A method for identifying a gap repair of a spent mine pit reservoir

Abstract

The application discloses a method for identifying and repairing gaps of abandoned mine reservoirs, and belongs to the technical field of mine ecological restoration. The technical problem to be solved is that the existing abandoned mine reservoir evaluation mainly adopts a static scoring mode, which cannot identify the safe and suitable domain under different water levels, and is difficult to determine the repairability of the constraint gap and the corresponding minimum engineering correction amount. The technical solution points are to obtain multi-dimensional basic data of the mine body, nature and society, set a virtual water storage loading sequence and multiple operation evaluation scenarios, establish a six-class rigid constraint set to calculate the relative constraint gap, construct a suitable water level envelope to identify the critical water level and the dominant gap, distinguish the repairable and non-repairable gaps, and then establish an engineering correction variable set, and finally output the reservoir construction suitability result by comparing the minimum correction amount and the counterfactual net benefit.

Description

Technical Field

[0001] This invention belongs to the field of mine ecological restoration technology, specifically relating to a method for identifying and repairing gaps in abandoned mine reservoirs. Background Technology

[0002] Mineral resource development provides crucial support for energy, industrial raw materials, and urban and rural construction. However, the closure of open-pit mines often leaves behind numerous abandoned mine pits. These pits typically feature steep walls, broken steps, enclosed or semi-enclosed basins, well-developed rock fissures, complex groundwater connections, concentrated rainwater runoff, and limited land use in the surrounding areas. Prolonged idleness can easily lead to land resource waste, fragmented landscapes, slope instability, ground subsidence, water pollution, dust pollution, and increased safety and protection costs. With the advancement of mine ecological restoration, comprehensive land use management, water resource security, and the dual-carbon strategy, abandoned mine pits are gradually transforming from simple objects awaiting reclamation into spatial resources that can be used for water resource regulation, ecological restoration, renewable energy, industrial heritage tourism, and public safety.

[0003] Among various reuse models, constructing reservoirs, water storage ponds, or mine lakes using the negative topography of existing mine pits has strong engineering appeal. Mine pits already form a certain reservoir basin space; if their slope stability, basin seepage prevention, water supply, water quality safety, flood control, and ecological space conditions meet the requirements, it can reduce some of the costs associated with land acquisition, resettlement, earthwork excavation, and reservoir formation. It may also generate multiple benefits such as water supply, irrigation, emergency backup water sources, flood control and retention, ecological restoration, landscape creation, and regional industrial development. In public engineering practice, some quarry pits have been transformed into reservoirs, lakes, or water storage projects, and some large mine pits have also been incorporated into pumped storage, combined water storage, or landscape ecological restoration schemes.

[0004] However, mine pit reservoirs are not simply a replacement for traditional valley reservoirs. The slope height, angle, weak interlayers, mining disturbance, unloading fissures, seepage channels, catchment boundaries, and water quality evolution of open-pit mines often exhibit significant heterogeneity and historical disturbance characteristics. After impoundment, water level rises, sudden drops, flooding, and long-term immersion will alter pore water pressure, soil and rock strength, and seepage boundaries; reservoir basin fissures, mining disturbances, and karst caves may cause leakage; and mine pit water bodies may also be affected by factors such as acidification, heavy metals, suspended solids, salinity, or nutrients. Therefore, before converting abandoned mine pits into reservoirs, the impoundability, safe impoundment height, engineering modification needs, the rationality of modification costs, and the comprehensive advantages of the reservoir construction plan compared to other reuse schemes should be simultaneously assessed.

[0005] Publicly published research has covered various aspects of mine lake utilization, risk assessment, pumped storage, mine ecological restoration, groundwater exchange, water quality evolution, slope stability, and comprehensive benefit evaluation. (Literature) This paper systematically reviews the beneficial uses of abandoned mine pit lakes, pointing out that they can be used for recreation, nature conservation, fisheries and aquaculture, drinking water or industrial water storage, greenhouse gas sequestration, flood control, waterway restoration, mine water treatment, and educational research. It also emphasizes that water quality, slope stability, and safety risks are crucial conditions for achieving these beneficial uses. The literature "A framework for assessing hazards related to topit lakes: application on European case studies" proposes a risk assessment framework for mining and natural disasters in mine pit lakes, incorporating potential ground movement, water pollution, and fire hazards into long-term stability assessments. These studies demonstrate that the utilization of mine pit water bodies has multifunctional value, but its realization hinges on a systematic evaluation of safety, water quality, and long-term risks.

[0006] Regarding the selection of reuse models for abandoned open-pit mines, existing literature employs methods such as GIS, multi-criteria decision-making, analytic hierarchy process (AHP), fuzzy comprehensive evaluation, inference rules, cost-benefit analysis, or ecosystem service value assessment to compare and select options for park development, tourism development, reclamation, photovoltaic power generation, pumped storage, and water utilization. While such studies can provide a basis for initial model screening and macro-level decision-making, most remain at the level of model matching or comprehensive scoring. They typically fail to directly link engineering physical processes such as water level loading, slope stability, reservoir leakage, water balance, and flood control with engineering corrections, and are also insufficient to determine whether mines with unmet current conditions can achieve reservoir construction conditions through limited engineering measures.

[0007] Regarding existing patents, the following aspects are considered: suitability, evaluation, minimum engineering correction, inversion, and... A public patent search using keywords such as "public patents" reveals that existing technologies are generally concentrated in the following five categories.

[0008] (1) Construction methods for direct modification or reclamation of mine pits; for example, the published patent CN106988320A, "Reclamation Method for Converting Abandoned Mine Pit into Reservoirs, Ponds and Pools in Limestone Mines", proposes to determine the weir crest elevation, spillway, water storage capacity, and slope step height, width and number of steps based on the terrain, and to carry out slope trimming, smooth blasting, detection and sealing of karst cave entrances, sealing of the pit inner wall and vegetation arrangement. This scheme belongs to the construction technology for reclamation of reservoirs, ponds and pools. Its contribution is to provide an engineering treatment path for the water storage space of limestone mine pits, but it does not establish the constraint response envelope under multiple water level loading conditions, nor does it invert the minimum engineering correction amount based on the constraint gap.

[0009] (2) Technologies for the combined use of pit bottom reservoirs, pumped storage, or open-pit mine space; for example, the published patent CN110409360A and its authorized text CN110409360B, "A Phased Construction Method for Pit Bottom Reservoirs Based on Intermediate Bridges in Inner-Drainage Open-Pit Mines," focus on the phased construction of intermediate bridges, spoil heaps, water barriers, water storage layers, and drainage equipment in inner-drainage open-pit mines; the published patent CN108643140A, "A System and Method for Pumped Storage Using Abandoned Open-Pit Mines," and the related utility model CN208415203U focus on the pumped storage operation process consisting of an upper reservoir, a lower reservoir, a dam, an electromechanical chamber, a water diversion tunnel, and a tailrace tunnel. These technologies address the construction and operation problems of specific energy or water storage projects and are generally not used in the project initiation or scheme comparison stage to determine whether an abandoned mine pit has the potential to become a reservoir, whether the required engineering modifications are minimal, and whether the net benefits are superior to other reuse schemes.

[0010] (3) Techniques for ecological restoration, revegetation, and evaluation of restoration effects in mines; for example, patent CN107950310A, "A Mode for the Development and Restoration of Abandoned Mine Pit and an Evaluation Method," improves the ecological environment of mine pits through surveying, size calculation, slope cutting, cleaning and reinforcement, retaining wall installation, topsoil spraying, drainage ditch layout, plant sowing, and maintenance. Its evaluation focuses on the survival rate of plant seeds. Patent CN113705951A, "A Method for Evaluating the Effect of Ecological Restoration in Mines," collects data on target mines, formulates ecological restoration evaluation schemes, determines evaluation indicators, and calculates the ecological restoration process and effects. Such schemes focus on the ecological restoration effect or vegetation restoration effectiveness, but do not solve the coupling and inversion problem between water level, seepage, slope, flood discharge, water quality, and engineering correction quantities when the mine pit is filled with water.

[0011] (4) Mining area carbon sink calculation and ecological carbon sink remote sensing evaluation technology; for example, the published patent CN114169792A and its authorized text CN114169792B "A method for calculating ecological carbon sink in mining areas" calculates the amount of ecological carbon sink in mining areas through land type zoning, sample collection, soil carbon sequestration and vegetation carbon sequestration data; the published patent CN115565063A and its authorized text CN115565063B "A method for calculating and analyzing the contribution of vegetation carbon sink in mining areas based on climate potential compensation" calculates the contribution of vegetation carbon sink influencing factors in mining areas through remote sensing images, fine land use classification, control area selection, CASA model and climate potential model. Such technologies can provide a reference for the carbon disturbance cost or carbon benefit accounting of the present invention, but their technical focus is on carbon sink calculation and does not involve the inversion of the constraint gap and engineering correction amount of mine reservoir construction.

[0012] (5) Monitoring and early warning technologies for reservoir dams or reservoir bank slopes; for example, the published patent CN103792593A, "A method for determining the stability of reservoir bank slopes based on reservoir water level and displacement monitoring," uses reservoir water level and displacement response to evaluate the stability of reservoir bank slopes; the authorized patent CN112381309B, "Method, device, system and storage medium for safety monitoring and early warning of reservoir dams," comprehensively assesses and warns of safety risks by integrating dam deformation, seepage pressure, seepage, water level and rainfall data; the published patent CN109785584A, "A method for predicting the stability of reservoir bank slopes by combining rainfall and reservoir water level changes with the combined hydrodynamic effects on reservoir bank slopes, and combines displacement monitoring to predict stability. This type of technology emphasizes monitoring during operation or single slope stability evaluation. Although it involves reservoir water level response and slope response, its purpose is not to form a multi-constrained suitable water level envelope before the construction of a reservoir in an abandoned mine pit, nor does it solve the joint inversion of engineering correction quantities and the judgment of counterfactual net benefits.

[0013] In summary, existing literature and patents provide an important foundation for the utilization of water bodies in abandoned mine pits, the construction of pit bottom reservoirs, pumped storage, ecological restoration, carbon sequestration assessment, and reservoir bank slope monitoring. However, the following key gaps still exist: First, existing suitability assessments are mostly static scoring or rule-based screening, lacking a method to form a multi-constraint response envelope by progressively loading according to the water level, making it difficult to identify safe and suitable zones at different water levels. Second, existing construction-based solutions can provide certain engineering treatment measures, but cannot deduce the minimum engineering correction required to meet the target water storage function before construction. Third, existing slope monitoring and early warning technologies mostly focus on slope stability during operation, failing to integrate slope stability, seepage prevention, water quantity, water quality, flood control, and ecological space constraints into the same restorability inversion framework. Fourth, existing benefit assessments tend to treat reservoir construction benefits as absolute benefits, failing to fully deduct engineering correction costs, residual risk costs, carbon disturbance costs, and opportunity benefits from alternative reuse schemes.

[0014] In view of this, the present invention is hereby proposed. Summary of the Invention

[0015] To address the aforementioned technical problems in the existing technology, this invention provides a method for identifying and repairing gaps in abandoned mine pit reservoirs. By forming a multi-constraint response envelope through virtual water storage loading, the method identifies constraint gaps and determines their repairability, providing precise engineering targeting basis for the utilization of abandoned mine pit reservoirs.

[0016] To achieve the above objectives, the technical solution of the present invention is as follows: A method for identifying and repairing gaps in abandoned mine reservoirs includes: S1. Obtain the mine's physical conditions, natural resource conditions, social resource conditions, and alternative reuse scheme conditions for the target abandoned mine, and construct a basic dataset for reservoir-based evaluation. S2. Based on the function of the target mine pit as a water storage reservoir, regulating reservoir, or mine pit lake, set up a virtual water storage loading sequence and an evaluation scenario set. The evaluation scenario set includes at least a normal water storage scenario, a rapid descent scenario, a design rainstorm and flood scenario, and a dry season with insufficient water supply scenario. S3. Establish a rigid constraint set consisting of slope stability constraints, reservoir basin seepage prevention constraints, water balance constraints, water quality safety constraints, flood regulation constraints, and ecological space constraints. Calculate the constraint response under each loading water level and each evaluation scenario, and determine the relative constraint gap based on the relative difference between the constraint response and the constraint threshold. S4. Construct an initial suitable water level envelope based on the relative constraint gap, and determine whether the target functional water level belongs to the initial suitable water level envelope; when the target functional water level does not belong to the initial suitable water level envelope, calculate the gap matrix of each constraint under all loading water levels and evaluation scenarios, and determine the critical water level, dominant gap type and gap source. S5, perform a repairability judgment on the constraint gap, and distinguish between unrepairable gaps and repairable gaps; if there is an unrepairable gap, output the evaluation result that the reservoir is not suitable for construction. S6. If only repairable gaps exist, then establish a set of engineering correction variables. The set of engineering correction variables shall include at least two of the following: water level adjustment variables, slope correction variables, seepage prevention correction variables, flood discharge correction variables, water quality correction variables, and ecological correction variables.

[0017] Further, in step S1, the conditions of the mine body include the mine boundary, the bottom elevation, the pit opening area, the mine depth, the relationship between water level and reservoir capacity, the relationship between water level and submerged area, the slope of the side slope, the width of the steps, the integrity of the rock mass, the distribution of weak interlayers, faults and fissures, the permeability coefficient, the groundwater level, the existing water accumulation and water quality indicators. The natural resource conditions include multi-year average rainfall, design rainfall, evaporation, catchment area, runoff coefficient, surface water inflow, groundwater recharge, ecological sensitivity, vegetation cover, and regional carbon sink baseline. The social resource conditions mentioned include water supply demand, irrigation demand, flood protection targets, transportation accessibility, power availability, distance from residential areas, industrial demand, and planning and control requirements.

[0018] Furthermore, in step S1, one or more of the following methods are used to obtain basic evaluation data: UAV oblique photography, LiDAR measurement, remote sensing imagery, geological drilling, on-site hydrological tests, pumping tests, water injection tests, slope monitoring, water quality testing, and local planning data. The basic evaluation data are then unified to the same coordinate system, the same elevation datum, and the same evaluation period. At least the following functions are established: water level and reservoir capacity function, water level and inundated area function, water level and water-receiving slope length function, and water level and seepage-receiving area function.

[0019] Furthermore, in step S2, the virtual water storage loading sequence is loaded step by step from the starting water level to the target functional water level or the verification water level according to the set water level loading step size; The water level loading step size is determined based on the mine pit depth, reservoir capacity curve slope, slope stability sensitivity, and leakage response sensitivity. When the water level and stability response or the water level and leakage response change drastically, the water level loading step size is reduced. For pumped storage reservoirs or combined regulation reservoirs, the evaluation scenario set also includes high-frequency water level fluctuation scenarios.

[0020] Furthermore, in step S3, for positive constraints such as safety factor, available water volume and flood control capacity, the larger the values, the more advantageous they are, the relative constraint gap is calculated according to the proportion of insufficient threshold. For adverse constraints such as leakage, pollutant concentration, and ecological occupation, where smaller values ​​are more advantageous, the relative constraint gap is calculated based on the excess ratio. For rule-based constraints such as ecological red lines, planning conflicts, and avoidance of major infrastructure, the relative constraint gap is assigned a value of 0 if satisfied and 1 if not satisfied.

[0021] Furthermore, in step S4, the initial suitable water level envelope is the set of water levels that meet the requirements under all rigid constraints and all evaluation scenarios; If the target functional water level falls within the initial suitable water level envelope, the target mine is determined to have the conditions for direct reservoir construction under the current conditions; if the target functional water level does not fall within the initial suitable water level envelope, the process proceeds to the identification of critical water level, dominant gap type, and gap source.

[0022] Furthermore, in step S4, the critical water level is the water level at which any constraint gap first appears during the loading process from the initial water level to the target functional water level; The dominant gap type is determined by the contribution rate of each constraint gap in all gaps. The contribution rate is used to identify slope instability, insufficient seepage prevention, insufficient water volume, insufficient flood storage capacity, substandard water quality, or ecological space conflict caused by rising water levels.

[0023] Furthermore, the slope stability constraint adopts the minimum slope stability safety factor required under reservoir construction or operation conditions as the threshold, and determines whether there is a gap based on the water level and the slope stability safety factor under the evaluation scenario. The slope stability safety factor is obtained through the infinite slope formula, Bishop method, Morgenstern-Price method, finite element strength reduction method or seepage stability coupled numerical analysis, and the effects of water level rise, rapid drop, long-term immersion and pore water pressure change on slope stability are considered in the calculation.

[0024] Furthermore, the seepage control constraints of the reservoir basin are expressed as the leakage rate per unit time, the predicted leakage rate within the control period, or the equivalent permeability coefficient. The water balance constraint is expressed as the difference between rainfall runoff, external water inflow, groundwater recharge, evaporation loss, ecological water demand, and target water demand. The flood storage constraints are expressed as the available flood control capacity between the normal storage level, the operating level, the flood control limit level, or the design flood level. The water quality safety constraints are expressed as the compliance rate of individual water quality indicators, the comprehensive water quality index, or the water quality level for the target purpose. The ecological space constraints are expressed as ecological red line conflicts, basic farmland occupation, and the impact of residents avoiding or protecting species.

[0025] Furthermore, in step S5, the irreparable gap includes one or more of the following: the target reservoir area is located within a prohibited development zone or an unadjustable ecological protection red line; there is an unmanageable major pollution source; there is a conflict between the mine pit and the major infrastructure that cannot be relocated; there is an unacceptable regional geological disaster risk; and the construction of the reservoir is in conflict with the explicit conflict of higher-level planning. The repairable gaps include constraint gaps that can be eliminated or reduced to an acceptable range through water level adjustment, slope cutting or support, seepage prevention curtains, crack sealing, water quality treatment, flood discharge facilities, or ecological buffer zones.

[0026] Furthermore, in step S6, the water level adjustment variables include the normal water level reduction, the tiered water storage control amount, or the allowable water level rise and fall rate limit. The slope correction variables include the amount of slope cutting, the increase in step width, the anchoring support strength, the slope toe ballast, or the strength of the waterproofing treatment of the weak layer. The seepage prevention correction variables include the depth of the seepage prevention curtain, the length of the curtain, the grouting range, the thickness of the bottom cover or the crack sealing strength; The flood discharge correction variables include the increase in flood discharge capacity, the amount of spillway widening, or the scale of flood discharge channel renovation. The water quality correction variables include the amount of bottom sediment removal, the size of the pre-sedimentation unit, the area of ​​the constructed wetland, or the water circulation and purification capacity. The ecological correction variables include the width of the ecological buffer zone, the proportion of the ecological shoreline, or the area of ​​disturbance recovery.

[0027] The beneficial effects of this invention include: (1) The evaluation of the construction of abandoned mine pit reservoirs is transformed from static suitability scoring into a technical method that combines virtual water storage loading response envelope, constraint gap identification and repairability judgment. This method can identify the reasons for the constraint overrun of the target water level in specific loading stages and evaluation scenarios, and judge whether the corresponding gap has engineering repairability. (2) By incorporating the water level loading sequence and evaluation scenario set into the constraint verification process, an initial suitable water level envelope can be formed, which can not only determine whether the mine pit has the conditions for reservoir construction, but also determine the safe water storage height and the water level and scenario with insufficient safety margin. (3) By combining the critical water level and the contribution rate of the dominant gap, the gap type and source that cause the target functional water level to be unattainable can be accurately identified, providing a clear target for subsequent engineering correction, rather than just outputting abstract grades of excellent, good, medium and poor. (4) The constraint gap is divided into unrepairable gap and repairable gap. This can quickly eliminate mines that do not meet the conditions for reservoirization in the early stage of evaluation, avoid ineffective engineering demonstration investment, and establish a set of engineering correction variables for repairable gap, laying the foundation for the subsequent minimum engineering correction amount inversion. Attached Figure Description

[0028] Figure 1 A flowchart of the method for identifying and repairing gaps in abandoned mine reservoirs provided by the present invention; Figure 2 This is a schematic diagram of the virtual water storage loading sequence and water level constraint response envelope provided by the present invention; Figure 3 A schematic diagram illustrating the identification and repairability determination of rigid constraint gaps provided by the present invention; Figure 4 This is a schematic diagram illustrating the inversion calculation of the engineering response matrix and the minimum engineering correction amount provided by the present invention. Figure 5 This is a schematic diagram of the counterfactual net benefit judgment and suitability level output provided by the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0030] It should be noted that the volumetric form of Darcy's law, the limit equilibrium formula for infinite slopes, the finite difference formula, and the water balance formula in this specification are all common calculation forms used in engineering analysis. The constraint gap, suitable water level envelope, and repairability criterion in this invention are calculation rules constructed around the suitability evaluation of abandoned mine pit reservoirs. The parameters of the above-mentioned custom calculation rules should be determined by field investigation, experiments, numerical simulation, standard thresholds, publicly available engineering data, or verified engineering economic data. Unverified example data should not be directly used as the basis for actual engineering design.

[0031] The following description of exemplary embodiments is merely illustrative and is not intended to limit the invention or its application or use in any way. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail herein, but where applicable, such techniques, methods, and apparatus should be considered part of this specification.

[0032] Example 1 See Figure 1 , Figure 1 This is a flowchart of a method for identifying and repairing gaps in abandoned mine pit reservoirs proposed in this invention. This method no longer treats the construction evaluation of abandoned mine pit reservoirs as a simple weighted average of indicators or a static comprehensive score. Instead, it transforms the proposed reservoir construction process into a set of calculable virtual water storage loading conditions. It performs a step-by-step verification of slope stability, seepage prevention, water quantity, water quality, flood regulation, and ecological space constraints of the target mine pit under different water levels, different water level rise and fall rates, different rainfall and flood conditions, and different dry seasons, forming a water level and constraint response envelope. When the target functional water level falls into an unsuitable area, the constraint gap is identified and its repairability is judged, and a set of engineering correction variables is established.

[0033] The core idea of ​​this invention is to replace one-time status quo evaluation with virtual water storage loading, determine the safe and suitable domain with response envelope, identify engineering shortcomings with gap identification, and distinguish technical boundaries with repairability judgment. Thus, the utilization of mine reservoirs is transformed from experience-based selection to a technical method driven by water level loading, involving multiple constraints, identifiable gaps, and assessable repairability.

[0034] The specific steps of this invention include: S1. Construct a basic dataset for the evaluation of abandoned mine pits becoming reservoirs: Obtain the inherent conditions of the target abandoned mine pit, natural resource conditions, social resource conditions, and alternative reuse scheme conditions to construct a basic dataset for reservoir-based evaluation. ; The conditions of the mine pit itself include the mine pit boundary, pit bottom elevation, pit mouth area, mine pit depth, water level and reservoir capacity relationship, water level and inundated area relationship, slope gradient, bench width, rock mass integrity, distribution of weak interlayers, faults and fissures, permeability coefficient, groundwater level, existing water volume and water quality indicators. Natural resource conditions include multi-year average rainfall, design rainfall, evaporation, catchment area, runoff coefficient, surface water inflow, groundwater recharge, ecological sensitivity, vegetation cover, and regional carbon sink baseline; social resource conditions include water supply demand, irrigation demand, flood protection targets, transportation accessibility, power availability, distance from settlements, industrial demand, and planning and control requirements.

[0035] Preferably, one or more of the following methods are used to obtain basic evaluation data: UAV oblique photography, LiDAR measurement, remote sensing imagery, geological drilling, on-site hydrological test, pumping test, water injection test, slope monitoring, water quality testing, and local planning data. The basic evaluation data are then unified to the same coordinate system, the same elevation datum, and the same evaluation period. For reservoir evaluation, at least a water level and reservoir capacity function should be established. Water level and inundated area function Water level and water-receiving slope length function Function of water level and leakage water-receiving area The specific formula is as follows:

[0036] in, This serves as the foundational dataset for the evaluation of the target mine's reservoir-like transformation. This is data on the conditions of the mine itself. For natural resource conditions data, For social resource conditions data, To replace the data for reuse schemes; for indicators with different dimensions and clearly defined upper and lower limits, range normalization can be used:

[0037] in, For the first One original indicator, The normalized index value, and These are the minimum and maximum reference values ​​for the indicator, respectively. Not equal to For indicators with clear engineering thresholds, such as safety factor, water quality grade, and permeability coefficient, normalization can also be performed using threshold ratio or constraint gap.

[0038] Among them, at least the functions of water level and reservoir capacity, water level and submerged area, water level and water-receiving slope length, and water level and seepage-receiving area should be established.

[0039] S2. Set up virtual water storage loading sequence and evaluation scenario set: Based on the intended function of the target mine pit as a water storage reservoir, regulating reservoir, or mine lake, set up a virtual water storage loading sequence. and evaluation scenario set The evaluation scenario set includes at least normal water storage scenario, rapid rainfall scenario, design rainstorm and flood scenario, and insufficient water supply scenario; the virtual water storage loading sequence loads the water level from the starting water level to the target functional water level or the check water level step by step according to the set water level loading step size. The water level loading step size is determined based on the mine pit depth, reservoir capacity curve slope, slope stability sensitivity, and leakage response sensitivity. When the water level and stability response or the water level and leakage response change drastically, the water level loading step size is reduced. For pumped storage reservoirs or combined regulation reservoirs, the evaluation scenario set also includes high-frequency water level fluctuation scenarios. The specific expression is:

[0040]

[0041] in, The initial water level, For the target functional water level or check water level, To adjust the water level loading step size, For the first An evaluation scenario. Virtual water storage loading step size. The value can be determined based on the mine pit depth, reservoir capacity curve slope, and slope sensitivity; when the water level and stability or the water level and leakage response change drastically, the value should be reduced. .

[0042] S3. Establish a rigid constraint set for reservoir construction and form a water level and constraint response envelope: Establish a rigid constraint set consisting of slope stability constraints, reservoir basin seepage prevention constraints, water balance constraints, water quality safety constraints, flood storage constraints, and ecological space constraints. Calculate the constraint response quantities under each loaded water level and each evaluation scenario, and determine the relative constraint gap based on the relative difference between the constraint response quantity and the constraint threshold. The specific formula is as follows:

[0043] in, For slope stability constraints, For the sake of reservoir basin seepage prevention constraints, For water balance constraints, For water quality safety constraints, For flood control and regulation, This invention addresses ecological space constraints. Different constraints have different engineering dimensions and varying degrees of advantage or disadvantage; therefore, it uses constraint response quantities as the primary consideration. With constraint threshold The relative difference between them defines the constraint gap. .

[0044] For positive constraints, larger values ​​for safety factor, available water volume, and flood control capacity are more advantageous. The relative constraint gap is calculated based on the proportion of insufficient threshold, using the following formula:

[0045]

[0046] in, For the first Constraints at water level ,scene and engineering correction variables The relative constraint gap below, For the first The threshold for the numerical constraint should be positive. An equal value of 0 indicates that the constraint is satisfied. A value greater than 0 indicates a gap exists in this constraint. For rule-based constraints such as ecological red lines, planning conflicts, and avoidance of major infrastructure, [the following can be considered]: Assign values ​​as 0 if the condition is met and 1 if the condition is not met.

[0047] Formula (6a) applies to constraints where larger values ​​are more favorable, while formula (6b) applies to constraints where smaller values ​​are more favorable. Based on formulas (6a) and (6b), the initial suitable water level envelope under the uncorrected state is constructed. :

[0048] in, This represents the set of water levels that meet the requirements under all rigid constraints and all evaluation scenarios. If the target functional water level... belong If, then the target mine pit has the conditions for direct silo construction under the current conditions; if Not belonging to Then it is necessary to identify the cause It cannot enter the constraint gap of the appropriate envelope.

[0049] Preferably, slope stability constraints can be expressed using the slope safety factor:

[0050] in, This refers to the minimum slope stability safety factor required under reservoir construction or operation conditions. Water level and scenarios The slope stability safety factor.

[0051] For preliminary evaluation, the infinite slope formula can be used:

[0052] in, For effective cohesion, The weight of the rock and soil is [not specified]. For potential sliding depth, For the slope angle, For the pore water pressure on the potential sliding surface, This is the effective internal friction angle.

[0053] The slope stability constraint adopts the minimum slope stability safety factor required under reservoir construction or operation conditions as the threshold, and determines whether there is a gap based on the water level and the slope stability safety factor under the evaluation scenario. The slope stability safety factor is obtained through infinite slope formula, Bishop method, Morgenstern-Price method, finite element strength reduction method, or seepage stability coupled numerical analysis. The calculations also take into account the effects of rising water levels, rapid drops, long-term immersion, and changes in pore water pressure on slope stability.

[0054] The seepage control constraints of the reservoir basin can be expressed as leakage per unit time or equivalent permeability coefficient. According to Darcy's law in volumetric form, the predicted leakage during the control period is:

[0055]

[0056] in, To control the predicted leakage amount within a certain period, The equivalent permeability coefficient, For hydraulic gradient, Water level The infiltration area of ​​the reservoir basin below To control the time period, To allow for leakage. In the preliminary evaluation, if the equivalent permeability coefficient is used as a substitute indicator, the value in formula (11) can be adjusted. and Replace with and .

[0057] Water balance constraints can be determined based on target water supply, ecological water replenishment, or water storage needs:

[0058]

[0059] in, To evaluate the amount of water available during the evaluation period, Rainfall within the same evaluation period, The runoff coefficient, For the catchment area, For external water replenishment, This refers to groundwater recharge. Evaporation depth within the same evaluation period. Water level The area of ​​the water surface below The amount of water required to maintain the ecological base flow or ecological water level. The target water demand; all terms in the formula should be in volume units.

[0060] Flood storage constraints can be expressed as reserved flood control capacity:

[0061]

[0062] in, Normal water storage level or operating water level With flood control limit water level or design flood level Available flood control capacity between The design should include the required flood control capacity. Water quality safety constraints can be expressed using the compliance rate of individual water quality indicators, the comprehensive water quality index, or the water quality level for the target use; ecological space constraints can be expressed using rules such as ecological red line conflicts, basic farmland occupation, resident avoidance, and impact on protected species.

[0063] S4. Identify critical water levels, constraint gaps, and gap sources: See [link / reference] Figure 2 An initial suitable water level envelope is constructed based on the relative constraint gap, and it is determined whether the target functional water level belongs to the initial suitable water level envelope. The initial suitable water level envelope is the set of water levels that meet the requirements under all rigid constraints and all evaluation scenarios. If the target functional water level belongs to the initial suitable water level envelope, it is determined that the target mine has the conditions for direct reservoir construction under the current conditions, and enters the counterfactual net benefit comparison. If the target functional water level does not belong to the initial suitable water level envelope, it enters the identification of critical water level, dominant gap type and gap source.

[0064] S5. Divide the constraint gap into irreparable gaps and repairable gaps: when the target function level... Not part of the initial suitable water level envelope At that time, calculate the gap matrix for each constraint under all loading water levels and evaluation scenarios. Determine the critical water level The dominant gap types and gap sources; the specific formula is:

[0065]

[0066] in, Water level and scenarios The constraint gap vector below, For the first The relative gap of the constraint in the uncorrected state. The water level at which any constraint gap first appears during the loading process from the initial water level to the target water level; if there are no gaps throughout the entire process, then... Empty.

[0067] To avoid making decisions based solely on a single worst-case scenario, the formula for calculating the dominant gap contribution rate is as follows:

[0068] in, For the first The contribution rate of each constraint to all constraint gaps; when the denominator is 0, it indicates that there are no constraint gaps and no calculation is needed. .like A higher value indicates that this constraint is the dominant shortcoming affecting the utilization of mine pit reservoirs. Through... and The combination of factors can identify whether rising water levels lead to slope instability, insufficient seepage prevention, insufficient water volume, insufficient flood storage capacity, substandard water quality, or whether ecological space constraints prevent the target water level from being achieved.

[0069] S6. Establish the set of engineering correction variables and the engineering response matrix: See [link / reference] Figure 3 The repairability of the constraint gap is determined. If there is an unrepairable gap, the evaluation result that the reservoir is not suitable for construction is output. If there is only a repairable gap, a set of engineering correction variables is established. The specific criteria for determining a constraint gap are as follows: if the constraint gap originates from conditions that cannot be eliminated through engineering measures under laws, regulations, or spatial control, it is determined to be an irreparable gap; if the constraint gap can be eliminated or reduced to an acceptable range through engineering measures such as water level adjustment, slope cutting or support, seepage prevention curtains, water quality treatment, flood discharge facilities, and ecological buffer zones, it is determined to be a repairable gap; the specific expression is:

[0070] in, For the set of unrepairable gaps, For the set of repairable gaps, For the first Repairable indicators of constraint gaps; when A value of 0 indicates that the item is irreparable. A value of 1 indicates that the problem is repairable; unrepairable gaps include, but are not limited to: the target reservoir area being located within a prohibited development zone or an unadjustable ecological protection red line; the presence of major pollution sources that cannot be controlled; conflicts between mine pits and major infrastructure that cannot be relocated; unacceptable regional geological disaster risks; or the construction of the reservoir being in clear conflict with higher-level plans.

[0071] If any irreparable gap exists, the evaluation result indicating that the reservoir is not suitable for construction will be output directly, and the constraint category, constraint gap value, and corresponding water level scenario that led to the exclusion will be recorded. If there is no irreparable gap, but a repairable gap exists, proceed to the next step.

[0072] Repairable gaps include constraint gaps that can be eliminated or reduced to permissible levels through water level adjustment, slope cutting or support, seepage prevention curtains, crack sealing, water quality treatment, flood discharge facilities or ecological buffer zones. Engineering Correction Variable Set It must include at least two of the following: water level adjustment variables, slope correction variables, seepage prevention correction variables, flood discharge correction variables, water quality correction variables, and ecological correction variables; the specific expression is:

[0073] in, As a variable for water level adjustment, it can represent the normal decrease in water level, the amount of water level control in stages, or the limit on the rate of rise and fall of water level. As a slope correction variable, it can represent the amount of slope cutting, the increase in step width, the strength of anchor support, the ballast at the slope toe, or the strength of water-tightening treatment of the weak layer. As a seepage prevention correction variable, it can represent the depth of the seepage prevention curtain, the length of the curtain, the grouting range, the thickness of the bottom cover or the crack sealing strength; As a flood discharge correction variable, it can represent the increase in flood discharge capacity, the amount of spillway widening, or the scale of flood discharge channel renovation; As a water quality correction variable, it can represent the amount of bottom sediment removal, the size of the pre-sedimentation unit, the area of ​​the constructed wetland, or the water circulation and purification capacity. As an ecological correction variable, it can represent the width of the ecological buffer zone, the proportion of the ecological shoreline, or the area of ​​disturbance recovery.

[0074] Example 2 This embodiment uses the set of engineering correction variables output from Embodiment 1 to conduct a counterfactual net benefit comparison between the corrected mine reservoir scheme and the alternative reuse scheme, outputting evaluation results such as directly suitable, suitable after correction, technically repairable but economically unsuitable, or irreparable and unsuitable; the specific steps include: S7. Use engineering response matrix or nonlinear response function to describe the effect of engineering correction variables on the reduction of constraint gap; The engineering response matrix calculates the unit reduction capacity of each engineering correction variable for each rigid constraint gap through finite difference calculation. If the response relationship between the engineering correction variable and the constraint gap is nonlinear, a nonlinear response function is used to represent the reduction effect of the engineering correction variable on the constraint gap. In the inversion process, the mutual influence between water level adjustment, slope correction, seepage prevention correction, flood discharge correction, water quality correction and ecological correction are considered together.

[0075] The impact of engineering correction variables on constraint gaps is represented by the engineering response matrix A or the nonlinear response function f. For cases where the local response can be obtained through numerical simulation, field tests, or similar engineering inversion, the engineering response matrix is ​​calculated using finite differences:

[0076] in, For the first The engineering adjustment variable for the first project The unit reduction capacity of the constraint gap, For the first The perturbation step size of each engineering correction variable. For the first A unit vector in each variable direction. If A value greater than 0 indicates that increasing the correction variable helps to reduce the corresponding constraint gap.

[0077] If the response relationship is highly nonlinear, then a nonlinear response function is used:

[0078] For example, lowering the normal water level can simultaneously improve slope stability and flood control, but may reduce water supply efficiency; installing seepage barriers can reduce leakage gaps, but will increase engineering costs and carbon disturbance; slope cutting and toe ballast can improve the safety factor, but will occupy reservoir capacity or increase waste disposal costs. Therefore, engineering correction variables should not be determined in isolation, but should be jointly inverted within the envelope of water level and constraint response.

[0079] S8, see reference Figure 4 Under the condition of satisfying all virtual water storage loading levels and rigid constraints under evaluation scenarios, with the goal of minimizing engineering correction costs, residual risk costs, and carbon disturbance costs, the minimum combination of engineering corrections required to achieve the target water storage function is inverted. ;

[0080]

[0081]

[0082] in, For engineering correction costs, To take into account the residual risk costs after engineering modifications, Costs of carbon emissions or ecological disturbances resulting from engineering modifications. For the first The allowable calculation error or safety-side tolerance margin under the constraint. and These are the lower and upper limits of the engineering correction variable, respectively. To adopt engineering correction variables The appropriate water level envelope afterward. The above three types of costs should be converted to the same evaluation caliber. If the above three formulas have no feasible solution, it is determined that the target mine is technically impossible to meet the conditions for dam construction through reasonable engineering modifications.

[0083] Engineering correction costs The cost can be calculated based on the unit quantity of work, using the following formula:

[0084] in, For the first The unit cost of the project is a variable that is adjusted for the type of project. To correspond to the amount of work, Fixed costs include investigation, design, construction organization, and monitoring deployment; the remaining risk cost can be calculated based on the extent to which the modified constraint gap exceeds the allowable gap. First, define the... The over-limit value of a constraint is given by the following formula:

[0085] in, For the first The maximum exceedance of the constraint across all water levels and evaluation scenarios; the remaining risk cost can be calculated using the following formula:

[0086] in, For the first Risk weights for each constraint; in practical engineering, probabilistic risk models, reliability analysis, or risk discounting methods approved by the competent authorities can also be used to calculate them. .

[0087] The cost of carbon disturbance can be calculated based on offsets from engineering materials, earthwork, energy consumption, vegetation destruction, and ecological restoration.

[0088] in, This is the carbon price or carbon cost conversion factor. Carbon emissions from material production and transportation Carbon emissions from earthwork disturbance. For energy carbon emissions during construction and operation, This formula is used to offset the carbon sink costs resulting from ecological restoration or vegetation recovery. It is only for calculating the net carbon disturbance costs caused by engineering modifications; the benefits of ecological carbon sinks or energy-based emission reductions during the operational period can be included. This is to avoid duplicate deductions.

[0089] S9. Based on the minimum engineering correction combination Calculate the overall benefits of the revised mine reservoir scheme. The comprehensive benefits of the revised mine pit reservoir plan include water resource benefits, flood control and disaster reduction benefits, ecological benefits, carbon benefits, economic benefits, and social benefits; the specific calculation formula is as follows:

[0090] in, For water resource benefits such as water supply, irrigation, emergency backup water source and ecological water replenishment; To achieve flood control and disaster reduction benefits such as peak shaving, flood diversion, flood retention, and reduction of downstream risks; Value for landscape improvement, soil and water conservation, habitat restoration, and aquatic ecosystem services; Net carbon benefits resulting from ecological restoration of carbon sinks, reducing disturbance by replacing traditional engineering construction, and synergistic utilization of renewable energy; For economic benefits such as tourism, fisheries, land conservation, and industrial synergy; It brings social benefits such as employment, public safety, resident satisfaction, science education, and enhancement of the region's image.

[0091] Water resource benefits can be estimated based on water supply volume and unit water price or alternative water supply costs. The specific formula is as follows:

[0092] in, For the first Water usage or replenishment volume This refers to the unit revenue or replacement cost of this type of water use.

[0093] The benefits of flood control and disaster reduction can be estimated based on the reduction in expected risk losses, using the following formula:

[0094] in, and These represent the probability of disaster occurrence and potential losses under conditions of no reservoir or alternative solutions. and These represent the probability of disaster and the potential losses after adopting the mine pit reservoir solution.

[0095] S10. Compare the counterfactual net benefits of the revised mine reservoir plan and the alternative reuse plan. Alternative reuse schemes This includes one or more of the following reuse options: natural waste disposal, ecological parks, backfilling and reclamation, photovoltaic utilization, specialty tourism, industrial warehousing, or other reuse schemes that comply with local planning; a counterfactual comparison will be made between the revised mine reservoir scheme and the alternative scheme to calculate the overall net benefit. The specific formula is as follows:

[0096]

[0097] in, The overall net benefit of the mine pit reservoir scheme relative to the optimal alternative reuse scheme; The annualized engineering cost for the minimum engineering correction combination; This represents the annualized residual risk cost. Annualized carbon disturbance cost; For the first The annualized comprehensive benefits of each alternative reuse scheme should be evaluated using a consistent evaluation period, discounted cash flow method, and monetary value.

[0098] The annualized project cost can be calculated using the capital recovery factor, and the specific formula is as follows:

[0099] in, To revise the one-time investment for the project, The discount rate is... For the evaluation period, This refers to the annual operating and maintenance costs. A value greater than 0 indicates that, after deducting the minimum engineering correction cost, residual risk cost, carbon disturbance cost, and opportunity benefits of alternative solutions, the mine reservoir project still has a net incremental benefit; if A value not greater than 0 indicates that while the mine reservoir solution may be technically feasible, it is not superior to the alternative reuse solution in terms of overall net benefits.

[0100] S11, see reference Figure 5 Based on the initial suitable water level envelope, constraint gap type, minimum engineering correction combination, and counterfactual net benefit, the reservoir construction suitability level and recommended engineering parameters are output. The suitability levels for reservoir construction include This type is directly suitable for database construction. After the class is corrected, it is suitable for database construction. This type of technology can repair [the problem], but it's not economically viable to build a database for it. Classes that are unrepairable should not be used for database creation; see Table 1 for details: Table 1

[0101] In addition to outputting the above-mentioned levels, the system should also output the recommended normal water level, maximum operating water level, allowable water level rise and fall rate, critical water level, suitable water level envelope, key slope correction areas, seepage prevention curtain or grouting range, flood discharge capacity, water quality treatment scale, ecological buffer zone width, monitoring layout recommendations, and sensitivity ranking of various correction variables. Furthermore, it should conduct sensitivity tests on slope safety factor, permeability coefficient, inflow, evaporation, unit cost of the project, discount rate, benefits of alternative solutions, and carbon price.

[0102] for For this type of project, the recommended engineering correction parameters are... and its safety-side rounded engineering parameters; for For this type of project, priority should be given to alternative reuse solutions; for For this type of project, irreparable gaps should be listed.

[0103] S12. Conduct parameter sensitivity tests and review evaluation results: To avoid bias in evaluation results due to errors in a single parameter, sensitivity tests should be conducted on key parameters such as slope safety factor, permeability coefficient, water inflow, evaporation, unit cost of the project, discount rate, benefits of alternative solutions, and carbon price. Sensitivity Indicators It can be calculated using the following formula:

[0104] in, For the first The sensitivity of this parameter to the overall net benefit. To represent the overall change in net benefit, For parameter changes, and To prevent or A small positive number that approaches zero can distort the ratio. If a parameter is too sensitive, its measurement accuracy should be increased or a stricter safety margin should be set. For mines that have already been monitored, the suitability level can be dynamically verified by re-executing the monitoring after the monitoring data is updated.

[0105] Example 3 This embodiment employs a method for identifying and repairing gaps in abandoned mine pit reservoirs proposed in this invention, selecting a scenario of converting a small, sunken quarry into a reservoir as the implementation object. Public information shows that the Gan'ao Reservoir in Beilun, Ningbo, was originally the Chunxiao Gan'ao Maoyangshan Quarry. A small reservoir with a capacity of over 6 million cubic meters was built using the deep pit formed during mining, with functions including flood diversion, flood control, emergency backup water supply, and irrigation. This embodiment only illustrates the application process of the method of this invention based on publicly available facts of such projects, and does not evaluate the actual safety status, actual investment returns, or design conclusions of the project.

[0106] B1. Establish the basic evaluation dataset. For the target mine pit, firstly, establish the water level and reservoir capacity function through topographic surveying, reservoir basin mapping, geological survey, hydrological survey, and water quality testing. Water level and inundated area function Water level and water-receiving slope length function and the function of water level and leakage water-receiving area For slope shear strength, permeability coefficient, allowable leakage, water supply demand, and unit price not disclosed in public information, these should be obtained through special surveys, tests, or project estimates in the formal evaluation, and should not be replaced by empirically assumed values.

[0107] B2. Set up a virtual water storage loading sequence. Based on the proposed reservoir's function, use the dead water level, normal storage water level, flood control water level, and check flood level as control water levels, and set several water level increments between adjacent control water levels. For sunken quarries, water level loading should focus on covering the slope saturation zone, historical mining benches, fractured zones, and any possible solution or fractured zones.

[0108] B3. Form the constraint response envelope. For each virtual water level The relative constraint gaps for slope stability, seepage prevention, water balance, water quality safety, flood regulation, and ecological space constraints are calculated using formula (6a) or formula (6b), respectively. When all All are zero or do not exceed the preset allowable gap. At that time, the water level enters the initial suitable water level envelope. When any When the gap exceeds the allowable gap, the constraint gap identification procedure is initiated.

[0109] B4. Identify repairable gaps. If the target mine has unavoidable ecological red lines, unmanageable pollution sources, major infrastructure conflicts, or unacceptable geological hazard risks, then output directly. Classification results: If the constraint gap is mainly manifested as insufficient local slope stability reserve, insufficient reservoir seepage prevention capacity, insufficient flood discharge capacity, insufficient water pretreatment, or insufficient ecological buffer zone, then it is judged as a repairable gap, and a set of engineering correction variables is established. .

[0110] B5. Inverting the minimum engineering correction amount. Based on the engineering response matrix or nonlinear response function, calculate the reduction effect of water level control, slope correction, seepage prevention correction, flood discharge correction, water quality correction and ecological correction on the difference of each constraint, and solve the combination of minimum engineering correction amounts through equations (23) to (25). In this embodiment scenario, if If a suitable water level envelope, after correction, exists and covers the target functional water level, then proceed to the net benefit assessment; if... If it does not exist, it is classified as category D.

[0111] B6. Conduct counterfactual net benefit assessment; will adopt... The proposed mine reservoir is compared with alternatives such as natural abandonment, ecological parks, backfilling and reclamation, photovoltaic utilization, or other plans that comply with the regulations. The overall net benefit is calculated according to formula (34). .like If the value is greater than zero, output Class or Class result; if The value should not be greater than zero, even if it can be corrected in engineering, it will still be output. This process avoids directly assuming a mine is suitable for reservoir construction simply because it has formed a reservoir basin, and it also avoids simply excluding mines with repairable gaps.

[0112] Example 4 This embodiment employs a method for identifying and repairing gaps in abandoned mine pit reservoirs proposed in this invention. Publicly available information shows that the Fushun West Open-pit Mine is 6.6 kilometers long from east to west, 2.2 kilometers wide from north to south, and approximately 420 meters deep, with a pit opening area exceeding 10 square kilometers, classifying it as a typical deep and large open-pit mine. Such mine pits are characterized by their large spatial scale, complex slope structures, and significant influence from weak rock layers and groundwater. Treatment approaches typically include revegetation, water storage, landscape restoration, zoned utilization, or other combined utilization methods.

[0113] For deep, large-scale mine pits, the focus of this invention's method is not on directly determining the suitability for reservoir construction based on the pit's volume, but rather on identifying the impact of different water storage stages on steep slopes, weak interlayers, groundwater boundaries, and long-term water quality evolution. During implementation, the water level intervals in the virtual water storage loading sequence should be set smaller than those for ordinary small mine pits, and zoned response calculations should be performed for mining benches, historical landslide areas, weak interlayers, fault fracture zones, and areas where groundwater is concentrated.

[0114] In slope stability constraint calculations, equation (9) can be used as a preliminary verification formula for shallow soil overburden or simplified working conditions. For steep rock slopes, composite slip surfaces, slip controlled by weak interlayers, or multi-stage step slopes, the limit equilibrium method, finite element strength reduction method, discrete element method, or approved geotechnical numerical method should be used to obtain the results. And use it as the input of equation (8).

[0115] When deep, large-scale mine pits experience breaches in slope stability, seepage prevention, or water quality constraints at certain water level sections, it should first be determined whether the breach is repairable. If an irreparable breach exists, output... If the damage can be repaired through measures such as lowering the target water level, zoned water storage, slope unloading, support, seepage prevention, drainage, water quality pretreatment, or monitoring and early warning, then it enters the next category. Inversion procedure. If the inversion results show that the engineering correction is too large, and the correction cost, residual risk cost, and carbon disturbance cost are deducted... If not greater than zero, then output kind.

[0116] This embodiment illustrates that for deep, large, and complex mine pits, suitability conclusions cannot be drawn solely based on reservoir size or potential storage capacity. This invention, through the inversion of the water storage response envelope and minimum engineering correction, can separate technical repairability from economic rationality, thereby avoiding the misjudgment of technically manageable but insufficiently net-beneficial solutions as suitable for reservoir construction.

[0117] Example 5 This embodiment employs a method for identifying and repairing gaps in abandoned mine pit reservoirs proposed in this invention, selecting a large-scale regulating reservoir or a scenario combining regulating reservoirs and pumped storage as the implementation object. Public information shows that the Xiong'an Regulating Reservoir Project consists of an upper reservoir, a lower reservoir, connecting works between the upper and lower reservoirs, a power generation system, a spillway system, and power transmission and transformation works, with a total storage capacity of approximately 240 million cubic meters, of which the lower reservoir has a capacity of approximately 77 million cubic meters, belonging to a large-scale regulating and energy-integrated utilization project scenario. This embodiment only uses the publicly disclosed engineering functions and scale characteristics to illustrate the applicability of the method of this invention in large-scale integrated utilization scenarios.

[0118] For large-scale water storage reservoirs or multi-use scenarios, scenarios such as water storage operation level, daily regulation water level of pumped storage, flood season limit water level, and extreme rainfall water level should be added to the virtual water storage loading in step S2, and different operation scenarios should be set in equation (4). In addition to conventional constraints on slope, seepage prevention, water quantity, water quality, and flood control, the impact of rapid water level fluctuations on bank stability and water quality disturbance should also be considered.

[0119] When the main engineering safety constraints have been met, and only low-intensity gaps exist such as water pretreatment, shoreline ecological restoration, operational monitoring, or localized seepage prevention, this invention can calculate the corresponding minimum engineering correction combination using equations (20) to (25). If the corrected solution is relative to the alternative solution... If it is greater than zero, then output Class or Class; if the primary safety constraints cannot be met, or the required corrections exceed the technically feasible boundary, then output Class; if the technology is feasible but the net benefit is insufficient, then output kind.

[0120] This embodiment illustrates that the present invention is not only applicable to the conversion of small quarry pits into reservoirs, but also to the preliminary scheme comparison of large-scale regulating reservoirs, mine pit lakes, pumped storage reservoirs, or combined regulating reservoir projects. Its evaluation object is not a single engineering structure, but rather the constraint response, correction requirements, and net benefit results under different water levels and operating scenarios.

[0121] Example 6 This embodiment adopts a method for identifying and repairing gaps in abandoned mine reservoirs proposed in this invention. For abandoned mines with different mineral types, different climate zones, different reservoir functions, and different planning objectives, the reservoir capacity, scale, or functional data in publicly available cases should not be mechanically applied. Instead, the following parameter adaptation logic should be followed.

[0122] Firstly, data is obtained through field investigations, experiments, and numerical simulations. The amount of water entering the reservoir, water quality indicators, and conditions for alternative solutions.

[0123] Secondly, rigid constraint thresholds should be determined based on the target functions. Different functional thresholds should be adopted for different emergency backup water sources, irrigation reservoirs, flood diversion and storage reservoirs, landscape reservoirs, and pumped storage reservoirs.

[0124] Third, the initial suitable water level envelope is determined through virtual water storage loading. The constraint gap set is then used to solve the problem using the engineering response matrix or nonlinear response function. Fourth, all calculation results should be aligned with engineering specifications, material specifications, construction modules, and planning conditions, and rounded or verified according to the safety principle.

[0125] If the input data comes only from publicly available information and lacks on-site survey and experimental data, the method of this invention can only be used for preliminary scheme identification and should not be used as the sole basis for construction drawing design, safety assessment, or investment decision-making. If used for formal engineering demonstration, at least the following data should be supplemented: reservoir basin mapping, geotechnical testing, permeability testing, water quality testing, design flood verification, slope stability assessment, ecological space compliance review, and project budget data.

[0126] The above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for identifying and repairing gaps in abandoned mine reservoirs, characterized in that, include: S1. Obtain the mine's physical conditions, natural resource conditions, social resource conditions, and alternative reuse scheme conditions for the target abandoned mine, and construct a basic dataset for reservoir-based evaluation. S2. Based on the function of the target mine pit as a water storage reservoir, regulating reservoir, or mine pit lake, set up a virtual water storage loading sequence and an evaluation scenario set. The evaluation scenario set includes at least a normal water storage scenario, a rapid descent scenario, a design rainstorm and flood scenario, and a dry season with insufficient water supply scenario. S3. Establish a rigid constraint set consisting of slope stability constraints, reservoir basin seepage prevention constraints, water balance constraints, water quality safety constraints, flood regulation constraints, and ecological space constraints. Calculate the constraint response under each loading water level and each evaluation scenario, and determine the relative constraint gap based on the relative difference between the constraint response and the constraint threshold. S4. Construct an initial suitable water level envelope based on the relative constraint gap, and determine whether the target functional water level belongs to the initial suitable water level envelope; when the target functional water level does not belong to the initial suitable water level envelope, calculate the gap matrix of each constraint under all loading water levels and evaluation scenarios, and determine the critical water level, dominant gap type and gap source. S5, perform a repairability judgment on the constraint gap, and distinguish between unrepairable gaps and repairable gaps; if there is an unrepairable gap, output the evaluation result that the reservoir is not suitable for construction. S6. If only repairable gaps exist, then establish a set of engineering correction variables. The set of engineering correction variables shall include at least two of the following: water level adjustment variables, slope correction variables, seepage prevention correction variables, flood discharge correction variables, water quality correction variables, and ecological correction variables.

2. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, In step S1, the conditions of the mine body include the mine boundary, the bottom elevation, the pit opening area, the mine depth, the relationship between water level and reservoir capacity, the relationship between water level and submerged area, the slope of the side slope, the width of the steps, the integrity of the rock mass, the distribution of weak interlayers, faults and fissures, the permeability coefficient, the groundwater level, the existing water accumulation and water quality indicators. The natural resource conditions include multi-year average rainfall, design rainfall, evaporation, catchment area, runoff coefficient, surface water inflow, groundwater recharge, ecological sensitivity, vegetation cover, and regional carbon sink baseline. The social resource conditions mentioned include water supply demand, irrigation demand, flood protection targets, transportation accessibility, power availability, distance from residential areas, industrial demand, and planning and control requirements.

3. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, In step S1, one or more of the following methods are used to obtain basic evaluation data: UAV oblique photography, LiDAR measurement, remote sensing imagery, geological drilling, on-site hydrological tests, pumping tests, water injection tests, slope monitoring, water quality testing, and local planning data. The basic evaluation data are then unified to the same coordinate system, the same elevation datum, and the same evaluation period. At least the following functions are established: water level and reservoir capacity function, water level and inundated area function, water level and water-receiving slope length function, and water level and seepage-receiving area function.

4. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, In step S2, the virtual water storage loading sequence is loaded step by step from the starting water level to the target functional water level or the check water level according to the set water level loading step size; The water level loading step size is determined based on the mine pit depth, reservoir capacity curve slope, slope stability sensitivity, and leakage response sensitivity. When the water level and stability response or the water level and leakage response change drastically, the water level loading step size is reduced. For pumped storage reservoirs or combined regulation reservoirs, the evaluation scenario set also includes high-frequency water level fluctuation scenarios.

5. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, In step S3, for positive constraints where larger values ​​for safety factor, available water volume, and flood control capacity are more advantageous, the relative constraint gap is calculated according to the proportion of insufficient threshold. For adverse constraints such as leakage, pollutant concentration, and ecological occupation, where smaller values ​​are more advantageous, the relative constraint gap is calculated based on the excess ratio. For rule-based constraints such as ecological red lines, planning conflicts, and avoidance of major infrastructure, the relative constraint gap is assigned a value of 0 if satisfied and 1 if not satisfied.

6. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, In step S4, the initial suitable water level envelope is the set of water levels that meet the requirements under all rigid constraints and all evaluation scenarios; If the target functional water level falls within the initial suitable water level envelope, the target mine is determined to have the conditions for direct reservoir construction under the current conditions; if the target functional water level does not fall within the initial suitable water level envelope, the process proceeds to the identification of critical water level, dominant gap type, and gap source.

7. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, In step S4, the critical water level is the water level at which any constraint gap first appears during the loading process from the initial water level to the target functional water level; The dominant gap type is determined by the contribution rate of each constraint gap in all gaps. The contribution rate is used to identify slope instability, insufficient seepage prevention, insufficient water volume, insufficient flood storage capacity, substandard water quality, or ecological space conflict caused by rising water levels.

8. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, The slope stability constraint adopts the minimum slope stability safety factor required under reservoir construction or operation conditions as the threshold, and judges whether there is a gap based on the water level and the slope stability safety factor under the evaluation scenario. The slope stability safety factor is obtained through the infinite slope formula, Bishop method, Morgenstern-Price method, finite element strength reduction method or seepage stability coupled numerical analysis, and the effects of water level rise, rapid drop, long-term immersion and pore water pressure change on slope stability are considered in the calculation.

9. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, The seepage control constraints of the reservoir basin are expressed as the leakage rate per unit time, the predicted leakage rate within the control period, or the equivalent permeability coefficient. The water balance constraint is expressed as the difference between rainfall runoff, external water inflow, groundwater recharge, evaporation loss, ecological water demand, and target water demand. The flood storage constraints are expressed as the available flood control capacity between the normal storage level, the operating level, the flood control limit level, or the design flood level. The water quality safety constraints are expressed as the compliance rate of individual water quality indicators, the comprehensive water quality index, or the water quality level for the target purpose. The ecological space constraints are expressed as ecological red line conflicts, basic farmland occupation, and the impact of residents avoiding or protecting species.

10. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, In step S5, the irreparable gap includes one or more of the following: the target reservoir area is located in a prohibited development zone or within an unadjustable ecological protection red line; there is an unmanageable major pollution source; there is a conflict between the mine pit and the major infrastructure that cannot be relocated; there is an unacceptable regional geological disaster risk; and the construction of the reservoir is in conflict with the superior plan. The repairable gaps include constraint gaps that can be eliminated or reduced to an acceptable range through water level adjustment, slope cutting or support, seepage prevention curtains, crack sealing, water quality treatment, flood discharge facilities, or ecological buffer zones.

11. The method for identifying and repairing gaps in abandoned mine reservoirs according to claim 1, characterized in that, In step S6, the water level adjustment variables include the normal water level reduction, the tiered water storage control amount, or the allowable water level rise and fall rate limit. The slope correction variables include the amount of slope cutting, the increase in step width, the anchoring support strength, the slope toe ballast, or the strength of the waterproofing treatment of the weak layer. The seepage prevention correction variables include the depth of the seepage prevention curtain, the length of the curtain, the grouting range, the thickness of the bottom cover or the crack sealing strength; The flood discharge correction variables include the increase in flood discharge capacity, the amount of spillway widening, or the scale of flood discharge channel renovation. The water quality correction variables include the amount of bottom sediment removal, the size of the pre-sedimentation unit, the area of ​​the constructed wetland, or the water circulation and purification capacity. The ecological correction variables include the width of the ecological buffer zone, the proportion of the ecological shoreline, or the area of ​​disturbance recovery.

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