Slope protection system based on intelligent drainage and multi-layer capillary barrier structure and construction method thereof

Abstract

The invention relates to the technical field of slope protection, in particular to a slope protection system based on intelligent drainage and a multi-layer capillary barrier structure and a construction method of the slope protection system. Comprising a multi-layer capillary barrier unit and an intelligent drainage device, wherein the multi-layer capillary barrier unit is formed by sequentially arranging a fine-grained soil layer, a medium-grained soil layer and a coarse-grained soil layer; the intelligent drainage device comprises a water soaking area and a drainage groove, wherein the water soaking area is connected with 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 the drainage groove is communicated with the water soaking area. According to the system, the diversion length of rainwater infiltration is prolonged through a multi-layer capillary barrier structure, layered management and rapid drainage of rainwater are optimized, an intelligent drainage device is further introduced, the stability of a slope under the extreme weather condition is ensured, and rainwater management is further optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of slope protection, and in particular to a slope protection system based on intelligent drainage and a multi-layer capillary barrier structure and a construction method thereof, which are suitable for slope stability and rainwater management under rainfall conditions. Background Art

[0002] Existing slope protection technologies mainly include the traditional slope protection system GeoBarrier System (GBS), capillary barrier structure and other slope reinforcement methods. These technologies can protect slopes to a certain extent, but they still have some shortcomings when facing complex and changing engineering conditions. Capillary barrier (CB) system is widely used to control rainwater infiltration and enhance slope stability. Traditional capillary barrier systems usually adopt a single-layer structure, which mainly relies on the permeability difference between fine-grained soil and coarse-grained soil to intercept rainwater and guide it to drain along the slope. For example, the capillary barrier diversion length prediction formula proposed by Steenhuis et al., based on the difference in permeability and water retention between fine sand layer and gravel layer, can effectively predict the limit length of rainwater infiltration.

[0003] Among them, GBS is a slope protection structure that combines a capillary barrier system. It uses the principle of capillary action by setting up a capillary barrier on the slope to control the infiltration and flow of rainwater, thereby reducing the water pressure on the slope and improving the stability of the slope. The specific steps include: laying geotextiles or geogrids on the slope, then filling with fine-grained soil or coarse-grained soil to form a capillary barrier layer; planting vegetation on top of the capillary barrier layer to increase the green coverage rate of the slope. Although GBS can effectively reduce rainwater erosion on the slope, improve the stability of the slope, and improve the ecological environment, traditional GBS and capillary barrier slope protection mainly use a single capillary barrier layer, and its protective effect is limited to a certain extent. In the case of large slopes or high rainfall intensity, the single capillary barrier layer is easily washed away and damaged by rainwater, and cannot effectively prevent the rapid infiltration of rainwater, resulting in increased water pressure inside the slope and the failure of its protective function.

[0004] The capillary barrier system for slope protection is a new technology, and people often overlook the installation of drainage channels. The present inventors found that existing capillary barrier systems for slope protection can cause rainwater to flow back into the slope when rainfall is excessive, exacerbating slope instability and significantly hindering the effectiveness of the capillary barrier system. Summary of the Invention

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

[0006] In order to achieve the above objectives, the technical solution adopted by the present invention is as follows: a slope protection system based on intelligent drainage and a multi-layer capillary barrier structure, including 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 in sequence, and an intelligent drainage device located at the bottom of the slope; the intelligent drainage device includes a waterlogging area 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 trough connected to the waterlogging area.

[0007] When diversion length is limited by the capillary gradient of a single interface, localized breakthroughs often occur during extreme rainfall. The present invention utilizes a multi-layer capillary barrier unit composed of a sequence of fine-grained, medium-grained, and coarse-grained soil layers. This transitions the diversion path from single lateral diversion through a single capillary barrier layer to multiple zigzag diversions, significantly increasing the total diversion length. The medium-grained soil layer acts as a transition layer, mitigating sudden permeability changes at the fine-coarse interface and reducing the risk of breakthroughs during extreme rainfall.

[0008] A first pump is provided at the bottom of the immersion area to discharge the water in the immersion area to the drainage trough to prevent the water in the immersion area from flowing back into the fine-grained soil layer, the medium-grained soil layer and the coarse-grained soil layer;

[0009] A float, a laser transmitter and a laser receiver are provided in the drainage trough. The float is fixed in the drainage trough by a rope, and the laser transmitter and the laser receiver are respectively 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 -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 -5 cm / s to 1×10 -3 cm / s, is fine sand or medium sand; the permeability coefficient of coarse-grained soil in the coarse-grained soil layer is 1×10 -3 cm / s to 1×10 -1cm / s, for gravel or coarse sand; the permeability coefficient of fine-grained soil in the fine-grained soil layer is less than the permeability coefficient of medium-grained soil in the medium-grained soil layer, which is less than the permeability coefficient of coarse-grained soil in the coarse-grained soil layer; the medium-grained soil layer or the coarse-grained soil layer is mixed with humidity-responsive materials, which can automatically adjust permeability according to humidity changes; the fine-grained soil layer is not mixed with humidity-responsive materials, so that the fine-grained soil layer maintains a constant water storage capacity and permeability to prevent damage to its conductivity characteristics.

[0011] The drainage trough 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 area; the multi-layer capillary barrier unit is arranged in a progressive manner along the slope and fixed by a connecting structure. The outermost side of the multi-layer capillary barrier unit is covered with organic soil to form an organic soil layer consistent with the original angle of the slope.

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

[0013] In a preferred embodiment, the ratio of the humidity-responsive material PNIPAM is determined by the relationship between the permeability coefficient adjustment range and the PNIPAM mass fraction:

[0014]

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

[0016] ω PNIPAM : PNIPAM mass fraction in the soil, dimensionless, i.e., 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 coarse-grained soil and PNIPAM added, or the total mass of the medium-grained soil layer with medium-grained soil and PNIPAM added;

[0017] K max : The maximum permeability coefficient that can be achieved after adding 0-20% PNIPAM to the soil at low humidity, in cm / s;

[0018] K min: The minimum permeability coefficient that can be achieved after adding 0-20% PNIPAM to the soil at high humidity, in cm / s.

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

[0020] a. Make the first geobag, the second geobag and the third geobag;

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

[0022] c. Arranging the filled first geobag, the second geobag, and the third geobag in three layers to form a multi-layer capillary barrier unit;

[0023] d. Arrange the constructed multi-layer capillary barrier units in a progressive manner along the slope and secure 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 consistent with the original angle of the slope;

[0025] f. Install intelligent drainage device;

[0026] g. Green plants with lush root systems should be evenly planted 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 smart drainage device includes:

[0028] f1. Set up a soaking area and drainage trough at the bottom of the slope, with the soaking area connected to the capillary barrier unit, and the drainage trough connected to the soaking area;

[0029] f2. Install a float in the drain tank and secure it with a rope to ensure it can float up and down freely and does not drift away;

[0030] f3. Install laser transmitters and laser receivers on both sides of the gutter to ensure they can function properly;

[0031] f4. Install a first water pump at the bottom of the flooded area and connect it to a power source to ensure that it can automatically start in an emergency and regularly pump all the water in the flooded area to the drain tank through the first water pump;

[0032] f5. Perform a test. When the float in the drain tank rises and blocks the laser, the laser receiver detects the signal interruption and the drain tank begins to drain water outwards.

[0033] In step f4, the pipeline of the first water pump passes through the water pipe, so that the water pumped from the flooded area enters the drain tank; the diameter of the water pipe is larger than the diameter of the first water pump pipeline passing through the water pipe; the height of the laser transmitter and the laser receiver is lower than the height of the water pipe.

[0034] The present invention is beneficial in that:

[0035] The present 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 conditions. It realizes intelligent, efficient, and ecological slope protection, and has significant social, economic, and technical effects.

[0036] The multi-layer capillary barrier structure of the present invention forms a multi-layer capillary barrier system by stacking fine-grained soil, medium-grained soil, and coarse-grained soil, significantly extending the diversion length of rainwater infiltration. Experiments have shown that compared with traditional single-layer capillary barriers, the multi-layer capillary barrier system of the present invention can extend the diversion length of rainwater infiltration, effectively reducing rainwater penetration into the deep layers of the slope, reducing the water pressure within the slope, and thus significantly improving the stability of the slope. For example, under conditions of simulated rainfall intensity of 100mm / h, the displacement of the slope of the traditional single-layer capillary barrier is approximately 5mm, while the displacement of the slope of the multi-layer capillary barrier of the present invention is only about 1.5mm, significantly enhancing the slope stability.

[0037] The present invention found that the existing slope protection technology has problems such as poor drainage, slow response and insufficient adaptability when facing complex engineering conditions and extreme weather. The multi-layer capillary barrier structure can effectively disperse the flow of rainwater, reduce the concentration of water flow in local areas, and enhance the erosion resistance of the slope. The intelligent drainage system of the present invention can automatically drain the water in the flooded area, and automatically start drainage when the water level in the drainage trough is too high, ensuring the stability of the slope under extreme weather conditions. Experimental tests show that the water in the flooded area is automatically drained, the drainage of the drainage trough is accelerated, and the water level in the drainage trough is quickly reduced to a safe range. Under the same rainfall intensity, the drainage speed of the present invention can be increased by about 3-5 times, effectively avoiding the backflow of rainwater into the slope, and further enhancing the stability of the slope.

[0038] The humidity-responsive material incorporated into the geobag automatically adjusts its permeability based on humidity changes. When humidity is high (e.g., during rainfall), the material's permeability decreases, slowing the flow of rainwater and preventing it from quickly penetrating deep into 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the 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 the construction of the intelligent drainage structure of the multi-layer capillary barrier slope protection system;

[0042] The meaning of the reference numerals in the figures:

[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-covering water-stop layer, 7-organic soil, 8-laser transmitter, 9-water pipe, 10-drainage trough, 11-floating ball, 12-immersion area, 13-first water pump, 14-laser receiver, 15-rope, 16-water level. DETAILED DESCRIPTION

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

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

[0046] The multi-layer capillary barrier system is designed to form multiple capillary barrier systems by superimposing fine-grained soil, medium-grained soil, and coarse-grained soil, significantly optimizing the protective performance of the GeoBarrier System (GBS). Under heavy rainfall conditions, the single-layer capillary barrier structure in the existing technology often causes rainwater to break through the barrier and penetrate deep into the slope due to insufficient diversion length, affecting the stability of the slope. In addition, the traditional structure has limited ability to disperse rainwater, easily forming concentrated water flow in local areas, aggravating slope erosion, and has poor adaptability to complex terrain and changing climate conditions. The present invention aims to extend the diversion length of rainwater infiltration, optimize the stratified management and rapid discharge of rainwater, and thus improve the hydrophobic efficiency through the innovative design of a multi-layer capillary barrier structure. At the same time, the multi-layer structure can effectively disperse the flow of rainwater, reduce the concentration of water flow in local areas, and enhance the erosion resistance of the slope. By optimizing the permeability and thickness of each layer of material, the present invention enables the system to adapt to complex terrain and changing climate conditions, expanding the application range of GBS. Ultimately, the present invention forms a multi-layer capillary barrier system through the rational combination of fine-grained soil, medium-grained soil, and coarse-grained soil, further improving the stability and rainwater management capabilities of GBS, and providing an efficient, stable, and adaptable solution for slope protection.

[0047] The working principle of the multi-layer capillary barrier structure can be explained by the differences in water retention and permeability of 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 soil layer and the fine-grained soil layer is inclined, the water accumulated in the fine-grained soil layer will flow downward along the inclined interface. As rainwater soaks the entire slope, the amount of water in the accumulated flow will also increase, causing the water content to increase and the pseudo-saturated zone to expand in the fine-grained soil layer near the boundary. When the fine-grained soil layer can no longer hold more water, the water infiltrating from the surface begins to infiltrate the lower medium-grained soil layer. The horizontal distance between the location where it appears and the location of the first breakthrough point (i.e., the first breakthrough point 4) is called the diversion length 1. When the 1-2 layers of capillary barriers are destroyed, the medium-grained soil layer and the coarse-grained soil can play the role of a second capillary barrier, forming a second breakthrough point 5 and a diversion length 2. These three together constitute a multi-layer 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 as follows: Figure 1 As an illustration.

[0048] A slope protection system based on intelligent drainage and a multi-layer capillary barrier structure includes a first geobag, a second geobag, a third geobag, a filler, and a connecting structure. Each of the first, second, and third geobags is a rectangular parallelepiped structure made of high-strength polyester fiber, exhibiting high tensile strength and durability, as well as a certain degree of water permeability, and can be used to construct a multi-layer capillary barrier unit.

[0049] The filler is made of a mixture of one or more of fine-grained soil, medium-grained soil, and coarse-grained soil, and is used to fill the first, second, and third geobags. The permeability coefficient of the fine-grained soil is usually 1×10 -7 cm / s to 1×10 -5 cm / s, such as clay, silty clay or silt sand; the permeability coefficient of the medium-grained soil is usually 1×10 -5 cm / s to 1×10 -3 cm / s, such as fine sand, medium sand or silty sand; the permeability coefficient of the coarse-grained soil is usually 1×10 - 3 cm / s to 1×10 -1 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, usually clay or silt; medium-grained soil has a permeability of 1×10 -4 cm / s, for fine sand or medium sand; the permeability coefficient of coarse-grained soil is 1×10 -2 cm / s, for gravel or coarse sand.

[0050] The connection structure is composed of one or more combinations of high-strength zippers, buckles, soil nails, anchor rods and geogrids, and is used to connect the first geobag, the second geobag and the third geobag to ensure the overall stability of the system.

[0051] The dimensions of the third geobag are 1.5m long, 0.6m wide and 0.3m high; the dimensions of the second geobag are 1.5m long, 0.4m wide and 0.3m high; the dimensions of the first geobag are 1.5m long, 0.3m wide and 0.3m high. The multi-layer capillary barrier unit is composed of the first geobag, the second geobag and the third geobag filled with filler. The width of the geobag is Figure 2 The length of the geobag in the left and right direction. The width of the geobag 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. Use high-strength polyester fiber material to make the first geobag, the second geobag and the third geobag;

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

[0055] c. Arranging the filled first geobag, the second geobag, and the third geobag in three layers to form a capillary barrier unit, staggered to form a multilayer structure;

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

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

[0058] f. Install intelligent drainage device;

[0059] g. Green plants with lush root systems should be evenly planted 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 geobags 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, green plants with lush root systems are evenly planted on the surface of the organic soil layer, and the water required for plant growth is provided by the capillary water layer in the fine-grained soil to enhance the ecological protection capacity of the slope. Figure 2 .

[0062] Those skilled in the art can select appropriate materials and thicknesses to implement the present invention according to specific engineering requirements. For example, in areas with heavy rainfall, fine-grained soil and medium-grained soil with lower permeability coefficients can be selected to enhance the ability to intercept and control rainwater; in areas with less rainfall, fine-grained soil and medium-grained soil with higher permeability coefficients can be selected to improve the efficiency of rainwater discharge. In addition, the thickness and material combination of each layer can be adjusted according to the geological conditions and climatic conditions of the slope to achieve the best slope protection effect. Among them, determining the permeability coefficient based on rainfall is a key step. In areas with heavy rainfall (frequent heavy rain and above (24h rainfall ≥ 25mm); the average number of heavy rain and above rainfall days per year ≥ 5 days or the historical maximum 24h rainfall ≥ 100mm (heavy rain level)), fine-grained soil and medium-grained soil with lower permeability coefficients should be preferred to enhance the ability to intercept and control rainwater. For example, the permeability coefficient of fine-grained soil can be selected as 1×10 -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 1×10 -5 cm / s to 1×10 -4 Fine sand or medium sand in the range of cm / s. A lower permeability coefficient helps to effectively slow down the infiltration rate of rainwater and increase the lateral diversion time of rainwater in the capillary barrier, thereby effectively reducing the internal water pressure of the slope. On the contrary, in areas with less rainfall (mainly moderate rain or less (24-hour rainfall <25mm); the average number of days with heavy rain or above in the year ≤2 days or the annual total rainfall <600mm (arid / semi-arid standard)), fine-grained soil and medium-grained soil with higher permeability coefficients should be selected to improve the drainage efficiency of rainwater. At this time, the permeability coefficient of fine-grained soil can be selected as 1×10 -6 cm / s to 1×10 -5 The permeability coefficient of medium-grained soil can be 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 quickly drain away retained water and prevent water accumulation.

[0063] In addition to the permeability coefficient, the thickness and material combination of each layer can also be fine-tuned according to the geological and climatic conditions of the slope. The fine-grained soil layer serves as the first capillary barrier. Its thickness can be increased to 0.4-0.5m in areas with high rainfall, while it can be adjusted to 0.2-0.3m in areas with low rainfall. The medium-grained soil layer serves as a transition layer. Its thickness can be increased to 0.5-0.6m in areas with high rainfall, and 0.3-0.4m in areas with low rainfall. The medium-grained soil layer or the coarse-grained soil layer may or may not be mixed with moisture-responsive materials. The coarse-grained soil layer is responsible for rapid drainage and is typically 0.3m or thicker, depending on the specific conditions of the slope. These parameters are further optimized to ensure that the system can provide optimal protection under various environmental conditions.

[0064] The intelligent drainage system of this invention aims to address the problem of backflow from flooded areas in existing slope protection systems, ensuring the efficient operation of the capillary barrier system. Through design and optimization, the system provides an intelligent, automated solution, significantly improving slope stability and protection in complex weather conditions.

[0065] Specifically, the intelligent drainage device of the present invention includes a waterlogging zone 12 connecting the boundaries of the coarse-grained and medium-grained soil layers, and the boundaries of the medium-grained and fine-grained soil layers, and a drainage trough 10 connected to the waterlogging zone. The waterlogging zone has a trapezoidal structure, wide at the top and narrow at the bottom, with a large saturated waterlogging area. It is composed of fine-grained soil, whose fine-grained properties enhance its water retention and storage capabilities. If the waterlogging zone contains too much water, it will flow back into the multi-layered capillary barrier, preventing the capillary barrier from functioning.

[0066] A first pumping pump 13 is provided at the bottom of the immersion area to discharge the water in the immersion area to the drainage trough to prevent the water in the immersion area from flowing back into the fine-grained soil layer, the medium-grained soil layer and the coarse-grained soil layer;

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

[0068] The water pipe 9 connects the drainage trough and the immersion area; the pipeline of the first water pump (the pipeline is not shown in the figure) passes through the water pipe, so that the water pumped out of the immersion area enters the drainage trough; the diameter of the water pipe is larger than the diameter of the pipeline of the first water pump passing through the water pipe. Therefore, if the preset pumping time has not arrived and the amount of water in the immersion area is already large, the water in the immersion area will directly enter the drainage trough through the water pipe; the height of the laser transmitter and laser receiver is lower than the height of the water pipe, so the water in the drainage trough will not flow back into the immersion area.

[0069] The intelligent drainage system of the present invention realizes the automatic drainage function by installing a float in the drainage trough. The float is fixed in the drainage trough by a rope to ensure that it can float freely and will not drift away when the water level rises. A laser transmitter 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 transmitter, the laser receiver detects the signal interruption and triggers the corresponding second water pump (not shown) to automatically start, accelerate drainage, and ensure that the water level in the drainage trough can be quickly reduced, thereby ensuring the normal operation of the capillary barrier system. Figure 3 As shown, the drainage troughs of the intelligent drainage system are located at the base of the slope and connected to the capillary barrier unit through a soaking zone. The soaking zone is aligned at the interface between the coarse-grained and medium-grained soil layers, and the medium-grained and fine-grained soil layers, promoting the drainage of seepage water. This is because the capillary barrier system exploits the permeability differences between soil layers of different particle sizes to guide rainwater downward along the inclined interface. When rainwater accumulates and saturates the fine-grained soil layer, it flows laterally along the interface between the fine-grained and medium-grained soil layers. Once it breaks through the capillary barrier, it continues its lateral flow at the interface between the medium-grained and coarse-grained soil layers. Therefore, placing the soaking zone at these interfaces directly intercepts and accelerates the drainage of this laterally flowing seepage water, preventing it from accumulating within the slope. This approach also effectively prevents backflow of rainwater. Existing systems are prone to overflowing drainage troughs during heavy rainfall, causing rainwater to backflow into the slope and exacerbate instability. By aligning the junction of the capillary barriers, the infiltrated water can be collected and discharged more effectively, avoiding backflow due to excessive water levels in the flooded area or drainage trough, thereby ensuring the normal operation of the capillary barrier system and the stability of the slope. Ultimately, this strategy of setting drainage points on key infiltration paths can more accurately control the moisture content inside the slope, prevent local water flow concentration, and further optimize the stratified management and rapid drainage of rainwater. The existing slope capillary barrier protection system is a new technology that often ignores the setting of drainage trough conditions. The drainage troughs in traditional slope protection systems may only be used to collect surface runoff or shallow seepage water, but do not consider the precise connection with the infiltration water flow path inside the capillary barrier. The present invention found that the existing slope capillary barrier protection system is prone to overflow when the amount of rainwater is too large, causing rainwater to backflow into the slope, further exacerbating the instability of the slope. Traditional drainage measures also require manual intervention, cannot respond to rainwater changes in real time, and are difficult to meet drainage needs under heavy rainfall conditions. The innovation of this invention lies in the placement of the intelligent drainage system's flooding area and drainage trough at the base of the slope. More importantly, they are connected to the capillary barrier unit and are aligned with the boundaries between the coarse-grained and medium-grained soil layers, as well as the boundaries between the medium-grained and fine-grained soil layers. This prevents accumulation of rainwater within the slope, effectively preventing backflow.

[0070] In addition, a moisture-responsive material, poly (N-isopropylacrylamide) (PNIPAM) (Shanghai MacLean Biochemical Technology Co., Ltd., average molecular weight approximately 110,000 g / mol (110,000 Daltons)), was incorporated into the geobag. PNIPAM undergoes a phase transition at specific humidity and temperature, altering its permeability to further optimize stormwater management. This material automatically adjusts its permeability in response to humidity fluctuations. During periods of high humidity (such as during rainfall, often accompanied by low temperatures), the material expands due to hydrophilicity, reducing permeability and slowing the flow of rainwater, preventing it from rapidly penetrating deep into the slope. During periods of low humidity (such as on sunny days), the material contracts due to hydrophobicity, increasing permeability and accelerating water drainage, thereby maintaining a dry and stable slope. The moisture-responsive material was evenly distributed within the geobag to ensure optimal permeability regulation. The fine-grained soil layer was not treated with the moisture-responsive material. Instead, the medium-grained and coarse-grained soil layers were treated with the moisture-responsive material, ensuring its even distribution within the geobag. This property helps optimize stormwater management and ensure slope stability under varying weather conditions. By slowing rainwater infiltration or accelerating water drainage, the moisture content within the slope can be effectively controlled, reducing water pressure and thus improving slope stability. The moisture-responsive material (PNIPAM) ratio can be directly preset to 0.1-15% (mass fraction), preferably 1-10% (mass fraction). The moisture-responsive material (PNIPAM) ratio can also be set based on the relationship between the permeability coefficient adjustment range and the PNIPAM mass fraction:

[0071]

[0072] in:

[0073] ΔK: The maximum adjustment range of soil permeability (cm / s). This value is used in the calculation of the formula. It represents the degree to which PNIPAM reduces the permeability under high humidity conditions and 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 related to the PNIPAM material properties (its own expansion / contraction efficiency) and soil properties (the soil's initial permeability). This coefficient, calibrated experimentally, reflects the permeability adjustment efficiency of a unit PNIPAM mass fraction and the synergistic effect of PNIPAM mixed with soils of varying particle sizes.

[0075] ω PNIPAM: PNIPAM mass fraction in the soil, dimensionless, i.e., 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 coarse-grained soil and PNIPAM added, or the total mass of the medium-grained soil layer with medium-grained soil and PNIPAM added;

[0076] K max : The maximum permeability coefficient that can be achieved after adding 0-20% PNIPAM to the soil at low humidity, in cm / s;

[0077] K min : The minimum permeability coefficient that can be achieved after adding 0-20% PNIPAM to the soil at high humidity, in cm / s.

[0078] K max and K min The measurement is performed directly after adding 0-20% PNIPAM to the coarse-grained or medium-grained soil. Low moisture refers to Sr ≤ 0.3; high moisture refers to Sr ≥ 0.9. Sr is the saturation of the coarse-grained or medium-grained soil without PNIPAM. In actual calculations, Sr = 0.3 for low moisture and Sr = 0.9 for high moisture.

[0079] The amount of PNIPAM material added to the medium-grained soil layer and the coarse-grained soil layer is calculated using the above formula. max and K min Directly measured through experiments.

[0080] 20% is the upper limit of PNIPAM to prevent excessive PNIPAM from affecting the soil structure and is based on existing literature. PNIPAM If the calculated ω is greater than 20%, add 20% by mass of PNIPAM to the medium-grained soil layer or the coarse-grained soil layer; PNIPAM If the content of PNIPAM is not greater than 20%, the calculated mass fraction of PNIPAM is added to the medium-grained soil layer or the coarse-grained soil layer.

[0081] This formula helps engineers quantify their goals for optimizing stormwater management. For example, if they want to reduce the permeability coefficient by a certain amount during rainfall or increase it by a certain amount during sunny days, they can use this formula to infer the required PNIPAM addition ratio.

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

[0083] f1. Set up a soaking area and drainage trough at the bottom of the slope, with the soaking area connected to the capillary barrier unit, and the drainage trough connected to the soaking area;

[0084] f2. Install a float in the drain tank and secure it with a rope to ensure it can float up and down freely and does not drift away;

[0085] f3. Install the laser transmitter and receiver on both sides of the drain trough and ensure 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 the signal interruption and triggers the second water pump to automatically start, accelerating drainage.

[0086] f4. Install a first water pump at the bottom of the flooded area and connect it to a power source to ensure that it can automatically start in an emergency and regularly pump all the water in the flooded area to the drain tank through the first water pump;

[0087] f5. Perform a test. When the float in the drain tank rises and blocks the laser, the laser receiver detects the signal interruption and the drain tank begins to drain water outwards.

[0088] When filling the geobags, the moisture-responsive material is mixed with the medium- and coarse-grained soil and ensured to be evenly distributed within the geobags to achieve optimal permeability regulation. All components are integrated into the slope protection system and comprehensive system testing is performed to ensure the moisture-responsive material's permeability regulation function is functioning properly.

[0089] Through the above-mentioned design and construction method, the intelligent drainage system of the present invention can effectively solve the drainage deficiencies of the existing slope protection system, provide an intelligent and automated solution, and significantly improve the stability and protection effect of the slope under complex weather conditions.

[0090] The following describes in detail a slope protection system based on intelligent drainage and a 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 a multi-layer capillary barrier structure

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

[0093] Three sizes of geobags were manufactured, one for filling fine-grained soil, one for filling medium-grained soil, and one for filling coarse-grained soil. The first geobag measured 1.5m x 0.6m x 0.3m, the second measured 1.5m x 0.4m x 0.3m, and the third measured 1.5m x 0.3m x 0.3m. These geobags possess high tensile strength and durability, while also possessing a certain degree of permeability, making them suitable for constructing multi-layer capillary barrier units.

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

[0095] Prepare the filling material. The fine-grained soil is selected with a permeability coefficient of 1×10 -6 Clay or silt with a permeability of 1×10 cm / s is used for medium-grained soil. -4 cm / s for fine sand or medium sand, and for coarse-grained soil, the permeability coefficient is 1×10 -2 These fillers are selected based on their different permeability properties to achieve the construction of a multi-layer capillary barrier.

[0096] When filling the geobags, follow the design requirements: fill the third geobag with fine-grained soil, the second geobag with medium-grained soil and PNIPAM, and the first geobag with coarse-grained soil and PNIPAM. Ensure that the soil is evenly distributed throughout the geobags to avoid voids.

[0097] The proportion of humidity-responsive material (PNIPAM) is calculated by the relationship between the permeability coefficient adjustment amplitude and the PNIPAM mass fraction:

[0098]

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

[0100] To install the intelligent drainage system, a flooded area and drainage troughs were set up at the base of the slope to ensure that the troughs could effectively collect and drain accumulated water. A float was installed in the trough and secured with ropes to ensure it could float freely up and down without drifting away. Laser transmitters and receivers were installed on both sides of the trough to ensure proper function. The system was then debugged. The specific structure and installation process of the intelligent drainage system are described above.

[0101] We use high-strength zippers, buckles, soil nails, anchors, or geogrids to connect the geobags to each other and ensure the stability of the entire system. These connections not only provide physical stability but also allow for efficient water transfer between different soil layers, further optimizing moisture management.

[0102] We cover the surface of the geobags with a layer of organic soil and plant suitable vegetation, such as green plants with lush root systems. These vegetation can not only reduce erosion on the slope surface, but also improve the ecological environment of the slope.

[0103] In terms of performance testing, we use permeameters to test soil layers of different particle sizes and record the permeability coefficient. Furthermore, under simulated rainfall conditions, we use earth pressure gauges and inclinometers to monitor changes in earth pressure and slope inclination to assess system stability.

[0104] Through this example, we demonstrated the effectiveness of a multi-layer capillary barrier structure in controlling rainwater infiltration and enhancing slope stability. Experimental results show that this system effectively extends the diversion distance of rainwater infiltration, improves water drainage efficiency, and enhances the slope's erosion resistance, providing significant social, economic, and ecological benefits.

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

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

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

[0108] We adjust the thickness and material ratio of each geobag layer based on regional rainfall and geological conditions. In areas with heavy rainfall, we increase the thickness of the fine and medium-grained soil layers to enhance rainwater interception and control capabilities; in areas with light rainfall, we reduce the thickness of the fine and medium-grained soil layers to improve rainwater drainage efficiency.

[0109] We conducted performance tests on the modified multi-layer capillary barrier structure under conditions simulating varying rainfall intensities and frequencies. The tests focused on permeability, stability, and ecological function. Permeability was tested using a permeameter, while stability was tested using an earth pressure gauge and inclinometer.

[0110] By rationally adjusting soil layer thickness and material ratios, the multi-layer capillary barrier structure maintains effective protection in diverse climates. In areas with heavy rainfall, the system effectively intercepts and controls rainwater, preventing slope erosion. In areas with light rainfall, the system quickly drains rainwater, preventing slope instability caused by water accumulation.

[0111] In areas with heavy rainfall, the depth and width of the drainage troughs should be increased, and the parameters of the float and pump should be optimized to improve drainage capacity. In areas with light rainfall, the size of the drainage troughs should be appropriately reduced to reduce construction costs.

[0112] We also analyzed the system's cost-effectiveness. We calculated material and construction costs in detail and evaluated benefits such as long-term stability and reduced maintenance costs. These results demonstrate that the proposed multi-layer capillary barrier slope protection system offers significant economic and ecological benefits.

[0113] Through this embodiment, we have demonstrated the adaptability and application potential of the multi-layer capillary barrier structure under different climatic conditions, and further verified the practicality and promotion value of the present invention.

[0114] In the description of the present invention, reference to terms such as "embodiment", "specific example" or "practical application" means that the specific features, structures, materials or characteristics described in combination with the embodiment are included in at least one embodiment or example of the present invention; the schematic 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 an appropriate manner in any 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 form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of the present invention.

Claims

1. A slope protection system based on intelligent drainage and multi-layer capillary barrier structure, characterized by: 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 in sequence, and an intelligent drainage device located at the bottom of the slope; the intelligent drainage device includes a immersion area 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 trough connected to the immersion area.

2. The slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 1 is characterized by: A first pump is provided at the bottom of the immersion area to discharge the water in the immersion area to the drainage trough to prevent the water in the immersion area from flowing back into the fine-grained soil layer, the medium-grained soil layer and the coarse-grained soil layer; A float, a laser transmitter and a laser receiver are provided in the drainage trough. The float is fixed in the drainage trough by a rope, and the laser transmitter and the laser receiver are respectively installed on both sides of the drainage trough.

3. The slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 1 is characterized by: The permeability coefficient of fine-grained soil in the fine-grained soil layer is 1×10 -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 -5 cm / s to 1×10 -3 cm / s, is fine sand or medium sand; the permeability coefficient of coarse-grained soil in the coarse-grained soil layer is 1×10 -3 cm / s to 1×10 -1 cm / s, for gravel or coarse sand; the permeability coefficient of fine-grained soil in the fine-grained soil layer is less than the permeability coefficient of medium-grained soil in the medium-grained soil layer, which is less than the permeability coefficient of coarse-grained soil in the coarse-grained soil layer; the medium-grained soil layer or the coarse-grained soil layer is mixed with humidity-responsive materials, which can automatically adjust permeability according to humidity changes; the fine-grained soil layer is not mixed with humidity-responsive materials.

4. The slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 1, characterized in that: The drainage trough 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 area; the multi-layer capillary barrier unit is arranged in a progressive manner along the slope and fixed by a connecting structure. The outermost side of the multi-layer capillary barrier unit is covered with organic soil to form an organic soil layer consistent with the original angle of the slope.

5. The slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 4 is characterized in that: The multi-layer capillary barrier units are arranged in a progressive manner along the slope, which means that the fine-grained soil layer, the medium-grained soil layer, and the coarse-grained soil layer are respectively composed of several levels of third geobags filled with fine-grained soil, several levels of second geobags filled with medium-grained soil, and several levels of first geobags filled with coarse-grained soil; in the horizontal direction, the second level third geobag filled with fine-grained soil, the second level second geobag filled with medium-grained soil, and the second level first geobag filled with coarse-grained soil are located 0.2-0.5m to the right of the first level third geobag filled with fine-grained soil, the first level second geobag filled with medium-grained soil, and the first level first geobag filled with coarse-grained soil; and so on.

6. The slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 3, characterized in that: The setting ratio of the humidity-responsive material PNIPAM is determined by the relationship between the permeability coefficient adjustment amplitude and the PNIPAM mass fraction: ΔK: The maximum adjustable range of the soil permeability coefficient that can be preset, in cm / s; |ΔK| is the absolute value of ΔK; ω PNIPAM : PNIPAM mass fraction in the soil, dimensionless, i.e., 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 coarse-grained soil and PNIPAM added, or the total mass of the medium-grained soil layer with medium-grained soil and PNIPAM added; K max : The maximum permeability coefficient that can be achieved after adding 0-20% PNIPAM to the soil at low humidity, in cm / s; K min : The minimum permeability coefficient that can be achieved after adding 0-20% PNIPAM to the soil at high humidity, in cm / s.

7. A construction method for a slope protection system based on intelligent drainage and a multi-layer capillary barrier structure according to any one of claims 1 to 6, characterized in that: The following steps are involved: a. Make the first geobag, the second geobag and the third geobag; b. Fill the third geobag, the second geobag, and the first geobag with fine-grained soil, medium-grained soil, and coarse-grained soil, respectively, and mix the moisture-responsive material into the medium-grained soil and / or coarse-grained soil; c. Arranging the filled first geobag, the second geobag, and the third geobag in three layers to form a multi-layer capillary barrier unit; d. Arrange the constructed multi-layer capillary barrier units in a progressive manner along the slope and secure them with connecting structures; e. Cover the outermost layer of the multi-layer capillary barrier unit with organic soil to form an organic soil layer consistent with the original angle of the slope; f. Install intelligent drainage device; g. Green plants with lush root systems should be evenly planted on the surface of the organic soil layer to enhance the ecological protection capacity of the slope.

8. The construction method of a slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 7, characterized in that: The setting ratio of the humidity-responsive material PNIPAM is determined by the relationship between the permeability coefficient adjustment amplitude and the PNIPAM mass fraction: ΔK: The maximum adjustable range of the soil permeability coefficient that can be preset, in cm / s; |ΔK| is the absolute value of ΔK; ω PNIPAM : PNIPAM mass fraction in the soil, dimensionless, i.e., 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 coarse-grained soil and PNIPAM added, or the total mass of the medium-grained soil layer with medium-grained soil and PNIPAM added; K max : The maximum permeability coefficient that can be achieved after adding 0-20% PNIPAM to the soil at low humidity, in cm / s; K min : The minimum permeability coefficient that can be achieved after adding 0-20% PNIPAM to the soil at high humidity, in cm / s.

9. The construction method of a slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 7, characterized in that: In step f, the installation of the smart drainage device includes: f1. Set up a soaking area and drainage trough at the bottom of the slope, with the soaking area connected to the capillary barrier unit, and the drainage trough connected to the soaking area; f2. Install a float in the drain tank and secure it with a rope to ensure it can float up and down freely and does not drift away; f3. Install laser transmitters and laser receivers on both sides of the gutter to ensure they can function properly; f4. Install a first water pump at the bottom of the flooded area and connect it to a power source to ensure that it can automatically start in an emergency and regularly pump all the water in the flooded area to the drain tank through the first water pump; f5. Perform a test. When the float in the drain tank rises and blocks the laser, the laser receiver detects the signal interruption and the drain tank begins to drain water outwards.

10. The construction method of a slope protection system based on intelligent drainage and multi-layer capillary barrier structure according to claim 9, characterized in that: In step f4, the pipeline of the first water pump passes through the water pipe, so that the water pumped from the flooded area enters the drain tank; the diameter of the water pipe is larger than the diameter of the first water pump pipeline passing through the water pipe; the height of the laser transmitter and the laser receiver is lower than the height of the water pipe.

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