Expansive soil or freeze-thaw frost heaving soil slope protection structure and construction method thereof

Abstract

The present application belongs to the technical field of hydraulic construction engineering, and particularly relates to an expansive soil or freeze-thaw frost heaving soil side slope protection structure and a construction method thereof. The main technical scheme is: through the processes of arranging the underground water permeable pipe in the soil base constituting the side slope, setting the drainage check valve and the underground water strong drainage mechanism, and laying the anti-seepage base material, the expansive soil or freeze-thaw frost heaving soil side slope protection structure is formed, which comprises the anti-seepage base material laid on the top, slope and bottom of the side slope, and the underground water strong drainage mechanism and the side slope lining structure arranged on the slope and the bottom. The anti-seepage base material is extended and laid to the top of the side slope structure, so that a relatively dry soil base area is formed between the top and the slope, the formation of the sliding layer structure on the surface of the expansive soil or water-containing freeze-thaw frost heaving soil in the area is effectively avoided, and the anti-seepage base material is anchored. The stability of the side slope is effectively ensured.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy construction engineering technology, specifically relating to a slope protection structure and construction method for expansive soil or freeze-thaw frost-susceptible soil. Background Technology

[0002] Slopes include those along water conveyance channels constructed in western and eastern my country, slopes of various large, medium, and small irrigation canals and reservoirs built throughout the country for agricultural irrigation, and engineering slopes formed by cutting through mountains and filling valleys for railway and highway construction. During operation, groundwater within these slope structures cannot be effectively managed, leading to deformation and collapse. The aforementioned slopes, especially those with expansive soil as their subsoil and those with freeze-thaw frost-susceptibility soil subsoil used in higher latitude regions, are particularly vulnerable to the hazards posed by groundwater in their subsoil.

[0003] Bentonite, a special type of soil foundation, is an unsaturated soil characterized by multiple cracks, strong swelling and shrinkage, and strength attenuation. When water seeps to a depth of approximately 0.8–1.2 meters, it forms a fixed bentonite layer. This layer is highly susceptible to slippage between itself and unwatered structural layers, creating a surface slip layer structure that leads to structural cracking, deformation, and slope instability. In the natural environment, the water absorption and loss of bentonite slopes occur repeatedly with the seasons and rainfall, resulting in strength attenuation due to the expansion and contraction of the soil structure, posing a long-term potential for damage to the slope protection structure. Furthermore, landslides caused by bentonite slopes are characterized by their shallowness, traction, gentle slope, long duration, and seasonality, making them particularly difficult to manage and protect.

[0004] Meanwhile, in high-latitude regions, irrigation canals, due to their seasonal water transport, experience frost heave during the cold winter months when water supply is interrupted. As the soil in the canal base freezes, the moisture in the soil freezes into ice, forming numerous ice interlayers and ice mirrors, creating a frost-susceptible soil structure. The relative displacement of soil particles and the resulting expansion of the soil base caused by frost heave is called frost heave. The outward manifestations of frost heave include uniform or uneven bulging, swelling, and cracking of the soil layer; after thawing, significant subsidence occurs, damaging the slope structure.

[0005] Therefore, it can be seen that whether it is bentonite or freeze-thawed heave soil, the slope foundation is damaged because the groundwater (or seepage water) contained in it cannot be effectively drained, resulting in diseased slopes and causing damage to the slopes and irrigation canals. Summary of the Invention

[0006] The primary objective of this invention is to provide a slope protection structure for expansive soil or freeze-thaw heave soil that can effectively mitigate the damage caused by expansion or freeze-thaw heave.

[0007] The second objective of this invention is to provide a construction method for the aforementioned slope protection structure.

[0008] To achieve the aforementioned first objective, the technical solution adopted by the present invention is as follows:

[0009] A slope protection structure for expansive soil or freeze-thaw frost-susceptible soil is characterized by: comprising an impermeable substrate laid at the top, slope, and bottom of the slope; groundwater drainage mechanisms installed at the slope and bottom; and a slope lining structure installed on the outer surface of the impermeable substrate; wherein...

[0010] The end of the impermeable substrate laid at the top of the slope is fixed to the soil base that forms the top of the slope;

[0011] The structure of the groundwater forced drainage mechanism includes a water collection tank for collecting groundwater, which is set in the soil foundation and has water collection holes on its periphery, and a drainage pump mechanism that is matched with it to forcefully discharge the collected water.

[0012] The additional technical features constituting the above-mentioned slope protection structure for expansive soil or freeze-thaw frost-susceptible soil also include:

[0013] The impermeable substrate includes an impermeable substrate body and a support structure consisting of several parallel support components arranged at intervals or continuously on its inner side. A geotextile layer with water permeability is provided on the outside of the support structure; a water flow channel is formed between the support structure and the geotextile.

[0014] — Drainage check valves are installed on the slope and at the bottom of the slope respectively, and the drainage check valves installed on the slope are located higher than the groundwater forced drainage mechanism.

[0015] —The slope drainage check valve is equipped with a water-collecting structure that is inclined and inserted deep into the soil foundation;

[0016] —The water collection tank of the slope drainage mechanism is equipped with a second water collection structure that is inclined to be inserted deep into the soil foundation;

[0017] —The water-gathering structure is composed of a permeable pipe with permeable holes;

[0018] —The water collection structure consists of a water collection trench, filter material filled in it, and permeable pipes;

[0019] —The end of the waterproof substrate laid at the top of the slope extends into the soil at the top of the slope;

[0020] —The end of the slope top seepage-proof substrate extends at least 0.5 meters into the slope top soil foundation;

[0021] —The end of the slope top seepage-proof substrate extends into the slope top soil foundation and is fixed by anchors;

[0022] —A foot is provided at the junction of the bottom of the slope and the bottom of the slope to stabilize the lining structure.

[0023] To achieve the second objective mentioned above, the technical solution adopted by the present invention is as follows:

[0024] A method for constructing slope protection structures for expansive soil or freeze-thaw frost-susceptible soil includes:

[0025] Step 1: Install groundwater permeable pipes at an angle in the soil foundation that forms the slope;

[0026] Step 2: Connect the water collection tank with water collection holes on the periphery and the groundwater permeable pipe and fix them in the soil foundation of the slope and the bottom of the slope, and then match the drainage pump mechanism.

[0027] Step 3: Connect the valve body of the drainage check valve to the underground water permeable pipe and fix them in the soil foundation at the bottom of the slope;

[0028] The fourth step is to fix the end of the impermeable substrate to the top of the slope of the expansive soil or freeze-thaw frost-susceptible soil, and then lay it on the top, surface and bottom of the slope.

[0029] The fifth step is to fix the lightweight concrete lining structure layer onto the aforementioned impermeable substrate.

[0030] Compared with existing technologies, the slope protection structure and construction method for expansive soil or freeze-thaw frost-susceptible soil provided by this invention have the following advantages: First, because the impermeable substrate is extended to the top of the slope structure, and groundwater drainage mechanisms are set at the slope and bottom, water in the slope subgrade can be forcibly removed, forming a relatively dry subgrade area between the top and the slope. This effectively avoids the formation of a slip layer structure on the surface of the expansive soil or water-bearing freeze-thaw frost-susceptible soil in this area and effectively prevents the occurrence of slippage. At the same time, the impermeable substrate is anchored so that it can withstand the sliding force formed by the weight of the lining structure, ensuring the safety of the slope lining structure. Second, because the valve body of the drainage check valve in the slope section and the water collection box of the drainage mechanism in the slope section are equipped with a water collection structure that is inclined and inserted deep into the slope subgrade, free water in the slope subgrade can be effectively discharged through seepage, and the migration of water can be guided in a purposeful manner. In addition, the water collection and permeable pipe can realize the anchoring effect on the slope structure, further enhancing the stability of the slope. Attached Figure Description

[0031] Figure 1 A schematic diagram of the cross-sectional structure of a slope protection structure for expansive soil foundation;

[0032] Figure 2 A schematic diagram of the cross-sectional structure of a slope protection structure for a freeze-thaw frost-susceptible soil foundation;

[0033] Figure 3This is a schematic diagram of the cross-sectional structure of the impermeable substrate that constitutes the above-mentioned slope protection structure. Detailed Implementation

[0034] The structure and working principle of the slope protection structure for expansive soil or freeze-thaw frost-susceptible soil provided by the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] like Figure 1 The diagram shows a cross-sectional view of a bentonite-based slope protection structure provided by the present invention. The slope protection structure includes an impermeable substrate 2 made of polyethylene or other plastic materials, extended and laid on the slope top substrate 11, the slope surface substrate 12, and the slope bottom substrate 13. Groundwater drainage mechanisms 31 and 32 are respectively installed on the slope and bottom of the slope. Each groundwater drainage mechanism includes a water collection tank 302 with water collection holes 301 on its periphery, located in the substrates 12 and 13, for collecting groundwater, and a matching drainage pump mechanism 303 capable of forcibly discharging the collected water. A slope lining structure 4 made of lightweight concrete is installed on the outer surface of the extended protection area at the slope top, the slope surface, and the impermeable substrate at the bottom. The end 20 of the impermeable substrate laid at the slope top is fixed to the slope top substrate 11 by an anchoring mechanism 21.

[0036] The aforementioned slope protection structure is particularly suitable for slopes with bentonite soil foundations. Its mechanism is as follows: the impermeable substrate made of polyethylene and other plastic materials, which is only laid on the slope surface and bottom soil foundation in the existing technology, is extended to the top soil foundation. This can effectively prevent the infiltration of surface water at the top of the slope, so that the slope soil foundation formed between the top of the slope and the slope surface forms a relatively dry soil foundation area A. This effectively avoids the formation of a slip layer structure on the surface of bentonite (expanded) soil or water-containing frost-susceptible soil, effectively overcoming the occurrence of slippage. At the same time, the impermeable substrate is anchored, which can greatly enhance the force that prevents the lining structure from slipping, ensuring the safety of the slope lining structure. In the above-mentioned slope protection structure, groundwater drainage mechanisms 31 and 32 are respectively installed on the slope and the bottom of the slope. During operation (water channel transport), the surface water and groundwater infiltrating into the slope soil foundation are collected into the water collection tank 302 through the water collection holes 301 set around the slope. The matching drainage pump mechanism 303 can force the water to be discharged, which can effectively reduce the water level in the slope soil foundation and ensure that the slope will not slip due to erosion and instability caused by high groundwater levels.

[0037] In the above-mentioned slope protection structures for expansive soil or freeze-thaw frost-susceptible soil

[0038] — Drainage check valves 51 and 52 are respectively installed on the slope and at the bottom of the slope, and the drainage check valve 51 installed on the slope is positioned higher than the groundwater forced drainage mechanism 31. The purpose of installing drainage check valves 51 and 52 is to solve the problem of groundwater discharge when the groundwater forced drainage mechanism 31 and 32 are not in force (forced drainage is seasonal, generally carried out between September and October when the ditch is closed, and the drainage pump mechanism 303 constituting the forced drainage mechanism is removed in the cold winter). When the groundwater forced drainage mechanism 31 is in the high water season in the slope soil, the groundwater forced drainage mechanism 31, which is located at a lower position, can collect more seepage water and force it to be discharged to ensure the low water holding capacity in the slope soil.

[0039] —In order to adapt this slope structure to high-latitude northern regions, such as Figure 2 As shown, a water-gathering structure 61 is installed on the valve body of the slope drainage check valve 51, which is inclined and inserted deep into the soil foundation 11. The structure constituting the water-gathering structure 61 preferably includes a water collection trench 601, a backfill gravel or medium-coarse sand filter material 604 that can effectively collect seepage water, and a permeable pipe 603 that is laid in the trench 601 and wrapped with a permeable geotextile material 602. The water-gathering structure can filter the collected seepage water and discharge it into the drainage check valve or water collection tank through the inclined permeable pipe. The moisture content of the slope subgrade is a major factor affecting its freeze-thaw heave. This structure aims to drain free water from the slope subgrade through seepage, guiding water migration in a targeted manner. Simultaneously, utilizing the layer-by-layer nature of the freeze-thaw process, as the slope top and sides thaw, the anchoring mechanism 21, deeply embedded in the slope top subgrade, remains frozen, effectively securing the impermeable substrate at the slope top and sides. This absorbs the sliding force of the slope's overall slope caused by surface thawing. Once the slope top subgrade is completely thawed, the surface layer of the slope top and sides retains water, forming a stable layer through seepage or evaporation. Anchoring the slope with permeable pipes further enhances its stability, and the high strength of the high-strength composite geomembrane further strengthens the self-bearing capacity of the slope lining structure.

[0040] In order to further improve the effective drainage of seepage water and freeze-thaw water in the slope soil foundation, a second water-gathering structure 62 with the same structure as the above-mentioned water-gathering structure 61 is provided on the water collection box 302 of the above-mentioned slope strong drainage mechanism. This can further improve the effective drainage of seepage water and freeze-thaw water in the slope soil foundation and thus improve the service life of the slope.

[0041] —Since the immersion depth of bentonite is generally 0.5-1.2 meters and the depth of frozen soil is about two meters, the end 20 of the impermeable substrate 2 laid at the top of the slope should preferably extend at least 0.5 meters into the soil base at the top of the slope. This allows the impermeable substrate 2 to form a relatively dry integral slope area A between the top of the slope and the slope, effectively preventing the formation of a slip layer structure on the surface of the water-containing freeze-thaw heave soil and effectively preventing the occurrence of slippage. At the same time, anchoring the impermeable substrate can effectively form a tensile-resistant integral structure, which can bear the sliding force formed by the gravity of the slope lining structure 4, ensuring the safety of the slope lining structure.

[0042] —A footing 14, preferably made of concrete, is provided at the junction of the slope foundation 12 and the bottom foundation 13 to stabilize the lining structure 4 on the slope.

[0043] The impermeable substrate laid at the top, slope, and bottom of the slope can be:

[0044] The geomembrane with a reinforcing layer is mainly used to prevent the water from the ditch formed on the slope from seeping into the slope soil, and has good seepage prevention performance. Secondly, because a reinforcing layer is set on the geomembrane layer to improve its tensile strength, it can bear the sliding force of the lining structure set on the geomembrane layer, and ensure the safety of the slope lining structure.

[0045] The impermeable substrate can also be as follows: Figure 3 The structure shown includes a waterproof substrate 21 made of plastic material and a support structure consisting of several parallel support components 22 arranged at intervals or continuously on its inner side. A geotextile layer 23 with water permeability is provided on the outside of the support structure. A water flow channel 24 is formed between the support structure and the geotextile. Seepage water and groundwater in the slope foundation enter the water flow channel through the geotextile layer and are collected and discharged into the drainage check valve 51 and / or the groundwater forced drainage mechanism 31.

[0046] The above-mentioned construction method for slope protection structures of expansive soil or freeze-thaw frost-susceptible soil includes an extended protection zone at the top of the slope, lightweight concrete on the slope surface, toothed grooves at the toe of the slope, a seepage prevention and water collection structure under the lining structure layer, and a groundwater depressurization structure. This includes: water collection trenches for collecting groundwater, backfilled with filter materials such as crushed stone or medium-coarse sand; permeable pipes for collecting groundwater, with geotextile wrapped around the outside of the permeable pipes to filter the collected groundwater; deep drainage pipes for collecting groundwater deep within the slope, serving both as groundwater collection and anchoring functions; high-strength composite geomembranes for groundwater seepage prevention and diversion, which, while ensuring the strength and rigidity of the geomembrane material, are equipped with water-conducting channels to collect seeping groundwater and allow it to enter the water collection pipes; anchoring trenches for the composite geomembrane to anchor it, capable of withstanding pressure from the upper lining structure and ensuring the safety of the slope lining structure; and vertical drainage... The water pipes are sealed at their penetration points using a connecting pressure plate, ensuring both the impermeability of the high-strength composite geomembrane and the strength of the connecting pipes. Lightweight concrete lining slabs, used as a protective structure, reduce their own weight while protecting the slope, minimizing the gravitational pressure of the lining structure on the slope soil. This adjusts the stress on the slope soil, providing an effective transition phase when the slope soil is subjected to external forces and drastic changes in water content, thus reducing damage to the slope lining structure. Supports are used to fix the overall lining structure. Anti-siltation check valves are used to discharge collected groundwater. These valves are hydraulically controlled pressure relief valves that prevent siltation at the outlet and backflow of water. They possess a degree of intelligence, actively collecting free water from the soil, reducing the slope's moisture content, and thus mitigating frost heave.

[0047] The intelligent check valve is used to force the discharge of collected groundwater. It is a type of intelligent check valve that can monitor groundwater pressure and level, siltation in collection pipes, and drainage flow, and can automatically start and stop to discharge groundwater into rivers or other areas. The intelligent control system used to start and stop the intelligent check valve is an analysis and control operation system composed of groundwater level sensors, underwater imaging equipment, water volume detection instruments, water pump electromagnetic switch cabinets, automatic start and stop switches for different sections, terminal analysis processors, and command centers.

[0048] For regions with seasonal frost heave and freeze-thaw cycles, this easy-to-install and disassemble structure allows the valve body to be removed before freezing damage occurs, and the outlet to be protected to prevent damage from extreme cold weather. In the spring, when the weather warms up and the spring thaw begins, the check valve can be reinstalled in its original position to resume operation.

Claims

1. A slope protection structure for expansive soil or freeze-thaw frost-susceptible soil, characterized in that: It includes an impermeable substrate laid at the top, slope, and bottom of the slope; a groundwater drainage mechanism is installed at the slope and bottom; and a slope lining structure is installed on the outer surface of the impermeable substrate; wherein, The end of the waterproofing substrate laid at the top of the slope is fixed to the soil base forming the top of the slope and extends at least 0.5 meters into the soil base of the top of the slope; at the same time, the end of the waterproofing substrate at the top of the slope is fixed by anchors. The structure of the groundwater forced drainage mechanism includes a water collection tank for collecting groundwater, which is set in the soil foundation and has water collection holes on its periphery, and a drainage pump mechanism that is matched with it to forcefully discharge the collected water. Drainage check valves are installed on the slope and at the bottom of the slope, with the drainage check valves on the slope positioned higher than the groundwater forced drainage mechanism. The slope drainage check valve is equipped with a water-collecting structure that is inclined and inserted deep into the soil foundation. The slope groundwater drainage mechanism is equipped with a second water-collecting structure that is obliquely inserted deep into the soil foundation. The water-collecting structure consists of a water-collecting trench, a filter material filled in it, and a permeable pipe; The slope lining structure is made of lightweight concrete.

2. The slope protection structure for expansive soil or freeze-thaw frost-susceptible soil according to claim 1, characterized in that: The impermeable substrate includes an impermeable substrate body and a support mechanism consisting of several parallel support components arranged at intervals or continuously on its inner side. A geotextile layer with water permeability is provided on the outside of the support mechanism. A water flow channel is formed between the support mechanism and the geotextile.

3. The slope protection structure for expansive soil or freeze-thaw frost-susceptible soil according to claim 1, characterized in that: A footing is provided at the junction of the slope and the bottom of the slope to stabilize the lining structure.

4. A construction method for a slope protection structure for expansive soil or freeze-thaw frost-susceptible soil as described in any one of claims 1-3, characterized in that... include: Step 1: Install permeable pipes at an angle in the soil foundation that forms the slope; Step 2: Connect the water collection tank with water collection holes on the periphery and the permeable pipe and fix them in the soil foundation of the slope, and then match the drainage pump mechanism. Step 3: Connect the valve body of the drainage check valve to the permeable pipe and fix it in the soil foundation of the slope; Step 4: Fix the end of the impermeable substrate to the top of the slope of the expansive soil or freeze-thaw frost-susceptible soil, and then lay it on the top, surface and bottom of the slope. Step 5: Fix the lightweight concrete lining structure layer onto the above-mentioned impermeable substrate.

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