability coefficient of fine-grained soil in the fine-grained soil layer is 1×10⁻⁶. -7 cm / s to 1×10 -5 cm / s, which is clay or silt; the permeability coefficient of medium-grained soil in the medium-grained soil layer is 1×10 cm / s. -5 cm / s to 1×10 -3 cm / s, which is fine or medium sand; the permeability coefficient of the coarse-grained soil in the coarse-grained soil layer is 1×10 cm / s. -3 cm / s to 1×10 -1cm / s, which is gravel or coarse sand; the permeability coefficient of fine-grained soil in the fine-grained soil layer is < the permeability coefficient of medium-grained soil in the medium-grained soil layer is < the permeability coefficient of coarse-grained soil in the coarse-grained soil layer; the medium-grained soil layer or the coarse-grained soil layer contains a moisture-responsive material that can automatically adjust the permeability according to changes in humidity; the fine-grained soil layer does not contain a moisture-responsive material to maintain a constant water storage capacity and permeability, and to prevent damage to its conductivity.

[0011] The drainage channel of the intelligent drainage device is set at the bottom of the slope and is connected to the multi-layer capillary barrier unit through the immersion zone. The multi-layer capillary barrier unit is arranged in a progressive manner along the slope and fixed by a connecting structure. The outermost layer of the multi-layer capillary barrier unit is covered with organic soil to form an organic soil layer with the same angle as the original slope.

[0012] The multi-layer capillary barrier unit is arranged in a progressive manner along the slope, meaning that the fine-grained soil layer, the medium-grained soil layer, and the coarse-grained soil layer are each composed of several levels of third geotextile bags filled with fine-grained soil, several levels of second geotextile bags filled with medium-grained soil, and several levels of first geotextile bags filled with coarse-grained soil. In the horizontal direction, the second level of third geotextile bags filled with fine-grained soil, the second level of second geotextile bags filled with medium-grained soil, and the first level of first geotextile bags filled with coarse-grained soil are located 0.2-0.5m (preferably 0.3m) to the right of the first level of third geotextile bags filled with fine-grained soil, the first level of second geotextile bags filled with medium-grained soil, and the first level of first geotextile bags filled with coarse-grained soil; and so on.

[0013] In a preferred embodiment, the proportion of humidity-responsive material PNIPAM is determined by the formula relating the permeability coefficient adjustment range to the PNIPAM mass fraction:

[0014]

[0015] ΔK: The maximum adjustable range of the soil permeability coefficient, in cm / s; |ΔK| is the absolute value of ΔK;

[0016] ω PNIPAM : The mass fraction of PNIPAM in the soil, dimensionless, that is, the ratio of the mass of PNIPAM material to the total mass of the soil; the soil is a coarse-grained soil layer or a medium-grained soil layer; the total mass of the soil is the total mass of the coarse-grained soil layer with added coarse-grained soil and PNIPAM, or the total mass of the medium-grained soil layer with added medium-grained soil and PNIPAM.

[0017] K max The maximum permeability coefficient that can be achieved in soil with the addition of 0-20% PNIPAM at low humidity, expressed in cm / s.

[0018] K minThe minimum permeability coefficient that can be achieved in soil with the addition of 0-20% PNIPAM under high humidity conditions, expressed in cm / s.

[0019] This invention also discloses a construction method for a slope protection system based on intelligent drainage and a multi-layer capillary barrier structure, comprising the following steps:

[0020] a. Construct the first geotextile bag, the second geotextile bag, and the third geotextile bag;

[0021] b. Fill the third geotextile bag, the second geotextile bag, and the first geotextile bag with fine-grained soil, medium-grained soil, and coarse-grained soil respectively, and mix moisture-responsive material into the medium-grained soil and / or coarse-grained soil.

[0022] c. The filled first geotextile bag, second geotextile bag and third geotextile bag are arranged in three layers to form a multi-layer capillary barrier unit;

[0023] d. Arrange the completed multi-layer capillary barrier units in a progressive manner along the slope and fix them with connecting structures;

[0024] e. Cover the outermost layer of the multi-layer capillary barrier unit with organic soil to form an organic soil layer that matches the original angle of the slope.

[0025] f. Install intelligent drainage devices;

[0026] g. Plant lush green plants with abundant root systems evenly on the surface of the organic soil layer to enhance the ecological protection capacity of the slope.

[0027] In step f, the installation of the intelligent drainage device includes:

[0028] f1. A immersion zone and a drainage ditch are set at the bottom of the slope. The immersion zone is connected to the capillary barrier unit, and the drainage ditch is connected to the immersion zone.

[0029] f2. Install a float in the drainage ditch and secure it with a rope to ensure that the float can float freely up and down without drifting away;

[0030] f3. Install laser emitters and laser receivers on both sides of the drainage channel to ensure they are functioning properly;

[0031] f4. Install the first water pump at the bottom of the immersion area and connect it to the power supply to ensure that it can be automatically started in an emergency and pump all the water in the immersion area to the drainage tank at regular intervals.

[0032] f5. During the test, when the float in the drainage tank rises and blocks the laser, the laser receiver can detect the signal interruption, and the drainage tank will perform an outward drainage operation.

[0033] In step f4, the pipeline of the first water pump passes through the water supply pipe, allowing water drawn from the immersion area to enter the drainage tank; the diameter of the water supply pipe is larger than the diameter of the first water pump pipeline passing through the water supply pipe; the height of the laser emitter and the laser receiver is lower than the height of the water supply pipe.

[0034] The advantages of this invention are:

[0035] This invention combines a multi-layer capillary barrier structure with an intelligent drainage system, effectively solving the problems of poor drainage, slow response, and insufficient adaptability of existing slope protection technologies under complex engineering conditions and extreme weather. It realizes intelligent, efficient, and ecological slope protection, and has significant social, economic, and technical benefits.

[0036] The multi-layer capillary barrier structure of this invention, formed by stacking fine-grained, medium-grained, and coarse-grained soil, significantly extends the infiltration length of rainwater. Experiments show that, compared with traditional single-layer capillary barriers, the multi-layer capillary barrier system of this invention can extend the infiltration length of rainwater, effectively reduce the infiltration of rainwater into deeper layers of the slope, lower the internal water pressure of the slope, and thus greatly improve the stability of the slope. For example, under simulated rainfall intensity of 100 mm / h, the displacement of a slope with a traditional single-layer capillary barrier is about 5 mm, while the displacement of a slope with the multi-layer capillary barrier of this invention is only about 1.5 mm, demonstrating significantly enhanced slope stability.

[0037] This invention reveals that existing slope protection technologies suffer from problems such as poor drainage, slow response, and insufficient adaptability when facing complex engineering conditions and extreme weather. A multi-layered capillary barrier structure can effectively disperse rainwater flow, reduce localized water concentration, and enhance the slope's resistance to erosion. The intelligent drainage system of this invention can automatically drain water from flooded areas and automatically activate drainage when the water level in the drainage ditch is too high, ensuring slope stability under extreme weather conditions. Experimental tests show that automatic drainage of water from flooded areas and accelerated drainage in the drainage ditch rapidly reduce the water level to a safe range. Under the same rainfall intensity, the drainage speed of this invention can be increased by approximately 3-5 times, effectively preventing rainwater backflow into the slope and further enhancing slope stability.

[0038] The humidity-responsive material added to the geotextile bags can automatically adjust its permeability according to changes in humidity. When humidity is high (e.g. during rainfall), the material's permeability decreases, slowing down the flow of rainwater and preventing it from rapidly penetrating into the deeper layers of the slope; when humidity is low (e.g. on sunny days), the material's permeability increases, accelerating water drainage and keeping the slope dry and stable. Attached Figure Description

[0039] Figure 1 Schematic diagram of a multi-layer capillary barrier system;

[0040] Figure 2 Schematic diagram of the construction of a multi-layer capillary barrier slope protection system;

[0041] Figure 3 Schematic diagram of intelligent drainage structure construction for multi-layer capillary barrier slope protection system;

[0042] Meaning of the reference numerals in the diagram:

[0043] 1-Fine-grained soil layer, 2-Medium-grained soil layer, 3-Coarse-grained soil layer, 4-First breakthrough point, 5-Second breakthrough point, 6-Water-stopping layer, 7-Organic soil, 8-Laser emitter, 9-Water pipe, 10-Drainage trough, 11-Float ball, 12-Immersion area, 13-First water pump, 14-Laser receiver, 15-Rope, 16-Water level. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0045] This invention provides a slope protection system based on intelligent drainage and multi-layer capillary barrier structure and its construction method.

[0046] This invention addresses the design of a multi-layered capillary barrier system. By layering fine-grained, medium-grained, and coarse-grained soils, multiple capillary barrier systems are formed, significantly optimizing the protective performance of the GeoBarrier System (GBS). Existing single-layer capillary barrier structures often suffer from insufficient flow length under heavy rainfall conditions, allowing rainwater to breach the barrier and infiltrate deeper into the slope, affecting slope stability. Furthermore, traditional structures have limited rainwater dispersion capabilities, easily leading to concentrated water flows in localized areas, exacerbating slope erosion, and exhibiting poor adaptability to complex terrain and variable climate conditions. This invention, through an innovative multi-layered capillary barrier structure design, aims to extend the flow length for rainwater infiltration, optimize rainwater stratification and rapid drainage, thereby improving drainage efficiency. Simultaneously, the multi-layered structure effectively disperses rainwater flow, reducing localized water flow concentration and enhancing the slope's erosion resistance. By optimizing the permeability and thickness of each layer, this invention enables the system to adapt to complex terrain and variable climate conditions, expanding the application range of GBS. Ultimately, this invention forms a multi-layer capillary barrier system through a reasonable combination of fine-grained soil, medium-grained soil, and coarse-grained soil, further enhancing the stability and rainwater management capabilities of GBS, and providing an efficient, stable, and highly adaptable solution for slope protection.

[0047] The working principle of the multi-layered capillary barrier structure can be explained by the differences in water retention and permeability among the coarse-grained soil layer 3, the medium-grained soil layer 2, and the fine-grained soil layer 1. If the boundary between the medium-grained and fine-grained soil layers is inclined, water accumulated in the fine-grained soil layer will flow downwards along the inclined interface. As rainwater permeates the entire slope, the volume of runoff will increase, leading to an increase in water content, and the pseudo-saturated zone will expand in the fine-grained soil layer near the boundary. When the fine-grained soil layer can no longer hold more water, water infiltrating from the surface begins to infiltrate into the lower medium-grained soil layer. The horizontal distance between the location where this infiltrates and the location of the first breach (i.e., the first breach point 4) is called the conduction length 1. When the first two layers of capillary barriers fail, the medium-grained and coarse-grained soil layers can act as a second capillary barrier, forming a second breach point 5 and a conduction length 2. These three layers together constitute a multi-layered capillary barrier. This structure utilizes the differences in hydraulic properties between soil layers of different particle sizes to enhance water storage capacity. The principle is based on... Figure 1 As an explanation.

[0048] A slope protection system based on intelligent drainage and a multi-layer capillary barrier structure includes a first geotextile bag, a second geotextile bag, a third geotextile bag, filling material, and a connecting structure. The first, second, and third geotextile bags are all cuboid structures made of high-strength polyester fiber material, possessing high tensile strength and durability, while also exhibiting a certain degree of permeability, enabling them to be used to construct multi-layer capillary barrier units.

[0049] The filling material is made of one or more mixtures of fine-grained soil, medium-grained soil, and coarse-grained soil, and is used to fill the first, second, and third geotextile bags. The permeability coefficient of the fine-grained soil is typically 1×10⁻⁶. -7 cm / s to 1×10 -5 cm / s, for example, clay, silty clay or silt; the permeability coefficient of the medium-grained soil is typically 1×10 cm / s. -5 cm / s to 1×10 -3 cm / s, for example, fine sand, medium sand, or silty sand; the permeability coefficient of the coarse-grained soil is typically 1×10 cm / s. - 3 cm / s to 1×10 -1 Permeability coefficients of cm / s or higher, such as gravel, coarse sand, or crushed stone. Preferably, the permeability coefficient of fine-grained soil is 1 × 10⁻⁶ cm / s or higher. - 6 cm / s, typically clay or silt; medium-grained soils have a permeability coefficient of 1×10 cm / s. -4 The permeability coefficient of the coarse-grained soil is 1×10 cm / s, indicating fine or medium sand. -2 cm / s, which is gravel or coarse sand.

[0050] The connecting structure consists of one or more combinations of high-strength zippers, buckles, soil nails, anchors, and geogrids, and is used to connect the first geotextile bag, the second geotextile bag, and the third geotextile bag to ensure the overall stability of the system.

[0051] The dimensions of the third geotextile bag are 1.5m long, 0.6m wide, and 0.3m high; the dimensions of the second geotextile bag are 1.5m long, 0.4m wide, and 0.3m high; and the dimensions of the first geotextile bag are 1.5m long, 0.3m wide, and 0.3m high. The multi-layer capillary barrier unit consists of the first, second, and third geotextile bags filled with filler material. The width of the geotextile bag is... Figure 2 The length of the geotextile bag in the left-right direction. The width of the geotextile bag is the thickness of the corresponding soil layer.

[0052] The present invention also provides a construction method based on the above structure, comprising the following steps:

[0053] a. High-strength polyester fiber material is selected to make the first, second, and third geotextile bags;

[0054] b. Fill the third geotextile bag, the second geotextile bag, and the first geotextile bag with fine-grained soil, medium-grained soil, and coarse-grained soil respectively, as needed;

[0055] c. The first, second, and third geotextile bags, after being filled, are arranged in three layers to form a capillary barrier unit, and are staggered to form a multi-layer structure;

[0056] d. The constructed multi-layer capillary barrier units are arranged in a progressive manner along the slope and fixed by connecting structures to improve overall stability; in the horizontal direction, the third geotextile bag filled with fine-grained soil in the second stage, the second geotextile bag filled with medium-grained soil in the second stage, and the first geotextile bag filled with coarse-grained soil in the second stage are located 0.2-0.5m (preferably 0.3m) to the right of the third geotextile bag filled with fine-grained soil in the first stage, the second geotextile bag filled with medium-grained soil in the first stage, and the first geotextile bag filled with coarse-grained soil in the first stage; and so on.

[0057] e. Cover the outermost layer of the multi-layered capillary barrier unit with organic soil to form an organic soil layer that matches the original angle of the slope.

[0058] f. Install intelligent drainage devices;

[0059] g. Plant lush green plants with abundant root systems evenly on the surface of the organic soil layer to enhance the ecological protection capacity of the slope.

[0060] Preferably, in the multi-layer capillary barrier unit, the geotextile bags are fixed and connected by a connecting structure to ensure the overall stability of the multi-layer capillary barrier system.

[0061] Preferably, in step g, lush green plants with extensive root systems are evenly planted on the surface of the organic soil layer. The water required for plant growth is provided by the capillary water layer in the fine-grained soil, thereby enhancing the ecological protection capacity of the slope. A construction diagram is shown below. Figure 2 .

[0062] Those skilled in the art can select appropriate materials and thicknesses according to specific engineering needs to implement this invention. For example, in areas with high rainfall, fine-grained and medium-grained soils with low permeability coefficients can be selected to enhance rainwater interception and control capabilities; in areas with low rainfall, fine-grained and medium-grained soils with high permeability coefficients can be selected to improve rainwater drainage efficiency. Furthermore, the thickness and material combination of each layer can be adjusted according to the geological and climatic conditions of the slope to achieve the best slope protection effect. Determining the permeability coefficient based on rainfall is a crucial step. In areas with high rainfall (frequent heavy rain or above (24-hour rainfall ≥ 25 mm); annual average number of days with heavy rain or above ≥ 5 days or historical maximum 24-hour rainfall ≥ 100 mm (torrential rain level)), fine-grained and medium-grained soils with low permeability coefficients should be prioritized to enhance rainwater interception and control capabilities. For example, the permeability coefficient of fine-grained soil can be selected as 1×10⁻⁶. -7 cm / s to 1×10 -6 Clay or silt in the range of cm / s; the permeability coefficient of medium-grained soil can be selected as 1×10. -5 cm / s to 1×10 -4 Fine or medium sand within the range of cm / s. A lower permeability coefficient helps to effectively slow down the infiltration rate of rainwater, increasing the lateral conduction time of rainwater within the capillary barrier, thereby effectively reducing the internal water pressure of the slope. Conversely, in areas with low rainfall (mainly moderate or below (24-hour rainfall <25mm); annual average number of days with heavy or above rainfall ≤2 days or annual total rainfall <600mm (arid / semi-arid standard)), fine-grained and medium-grained soils with higher permeability coefficients should be selected to improve rainwater drainage efficiency. In this case, a permeability coefficient of 1×10⁻⁶ can be selected for fine-grained soils. -6 cm / s to 1×10 -5 Silt or fine sand in the range of cm / s; the permeability coefficient of medium-grained soil can be selected as 1×10. -4 cm / s to 1×10 -3 Medium or coarse sand in the cm / s range. A higher permeability coefficient will help the capillary barrier system to quickly drain trapped water and prevent water accumulation.

[0063] Besides the permeability coefficient, the thickness and material composition of each layer can be finely adjusted according to the geological and climatic conditions of the slope. The fine-grained soil layer, acting as the first capillary barrier, can be 0.4-0.5m thick in areas with high rainfall, while adjusting to 0.2-0.3m in areas with low rainfall. The medium-grained soil layer, serving as a transition layer, can be 0.5-0.6m thick in areas with high rainfall, and 0.3-0.4m thick in areas with low rainfall. The medium-grained or coarse-grained soil layers may or may not contain moisture-responsive materials. The coarse-grained soil layer is responsible for rapid drainage, and its thickness is typically 0.3m or greater, depending on the specific slope conditions. These parameters are further optimized to ensure the system performs optimally under various environmental conditions.

[0064] The intelligent drainage system of this invention aims to solve the problem of backflow in the flooded area of ​​existing slope protection systems, ensuring the efficient operation of the capillary barrier system. Through design and optimization, the system provides an intelligent and automated solution that significantly improves the stability and protective effect of slopes under complex weather conditions.

[0065] Specifically, the intelligent drainage device of the present invention includes a immersion zone 12 connecting the boundaries of coarse-grained soil layers and medium-grained soil layers, and the boundaries of medium-grained soil layers and fine-grained soil layers, and a drainage channel 10 communicating with the immersion zone. The immersion zone has a trapezoidal structure that is wider at the top and narrower at the bottom, with a large saturated immersion area. It is composed of fine-grained soil, and its fine-grained characteristics give it better water retention and storage properties. If there is too much water in the immersion zone, it will flow back to the multi-layered capillary barrier, thereby preventing the capillary barrier from functioning.

[0066] A first water pump 13 is installed at the bottom of the immersion zone to pump the water in the immersion zone to the drainage ditch to prevent the water in the immersion zone from flowing back to the fine-grained soil layer, medium-grained soil layer and coarse-grained soil layer.

[0067] The drainage trough is equipped with a float 16, a laser emitter 8, and a laser receiver 14. The float is fixed in the drainage trough by a rope 15, and the laser emitter and laser receiver are respectively installed on both sides of the drainage trough.

[0068] Water supply pipe 9 connects the drainage tank and the immersion area; the pipeline of the first water pump (not shown) passes through the water supply pipe, allowing water pumped from the immersion area to enter the drainage tank; the diameter of the water supply pipe is larger than the diameter of the pipeline of the first water pump passing through the water supply pipe, so if the preset pumping time has not been reached and the water volume in the immersion area is already large, the water in the immersion area will directly enter the drainage tank through the water supply pipe; the height of the laser transmitter and laser receiver is lower than the height of the water supply pipe, so the water in the drainage tank will not flow back into the immersion area.

[0069] The intelligent drainage system of this invention achieves automatic drainage by installing a float in a drainage trough. The float is fixed in the drainage trough by a rope, ensuring it can float freely and will not drift away when the water level rises. A laser emitter and a laser receiver are also installed in the drainage trough to detect the position of the float. When the water level in the drainage trough rises, the float rises accordingly. When the float rises to a certain level and blocks the laser emitted by the laser emitter, the laser receiver detects a signal interruption, triggering a corresponding second water pump (not shown) to automatically start, accelerating drainage and ensuring that the water level in the drainage trough can drop rapidly, thereby ensuring the normal operation of the capillary barrier system. Figure 3 As shown, the drainage channel of the intelligent drainage device is located at the bottom of the slope and connected to the capillary barrier unit through a soaking zone. The soaking zone is positioned at the interface between the coarse-grained and medium-grained soil layers, and between the medium-grained and fine-grained soil layers, which promotes the discharge of infiltrated water. This is because the capillary barrier system utilizes the permeability differences between soil layers of different particle sizes to guide rainwater downwards along the inclined interface; when rainwater accumulates and becomes saturated in the fine-grained soil layer, it flows laterally along the interface between the fine-grained and medium-grained soil layers; when rainwater breaks through the capillary barrier, it continues to flow laterally at the interface between the medium-grained and coarse-grained soil layers. Therefore, placing the soaking zone at these interfaces can directly intercept and accelerate the discharge of this laterally flowing infiltrated water, preventing its accumulation inside the slope. In addition, this measure can also effectively prevent rainwater backflow. Existing systems are prone to overflowing drainage channels when rainfall is excessive, leading to rainwater backflow into the slope and exacerbating instability. By aligning the capillary barrier junctions, infiltrated water can be collected and drained more effectively, preventing backflow due to excessively high water levels in the flooded area or drainage channels, thus ensuring the normal operation of the capillary barrier system and slope stability. Ultimately, this strategy of setting drainage points along key infiltration paths allows for more precise control of the internal moisture content of the slope, preventing localized water concentration and further optimizing the stratified management and rapid drainage of rainwater. Existing capillary barrier protection systems for slopes are relatively new technologies and often neglect the design of drainage channels. Drainage channels in traditional slope protection systems may only be used to collect surface runoff or shallow infiltrate, without considering precise connection with the infiltrated water flow path within the capillary barrier. This invention reveals that existing capillary barrier protection systems for slopes are prone to overflowing under excessive rainfall, leading to backflow of rainwater into the slope and further exacerbating slope instability. Traditional drainage measures also require manual intervention, cannot respond to real-time changes in rainfall, and are insufficient to meet drainage needs under heavy rainfall conditions. The innovation of this invention lies in the fact that the immersion zone and drainage channel of the intelligent drainage device are located at the bottom of the slope, but more importantly, they are connected to the capillary barrier unit and aligned with the boundaries between the coarse-grained soil layer and the medium-grained soil layer, as well as the boundaries between the medium-grained soil layer and the fine-grained soil layer. This prevents rainwater from accumulating inside the slope, thereby effectively preventing rainwater backflow.

[0070] In addition, a humidity-responsive material, poly(N-isopropylacrylamide) (PNIPAM, developed by Shanghai Maclean Biochemical Technology Co., Ltd., with an average molecular weight of approximately 110,000 g / mol (110,000 Daltons),) was added to the geotextile bags. PNIPAM undergoes a phase transition at specific humidity / temperature conditions, altering its permeability to further optimize rainwater management. This material automatically adjusts its permeability according to humidity changes. At higher humidity levels (e.g., during rainfall, often accompanied by low temperatures), the material hydrophilically expands, reducing permeability and slowing rainwater flow, preventing rapid infiltration into deeper slope layers. Conversely, at lower humidity levels (e.g., on sunny days), the material hydrophobically shrinks, increasing permeability and accelerating water drainage, maintaining slope dryness and stability. The humidity-responsive material is evenly distributed within the geotextile bags to ensure optimal permeability regulation. No humidity-responsive material is placed in the fine-grained soil layer. The material is placed in the medium-grained and coarse-grained soil layers, ensuring even distribution within the geotextile bags. This characteristic helps optimize stormwater management and ensure slope stability under different weather conditions. By slowing down rainwater infiltration or accelerating water drainage, the moisture content inside the slope can be effectively controlled, reducing water pressure and thus improving slope stability. The proportion of humidity-responsive material (PNIPAM) can be directly preset to 0.1-15% (mass fraction), more preferably 1-10% (mass fraction); the PNIPAM proportion can also be set using the formula relating the permeability coefficient adjustment range to the PNIPAM mass fraction:

[0071]

[0072] in:

[0073] ΔK: The maximum adjustment range (cm / s) of the soil permeability coefficient, only its value is used in the formula calculation. This represents the degree to which PNIPAM reduces the permeability coefficient under high humidity conditions and the degree to which it increases it under low humidity conditions. It can be preset according to needs, for example, it can be preset to ±10. -4 ~10 -1 cm / s.

[0074] α: A dimensionless coefficient relating PNIPAM material properties (its own expansion / shrinkage efficiency) to soil properties (the soil's initial permeability characteristics). This coefficient needs to be calibrated experimentally and reflects the efficiency of the effect of unit PNIPAM mass fraction on the permeability coefficient adjustment capacity, as well as the synergistic effect of PNIPAM when mixed with soils of different particle sizes.

[0075] ω PNIPAM: The mass fraction of PNIPAM in the soil, dimensionless, that is, the ratio of the mass of PNIPAM material to the total mass of the soil; the soil is a coarse-grained soil layer or a medium-grained soil layer; the total mass of the soil is the total mass of the coarse-grained soil layer with added coarse-grained soil and PNIPAM, or the total mass of the medium-grained soil layer with added medium-grained soil and PNIPAM.

[0076] K max The maximum permeability coefficient that can be achieved in soil with the addition of 0-20% PNIPAM at low humidity, expressed in cm / s.

[0077] K min The minimum permeability coefficient that can be achieved in soil with the addition of 0-20% PNIPAM under high humidity conditions, expressed in cm / s.

[0078] K max and K min For testing, soil samples from coarse-grained or medium-grained soil layers were mixed with 0–20% PNIPAM and then directly measured. Low humidity refers to Sr ≤ 0.3; high humidity refers to Sr ≥ 0.9. Sr represents the saturation of the coarse-grained or medium-grained soil layer without PNIPAM. In actual calculations, Sr = 0.3 can be directly used for low humidity; Sr = 0.9 can be directly used for high humidity.

[0079] The amount of PNIPAM material added to the medium-grained soil layer and the coarse-grained soil layer was calculated using the above formulas. K max and K min It was determined directly through actual experiments.

[0080] Of this, 20% is an upper limit threshold for PNIPAM set based on existing literature to prevent excessive PNIPAM material from affecting the soil structure. If the calculated ω... PNIPAM If the content is greater than 20%, then add 20% PNIPAM by mass to the medium-grained or coarse-grained soil layer; if the calculated ω PNIPAM If the content is not greater than 20%, then add the calculated mass fraction of PNIPAM to the medium-grained soil layer or the coarse-grained soil layer.

[0081] This formula helps engineers quantitatively set goals for optimizing stormwater management. For example, if the goal is to reduce the infiltration coefficient to a certain extent during rainfall or increase it to a certain extent during sunny days, the required PNIPAM addition ratio can be calculated using this formula.

[0082] The present invention also provides a construction method based on the above structure, comprising the following steps:

[0083] f1. A immersion zone and a drainage ditch are set at the bottom of the slope. The immersion zone is connected to the capillary barrier unit, and the drainage ditch is connected to the immersion zone.

[0084] f2. Install a float in the drainage ditch and secure it with a rope to ensure that the float can float freely up and down without drifting away;

[0085] f3. Install laser emitters and receivers on both sides of the drainage ditch, ensuring they are functioning properly; install a second water pump (not shown) and connect it to a power source. When the float rises and blocks the laser, the laser receiver detects a signal interruption, triggering the second water pump to start automatically and accelerate drainage.

[0086] f4. Install the first water pump at the bottom of the immersion area and connect it to the power supply to ensure that it can be automatically started in an emergency and pump all the water in the immersion area to the drainage tank at regular intervals.

[0087] f5. During the test, when the float in the drainage tank rises and blocks the laser, the laser receiver can detect the signal interruption, and the drainage tank will perform an outward drainage operation.

[0088] When filling geotextile bags, mix the moisture-responsive material with medium- and coarse-grained soil, ensuring the material is evenly distributed within the bags for optimal permeability regulation. Integrate all components into the slope protection system and conduct comprehensive system testing to ensure the moisture-responsive material's permeability regulation function is working correctly.

[0089] Through the above design and construction methods, the intelligent drainage system of the present invention can effectively solve the shortcomings of existing slope protection systems in terms of drainage, provide an intelligent and automated solution, and significantly improve the stability and protection effect of slopes under complex weather conditions.

[0090] The following describes in detail a slope protection system based on intelligent drainage and multi-layer capillary barrier structure and its construction method, including the specific preparation process, performance testing, and application effects under different conditions.

[0091] Example 1: Construction and performance testing of multilayer capillary barrier structures

[0092] In this embodiment, we will construct a multi-layer capillary barrier structure and conduct performance tests on it to verify its effectiveness in controlling rainwater infiltration and enhancing slope stability.

[0093] Three geotextile bags of different sizes were fabricated for filling fine-grained, medium-grained, and coarse-grained soils, respectively. The first geotextile bag measures 1.5m × 0.6m × 0.3m, the second 1.5m × 0.4m × 0.3m, and the third 1.5m × 0.3m × 0.3m. These geotextile bags possess high tensile strength and durability, while also exhibiting some permeability, making them suitable for constructing multi-layered capillary barrier units.

[0094] In the horizontal direction, the third geotextile bag filled with fine-grained soil in the second stage, the second geotextile bag filled with medium-grained soil in the second stage, and the first geotextile bag filled with coarse-grained soil in the second stage are located 0.3m to the right of the third geotextile bag filled with fine-grained soil in the first stage, the second geotextile bag filled with medium-grained soil in the first stage, and the first geotextile bag filled with coarse-grained soil in the first stage; and so on.

[0095] Prepare the backfill material. Use fine-grained soil with a permeability coefficient of 1×10⁻⁶. -6 For clay or silt with a permeability of cm / s, and for medium-grained soils, a permeability coefficient of 1×10⁻⁶ is selected. -4 For fine or medium sand with a permeability coefficient of cm / s, coarse-grained soil has a permeability coefficient of 1×10⁻⁶. -2 Gravel or coarse sand with a permeability of cm / s. The selection of these fillers is based on their different permeability properties to achieve the construction of a multi-layered capillary barrier.

[0096] When filling the geotextile bags, according to the design requirements, fill the third geotextile bag with fine-grained soil, the second geotextile bag with medium-grained soil and PNIPAM, and the first geotextile bag with coarse-grained soil and PNIPAM. During the filling process, ensure that the soil inside the geotextile bags is evenly filled and avoid voids.

[0097] The proportion of humidity-responsive material (PNIPAM) is calculated using the formula relating the permeability coefficient adjustment range to the PNIPAM mass fraction:

[0098]

[0099] The filled geotextile bags are arranged in three layers to form a multi-layered capillary barrier unit. This arrangement helps to form a multi-layered structure, improving the efficiency of rainwater retention and drainage.

[0100] For the installation of the intelligent drainage system, a immersion area and drainage ditch are set up at the bottom of the slope to ensure that the drainage ditch can effectively collect and drain the accumulated water within the slope. Floats are installed inside the drainage ditch and secured with ropes to ensure that the floats can float freely up and down without drifting away. Laser transmitters and receivers are installed on both sides of the drainage ditch to ensure they function properly. System linkage debugging is then performed. The specific structure and installation process of the intelligent drainage system are as described above.

[0101] For securing geotextile bags, we employ high-strength zippers, buckles, soil nails, anchor bolts, or geogrids to connect the bags, ensuring the stability of the entire system. These connections not only provide physical stability but also allow for effective water transfer between different soil layers, further optimizing water management.

[0102] We cover the surface of the geotextile bags with a layer of organic soil and plant suitable vegetation, such as lush green plants. This vegetation not only reduces erosion on the slope surface but also improves the ecological environment of the slope.

[0103] For performance testing, we used a permeameter to conduct permeability tests on soil layers with different particle sizes and recorded the permeability coefficients. Simultaneously, under simulated rainfall conditions, we used an earth pressure gauge and a tiltmeter to monitor changes in earth pressure and slope inclination, assessing the system's stability.

[0104] This embodiment demonstrates the effectiveness of multi-layer capillary barrier structures in controlling rainwater infiltration and enhancing slope stability. Experimental results show that this system can effectively extend the infiltration flow length of rainwater, improve drainage efficiency, and enhance the erosion resistance of slopes, resulting in significant social, economic, and ecological benefits.

[0105] For example, under simulated rainfall intensity of 100 mm / h, rainfall duration of 2 hours, and slope gradient of 40 degrees, the displacement of a traditional single-layer capillary barrier slope is approximately 5 mm, while the displacement of the multi-layer capillary barrier slope of the present invention is only about 1.5 mm, significantly enhancing slope stability.

[0106] Example 2: Adaptability test of multi-layer capillary barrier structure under different climatic conditions in intelligent drainage system

[0107] In this embodiment, we will test the adaptability of the multi-layer capillary barrier structure under different climatic conditions in the intelligent drainage system to demonstrate its application potential in diverse environments.

[0108] We adjust the thickness and material ratio of each layer of geotextile bags according to the region's rainfall and geological conditions. In areas with high rainfall, we increase the thickness of the fine-grained and medium-grained soil layers to enhance rainwater interception and control capabilities; in areas with low rainfall, we reduce the thickness of the fine-grained and medium-grained soil layers to improve rainwater drainage efficiency.

[0109] We conducted performance tests on the adjusted multi-layer capillary barrier structure under simulated rainfall intensities and frequencies. The tests covered three aspects: permeability, stability, and ecological function. Permeability tests were performed using a permeameter, while stability tests were conducted using a soil pressure gauge and a tiltmeter.

[0110] By rationally adjusting the soil layer thickness and material ratio, the multi-layer capillary barrier structure can maintain good protective performance under different climatic conditions. In areas with high rainfall, the system can effectively intercept and control rainwater to prevent slope erosion; in areas with low rainfall, the system can quickly drain rainwater to avoid slope instability caused by water accumulation.

[0111] In areas with high rainfall, increase the depth and width of drainage channels and optimize the parameters of floats and pumps to improve drainage capacity. In areas with low rainfall, appropriately reduce the size of drainage channels to lower construction costs.

[0112] Furthermore, we conducted a cost-benefit analysis of the system. We calculated material costs, construction costs, and other expenses in detail, and evaluated benefits such as long-term stability and reduced maintenance costs. The analysis results show that the multi-layer capillary barrier structure slope protection system of this invention has high economic and ecological benefits.

[0113] Through this embodiment, we demonstrate the adaptability and application potential of the multilayer capillary barrier structure under different climatic conditions, further verifying the practicality and promotional value of the present invention.

[0114] In the description of this invention, references to terms such as “embodiment,” “specific example,” or “practical application” indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment or example of the invention; the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example, and the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0115] The above embodiments are only used to illustrate the technical solutions of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A slope protection system based on intelligent drainage and multi-layer capillary barrier structure, characterized in that: It includes a multi-layer capillary barrier unit consisting of a fine-grained soil layer, a medium-grained soil layer, and a coarse-grained soil layer arranged in sequence, and an intelligent drainage device located at the bottom of the slope; the intelligent drainage device includes a water immersion zone connecting the junction of the coarse-grained soil layer and the medium-grained soil layer and the junction of the medium-grained soil layer and the fine-grained soil layer, and a drainage ditch connected to the water immersion zone. A first water pump is installed at the bottom of the immersion zone to pump water from the immersion zone to a drainage ditch to prevent water from flowing back into the fine-grained soil layer, medium-grained soil layer and coarse-grained soil layer. The drainage trough is equipped with a float, a laser emitter, and a laser receiver. The float is fixed in the drainage trough by a rope, and the laser emitter and laser receiver are installed on both sides of the drainage trough. The permeability coefficient of fine-grained soil in the fine-grained soil layer is 1×10⁻⁶. -7 cm / s to 1×10 -5 cm / s, which is clay or silt; the permeability coefficient of medium-grained soil in the medium-grained soil layer is 1×10 cm / s. -5 cm / s to 1×10 -3 cm / s, which is fine or medium sand; the permeability coefficient of the coarse-grained soil in the coarse-grained soil layer is 1×10 cm / s. -3 cm / s to 1×10 -1 cm / s, which is gravel or coarse sand; the permeability coefficient of fine-grained soil in the fine-grained soil layer is < the permeability coefficient of medium-grained soil in the medium-grained soil layer is < the permeability coefficient of coarse-grained soil in the coarse-grained soil layer; the medium-grained soil layer or the coarse-grained soil layer contains a humidity-responsive material that can automatically adjust the permeability according to changes in humidity; the fine-grained soil layer does not contain a humidity-responsive material. The drainage channel of the intelligent drainage device is set at the bottom of the slope and is connected to the multi-layer capillary barrier unit through the immersion zone. The multi-layer capillary barrier unit is arranged in a progressive manner along the slope and fixed by the connecting structure. The outermost layer of the multi-layer capillary barrier unit is covered with organic soil to form an organic soil layer with the same angle as the original slope. The multi-layered capillary barrier unit is arranged in a progressive manner along the slope, meaning that the fine-grained soil layer, medium-grained soil layer, and coarse-grained soil layer are each composed of several levels of third geotextile bags filled with fine-grained soil, several levels of second geotextile bags filled with medium-grained soil, and several levels of first geotextile bags filled with coarse-grained soil. In the horizontal direction, the second level of third geotextile bags filled with fine-grained soil, the second level of second geotextile bags filled with medium-grained soil, and the first level of first geotextile bags filled with coarse-grained soil are located 0.2-0.5m to the right of the first level of third geotextile bags filled with fine-grained soil, the first level of second geotextile bags filled with medium-grained soil, and the first level of first geotextile bags filled with coarse-grained soil; and so on. The proportion of humidity-responsive material PNIPAM is determined by the formula relating the permeability coefficient adjustment range to the PNIPAM mass fraction: ； : The maximum adjustable range of the soil permeability coefficient, which can be preset, in cm / s; for The absolute value; : The mass fraction of PNIPAM in the soil, dimensionless, that is, the ratio of the mass of PNIPAM material to the total mass of the soil; the soil is a coarse-grained soil layer or a medium-grained soil layer; the total mass of the soil is the total mass of the coarse-grained soil layer with added coarse-grained soil and PNIPAM, or the total mass of the medium-grained soil layer with added medium-grained soil and PNIPAM. The maximum permeability coefficient that can be achieved in soil with the addition of 0-20% PNIPAM at low humidity, expressed in cm / s. The minimum permeability coefficient that can be achieved in soil with the addition of 0-20% PNIPAM under high humidity conditions, expressed in cm / s.

2. A construction method for a slope protection system based on intelligent drainage and multi-layer capillary barrier structure as described in claim 1, characterized in that: Includes the following steps: a. Construct the first geotextile bag, the second geotextile bag, and the third geotextile bag; b. Fill the third geotextile bag, the second geotextile bag, and the first geotextile bag with fine-grained soil, medium-grained soil, and coarse-grained soil respectively, and mix moisture-responsive material into the medium-grained soil and / or coarse-grained soil; c. The filled first geotextile bag, second geotextile bag and third geotextile bag are arranged in three layers to form a multi-layer capillary barrier unit; d. Arrange the completed multi-layer capillary barrier units in a progressive manner along the slope and fix them with connecting structures; e. Cover the outermost layer of the multi-layered capillary barrier unit with organic soil to form an organic soil layer that matches the original angle of the slope; f. Install intelligent drainage systems; g. Plant lush green plants with extensive root systems evenly on the surface of the organic soil layer to enhance the ecological protection capacity of the slope.

3. The construction method of a slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 2, characterized in that: The proportion of humidity-responsive material PNIPAM is determined by the formula relating the permeability coefficient adjustment range to the PNIPAM mass fraction: ； : The maximum adjustable range of the soil permeability coefficient, which can be preset, in cm / s; for The absolute value; : The mass fraction of PNIPAM in the soil, dimensionless, that is, the ratio of the mass of PNIPAM material to the total mass of the soil; the soil is a coarse-grained soil layer or a medium-grained soil layer; the total mass of the soil is the total mass of the coarse-grained soil layer with added coarse-grained soil and PNIPAM, or the total mass of the medium-grained soil layer with added medium-grained soil and PNIPAM. The maximum permeability coefficient that can be achieved in soil with the addition of 0-20% PNIPAM at low humidity, expressed in cm / s. The minimum permeability coefficient that can be achieved in soil with the addition of 0-20% PNIPAM under high humidity conditions, expressed in cm / s.

4. The construction method of a slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 2, characterized in that: In step f, the installation of the intelligent drainage device includes: f1. A immersion zone and a drainage ditch are set at the bottom of the slope. The immersion zone is connected to the capillary barrier unit, and the drainage ditch is connected to the immersion zone. f2. Install a float in the drainage ditch and secure it with a rope to ensure that the float can float freely up and down without drifting away; f3. Install laser emitters and laser receivers on both sides of the drainage ditch and ensure they are functioning properly; f4. Install the first water pump at the bottom of the immersion area and connect it to the power supply to ensure that it can be started automatically in an emergency and pump all the water in the immersion area to the drainage tank at regular intervals. f5. During the test, when the float in the drainage tank rises and blocks the laser, the laser receiver can detect the signal interruption, and the drainage tank will perform an outward drainage operation.

5. The construction method of a slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 4, characterized in that: In step f4, the pipeline of the first water pump passes through the water supply pipe, allowing water drawn from the immersion area to enter the drainage tank; the diameter of the water supply pipe is larger than the diameter of the first water pump pipeline passing through the water supply pipe; the height of the laser emitter and the laser receiver is lower than the height of the water supply pipe.

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