A soil layer repairing structure for reconstructing a water field in a mining subsidence area and a construction method thereof
Patent Information
- Application Number
- CN202611246805.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-17
- Publication Date
- 2026-11-03
AI Technical Summary
Mining subsidence areas are prone to geological disasters such as surface collapse, cracks, and landslides. Traditional transformation technologies are difficult to adapt to dynamic deformation, the impermeable layer is prone to breakage, the water storage efficiency is low, the soil structure collapses, the water retention capacity is insufficient, the transformed paddy fields are prone to leakage, and the maintenance cost is high.
The structure consists of a bottom-up arrangement of a gangue layer, a filter layer, an impermeable layer, and a plow layer. Venting components are installed at intervals in the gangue layer. The venting components are made of crescent-shaped or circular HDPE pipes, and the vent holes are located on the arc-shaped inner pipe. The impermeable layer is made of clay and impermeable geomembrane. Combined with mechanical compaction and soil backfilling, a stable soil structure is formed.
It effectively prevents secondary subsidence and seepage, improves the water storage capacity and long-term stability of paddy fields, reduces maintenance costs, improves soil structure, promotes uniform distribution of water and nutrients, has excellent aeration and permeability, and adapts to the dynamic deformation of mining subsidence areas.
Smart Images
Figure CN123023487A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of farmland improvement technology in mining subsidence areas, specifically relating to a soil layer repair structure and construction method for paddy field improvement in mining subsidence areas. Background Technology
[0002] After mining operations cease, surface subsidence and cracking occur frequently in mining areas, significantly altering the original landforms and drastically reducing surface vegetation cover. The original topsoil structure and groundwater system are also damaged, resulting in loose soil structure, reduced water and fertilizer retention capacity, severe soil fertility loss, and shortages of irrigation water for farmland. This causes existing farmland to gradually lose its agricultural productivity and eventually become abandoned land, resulting not only in the waste of land resources but also in severe ecosystem degradation. Traditional methods of maintaining cultivated land are insufficient to address the ecological and environmental challenges posed by mining. There is an urgent need to develop new technologies and methods to achieve ecological restoration and land reclamation in mining subsidence areas, restore land productivity, improve the ecological environment, and achieve coordinated development between coal resource development, ecological environmental protection, and the restoration of arable land and paddy fields. In the process of transforming farmland in mining subsidence areas, it is necessary to overcome the triple barriers of geological dynamism, water and soil system disorder, and ecological fragility. However, ordinary mountain transformation technologies are difficult to directly apply due to their lack of deformation adaptability, system synergy, and pollution control capabilities. Therefore, it is necessary to develop a targeted "geology-ecology-engineering" collaborative restoration technology system.
[0003] Currently, the challenges in implementing farmland restoration in mining subsidence areas in southwestern mountainous regions include: continuous foundation subsidence, with continuous creep of overlying strata in mined-out areas leading to surface subsidence cycles of 10-20 years. Ordinary foundation stabilization technologies (such as dynamic compaction and replacement) cannot adapt to dynamic deformation, easily triggering secondary collapses and fractures of the impermeable layer; interconnected crack networks, with numerous hidden cracks (10-50cm wide) developing in the subsidence area, forming seepage channels. Traditional impermeable measures (single clay layer or geomembrane) are easily torn apart, resulting in water storage efficiency of less than 30%; soil structure disintegration, with subsidence causing shear damage to the topsoil, abnormal soil porosity (>60%), and a 50-70% reduction in water retention capacity, far below the 25-35% water holding capacity required for paddy fields; and abandoned ore areas, especially areas with concentrated gangue, are highly susceptible to inducing point-area or even surface-area seepage during the use of restored paddy fields.
[0004] In addition, geological disasters such as surface collapse, cracks, and landslides frequently occur in mining subsidence areas. The existing technology for transforming paddy fields has a simple structure, poor resistance to geological disasters, a short "shelf life" after transformation, and high maintenance costs. Summary of the Invention
[0005] At least in order to solve the technical problems mentioned in the background art, the present invention aims to provide a soil layer repair structure and construction method for paddy field transformation in mining subsidence areas.
[0006] The present invention adopts the following technical solution.
[0007] A soil layer repair structure for paddy field transformation in mining subsidence areas includes a gangue layer, a filter layer, an impermeable layer, a plow layer, and a tillage layer arranged sequentially from bottom to top. The gangue layer is provided with venting components arranged at intervals, the spacing between adjacent venting components is no more than 200mm, the slope of the venting components is no less than 2%, and the diameter of the venting holes on the venting components is 10~20mm.
[0008] One preferred embodiment is that the venting component uses a circular HDPE pipe with a circular cross-section, and the vent holes are located on the side and bottom of the circular HDPE pipe, with the top of the circular HDPE pipe located at the bottom of the waterproof layer.
[0009] The second preferred option is to use a crescent-shaped HDPE pipe with a crescent-shaped cross-section for the venting component. The vent is located on the arc-shaped inner tube of the crescent-shaped HDPE pipe. The inner wall of the crescent-shaped HDPE pipe contains the gangue, and the arc-shaped outer tube supports the seepage barrier. The inner cavity height of the crescent-shaped HDPE pipe is no more than 10mm. This design not only allows for the smooth discharge of gas generated within the gangue but also effectively prevents point-area or even surface-area seepage during the use of the modified paddy field. Furthermore, it prevents localized collapse at the location of the venting component during foundation compaction.
[0010] A construction method for a soil layer repair structure used in the conversion of paddy fields in mining subsidence areas includes the following steps: Step 1: Clear weeds and debris from the target area; Step 2: Plan the plot of land, drive stakes and lay out lines at the edges to obtain the target field area; Step 3: In the target field area, the topsoil is stripped, the foundation trench is excavated, the field ridge foundation is constructed, the land is leveled, the foundation is compacted to build the plow layer, and the topsoil is back-covered and leveled to build the tillage layer. Step 4: After step 3 is completed, water storage and paddy field soaking, mechanical pulping, and water storage observation are carried out. The compaction of the foundation and the construction of the plow layer include: mechanically rolling the gangue layer to compaction, then laying the air venting components, filter layer, impermeable layer and plow layer in sequence, and compacting the plow layer; the compacted plow layer soil bulk density is 1.8~2.0g / cm3; After the foundation trench is excavated, the minimum slope coefficient in each direction of the cross section shall not exceed 1:1.5; When stripping topsoil, the stripping thickness for dry land is 0.2~0.3m and the stripping thickness for field ridges is 0.1~0.15m.
[0011] Furthermore, before the topsoil is back-covered and leveled to form the tillage layer, the stripped topsoil is mixed with water and crushed to form mud. After settling, it is filled into the surface of the plow bottom. After the field is flooded, mechanical plowing, harrowing, and edge trimming are also carried out. Edge trimming involves plowing and crushing the edges of the field, with each meter of edge trimmed to a width of 1.5 to 2 meters.
[0012] Furthermore, the operation steps for laying the exhaust components are as follows: first, lay some gangue and compact it, then lay the arc-shaped inner pipe, then place standard-sized small gangue on the top of the arc-shaped inner pipe, with the small gangue size being 8~10mm, then lay the arc-shaped outer pipe on the small gangue, at which point the small gangue is sandwiched between the arc-shaped inner pipe and the arc-shaped outer pipe, and finally lay the remaining gangue around the arc-shaped outer pipe.
[0013] Furthermore, the impermeable layer is constructed using clay and an impermeable geomembrane; the clay thickness of both the upper and lower clay layers is ≥30cm, and the clay must be compacted in layers, each ≤25cm thick, with a dry apparent density ≥1600kg / m³ and a permeability coefficient ≤1×10⁻ 7 cm / s; tensile strength of the impermeable geomembrane between clay layers ≥25MPa, elongation at break ≥700%.
[0014] Furthermore, one end of the exhaust component extends outward to the outside of the paddy field ridge.
[0015] Beneficial effects: The solution of this invention can not only adapt to the dynamic deformation of mining subsidence areas, greatly reducing the risk of secondary collapse and seepage layer fracture, and preventing the formation of seepage channels in the modified area, but also smoothly discharge the gas generated in the gangue. It can effectively prevent point or even surface seepage in the modified paddy fields during use, and prevent local collapse at the location of the exhaust components during foundation compaction. This invention is a dry-to-paddy field conversion project targeting the characteristics of frequent surface collapses, cracks, landslides and other geological disasters in mining subsidence areas. It can effectively cope with frequent geological disasters, ensure the water storage capacity, long-term stability and safety of the paddy fields, and the modified paddy fields have a long "shelf life" and low maintenance costs. This invention takes into account seepage prevention effect, environmental friendliness, low cost, improves soil layer structure, promotes uniform distribution of water and nutrients, and has excellent aeration and permeability. Attached Figure Description
[0016] Figure 1 This is a diagram of the soil layer repair structure in the mining subsidence area in Example 1; Figure 2 This is a schematic diagram of the exhaust component in Example 1; Figure 3 This is an image of the mining subsidence area before its modification in Example 1; Figure 4 This is an image of the mining subsidence area after its modification in Example 1; Figure 5This is a diagram of the soil layer repair structure in the mining subsidence area in Example 2. Detailed Implementation
[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] Example 1 Combination Figure 1 and Figure 2 As shown, a soil remediation structure for paddy field transformation in mining subsidence areas includes, from bottom to top, a gangue layer 1, a filter layer 2, an impermeable layer 3, a plow layer 4, and a topsoil layer 5. The gangue layer 1 is equipped with spaced-apart venting components 6, with a spacing of 200mm between adjacent venting components 6. The slope of the venting components 6 is 3%, and the diameter of the vent holes 7 on the venting components 6 is 20mm. One end of the venting components 6 extends outward to the outside of the paddy field ridge. The venting components 6 are made of crescent-shaped HDPE pipes with a crescent-shaped cross-section. The vent holes 7 are located on the arc-shaped inner tube 8 of the crescent-shaped HDPE pipe. The inner space of the crescent-shaped HDPE pipe 8 accommodates the gangue, and the arc-shaped outer tube 9 of the crescent-shaped HDPE pipe supports the impermeable layer 3. The maximum height of the inner cavity of the crescent-shaped HDPE pipe is 10mm.
[0019] Taking the dry land to paddy field conversion project in Wangjiaba Village, Nantong Town, Wansheng Economic Development Zone as an example, before the renovation, the dry land was like... Figure 3 As shown: The background of this project is that the previous mining operations caused significant damage to the original landforms, topsoil, and surface vegetation in the area. Over-exploitation and over-utilization of some farmland led to a decline in soil fertility and groundwater levels, gradually turning it into abandoned land. This farming practice poses a severe challenge to the farmland ecosystem. Therefore, it is necessary to comprehensively promote the reclamation of paddy fields, strive to create green and ecological farmland, and build a sound agricultural environment.
[0020] This project implements a method for converting dry land into paddy fields (i.e., a construction method for soil layer restoration structures used in the conversion of paddy fields in mining subsidence areas), and the converted area is as follows: Figure 4 As shown, the steps are as follows: Step 1: Remove weeds and debris. For some abandoned field ridges, use weeding machinery to remove weeds and shrubs in the field, and then use double-wheeled vehicles to transport the cleared weeds and shrubs to the designated location for stacking. Step 2: Divide the coal mining subsidence area into blocks according to the geological environment or the original dry farmland area. Mark the edge of the blocks by driving stakes and laying lines to obtain the target field area for reference in subsequent operations. Specifically, based on the original natural platform, lay out the lines for each platform, spread ash lines, determine the platform position, determine the location of the embankment, topsoil pile, and the edge line for removing soil and opening the box. Step 3: In the target field, perform topsoil stripping, trench excavation, construction of field ridge foundations, land leveling, compaction of the foundation to build the plow layer, and topsoil back-covering and leveling to build the topsoil layer; specifically as follows: Topsoil stripping: For dry land converted to paddy fields within the project area, strip 0.2m of topsoil (0.2~0.3m of topsoil stripping thickness), and for paddy field ridges in the dry land converted to paddy fields, strip 0.1m of topsoil (0.1~0.15m of topsoil stripping thickness). For land retained as dry land and other land, no topsoil stripping is required. The stripped topsoil is piled in a designated area. Due to the short piling time, there are no requirements for the height or shape of the pile, and it can be handled flexibly according to the actual situation. Excavation of foundation trenches and land leveling: excavating high areas and filling low areas, and pushing the soil from the excavated area to the filled area to make the surface flatness of the merged fields basically uniform; during the land leveling process, fields are also merged. The soil movement during field merging adopts the top-cutting and bottom-filling method, that is, the soil from the higher area is deeply pried down and overturned to the lower area, which facilitates the merging and transformation of smaller fields, thereby improving the efficiency of subsequent cultivation; among them, in the process of paddy field transformation in coal mining subsidence areas, foundation trench excavation is one of the core links in the construction of field ridge foundation. Foundation trench excavation must be carried out after the topsoil stripping is completed, mainly serving the needs of field ridge foundation construction and the anchoring of the plow bottom layer 4 seepage prevention system, and controlling the minimum slope coefficient of each direction of the cross section not to exceed 1:1.5; New field embankments (construction of field embankment foundation 11): The field embankments are constructed using rammed clay, with a top width of 0.5m and an inner slope ratio of 1:0.5. The outer slope ratio is set according to the different heights of the field embankments: {1:0.5 for field embankments with a height less than 1m (excluding 1m), 1:0.75 for field embankments with a height less than 1.5m (excluding 1.5m), and 1:1 for field embankments with a height greater than or equal to 1.5m}. In addition, 1-2 drainage outlets are set for each field embankment according to the actual situation. The drainage outlets are 0.4m × 0.3m in size. The drainage outlets are designed to ensure water system interconnection between adjacent fields after the dry land is converted into paddy fields, and also to ensure the safety of pedestrians on the field embankments. The drainage outlets are constructed using rammed soil and are rammed when constructing field embankment 12. The foundation is compacted by plowing the bottom layer 4: the gangue layer is mechanically rolled until compacted, and then the air venting component 6, the filter layer 2, the impermeable layer 3 and the plow bottom layer 4 are laid in sequence and compacted. The materials for the impermeable layer 3 are clay and impermeable geomembrane (materials are shown in Table 1). Table 1 Materials for the Impermeable Layer 3
[0021] The steps of mechanically compacting the gangue layer and then laying the exhaust component 6 include: first laying a portion of gangue and compacting it; then laying the arc-shaped inner pipe 8 (one arc-shaped inner pipe 8 and a corresponding arc-shaped outer pipe 9 are laid every 200mm); then placing standard-sized small gangue 10 on top of the arc-shaped inner pipe 8, with a standard size of 8~10mm; then laying the arc-shaped outer pipe 9 on the small gangue 10, where the small gangue 10 is sandwiched between the arc-shaped inner pipe 8 and the arc-shaped outer pipe 9; finally, laying the remaining gangue around the arc-shaped outer pipe 9; the width of each arc-shaped inner pipe 8 is 300mm. The impermeable layer 3 consists of an upper clay layer, an impermeable geomembrane, and a lower clay layer. The clay thickness of the upper and lower clay layers is ≥30cm. The clay needs to be compacted in layers, each ≤25cm thick, with a dry apparent density ≥1600kg / m³ and a permeability coefficient ≤1×10⁻⁻⁻⁶. 7 cm / s; tensile strength of the impermeable geomembrane between clay layers ≥25MPa, elongation at break ≥700%; During the movement of deep soil, the original structure of the plow pan 4 will be damaged. Therefore, after completing the previous step, the leveled deep soil needs to be compacted. The original soil is compacted by mechanical rolling, with moistened soil (wet clay) in between, for a total of 2 times. The filling area should be the focus of rolling. The bulk density of the compacted plow pan 4 soil should be controlled between 1.8 and 2.0 g / cm3. The stripped topsoil is mixed with water and crushed to form a slurry. After settling, it is filled onto the surface of the plow bottom layer 4. This fills the pores of the plow bottom layer 4 and improves the structural stability. On the other hand, it also forms an intermediate layer between the plow bottom layer 4 and the subsequent tillage layer, further improving the structural stability. Topsoil backfilling and leveling to construct the tillage layer (land leveling): After the plow layer 4 is compacted, the flatness of the field cannot meet the design requirements. The stripped topsoil is backfilled into the merged field, and then the details are leveled manually and evenly spread to ensure that the flatness of the field surface reaches ±3cm. Step 4: After topsoil backfilling, follow the technical specifications for converting dry land to paddy fields, including soaking and slurrying, mechanical plowing, harrowing, and edge trimming. Simultaneously, monitor water levels and promptly identify and repair any leaks. Details are as follows: After the field embankments are built, water is diverted into the fields through irrigation ditches to soak the soil. Then, a rotary tiller is used to plow once and harrow three times. This restores the soil's topsoil structure, improves its water retention capacity (the moisture level suitable for seed germination and crop growth), eliminates some weeds, reduces pests and diseases, levels the surface, and improves the standard of mechanized agricultural operations. Under ideal conditions, this method is more economical than manual or animal-powered plowing and harrowing. After mechanical plowing and harrowing, manual labor or oxen are used to plow and break up the edges of the fields, with each meter of edge broken up to a width of 2 meters. After the rotary tiller has broken up the soil, embankments are built. The soil is then manually tamped down using harrows and hoes, and then, from bottom to top, carried to the new embankments, compacted, and straightened to form a smooth surface. The initial ridge is left to stand for 2-3 days to allow the mud slurry on the new ridge surface to fill the gaps. The ridge-building process (step 12) is repeated once. Finally, after completing the mud slurry preparation, the ridge-building process (step 12) is repeated once more. This process is repeated three times to form the final ridge. The designed thickness of the ridge-building process (step 12) is 100mm, but the actual thickness can be adjusted according to the water storage conditions of the field. After the field is plowed, the soil clods are broken up by machinery to form mud slurry, which is then allowed to settle. The mud slurry can fill the gaps in the plow layer (step 4) to prevent leakage. After the above processes, the field can basically meet the water storage requirements. If there is local leakage, the field contractor is responsible for plowing, harrowing, and mud slurry preparation until the field has stable water and meets the local farming requirements.
[0022] The scheme described in this embodiment not only adapts to the dynamic deformation of mining subsidence areas, greatly reducing the risk of secondary collapse and fracture of the anti-seepage layer 3, and preventing the formation of seepage channels in the modified area, but also smoothly discharges the gas generated in the gangue, effectively preventing point or even surface seepage during the use of the modified paddy field, and preventing local collapse at the location of the exhaust components during foundation compaction. This scheme is a dry-to-paddy field conversion project designed for the characteristics of frequent geological disasters such as surface collapse, cracks, and landslides in mining subsidence areas. It can effectively cope with frequent geological disasters, ensuring the water storage capacity, long-term stability, and safety of the paddy field. The modified paddy field has a long "shelf life" and low maintenance costs. This scheme takes into account the anti-seepage effect, environmental friendliness, low cost, improves the soil layer structure, promotes the uniform distribution of water and nutrients, and has excellent aeration and permeability. In this embodiment, one key point is that the crescent-shaped HDPE pipe can effectively collect the gas generated by the gangue layer and smoothly discharge it through the exhaust component. Small gangue is sandwiched between the arc-shaped inner pipe and the arc-shaped outer pipe. This structure cleverly utilizes the principle of arch support, ensuring the stability and safety of the entire soil structure while ensuring smooth exhaust, thus guaranteeing the water storage capacity of the paddy field, and also has a good anti-pressure effect.
[0023] In the comparative scheme (experimental field), the venting components were omitted. During the first year of water storage after the paddy field was modified, intermittent bubbling occurred in the paddy field, and leakage eventually occurred near the bubbling area. In contrast, in the scheme of Example 1, no bubbling occurred during the first two years of water storage after the paddy field was modified, and no leakage or collapse occurred.
[0024] Example 2 A soil remediation structure for paddy field transformation in mining subsidence areas, referring to Example 1, differs from Example 1 in that it combines... Figure 5 As shown, the venting component 6 uses a circular HDPE pipe with a circular cross-section. Venting holes 7 are located on the side and bottom of the circular HDPE pipe, and the top of the circular HDPE pipe is located at the bottom of the impermeable layer 3. The steps of mechanically compacting the gangue layer before laying the venting component 6 include: first laying a portion of the gangue and compacting it, and then laying the circular HDPE pipe (one pipe every 200 mm).
Claims
1. A soil layer repair structure for paddy field transformation in mining subsidence areas, characterized in that: It includes a gangue layer (1), a filter layer (2), an impermeable layer (3), a plow layer (4), and a tillage layer (5) arranged sequentially from bottom to top. The gangue layer (1) is provided with venting components (6) arranged at intervals. The distance between adjacent venting components (6) is no more than 200 mm. The slope of the venting component (6) is no less than 2%. The diameter of the venting holes (7) on the venting component (6) is 10~20 mm.
2. The soil layer repair structure for paddy field transformation in mining subsidence areas according to claim 1, characterized in that: The exhaust component (6) is made of HDPE pipe with a circular cross section. The exhaust holes (7) are set on the side and bottom of the circular HDPE pipe. The top of the circular HDPE pipe is located at the bottom of the anti-seepage layer (3).
3. The soil layer repair structure for paddy field transformation in mining subsidence areas according to claim 1, characterized in that: The exhaust component (6) uses a crescent-shaped HDPE pipe. The exhaust hole (7) is set on the arc-shaped inner pipe (8) of the crescent-shaped HDPE pipe. The inner space of the crescent-shaped HDPE pipe (8) can accommodate gangue. The arc-shaped outer pipe (9) of the crescent-shaped HDPE pipe can support the seepage prevention layer (3). The inner cavity height of the crescent-shaped HDPE pipe is not greater than 10mm.
4. A construction method for a soil layer repair structure for paddy field reconstruction in mining subsidence areas as described in any one of claims 1-3, characterized in that: Includes the following steps: Step 1: Clear weeds and debris from the target area; Step 2: Plan the plot of land, drive stakes and lay out lines at the edges to obtain the target field area; Step 3: In the target field area, the topsoil is stripped, the foundation trench is excavated, the field ridge foundation is constructed (11), the land is leveled, the foundation is compacted to build the plow layer, and the topsoil is back-covered and leveled to build the tillage layer. Step 4: After step 3 is completed, water storage and paddy field soaking, mechanical pulping, and water storage observation are carried out. The compaction of the foundation and the plow bottom layer includes: mechanically rolling the gangue layer to compaction, then laying the air venting component (6), the filter layer (2), the seepage prevention layer (3) and the plow bottom layer (4) in sequence, and compacting the plow bottom layer (4); the compacted plow bottom layer (4) has a soil bulk density of 1.8~2.0 g / cm3; After the foundation trench is excavated, the minimum slope coefficient in each direction of the cross section shall not exceed 1:1.5; When stripping topsoil, the stripping thickness for dry land is 0.2~0.3m and the stripping thickness for field ridges is 0.1~0.15m.
5. The construction method according to claim 4, characterized in that: Before the topsoil is backfilled and leveled to form the tillage layer, the stripped topsoil is mixed with water and crushed to form mud. After settling, it is filled into the surface of the plow layer. After the field is flooded, mechanical plowing, harrowing and edge trimming are also carried out. Edge trimming involves plowing and crushing the edges of the field, with each meter of edge trimmed to a width of 1.5 to 2 meters.
6. The construction method according to claim 5, characterized in that, The steps for laying the exhaust components (6) are as follows: first, lay some gangue and compact it, then lay the arc-shaped inner pipe (8), then place a standard-sized small gangue (10) on the top of the arc-shaped inner pipe (8). The small gangue (10) is 8~10mm in size. Then lay the arc-shaped outer pipe (9) on the small gangue (10). At this time, the small gangue (10) is sandwiched between the arc-shaped inner pipe (8) and the arc-shaped outer pipe (9). Finally, lay the remaining gangue around the arc-shaped outer pipe (9).
7. The construction method according to claim 6, characterized in that, The impermeable layer (3) is made of clay and impermeable geomembrane; the thickness of the upper and lower clay layers is ≥30cm, the clay needs to be compacted in layers, each layer is ≤25cm, its dry apparent density is ≥1600kg / m³, and its permeability coefficient is ≤1×10⁻ 7 cm / s; tensile strength of the impermeable geomembrane between clay layers ≥25MPa, elongation at break ≥700%.
8. The construction method according to claim 7, characterized in that: One end of the exhaust component (6) extends outward to the outside of the field ridge.