Karst region waste dump water and soil conservation system and construction method

Abstract

The present application relates to the technical field of water and soil conservation, and discloses a water and soil conservation system for a waste dump in a karst region and a construction method. The system comprises a stepped waste dump body arranged in a karst depression, a water interception and drainage unit, a stepped water storage unit and a reclamation unit. The water interception and drainage unit collects water from the waste dump and transports it to the stepped water storage unit for storage. The water discharge holes in the retaining wall of the stepped water storage unit are connected to the reclamation unit, enabling self-flow irrigation in the dry season. The present application also arranges the height difference between the drainage ditches behind the retaining wall and the drainage ditches on the bank slope, thereby constructing a three-level regulation system for small water storage, medium water diversion and large water discharge. The present application effectively solves the problems of low water retention rate and poor survival rate of reclamation vegetation in waste dumps in karst regions, and realizes the cross-time scale allocation of water resources and the land resource utilization.

Description

Technical Field

[0001] This invention relates to the field of soil and water conservation technology, specifically to a soil and water conservation system and construction method for spoil heaps in karst areas. Background Technology

[0002] Enclosed or semi-enclosed karst depressions are typical topographic units of karst landforms. They typically contain sinkholes and karst conduits, which form natural drainage channels for rainfall and surface runoff, giving karst depressions unique hydrological characteristics. During the rainy season, rainfall rapidly infiltrates along karst conduits, and runoff quickly dissipates. During the dry season, due to the lack of water-retaining media and water-blocking structures on the surface of the depression, residual water continues to leak away under the strong infiltration of the karst conduits, rapidly depleting surface water and resulting in extremely poor water-holding capacity. This hydrological characteristic leads to seasonal drought even in areas with abundant rainfall, with the surface soil remaining chronically water-deficient.

[0003] Due to the naturally enclosed topography of karst depressions, they are often chosen as storage sites for construction waste. Currently, the most commonly used solution in soil and water conservation engineering for waste disposal sites is the interception and drainage unit. The core design concept of this system is to set up interception ditches, drainage ditches, and rapid flow channels at the top of the waste disposal site, at each level of platform, and at the foot of the slope. This allows for the rapid collection of upstream runoff, surface runoff, and seepage water from within the slope, which is then diverted away from the waste body through drainage ditches and tunnels into downstream natural channels. This ensures that the waste body is not eroded by water flow and maintains its stability.

[0004] However, while rapid drainage units can ensure the stability of the spoil mass during the rainy season, they also completely sever the original hydrological cycle of the depression. That is, precious water resources are quickly drained away during the rainy season, and during the dry season, the surface soil of the spoil mass loses water rapidly due to the permeability of the karst channels. The reclaimed vegetation withers and dies on a large scale due to extreme water shortage, and the cost of replanting and maintenance is extremely high. A large number of karst depression spoil heaps face the dilemma of failed reclamation. Summary of the Invention

[0005] This invention provides a water and soil conservation system and construction method for karst spoil heaps, in order to solve the problems of low survival rate of reclaimed vegetation, high management and maintenance costs, and poor reclamation effect caused by rapid water loss in existing karst spoil heaps.

[0006] In a first aspect, the present invention provides a water and soil conservation system for karst spoil heaps, comprising a stepped spoil heap, a drainage unit, a tiered water storage unit, and a reclamation unit. The stepped spoil heap is situated within a karst depression; the drainage unit is located at the top of the slope, at each level of the stepped spoil heap, and at the toe of the slope, for collecting upstream runoff, surface runoff, and internal seepage from the slope; the tiered water storage unit is located on the steps of the stepped spoil heap at different elevations and is connected to the drainage unit, for receiving and storing the water collected by the drainage unit; the reclamation unit covers the surface of the stepped spoil heap for planting vegetation; the retaining wall of the tiered water storage unit adjacent to the reclamation unit has drainage holes, which connect the tiered water storage unit and the reclamation unit.

[0007] Beneficial Effects: By setting up tiered water storage units connected to the interception and drainage units, surface runoff that would otherwise be rapidly drained away during the rainy season is effectively intercepted and stored within the spoil heap. During the dry season, the water stored in the water storage units can be precisely replenished to the reclamation units through drainage holes in the retaining walls, effectively alleviating the problem of rapid water loss of the surface soil caused by seepage from sinkholes in karst areas, improving the overall water retention rate of the spoil heap, and realizing the cross-timescale allocation and efficient utilization of water resources. Furthermore, by utilizing tiered water storage units at different elevations within the stepped spoil heap, combined with drainage holes at different heights in the retaining walls, zoned and graded water supply can be implemented according to the differentiated water requirements of different areas and vegetation within the reclamation unit, constructing a graded and differentiated irrigation system and improving the efficiency of land resource utilization.

[0008] In one optional embodiment, the interception and drainage unit includes a water collection trough, a water interception ditch, and a drainage ditch. The water collection trough is located in the upstream water collection ditch of the stepped slag heap and is used to collect water from upstream. The water interception ditch is located at the intersection of the stepped slag heap and the karst depression and is used to intercept water from the surrounding area of ​​the slag heap. The drainage ditch is connected to the bottom and / or middle of the water interception ditch and is used to transport the water collected by the water interception ditch downstream.

[0009] Beneficial effects: By placing the catchment trough within the upstream catchment channel of the slag heap, water from the upstream channel can be effectively intercepted. Furthermore, by setting up an intercepting ditch at the intersection of the slag heap and the karst depression, surface runoff around the slag heap can be precisely intercepted. This achieves comprehensive collection and aggregation of water from different sources and along different paths within the catchment area of ​​the slag heap, ensuring that precious water resources during the rainy season are fully captured and channeled into the storage units, solving the water waste problem caused by insufficient collection in traditional systems. Simultaneously, by connecting the drainage ditch to the bottom and / or middle of the intercepting ditch, water from different water layers within the intercepting ditch can be orderly diverted along different paths. That is, water at the bottom can be preferentially introduced into the cascade storage units through the bottom drainage ditch for use in irrigation during the dry season; while water in the middle can be appropriately diverted through the slope drains via the middle drainage ditch, avoiding overloading of the storage units and achieving differentiated regulation of storage and diversion.

[0010] In one optional embodiment, the top of the retaining wall of the cascade water storage unit is provided with an overflow meter hole, and a drainage ditch is provided behind the retaining wall of the cascade water storage unit. The beginning of the drainage ditch is connected to the bottom of the intercepting ditch, and the end is connected to the overflow meter hole. Under low flow conditions, the bottom water of the intercepting ditch is introduced into the cascade water storage unit for storage through the drainage ditch behind the retaining wall.

[0011] Beneficial Effects: By setting up a drainage ditch behind the retaining wall, with its starting end connected to the bottom of the intercepting ditch and its end connected to an overflow meter, the bottom water collected by the intercepting ditch can be preferentially guided into the water storage unit for storage under low flow conditions. This establishes a low-flow-priority storage mechanism, solving the problem of water shortage during the dry season caused by the rapid drainage of rainwater resources during the rainy season. Furthermore, by installing overflow meters at the top of the retaining wall of the cascade water storage unit, when the water storage unit is full or the inflow increases, excess water can be safely discharged through the overflow meters at the top of the retaining wall, achieving graded treatment of runoff based on volume, balancing water storage needs with system flood control safety. At the same time, the arrangement of the drainage ditch behind the retaining wall makes full use of the natural elevation difference between the intercepting ditch and the water storage unit, allowing the bottom water of the intercepting ditch to flow into the water storage unit by gravity without the need for any external power equipment, reducing the system's construction costs and operation and maintenance energy consumption.

[0012] In one optional embodiment, the slope side of the stepped slag heap is provided with sinkholes, and the middle part of the intercepting ditch is connected to the sinkholes on the slope side through the slope drainage ditch; under medium flow conditions, the middle layer water collected by the intercepting ditch is introduced into the sinkholes on the slope side through the slope drainage ditch for diversion and discharge.

[0013] Beneficial Effects: By setting the drainage ditches behind the retaining wall and those on the bank slope at different heights, a dual-channel diversion system based on both vertical water stratification and flow rate is constructed. Specifically, at low flow rates, bottom water preferentially enters the storage unit via the drainage ditches behind the retaining wall; at medium flow rates, middle-layer water is safely diverted through the bank slope drainage ditches into the bank slope sinkholes. This achieves differentiated treatment of different water layers within the intercepting ditch, preventing middle-layer water from crowding out the effective storage capacity of the storage unit and ensuring sufficient storage space under low to medium flow conditions, significantly improving the system's adaptability to complex water inflow processes. Simultaneously, the naturally distributed sinkholes on the karst depression slopes serve as natural outlets for the diversion and discharge of intermediate water. Water from the central part of the intercepting ditch is directly diverted into the sinkholes via the slope drainage ditches, restoring and utilizing the original natural drainage function of the karst depression. This eliminates the need for separate drainage tunnels or long-distance drainage channels, reducing concrete work and earthwork excavation, lowering project costs and construction time, and achieving low-cost ecological drainage treatment. In other words, the water storage unit combines water storage and small-flow regulation, while the natural sinkholes handle both intermediate water diversion and auxiliary discharge of floods exceeding standard levels. The two complement each other and work synergistically to enhance the overall adaptability and safety redundancy of the spoil heap's water and soil conservation system in the face of varying rainfall levels.

[0014] In one optional implementation, under high flow conditions, the upper water body of the intercepting ditch is naturally discharged into the downstream natural channel through the intercepting ditch, and the overflow orifices of each stage of the cascade water storage unit and the overflow surface connecting adjacent cascade water storage units serve as the main flood discharge channel.

[0015] Beneficial effects: Under high flow conditions, the system utilizes the upper layer of water in the intercepting ditch to naturally flow down to the downstream natural channel. Simultaneously, the overflow outlets at the top of the retaining walls of each water storage unit and the overflow surfaces connecting adjacent units serve as the main flood discharge channels. These two discharge paths work in tandem, discharging floodwaters from the perimeter of the spoil heap and from the surface of the spoil heap itself, ensuring that floodwaters exceeding standard levels can be quickly and safely discharged away from the spoil heap. This avoids the risk of overtopping or dam failure due to insufficient flow capacity of a single discharge channel, guaranteeing the structural safety and flood control stability of the spoil heap under extreme rainstorm conditions. By organically combining with low-flow storage and medium-flow diversion mechanisms, a complete three-level gradient control system based on automatic triggering of inflow volume is constructed. During low flows, bottom water is preferentially stored through drainage ditches after passing through retaining walls; during medium flows, mid-layer water is diverted and discharged through slope drainage ditches; and during high flows, upper-layer water naturally flows down through intercepting ditches, with each level of overflow orifice and overflow surface serving as the main flood discharge channel. This allows the spoil heap's water and soil conservation system to automatically switch to the corresponding operating mode when facing different levels of rainfall. Simultaneously, the overflow surfaces connecting adjacent cascade storage units utilize the natural topographical differences between different elevations of the stepped spoil heaps, causing floodwaters discharged from the overflow orifices to cascade down the overflow surfaces in a stepped manner, continuously reducing water kinetic energy, effectively lowering flood velocity and scouring force, and mitigating impact damage to the slope and toe structure.

[0016] In one optional embodiment, the cascade water storage unit includes, from bottom to top, a transition material layer, a clay impermeable layer, a transition material protective layer, and a rubble erosion control layer laid on the step surface of the stepped slag heap. The transition material layer is laid between the step surface of the stepped slag heap and the bottom surface of the clay impermeable layer. The rubble erosion control layer is laid on the top surface of the transition material protective layer and covers the entire bottom area of ​​the cascade water storage unit. The retaining wall of the cascade water storage unit is arranged above the rubble erosion control layer.

[0017] Beneficial effects: By setting a clay impermeable layer at the bottom of the cascade water storage unit and laying it on top of the transition material layer, a continuous and dense water-blocking barrier is formed through compaction. This cuts off the vertical seepage path of water within the water storage unit to the bottom slag and karst channels, ensuring that the valuable water resources collected during the rainy season can be stored stably and for a long time within the water storage unit, providing a reliable water source for reclamation irrigation during the dry season. Furthermore, by laying the lower transition material layer between the step surface of the slag heap and the bottom surface of the clay impermeable layer, it serves two purposes: firstly, as a leveling layer; and secondly, as a filter layer, preventing fine particles from the lower slag from entering the clay layer and causing structural damage due to seepage. The upper transition material protective layer covers the top surface of the clay impermeable layer, effectively protecting the clay layer from water erosion and external disturbances during subsequent construction and operation. Specifically, transition material layers and protective transition material layers are set on the upper and lower sides of the clay impermeable layer, respectively, to improve the service life and seepage prevention reliability of the clay impermeable layer and avoid the risk of water storage failure due to damage to the impermeable layer. Furthermore, by laying a riprap layer on top of the protective transition material layer and covering the entire bottom area of ​​the water storage unit, it can effectively resist the scouring and erosion of the overflow flow when participating in large-volume flood discharge as the main flood discharge channel, preventing the bottom structure from being hollowed out and damaged. It can also provide a stable foundation bearing layer for the retaining wall, enhancing the retaining wall's anti-sliding and anti-overturning stability. This arrangement constructs a bottom structural system for the water storage unit with clearly defined functional zones and an orderly hierarchical combination.

[0018] In one optional embodiment, the drainage holes are multiple sets of through holes arranged in layers along the height direction of the retaining wall. Each set of drainage holes is spaced apart along the length direction of the retaining wall. Any one of the drainage holes penetrates the wall body of the retaining wall. The inlet end of the drainage hole is connected to the internal water body of the cascade water storage unit, and the outlet end of the drainage hole extends to the side of the retaining wall away from the cascade water storage unit and is located above the reclamation unit. Each set of drainage holes corresponds to the reclamation unit at a different elevation.

[0019] Beneficial Effects: By layering multiple sets of drainage holes along the height of the retaining wall, with each set corresponding to a reclamation unit at a different elevation, a three-dimensional irrigation network covering all levels of the slag heap is formed. This allows reclamation units at different elevations to receive independent water replenishment. Operators can select and open the appropriate drainage hole sets based on the type of vegetation, water requirements, and soil moisture conditions within each reclamation unit, achieving precise allocation and on-demand supply of water resources. Simultaneously, the spacing of each set of drainage holes along the length of the retaining wall creates a uniformly distributed array of outlet points above the reclamation unit. When a set of drainage holes is opened for irrigation, water flows out simultaneously from multiple points along the length of the retaining wall, evenly covering the entire surface of the reclamation unit. This avoids water concentration and uneven irrigation caused by single-point outlets, achieving uniform irrigation and improving the overall growth and survival rate of the reclaimed vegetation. Furthermore, by connecting the inlet end of the drainage hole to the water body inside the water storage unit, and extending the outlet end to the side of the retaining wall away from the water storage unit and above the reclamation unit, the natural elevation difference between the water body of the water storage unit and the reclamation unit is fully utilized, so that irrigation water can flow into the reclamation unit by gravity without the need for additional power equipment such as water pumps, thus reducing operating costs and maintenance intensity.

[0020] In one optional embodiment, the reclamation unit includes a clay cover layer and a vegetation layer. The clay cover layer covers the surface of each step of the stepped spoil heap; the vegetation layer is planted on the clay cover layer; the outlet of the drainage hole is located above the clay cover layer at the corresponding elevation, and the water discharged from the drainage hole flows over the surface of the clay cover layer or is transported to the root area of ​​the vegetation layer through irrigation pipes.

[0021] Beneficial effects: By setting a clay cover layer on each step surface of the stepped spoil heap as the foundation of the reclamation unit, the clay's fine particles and low permeability coefficient allow it to effectively absorb and retain a large amount of water within the root zone after rainfall or irrigation, significantly slowing down the rate of vertical infiltration and evaporation. Simultaneously, the outlet of the drainage holes is located above the clay cover layer, ensuring that the water supplied to the water storage unit first wets the surface of the clay cover layer before slowly infiltrating into the vegetation root zone, thus overcoming the natural limitation of surface soil in karst spoil heaps failing to retain water.

[0022] In one optional embodiment, the karst spoil heap water and soil conservation system further includes a sinkhole treatment unit, which is located at the sinkhole opening at the bottom of the karst depression and includes a concrete arch, a drainage pipe, and geotextile. The concrete arch is an arch-shaped structure. Both ends of the concrete arch rest on the bedrock outside the entrance of the sinkhole. The concrete arch spans above the entrance of the sinkhole, serving to bear the load of the bottom slag heap of the stepped slag heap and transfer the load to the bedrock on both sides. The drainage pipe is embedded within the concrete arch and runs vertically through the upper and lower sides of the concrete arch. The upper inlet of the drainage pipe is located on the top surface of the concrete arch and adjacent to the bottom slag heap of the stepped slag heap. The lower outlet of the drainage pipe is located on the bottom surface of the concrete arch and connects to the internal space of the sinkhole, serving to guide seepage water from inside the stepped slag heap into the sinkhole. The geotextile covers the upper inlet of the drainage pipe and is laid on the top surface of the concrete arch around the inlet of the drainage pipe, serving to filter fine particles in the seepage water inside the stepped slag heap and prevent fine particles from entering the drainage pipe and causing blockage.

[0023] Beneficial Effects: A concrete arch is constructed at the entrance of the sinkhole, allowing both ends of the arch to rest stably on the bedrock outside the entrance. Utilizing the excellent load-bearing characteristics of the arch structure, the vertical load transmitted from the bottom of the stepped slag heap is transformed into horizontal thrust and compressive stress on the bedrock on both sides. This effectively crosses the weak, hollow area of ​​the sinkhole, preventing the slag load from directly acting on the unstable rock mass above the sinkhole, ensuring the long-term load-bearing safety and overall stability of the slag heap's bottom structure. Furthermore, by embedding drainage pipes vertically through both sides of the concrete arch, with the upper inlet adjacent to the bottom of the slag heap and the lower outlet connecting to the interior space of the sinkhole, an orderly and controllable drainage path is maintained within the slag heap. This prevents the slag heap from weakening or being damaged by seepage due to water accumulation above the sinkhole, and also avoids the risk of secondary geological disasters caused by a complete disruption of the overall drainage pattern after the sinkhole is sealed. This achieves the safety management goal of predictable, controllable, and manageable seepage within the slag heap. Furthermore, by covering the upper inlet of the drainage pipe with geotextile and laying it on the arched surface around the inlet, a permeable yet particle-blocking filter interface is formed between the drainage pipe inlet and the slag heap. This allows water to pass through smoothly while effectively intercepting fine particles, ensuring the drainage pipe maintains a smooth flow state in the long term. This effectively extends the service life of the sinkhole treatment unit and avoids the potential ecological risk of large-scale loss of fine particles along the sinkhole, clogging the karst pipes. In other words, this combination of structural reinforcement with a concrete arch, drainage pipe for seepage control, and geotextile for reverse filtration achieves the dual functions of slag heap support and orderly drainage in situ within the sinkhole, preserving the natural drainage pattern of the karst depression and avoiding the damage to the regional hydrological environment caused by large-scale closure and modification.

[0024] Secondly, the present invention also provides a construction method for a karst spoil heap water and soil conservation system, which is applied to the karst spoil heap water and soil conservation system provided in the first aspect, and includes the following steps: S1: Spoil is piled up in layers from bottom to top in the karst depression, and compacted to form a stepped spoil heap with multiple steps; S2: Drainage interception units are constructed at the top of the stepped spoil heap, at each level of platform and at the bottom of the slope to collect upstream runoff, slope runoff and seepage water inside the slope; S3: Cascade water storage units are constructed on each level of the stepped spoil heap, and the cascade water storage units are connected to the drainage interception units so that the water collected by the drainage interception units can enter the cascade water storage units for storage; S4: Reclamation substrate is covered on the surface of the stepped spoil heap and vegetation is planted to form reclamation units; S5: Drainage holes are opened on the retaining walls of the cascade water storage units and the drainage holes are connected to the reclamation units so that the water stored in the cascade water storage units can be supplied to the reclamation units through the drainage holes.

[0025] Beneficial Effects: By setting the construction sequence of waste dump formation, drainage system construction, water storage unit construction, reclamation and restoration, and irrigation connection, the waste dumping and water and soil conservation system construction are organically integrated into a whole project. This allows the construction of water and soil conservation facilities to proceed simultaneously with the waste dumping process, avoiding repeated excavation, secondary disturbance, and project delays caused by large-scale structural modifications after waste dumping is completed. Specifically, by arranging the construction of the drainage unit before the construction of the cascade water storage unit, the drainage system can effectively guide surface runoff and slope runoff during the construction period even before the water storage unit is built. This ensures that the waste dump remains under controlled water and soil conservation throughout the entire construction cycle, preventing slope erosion and early-stage soil loss caused by disorderly scouring by rainfall runoff during construction. Furthermore, by scheduling the construction of the reclamation units before the opening of the drainage holes, the location, elevation, and number of drainage holes can be precisely matched and positioned according to the actual type of vegetation, root distribution, and spatial layout planted on site. This allows the water stored in the water storage unit to be supplied to the root zone of the vegetation in the corresponding elevation reclamation unit through the drainage holes. This avoids water waste and irrigation failure caused by misalignment of holes and vegetation, and the inability of irrigation water to effectively reach the target root zone due to opening holes before planting. Furthermore, by constructing a complete technological chain from water collection to water storage and then to precision irrigation, the cascade water storage unit is connected to the interception and drainage unit during the construction phase, and the reclamation unit obtains a stable irrigation water source through the drainage holes after planting vegetation. This allows the water storage unit to form a complete water cycle closed loop from the beginning of operation, storing water during the rainy season and replenishing it during the dry season. This avoids the industry pain points of traditional spoil heaps, such as the rapid drainage of water resources by the interception and drainage system, the lack of effective hydraulic connection between the water storage facilities and the reclamation unit, which leads to excessive water loss of the soil cover during the dry season, large-scale death of reclaimed vegetation due to water shortage, and continuously rising costs of replanting and maintenance. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a longitudinal cross-sectional schematic diagram of a soil and water conservation system for a karst spoil heap provided in an embodiment of the present invention. Figure 2 for Figure 1 A magnified view of part A in the middle; Figure 3 for Figure 1 A magnified view of part B in the middle section; Figure 4 A cross-sectional schematic diagram of a water and soil conservation system for a karst spoil heap provided in an embodiment of the present invention; Figure 5 for Figure 4 A magnified view of part C in the middle; Figure 6 This is a schematic diagram of the layout of a soil and water conservation system for a karst spoil heap provided in an embodiment of the present invention; Figure 7 A cross-sectional schematic diagram of a sinkhole treatment unit in a karst spoil heap water conservation system provided in an embodiment of the present invention; Figure 8 A schematic flowchart illustrating the construction method of a soil and water conservation system for a karst spoil heap provided in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 1. Stepped slag heap; 2. Karst depression; 201. Clay layer; 3. Interception and drainage unit; 301. Water collection trough; 302. Interception ditch; 303. Drainage side ditch; 304. Rapid flow channel; 4. Cascade water storage unit; 401. Retaining wall; 402. Drainage hole; 403. Overflow outlet; 404. Transition material layer; 405. Clay anti-seepage layer; 406. Transition material protective layer; 407. Rubble erosion protection layer; 408. Water body; 409. Mortar-grouted masonry; 5. Reclamation Unit; 501. Clay Cover Layer; 502. Vegetation Layer; 6. Sinkhole; 7. Overflow surface; 8. Sinkhole treatment unit; 801. Concrete arch; 802. Drainage pipe; 803. Geotextile. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments 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, 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.

[0030] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] According to embodiments of the present invention, on one hand, a water and soil conservation system for karst spoil heaps is provided, such as... Figures 1 to 7 As shown, it includes a stepped slag heap 1, a drainage unit 3, a cascade water storage unit 4, and a reclamation unit 5.

[0034] The stepped spoil heap 1 serves as the foundation of the entire system and is situated within the karst depression 2. It is a multi-tiered structure formed by layering and compacting engineering waste within the depression from bottom to top. The installation of this stepped spoil heap 1 not only solves the problem of disposing of large amounts of waste during construction but also levels the previously rugged and unusable karst depression 2, creating conditions for subsequent land resource utilization.

[0035] The interception and drainage unit 3 is set at the top of the slope, the various platforms and the foot of the slope of the stepped slag pile 1. Its core function is to systematically collect the upstream runoff of the slag yard, the runoff from the slope around the slag yard and the seepage inside the slope (slag pile), and to orderly collect the originally disorderly or rapidly flowing water, so as to prevent rainwater from eroding the slope of the slag pile. It is the primary link to ensure the stability of the slag yard and realize the recycling of water resources.

[0036] The cascade water storage unit 4 serves as the core water storage and regulation hub of the system. Multiple units are configured and located on different elevations of the stepped spoil heap 1. Each cascade water storage unit 4 is hydraulically connected to the intercepting and drainage unit 3, serving to receive and store surface runoff collected and transported by the intercepting and drainage unit 3. This stepped layout effectively transforms the rapid drainage of precious rainfall resources during the rainy season into efficient interception, significantly enhancing the water conservation capacity of the spoil heap in the karst region.

[0037] The reclamation unit 5 covers the surface of each step of the stepped slag heap 1 and is used for planting vegetation.

[0038] like Figure 4 As shown, specifically, reclamation unit 5 includes a clay cover layer 501 laid on the surface of the spoil heap and a vegetation layer 502 planted on the clay layer 501. This unit is the final carrier for realizing the ecological restoration of the spoil heap and the utilization of land resources.

[0039] like Figure 1 , Figure 4 and Figure 5 As shown, the retaining wall 401 of the cascade water storage unit 4, adjacent to the reclamation unit 5, is equipped with a drainage hole 402. This drainage hole 402 penetrates the retaining wall 401, with its inlet connected to the water body 408 inside the water storage unit, and its outlet extending above or inside the reclamation unit 5, thus connecting the cascade water storage unit 4 and the reclamation unit 5. During the dry season, the water body 408 stored in the higher or same-level water storage unit can flow by gravity through this drainage hole 402 to the reclamation unit 5 for precise irrigation of the vegetation.

[0040] By setting up a cascaded water storage unit 4 connected to the interception and drainage unit 3, the surface runoff that would otherwise be quickly drained away during the rainy season is effectively intercepted and stored inside the spoil heap. During the dry season, the water 408 stored in the water storage unit can be precisely replenished to the reclamation unit 5 through the drainage holes 402 on the retaining wall 401, effectively alleviating the problem of rapid water loss of the surface soil caused by seepage from the sinkholes 6 in karst areas, improving the overall water retention rate of the spoil heap, and realizing the cross-timescale allocation and efficient utilization of water resources.

[0041] Meanwhile, by utilizing the tiered water storage units 4 at different elevations of the stepped slag heap 1, combined with the drainage holes 402 set at different heights of the retaining wall 401, it is possible to carry out zoned and graded water supply according to the differentiated water demand characteristics of different areas and different vegetation within the reclamation unit 5, thereby constructing a graded and differentiated irrigation system and improving the efficiency of land resource utilization.

[0042] The specific implementation methods of each of the above units will be described in detail below.

[0043] Regarding the drainage unit 3, its specific structure is not strictly limited. Under the premise of meeting the basic functions of water collection and diversion, it can be one or more of the following combinations: masonry open ditch, cast-in-place concrete ditch, or ecological soil ditch.

[0044] Preferably, in order to balance durability, ease of construction and economy, the drainage unit 3 adopts a masonry structure combined with concrete plastering.

[0045] Specifically, such as Figure 1 and Figure 6 As shown, the interception and drainage unit 3 includes a water collection trough 301, a water interception ditch 302, a drainage side ditch 303, and a rapid flow trough 304.

[0046] The water collection channel 301 is located in the upstream water collection channel of the stepped slag heap 1, and its orientation is basically consistent with the flow direction of the channel. It is used to efficiently intercept and collect water from a large area upstream, such as slope runoff. The cross-sectional dimensions of the water collection channel 301 are calculated and determined based on the upstream catchment area and the design storm flood peak flow to ensure that its flow capacity meets the requirements.

[0047] Interception ditch 302 is located at the intersection of the stepped slag heap 1 and the surrounding karst depression 2, i.e., on the boundary line of the slag heap slope. Interception ditch 302 is arranged in a ring around the slag heap to precisely intercept water from the surrounding slope outside the slag heap area that may erode the slag heap slope, and guide it to a designated path to prevent it from overflowing into the slag heap surface.

[0048] The drainage ditch 303 is a key link connecting the intercepting ditch 302 to the downstream water storage unit or natural drainage channel. The drainage ditch 303 is connected to the bottom and / or middle of the intercepting ditch 302.

[0049] Specifically, a bottom drainage ditch 303 is provided at the bottom of the intercepting ditch 302. The end of the ditch is connected to the cascade water storage unit 4 or the drainage ditch 303 behind the retaining wall, which is used to transport water 408 to the water storage unit. A middle drainage ditch 303 is provided on the middle side wall of the intercepting ditch 302. The end of the ditch is connected to the natural sinkhole 6 on the bank slope, which is used to divert and discharge part of the middle layer water 408.

[0050] By setting the water collection trough 301 in the upstream water collection channel of the slag dump, the water coming from the upstream channel can be effectively intercepted. Then, by setting the intercepting ditch 302 at the intersection of the slag pile and the karst depression 2, the runoff from the surrounding slope of the slag dump can be accurately intercepted. This achieves comprehensive collection and aggregation of water bodies 408 from different sources and along different paths within the catchment area of ​​the slag dump, ensuring that precious water resources during the rainy season can be fully captured and introduced into the water storage unit, thus solving the problem of water waste caused by insufficient collection in traditional systems.

[0051] Meanwhile, by connecting the drainage ditch 303 to the bottom and / or middle of the intercepting ditch 302, the water bodies 408 of different water layers in the intercepting ditch 302 can be diverted in an orderly manner along different paths. That is, the bottom water body 408 can be preferentially introduced into the cascade water storage unit 4 through the bottom drainage ditch 303 for storage and irrigation during the dry season; while the middle water body 408 can be appropriately diverted through the middle drainage ditch 303 and the bank slope sinkhole 6 to avoid overloading of the water storage unit and achieve differentiated regulation of storage and diversion.

[0052] When the slope of the slag heap is steep and water flow is concentrated, a rapid flow channel 304 can be installed on the slope. The top of the rapid flow channel 304 connects to the upper intercepting ditch 302 or the platform drainage ditch, and the bottom connects to the lower intercepting ditch 302 or energy dissipation facilities. The rapid flow channel 304 is used to safely and quickly transport the slope runoff to the bottom of the slag heap, preventing high-speed water flow from eroding and damaging the slope cover and vegetation.

[0053] It can be noted that the specific structure of the water collection trough 301 in the above-mentioned drainage unit 3 is not strictly limited. It can be a masonry trough with a trapezoidal or rectangular cross section, a cast-in-place concrete trough, or a dry-laid stone trough.

[0054] Preferably, in order to balance erosion resistance and ease of construction, the drainage trough 301 is preferably constructed with masonry, and the bottom and sidewalls are finished with cement mortar.

[0055] Furthermore, the water collection trough 301 is located at the bottom of the natural drainage channel upstream of the stepped slag heap 1, and its orientation is arranged along the main flow direction of the channel. The longitudinal slope of the trough bottom is consistent with the bottom slope of the natural channel to ensure smooth water collection. The end of the water collection trough 301 is directly connected to the intercepting ditch 302 around the slag heap, so that the upstream water can smoothly enter the intercepting ditch 302 through the water collection trough 301, and then be distributed to the water storage unit or diversion unit by the intercepting ditch 302.

[0056] It can be noted that the specific location and structural form of the rapid flow channel 304 in the above-mentioned interception and drainage unit 3 are not strictly limited. It can be a stepped rapid flow channel, a concrete steep channel, or an ecological grass-planted rapid flow channel.

[0057] Preferably, to ensure drainage safety and energy dissipation effect on steep slope sections, the rapid flow channel 304 adopts a stepped structure.

[0058] Specifically, the rapid flow channel 304 is installed on the steep slope section of the stepped slag heap 1 where water collects in concentrated areas. It is used to safely and quickly transport the water 408 collected by the upper intercepting ditch 302 or platform drainage ditch to the bottom of the slag heap or the lower intercepting ditch 302. The top of the rapid flow channel 304 connects to the outlet of the upper intercepting ditch 302 or the platform drainage ditch 303, and the bottom connects to the lower intercepting ditch 302 or the stilling basin. The bottom of the rapid flow channel 304 is longitudinally arranged with multiple stilling sills along the slope, spaced apart from each other. This allows the high-speed water flow to continuously reduce its kinetic energy as it falls step by step, minimizing scouring and damage to the channel bottom and downstream structures.

[0059] The cascade water storage unit 4 is the core facility for realizing the spatial and temporal redistribution of water resources. Its specific structural form is not limited and can be an earthen water storage pond, a cofferdam water storage pool, or a reinforced concrete water storage pool, etc.

[0060] Preferably, in order to reduce costs and facilitate the use of local materials while ensuring seepage prevention performance, the cascade water storage unit 4 preferably adopts a soil-rock composite structure and is combined with retaining wall 401 for enclosure.

[0061] Specifically, each cascade water storage unit 4 mainly consists of three parts: basic treatment measures, water-retaining structure, and water-discharge structure.

[0062] Among them, such as Figure 1 and Figure 2 As shown, the basic treatment measures are set on the top of the stepped slag heap 1. Its structure includes, from bottom to top, a transition material layer 404, a clay impermeable layer 405, a transition material protective layer 406, and a rubble erosion protection layer 407 laid on the step surface of the stepped slag heap 1.

[0063] Specifically, a transition material layer 404 is first laid, which is directly located on the step surface of the slag heap and serves to level the base layer and provide reverse filtration protection. On top of the transition material layer 404, a clay impermeable layer 405 is laid. This clay layer 201 needs to be compacted to form a continuous and dense water barrier, which is the key to preventing water 408 from seeping into the water storage unit. On top of the clay impermeable layer 405, a transition material protective layer 406 is laid to protect the clay layer 201 from water erosion and external disturbance. Finally, a riprap anti-erosion layer 407 is laid on top of the transition material protective layer 406, which covers the bottom area of ​​the entire water storage unit.

[0064] By setting a clay impermeable layer 405 at the bottom of the cascade water storage unit 4 and laying it on top of the transition material layer 404, a continuous and dense water barrier is formed by compaction, cutting off the vertical seepage path of the water body 408 in the water storage unit to the bottom slag and karst channels, ensuring that the valuable water resources collected during the rainy season can be stored stably in the water storage unit for a long time, and providing a reliable water source guarantee for reclamation irrigation during the dry season.

[0065] Furthermore, by laying the lower transition material layer 404 between the step surface of the stepped slag body 1 and the bottom surface of the clay anti-seepage layer 405, it serves two purposes: firstly, as a leveling layer; and secondly, as a filter layer, to prevent fine particles of the lower slag body from entering the clay layer 201 under the action of seepage and causing structural damage.

[0066] The upper transition material protective layer 406 covers the top surface of the clay impermeable layer 405, effectively protecting the clay layer 201 from water erosion and external disturbances during subsequent construction and operation.

[0067] That is, a transition material layer 404 and a transition material protection layer 406 are respectively set on the upper and lower sides of the clay impermeable layer 405 to improve the service life and impermeability of the clay impermeable layer 405 and avoid the risk of water storage failure due to the damage of the impermeable layer.

[0068] Furthermore, by laying a riprap anti-erosion layer 407 on the top surface of the transition material protective layer 406 and covering the entire bottom area of ​​the water storage unit, it can effectively resist the scouring and erosion of the overflow water flow when participating in large-flow flood discharge as the main flood discharge channel, prevent the bottom structure from being hollowed out and damaged, and also provide a stable foundation bearing layer for the retaining wall 401, enhancing the anti-sliding and anti-overturning stability of the retaining wall 401.

[0069] It can be explained that in the basic treatment measures of the above-mentioned cascade water storage unit 4, the transition material layer 404 is made of well-graded crushed stone or gravel, which is compacted by a plate vibratory tamper after being laid; the clay anti-seepage layer 405 is made of clay stored in the topsoil storage yard or qualified clay purchased from outside, which is compacted in layers by a roller after being laid to meet the anti-seepage requirements; the material of the transition material protection layer 406 is the same as that of the lower transition material, which is used to protect the clay anti-seepage layer 405 from water flow erosion and external disturbance. The stones are tightly interlocked and the surface is basically flat to resist the erosion during large-flow flood discharge.

[0070] like Figures 1 to 6 As shown, the main water-retaining structure is retaining wall 401. This retaining wall 401 is located on the outer side of the water storage unit (i.e., the side closest to reclamation unit 5), and is constructed using masonry 409, possessing advantages such as high strength, strong erosion resistance, and good durability. The thickness and height of retaining wall 401 are determined based on calculations of the water storage depth and lateral earth pressure.

[0071] This design creates a well-defined functional zoning and hierarchically ordered bottom structure system for the water storage unit.

[0072] The drainage structure mainly includes the overflow meter hole 403 and the wall drainage hole 402.

[0073] Specifically, such as Figure 1 and Figure 3As shown, the overflow meter orifice 403 is located on the top of the downstream side retaining wall 401 of the water storage unit, and its width is determined according to the design flood discharge flow.

[0074] Furthermore, by providing an overflow meter hole 403 at the top of the retaining wall 401 of the cascade water storage unit 4, when the water storage unit is full or the inflow increases, the excess water can be safely discharged through the overflow meter hole 403 at the top of the retaining wall 401, so as to realize the graded treatment of runoff according to the amount, and take into account both water storage needs and system flood control safety.

[0075] Meanwhile, the arrangement of the drainage ditch 303 behind the retaining wall makes full use of the natural elevation difference between the intercepting ditch 302 and the water storage unit, so that the bottom water 408 of the intercepting ditch 302 can flow into the water storage unit by gravity without the need for any external power equipment, thus reducing the construction cost and operation and maintenance energy consumption of the system.

[0076] like Figure 1 , Figure 4 and Figure 5 As shown, the drainage holes 402 are multiple sets of through holes arranged in layers along the height direction of the retaining wall 401. Each set of drainage holes 402 is arranged at intervals along the length direction of the retaining wall 401. Any drainage hole 402 penetrates the wall body of the retaining wall 401. The water inlet end of the drainage hole 402 is connected to the internal water body 408 of the cascade water storage unit 4. The water outlet end of the drainage hole 402 extends to the side of the retaining wall 401 away from the cascade water storage unit 4 and is located above the reclamation unit 5. Each set of drainage holes 402 corresponds to a reclamation unit 5 at a different elevation.

[0077] By setting multiple sets of drainage holes 402 in layers along the height of the retaining wall 401, and making each set of drainage holes 402 correspond to a reclamation unit 5 at a different elevation, a three-dimensional irrigation network covering the steps of the slag heap is formed. This allows reclamation units 5 at different elevations to receive water supply independently. Operators can select to open the corresponding set of drainage holes 402 for targeted irrigation based on the type of vegetation, water requirements, and soil moisture in each reclamation unit 5, thereby achieving refined allocation and on-demand supply of water resources.

[0078] Meanwhile, each set of drainage holes 402 is arranged at intervals along the length of the retaining wall 401, so that the water outlet end forms a uniformly distributed array of water outlet points above the reclamation unit 5. When a set of drainage holes 402 is opened for irrigation, the water body 408 flows out synchronously from multiple points along the length of the retaining wall 401, uniformly covering the entire surface of the reclamation unit 5, avoiding the problem of concentrated water volume and uneven irrigation caused by single-point water outlet, achieving uniform irrigation, and improving the overall growth and survival rate of the reclaimed vegetation.

[0079] Furthermore, by connecting the inlet end of the drain hole 402 to the water body 408 inside the water storage unit, and extending the outlet end to the side of the retaining wall 401 away from the water storage unit and above the reclamation unit 5, the natural elevation difference between the water body 408 of the water storage unit and the reclamation unit 5 is fully utilized, so that irrigation water can flow into the reclamation unit 5 by gravity, without the need for additional power equipment such as water pumps, thus reducing operating costs and maintenance intensity.

[0080] In this embodiment, the cascade water storage unit 4 and the diversion unit work together to form a three-level gradient control system based on the automatic response of the incoming water flow rate.

[0081] Its specific regulatory pathways include: Behind the retaining wall 401 of the cascade water storage unit 4, there is a drainage ditch 303. The beginning of the drainage ditch 303 is connected to the bottom of the intercepting ditch 302, and the end is connected to the overflow meter hole 403.

[0082] Under low flow conditions, such as during the dry season or light rain, the sediment-laden water 408 at the bottom of the intercepting ditch 302, due to its small flow rate and low velocity, is preferentially introduced into the cascade water storage unit 4 through the drainage ditch 303 behind the retaining wall for storage.

[0083] By setting up a drainage ditch 303 behind the retaining wall 401, with its beginning connected to the bottom of the intercepting ditch 302 and its end connected to the overflow meter hole 403, the bottom water 408 collected by the intercepting ditch 302 can be preferentially guided into the water storage unit for storage under low flow conditions, thus establishing a low flow priority storage mechanism to solve the problem of water shortage in the dry season caused by the rapid drainage of water resources during the rainy season.

[0084] Under medium flow conditions, such as moderate to heavy rain, when the inflow exceeds the storage capacity of the water storage unit, the water level in the intercepting ditch 302 rises, and the middle layer water 408 is diverted and discharged through the bank slope drainage ditch 303 set in the middle of the intercepting ditch 302 into the natural sinkhole 6 on the bank slope of the slag yard.

[0085] This mechanism effectively prevents the middle water layer 408 from encroaching on the effective storage capacity of the water storage unit, ensuring that the water storage unit can maintain sufficient water storage space under small and medium flow conditions, and improving the system's adaptability to complex water inflow processes.

[0086] Meanwhile, the sinkholes 6 naturally distributed on the bank slope of the karst depression 2 are used as diversion outlets. Water 408 is directly introduced into the sinkholes 6 through the bank slope drainage ditch 303, restoring and utilizing the original natural drainage function of the karst depression 2. There is no need to set up a separate drainage tunnel or excavate a long drainage channel, which reduces the amount of concrete engineering and earthwork excavation, reduces the project cost and construction period, and realizes low-cost ecological drainage treatment.

[0087] Under high flow conditions, such as excessive rainfall, on the one hand, the upper water body 408 of the intercepting ditch 302 can naturally flow down to the downstream natural channel along the intercepting ditch 302; on the other hand, after the various levels of the cascade water storage units 4 are full, the excess floodwater overflows through the overflow surface hole 403 at the top of the retaining wall 401 and falls down step by step along the overflow surface 7 connecting the adjacent water storage units.

[0088] Overflow outlet 403 and overflow surface 7 together form the main flood discharge channel, ensuring that floodwaters exceeding the standard can be quickly and safely discharged away from the spoil heap. The two flood discharge paths work together, discharging floodwaters from the periphery of the spoil heap and the surface of the spoil body respectively, effectively avoiding the risk of overtopping or dam failure caused by insufficient flow capacity of a single flood discharge channel, and ensuring the structural safety and flood discharge stability of the spoil heap under extreme rainstorm conditions.

[0089] At the same time, by utilizing the natural topographical elevation difference between different elevations of the stepped slag heap 1, the floodwater discharged from the overflow orifice 403 falls step by step along the overflow surface 7, continuously reducing the kinetic energy of the water flow, effectively reducing the flow velocity and scouring force of the flood, and mitigating the impact damage to the slope and slope toe structure.

[0090] It can be noted that the specific structural form of the overflow surface 7 between adjacent cascade water storage units 4 is not strictly limited; it can be a mortar-grouted stone surface, a cast-in-place concrete surface, or a dry-laid stone surface.

[0091] Preferably, to balance erosion resistance and construction economy, the overflow surface 7 is preferably constructed using masonry.

[0092] Specifically, the overflow surface 7 is located between the upper and lower water storage units and is arranged along the slope of the slag pile. Its top end is connected to the overflow meter hole 403 at the top of the retaining wall 401 of the upper water storage unit, and its bottom end is connected to the internal space of the lower water storage unit or the top of the retaining wall 401.

[0093] In summary, the three-tiered gradient regulation mechanism—achieving water storage under low-flow conditions, diversion under medium-flow conditions, and flood discharge under high-flow conditions—forms an organic whole with the interception and drainage unit 3, the cascade water storage unit 4, and the diversion unit. The water storage unit balances water storage and low-flow regulation, while the natural sinkhole 6 balances medium-flow diversion and auxiliary discharge of floods exceeding standard levels. The two complement each other and work together, enabling the spoil heap water conservation system to automatically and efficiently switch to the corresponding working mode when facing different levels of rainfall, thus maximizing water resource utilization and ensuring the safety of system operation.

[0094] Reclamation Unit 5 is the final step in achieving ecological restoration of the spoil heap. There are no specific restrictions on the types of crops planted there; selection can be based on local climate, soil conditions, and market demand.

[0095] Preferably, in order to build a stable and efficient ecosystem and enhance economic value, reclamation unit 5 preferably adopts a three-dimensional planting model with irrigation above and crops below.

[0096] Among them, such as Figure 1 , Figure 4 and Figure 6 As shown, reclamation unit 5 includes a clay cover layer 501 and a vegetation layer 502. The clay cover layer 501 covers the surface of each step of the stepped slag heap 1; the vegetation layer 502 is planted on the clay cover layer 501; the outlet of the drainage hole 402 is located above the clay cover layer 501 at the corresponding elevation, and the water 408 discharged from the drainage hole 402 flows over the surface of the clay cover layer 501 or is transported to the root area of ​​the vegetation layer 502 through irrigation pipes.

[0097] A clay cover layer 501 is set on each step surface of the stepped slag heap 1 as the foundation of the reclamation unit 5. The clay has fine particles and low permeability coefficient, which can effectively absorb and retain a large amount of water in the root distribution layer after rainfall or irrigation, significantly slowing down the rate of vertical infiltration and evaporation of water.

[0098] Meanwhile, the outlet of the drainage hole 402 is located above the clay cover layer 501, so that the water body 408 supplied by the water storage unit first wets the surface of the clay cover layer 501 and then slowly seeps down to the root area of ​​the vegetation, which improves the natural defect that the surface soil of the karst spoil heap cannot retain water, increases the survival rate of the reclaimed vegetation and reduces the cost of later maintenance.

[0099] Among them, the slag heap platforms located at the upper elevation, due to stronger winds and relatively poor irrigation conditions, can be prioritized for planting drought-resistant shrubs and herbaceous plants with strong soil-fixing capabilities to form an ecological protective barrier. The slag heap platforms located at the middle and lower elevations, with relatively gentle terrain and better soil and water conditions, can be planted with regional economic crops such as tobacco, corn, and forage grass, realizing the resource utilization of land and economic output.

[0100] It should be noted that there are no strict restrictions on the types of vegetation to be planted on different elevation platforms; the choice can be made based on local climate conditions, soil characteristics, and market demand.

[0101] Preferably, in order to maximize land resource utilization efficiency and reduce management costs, reclamation unit 5 adopts a graded differentiated planting model.

[0102] Specifically, the slag yard platform located at the upper elevation usually consists of the top of the slag yard and two steps above it. Due to the high wind speed and relatively difficult access to irrigation water, drought-resistant and barren-tolerant shrubs and herbaceous plants, such as Amorpha fruticosa, Lespedeza bicolor, and Vetiver, are given priority for planting to form an ecological protection barrier and play a role in soil stabilization and slope protection.

[0103] The slag heap platform, located at a mid-elevation level, typically has two to three steps in the middle with relatively good soil and water conditions. Irrigation water can be easily obtained through the drainage holes 402 of the retaining wall 401. Priority should be given to planting shrubby cash crops with high economic value, such as Sichuan pepper, wolfberry, and camellia.

[0104] The slag heap platform, located at a lower elevation, typically consists of one or two steps at the bottom. It is flat, has the highest water supply security, and is the preferred location for planting crops such as corn, tobacco, and pasture.

[0105] Since the spoil heap is built directly on the karst depression 2, it inevitably faces the major safety hazard of the sinkhole 6 at the bottom. Therefore, a sinkhole treatment unit 8 is specially set up at the entrance of the sinkhole 6 at the bottom of the karst depression 2.

[0106] It can be noted that the specific structure of the sinkhole treatment unit 8 is not strictly limited, as long as it can bear the load of the slag heap and drain the internal seepage water.

[0107] Preferably, such as Figure 1 and Figure 7 As shown, the sinkhole treatment unit 8 is mainly reinforced with a concrete arch 801 structure.

[0108] Specifically, the sinkhole treatment unit 8 includes a concrete arch 801, a drainage pipe 802, and a geotextile 803.

[0109] The concrete arch 801 is an arched structure. Its two ends are situated on the bedrock outside the entrance of the sinkhole 6, spanning above the entrance. In this way, the concrete arch 801 can bear the enormous load of the slag heap 1 transmitted from the bottom of the upper step. Utilizing the excellent load-bearing characteristics of the arch structure, it transforms the vertical load into a horizontal thrust on the bedrock on both sides, effectively traversing the weak, hollow area of ​​the sinkhole 6 and preventing the slag heap load from directly acting on the unstable rock mass at the top of the sinkhole.

[0110] Furthermore, the concrete arch 801 is made of cast-in-place plain concrete or reinforced concrete of grade C25 or above. Before the concrete arch 801 is poured, the bedrock outside the entrance of the sinkhole 6 should be cleaned and roughened to ensure that the arch foot is in close contact with the bedrock. If necessary, shallow grooves or steps should be set at the arch foot to enhance the anti-slip stability of the arch.

[0111] The drainage pipe 802 is a pre-embedded pipe fitting, embedded in the arch body of the concrete arch 801, and runs vertically through the upper and lower sides of the concrete arch 801. The upper inlet of the drainage pipe 802 is located on the top surface of the concrete arch 801 and is adjacent to the bottom of the slag heap of the stepped slag heap 1. The lower outlet of the drainage pipe 802 is located on the bottom surface of the concrete arch 801 and is connected to the internal space of the downhole 6. The drainage pipe 802 is used to orderly and controllably guide the seepage water formed inside the slag heap due to rainfall infiltration or groundwater rise into the downhole 6 below, so as to prevent the slag heap from being reduced in strength or damaged by seepage due to water immersion above the downhole 6.

[0112] Furthermore, the drainage pipe 802 uses PVC pipes or steel pipes with diameters ranging from DN100 to DN300, which are embedded in the arch body of the concrete arch 801. The positioning and fixing of the pipes are completed before the concrete is poured. The pipes are set vertically, and their center lines are basically coincident with the center lines of the downhole 6. The number of drainage pipes 802 is determined according to the flow capacity of the downhole 6 and the seepage volume inside the slag heap, and they are evenly distributed in the mid-span area of ​​the arch body.

[0113] Geotextile 803 covers the upper inlet of drainage pipe 802 and is laid on the top surface of concrete arch 801 around the inlet of drainage pipe 802. Geotextile 803 forms a water-permeable and particle-blocking filter interface between the inlet of drainage pipe 802 and the slag heap, allowing water inside the slag heap to pass smoothly through geotextile 803 into drainage pipe 802, while effectively intercepting fine particulate materials in water body 408 to prevent them from entering drainage pipe 802 and causing blockage.

[0114] Furthermore, the geotextile 803 is made of non-woven geotextile 803 to ensure good water permeability and particle barrier performance. The geotextile 803 is laid at the upper inlet of the drainage pipe 802 and extends to the top surface of the concrete arch 801 around the inlet of the drainage pipe 802. It is fixed with U-shaped nails or pressure strips to prevent the geotextile 803 from shifting or being damaged during the backfilling process.

[0115] A concrete arch 801 is installed at the entrance of sinkhole 6, so that the two ends of the arch are stably placed on the bedrock outside the entrance. Utilizing the excellent stress characteristics of the arch structure, the vertical load transmitted from the bottom of the slag heap 1 is transformed into horizontal thrust and compressive stress on the bedrock on both sides through the arch. This effectively crosses the weak cavity area of ​​sinkhole 6, avoids the slag heap load from acting directly on the unstable rock mass at the top of the tunnel, and ensures the long-term bearing safety and overall stability of the bottom structure of the slag heap.

[0116] Furthermore, by embedding drainage pipes 802 that run vertically through the upper and lower sides of the concrete arch 801, the upper inlet of the drainage pipes 802 is adjacent to the bottom of the slag heap, and the lower outlet is connected to the internal space of the sinkhole 6. This maintains an orderly and controllable discharge path inside the slag heap, which not only prevents the slag heap from weakening or being damaged by seepage due to water accumulation above the sinkhole 6, but also avoids the risk of secondary geological disasters caused by a complete disruption of the overall drainage pattern of the area after the sinkhole 6 is completely sealed. This achieves the safety management goal of predictable, controllable, and dredging water seepage inside the slag heap.

[0117] Furthermore, by covering the upper inlet of the drainage pipe 802 with geotextile 803 and laying it on the arched surface around the inlet of the drainage pipe 802, the geotextile 803 forms a water-permeable and particle-blocking filter interface between the inlet of the drainage pipe 802 and the slag heap. This allows water to pass through smoothly while effectively intercepting fine particles, ensuring that the drainage pipe 802 maintains a smooth flow state for a long time. This effectively extends the service life of the sinkhole treatment unit 8, reduces the frequency and cost of later maintenance and dredging, and avoids the potential ecological risks of fine particles being lost in large quantities along the sinkhole 6, leading to instability of the internal structure of the slag heap or blockage of karst pipes.

[0118] That is, by using the combination of concrete arch 801 for structural reinforcement, drainage pipe 802 for drainage and seepage control, and geotextile 803 for reverse filtration, the sinkhole 6 achieves the dual functions of slag bearing and orderly drainage in situ, preserving the natural sinkhole drainage pattern of karst depression 2 and avoiding the damage to the regional hydrological environment caused by large-scale blocking and modification.

[0119] According to an embodiment of the present invention, another aspect provides a construction method for a soil and water conservation system for a karst spoil heap, which organically integrates spoil heap storage with the construction of a soil and water conservation system and adopts a step-by-step collaborative implementation strategy.

[0120] Specifically, such as Figure 8 As shown, it includes the following steps: S1: Waste slag is piled up in layers from bottom to top in the karst depression 2, and after being compacted, it forms a stepped slag body 1 with multiple steps.

[0121] During the filling process, the thickness of each layer of waste is controlled within the design requirements, and vibratory compaction equipment is used to fully compact it until the design density requirements are met. The number of steps, height, and platform width are determined comprehensively based on the topographic conditions of karst depression 2, the total amount of waste, and the layout requirements of subsequent water storage units and reclamation units 5.

[0122] S2: Construct drainage interception units 3 at the top of the slope, at each level of the platform and at the bottom of the slope of the stepped slag heap 1, to collect upstream runoff, slope surface runoff and seepage water inside the slope.

[0123] During construction, a catchment channel 301 was first excavated in the upstream drainage channel of the slag heap. A intercepting ditch 302 was then excavated along contour lines at the intersection of the slag heap and the surrounding mountains. Drainage side ditches 303 were then installed on the inner sides of each level of platform, based on the slope's water catchment conditions. The cross-sectional dimensions of the intercepting and drainage ditches were determined based on the design stormwater peak flow to ensure their flow capacity met requirements. The ditches were constructed using mortar-grouted masonry 409, with the bottom and sidewalls finished with cement mortar to enhance erosion resistance and seepage prevention.

[0124] S3: Construct cascade water storage units 4 on each step surface of the slag heap 1, and connect the cascade water storage units 4 with the drainage interception unit 3 so that the water 408 collected by the drainage interception unit 3 can enter the cascade water storage units 4 for storage.

[0125] The foundation treatment measures for the cascade water storage unit 4 were carried out simultaneously with the construction of the retaining wall 401. First, the foundation was excavated on each step surface, and from bottom to top, a transition material layer 404, a clay impermeable layer 405, a transition material protective layer 406, and a rubble erosion protection layer 407 were laid. Each layer was compacted after laying to ensure a dense and stable structure. Subsequently, a masonry retaining wall 401 was constructed on the outside of the water storage unit. The height and thickness of the retaining wall 401 were determined based on calculations of the water storage depth and lateral pressure. The location and width of an overflow orifice 403 were pre-reserved at the top of the retaining wall 401 to ensure it matched the designed flood discharge capacity. During the foundation treatment and retaining wall 401 construction, the end of the drainage ditch 303 was simultaneously connected to the water storage unit to ensure effective hydraulic connection between the drainage system and the water storage system.

[0126] S4: Cover the surface of the stepped slag heap 1 with reclamation substrate and plant vegetation to form reclamation unit 5.

[0127] The thickness of the reclamation substrate is determined based on the vegetation type and root depth requirements. After the substrate is covered, appropriate plant species are planted on the terraces at different elevations according to the planning scheme. The upper elevation platforms are mainly planted with shrubs and herbaceous plants, while the middle and lower elevation platforms are mainly planted with cash crops, forming a differentiated three-dimensional reclamation model.

[0128] S5: A drainage hole 402 is opened on the retaining wall 401 of the cascade water storage unit 4, and the drainage hole 402 is connected to the reclamation unit 5 so that the water 408 stored in the cascade water storage unit 4 can be supplied to the reclamation unit 5 through the drainage hole 402.

[0129] The location and number of drainage holes 402 are determined based on the type, distribution, and water requirements of the plants planted within the reclamation unit 5. The drainage holes 402 are arranged in layers along the height of the retaining wall 401, with each group of drainage holes 402 spaced apart along the length of the retaining wall 401. Drilling or pre-drilling methods are used to ensure that the holes penetrate the wall and have a consistent diameter. The outlet end is located above the corresponding elevation of the reclamation unit 5, allowing irrigation water to flow by gravity to the root zone of the vegetation.

[0130] By setting the construction sequence of waste stockpile formation, drainage system construction, water storage unit construction, reclamation and restoration, and irrigation connection, the waste stockpile and water and soil conservation system construction are organically integrated into a whole project. This allows the construction of water and soil conservation facilities to proceed simultaneously with the waste stockpile process, avoiding repeated excavation, secondary disturbance, and construction delays caused by large-scale structural modifications after the waste stockpile is completed.

[0131] By arranging the construction of the interception and drainage unit 3 before the construction of the cascade water storage unit 4, the interception and drainage system can play an orderly guiding role in surface runoff and slope water in the construction period before the water storage unit is built. This ensures that the spoil disposal site is always in a controlled state of soil and water conservation throughout the entire construction period, avoiding the problems of spoil slope erosion and early soil and water loss caused by disorderly scouring of rainwater runoff during the construction process.

[0132] Furthermore, by arranging the construction of reclamation unit 5 before the opening of drainage holes 402, the location, elevation, and number of drainage holes 402 can be precisely matched and positioned according to the actual type of vegetation, root distribution, and spatial layout planted on site. This allows the water stored in the water storage unit 408 to be supplied to the root zone of the vegetation in the corresponding elevation reclamation unit 5 through drainage holes 402. This avoids water waste and irrigation failure caused by misalignment of holes and vegetation, and the inability of irrigation water to effectively reach the target root zone due to opening holes before planting.

[0133] Furthermore, by constructing a complete technical chain from water collection to water storage and then to precision irrigation, since the cascade water storage unit 4 is connected to the interception and drainage unit 3 during the construction phase, and the reclamation unit 5 obtains a stable irrigation water source through the drainage hole 402 after planting vegetation, the water storage unit forms a complete water cycle closed loop of rainy season storage and dry season replenishment at the beginning of operation. This avoids the industry pain points of traditional spoil heaps, such as the rapid drainage of water resources by the interception and drainage system, the lack of effective hydraulic connection between the water storage facilities and the reclamation unit 5, which leads to excessive water loss of the soil cover in the dry season, large-scale death of reclaimed vegetation due to water shortage, and the continuous increase in the cost of replanting and maintenance.

[0134] It can be noted that, in the above construction method, before step S1, there are also steps of pre-treatment of karst depression 2 and treatment of sinkhole 6.

[0135] Specifically, before the waste dumping, the surface of the karst depression 2 to be dumped was thoroughly cleared, the original clay layer 201 at the bottom of the depression was removed, and it was stored in the adjacent topsoil storage site for later reclamation and backfilling.

[0136] Meanwhile, a detailed investigation was conducted on sinkhole 6 within karst depression 2, and its location, size, and flow capacity were recorded.

[0137] Subsequently, the construction of the treatment structure for sinkhole 6 was completed: the two ends of the concrete arch 801 were placed on the intact bedrock outside the entrance of sinkhole 6, so that the arch spanned above the entrance; drainage pipes 802 were pre-embedded and fixed in the concrete arch 801, so that the drainage pipes 802 ran vertically through the upper and lower sides of the arch; geotextile 803 was covered at the upper inlet of the drainage pipe 802, and the geotextile 803 was laid on the top surface of the concrete arch 801 around the inlet of the drainage pipe 802.

[0138] The treatment structure of the sinkhole 6 was completed before the waste disposal in step S1, which allowed the subsequent waste disposal work to be carried out on a safe and stable basis.

[0139] It can be noted that, in the above construction methods, the excavation and stockpiling of the clay at the bottom of the karst depression 2 has specific technological requirements.

[0140] Specifically, before constructing the sinkhole 6 treatment structure, the surface of the karst depression 2 to be filled was first cleared, removing surface vegetation, humus and debris.

[0141] Subsequently, the natural clay layer 201 accumulated at the bottom of the karst depression 2 is excavated. The excavation depth is determined according to the actual thickness of the clay layer 201 until stable bedrock is exposed or the construction requirements of the foundation structure of the sinkhole 6 are met.

[0142] Excavated clay must not be discarded or randomly piled up, but should be centrally stored in a nearby topsoil storage area. The selection of the topsoil storage area should follow the principle of proximity, and the site should have drainage conditions to prevent the stored clay from being washed away during the rainy season. The stored clay should be covered with dustproof netting to reduce wind and water erosion losses. This portion of clay can be used as reclamation substrate soil or as clay impermeable layer 405 material in the later construction of reclamation unit 5, realizing the recycling of valuable topsoil resources.

[0143] It should be noted that the above construction method also includes the construction steps of the diversion unit.

[0144] Specifically, after the main construction of the interception and drainage unit 3 and the cascade water storage unit 4 is completed, the drainage ditch 303 behind the retaining wall and the drainage ditch 303 on the bank slope also need to be constructed.

[0145] The beginning of the drainage ditch 303 behind the retaining wall is connected to the bottom of the intercepting ditch 302, and the end is connected to the overflow meter hole 403 at the top of the retaining wall 401 of the water storage unit. It is used to introduce the bottom water 408 of the intercepting ditch 302 into the cascade water storage unit 4 for storage under low flow conditions.

[0146] The beginning of the bank slope drainage ditch 303 is connected to the middle of the intercepting ditch 302, and the end is connected to the natural sinkhole 6 on the bank slope of the slag yard. It is used to divert the water 408 in the middle layer of the intercepting ditch 302 into the sinkhole 6 for diversion and discharge under medium flow conditions.

[0147] There is a height difference between the bottom elevation of the drainage ditch 303 behind the retaining wall and the drainage ditch 303 on the bank slope, so as to ensure the stratified scheduling of water body 408 under different water level conditions.

[0148] It can be noted that the timing of opening the drain hole 402 in step S5 of the above construction method has specific technical considerations.

[0149] The drainage holes 402 should be opened after the vegetation planting in reclamation unit 5 is completed, rather than being pre-reserved during the construction of retaining wall 401. After the vegetation planting is completed, the opening position and number of drainage holes 402 at each elevation should be accurately determined according to the actual type of vegetation planted on site, the distribution range of the root system, and the spatial layout. This ensures that the water outlet can effectively connect with the root area of ​​the corresponding vegetation in reclamation unit 5, thereby avoiding the problem of misalignment between the hole position and the vegetation root system and the inability of irrigation water to effectively reach the target area due to opening the holes before planting.

[0150] It can be noted that the above construction method includes a system commissioning and operation management step after step S5.

[0151] Specifically, after the water storage unit is built and stores water, the opening and closing status of the drainage holes 402 at different elevations on the retaining wall 401 is adjusted according to the rainfall and the actual water demand of the reclamation unit 5.

[0152] During non-flood seasons or dry seasons, the corresponding set of drainage holes 402 are opened to allow the water stored in the water storage unit 408 to flow by gravity to irrigate the reclamation unit 5; during the rainy season or when the water level in the water storage unit is too high, the opening of the drainage holes 402 is closed or reduced, and flood discharge safety is ensured by prioritizing the overflow surface hole 403 and the overflow surface 7.

[0153] Through the above-mentioned debugging and operation management, the goal of water and soil conservation in all seasons and under all working conditions can be achieved, including water storage during the rainy season, irrigation during the dry season, small-scale water storage, medium-scale water diversion, and large-scale water discharge.

[0154] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A water and soil conservation system for spoil heaps in karst areas, characterized in that, include: A stepped slag heap (1) is set in a karst depression (2); Interception and drainage unit (3) is set at the top of the slope, the platform at each level and the foot of the slope of the stepped slag heap (1) to collect upstream runoff, slope runoff and seepage inside the slope. A tiered water storage unit (4) is set on the step surface of the stepped slag heap (1) at different elevations and is connected to the intercepting and drainage unit (3) for receiving and storing the water (408) collected by the intercepting and drainage unit (3). The reclamation unit (5) is covered on the surface of the stepped slag heap (1) and used for planting vegetation; The cascade water storage unit (4) has a drain hole (402) on the retaining wall (401) on the side of the reclamation unit (5), and the drain hole (402) connects the cascade water storage unit (4) and the reclamation unit (5).

2. The water and soil conservation system for karst spoil heaps according to claim 1, characterized in that, The drainage unit (3) includes: A water collection trough (301) is provided in the upstream water collection channel of the stepped slag heap (1) for collecting upstream water. Interception ditch (302) is set at the intersection of the stepped slag heap (1) and the karst depression (2) to intercept water coming from the surrounding area of ​​the slag heap; A drainage ditch (303) is connected to the bottom and / or middle of the intercepting ditch (302) for conveying the water (408) collected by the intercepting ditch (302) downstream.

3. The water and soil conservation system for karst spoil heaps according to claim 2, characterized in that, The top of the retaining wall (401) of the stepped water storage unit (4) is provided with an overflow meter hole (403), and a retaining wall drainage ditch (303) is provided behind the retaining wall (401) of the stepped water storage unit (4). The beginning of the retaining wall drainage ditch (303) is connected to the bottom of the intercepting ditch (302), and the end is connected to the overflow meter hole (403). Under low flow conditions, the bottom water (408) of the intercepting ditch (302) is introduced into the cascade water storage unit (4) through the drainage ditch (303) behind the retaining wall for storage.

4. The water and soil conservation system for karst spoil heaps according to claim 3, characterized in that, The slope side of the stepped slag heap (1) is provided with sinkholes (6), and the middle part of the intercepting ditch (302) is connected to the sinkholes (6) on the slope side through the slope drainage ditch (303). Under medium flow conditions, the intermediate water (408) collected by the intercepting ditch (302) is diverted and discharged into the sinkhole (6) on the bank slope through the bank slope drainage ditch (303).

5. The water and soil conservation system for karst spoil heaps according to claim 4, characterized in that, Under high flow conditions, the upper water body (408) of the intercepting ditch (302) is naturally discharged into the downstream natural channel through the intercepting ditch (302), and the overflow surface (403) of each stage of the cascade water storage unit (4) and the overflow surface (7) connecting the adjacent cascade water storage units (4) serve as the main flood discharge channel.

6. The water and soil conservation system for karst spoil heaps according to any one of claims 1-4, characterized in that, The cascade water storage unit (4) includes a transition material layer (404), a clay impermeable layer (405), a transition material protective layer (406), and a boulders erosion control layer (407) laid sequentially from bottom to top on the step surface of the stepped slag heap (1). The transition material layer (404) is laid between the step surface of the stepped slag heap (1) and the bottom surface of the clay impermeable layer (405). The boulders erosion control layer (407) is laid on the top surface of the transition material protective layer (406) and covers the entire bottom area of ​​the cascade water storage unit (4). The retaining wall (401) of the cascade water storage unit (4) is located above the riprap layer (407).

7. The water and soil conservation system for karst spoil heaps according to any one of claims 1-4, characterized in that, The drainage holes (402) are multiple sets of through holes arranged in layers along the height direction of the retaining wall (401). Each set of drainage holes (402) is arranged at intervals along the length direction of the retaining wall (401). Any drainage hole (402) penetrates the wall body of the retaining wall (401). The water inlet end of the drainage hole (402) is connected to the internal water body (408) of the cascade water storage unit (4). The water outlet end of the drainage hole (402) extends to the side of the retaining wall (401) away from the cascade water storage unit (4) and is located above the reclamation unit (5). Each set of drainage holes (402) corresponds to the reclamation unit (5) at different elevations.

8. The water and soil conservation system for karst spoil heaps according to any one of claims 1-4, characterized in that, The reclamation unit (5) includes: A clay cover layer (501) is applied to each step surface of the stepped slag heap (1); A vegetation layer (502) is planted on the clay cover layer (501); The outlet of the drainage hole (402) is located above the clay cover layer (501) at the corresponding elevation. The water (408) discharged from the drainage hole (402) flows over the surface of the clay cover layer (501) or is transported to the root area of ​​the vegetation layer (502) through irrigation pipes.

9. The water and soil conservation system for karst spoil heaps according to any one of claims 1-4, characterized in that, It also includes a sinkhole treatment unit (8), which is located at the entrance of the sinkhole (6) at the bottom of the karst depression (2). The sinkhole treatment unit (8) includes: The concrete arch (801) is an arch-shaped structure. The two ends of the concrete arch (801) are respectively located on the bedrock outside the opening of the sinkhole (6). The concrete arch (801) spans above the opening of the sinkhole (6) and is used to bear the load of the slag at the bottom of the stepped slag body (1) and transfer the load to the bedrock on both sides. Drainage pipe (802) is embedded in the arch body of the concrete arch (801) and runs vertically through the upper and lower sides of the concrete arch (801). The upper inlet of the drainage pipe (802) is located on the top surface of the concrete arch (801) and is adjacent to the bottom slag heap of the stepped slag heap (1). The lower outlet of the drainage pipe (802) is located on the bottom surface of the concrete arch (801) and is connected to the internal space of the drain hole (6). It is used to guide the seepage water inside the stepped slag heap (1) into the drain hole (6). Geotextile (803) is used to cover the upper inlet of the drainage pipe (802) and to lay on the top surface of the concrete arch (801) around the inlet of the drainage pipe (802) to filter fine particulate materials in the seepage water inside the stepped slag body (1) and prevent fine particles from entering the drainage pipe (802) and causing blockage.

10. A construction method for a soil and water conservation system for a karst spoil heap, applicable to the soil and water conservation system for a karst spoil heap as described in any one of claims 1-9, characterized in that, Includes the following steps: S1: In the karst depression (2), waste slag is piled up in layers from bottom to top, and after being compacted, it forms a stepped slag body (1) with multiple steps. S2: Construct drainage units (3) at the top of the slope, at each level of the platform and at the bottom of the slope of the stepped slag pile (1) to collect upstream runoff, slope surface runoff and seepage inside the slope. S3: Construct a tiered water storage unit (4) on each step surface of the stepped slag pile (1), and connect the tiered water storage unit (4) with the intercepting drainage unit (3) so that the water body (408) collected by the intercepting drainage unit (3) can enter the tiered water storage unit (4) for storage. S4: Cover the surface of the stepped slag heap (1) with reclamation substrate and plant vegetation to form a reclamation unit (5). S5: Open a drainage hole (402) on the retaining wall (401) of the cascade water storage unit (4) and connect the drainage hole (402) with the reclamation unit (5) so that the water (408) stored in the cascade water storage unit (4) can be supplied to the reclamation unit (5) through the drainage hole (402).

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