A three-dimensional storage method suitable for open-pit mine water

Abstract

The present invention discloses a three-dimensional storage method for open-pit mine water, which belongs to the field of open-pit mining water resource protection technology. The method comprises the following steps: conducting regional geological and hydrogeological surveys of the open-pit mine area to obtain the regional topography and hydrogeological parameters of the open-pit mine area; determining the water inflow and water quality characteristics of the open-pit mine, establishing a dynamic monitoring system for the water inflow and data collection mechanism; planning a three-dimensional storage system for open-pit mine water, determining the water quality standard and storable water volume of the three-dimensional storage system based on the water inflow, and constructing the system according to the process requirements of the three-dimensional storage system; determining the water use path and water use principle of the open-pit mine area, and using the three-dimensional storage system to dynamically store and use water according to the operation plan of the open-pit mine, thereby completing the three-dimensional storage and resource utilization of water resources in the open-pit mine area. The present invention can effectively manage and utilize the water resources of the open-pit mine, improve the utilization rate of water resources, and realize the protection and restoration of groundwater resources.

Description

Technical Field

[0001] The present invention relates to the technical field of open-pit mining water resource protection, and in particular to a three-dimensional storage method suitable for open-pit mine water. Background Art

[0002] Open-pit coal mining generally produces a large amount of mine water, which often causes the loss of groundwater resources within the mining area, the gradual expansion of the drop funnel area, and the gradual increase in the depth of the water level. At the same time, the mine water needs to be drained away in a timely manner to ensure safe production in the mine. Open-pit mines also consume a large amount of production water and ecological water during normal production, and the surrounding areas of the mining area also require a large amount of living, agricultural and ecological water. There is a huge contradiction between the inability to efficiently store mine water in open-pit coal mining and the extreme shortage of production water. The existing open-pit coal mine water storage methods mainly include surface water reservoirs, pit bottom water reservoirs, etc. Large-scale surface water reservoirs and pit bottom water reservoirs have a single water storage method, and it is difficult to store water for a long time and maintain its resource properties. Summary of the Invention

[0003] Technical problem to be solved: In response to the technical problem that water resources cannot be effectively utilized in the open-pit mining process of existing technologies, the present invention provides a three-dimensional storage method suitable for open-pit mine water. Taking into account the geological conditions, hydrogeological conditions and environmental protection needs of the mining area, an advanced three-dimensional storage system is established, which can effectively manage and utilize the water resources of open-pit mines, reduce the negative impact on the environment, improve the recycling efficiency of water resources, and replenish groundwater resources to achieve protection and restoration of groundwater resources.

[0004] Technical solution: The present invention provides a three-dimensional storage method for open-pit mine water, which includes the following steps:

[0005] Step 1: Conduct regional geological and hydrogeological surveys of the open-pit mine area to obtain the topographic and geomorphological parameters of the open-pit mine area, as well as the hydrogeological parameters of the spoil dump, Quaternary aquifer, and bedrock aquifer deep within the coal seam floor;

[0006] Step 2: Determine the water inflow and water quality characteristics of the open pit mine, and establish a dynamic monitoring system and data collection mechanism for the water inflow;

[0007] Step 3: Plan a three-dimensional storage system for open-pit mine water. The three-dimensional storage system includes five types of storage systems: surface water storage system, pit bottom water storage system, spoil dump reconstruction ecological aquifer water storage system, Quaternary loose aquifer water storage system, and coal seam floor deep bedrock aquifer water storage system. Based on the water inflow from the open-pit mine, determine the corresponding water quality standards and storage capacity of the five storage systems, and then carry out construction according to the process requirements of the three-dimensional storage system.

[0008] Step 4: Determine the water use channels and principles in the open-pit mine area. Based on the operation plan of the open-pit mine, use the surface water storage system, pit bottom water storage system, spoil dump reconstruction ecological aquifer water storage system, Quaternary loose aquifer water storage system and coal seam floor deep bedrock aquifer water storage system to dynamically store and use water, and complete the three-dimensional storage and resource utilization of water resources in the open-pit mine area.

[0009] Preferably, the hydrogeological parameters in step 1 include aquifer water level, aquifer permeability, aquifer water storage coefficient, mine water inflow, mine water inflow point, mine mining plan, spoil dump size and spoil dump permeability.

[0010] Preferably, the specific steps for constructing the surface water storage system in step 3 are:

[0011] Step S1: Conducting geological survey of the open-pit mine area to obtain soil type and groundwater level parameters;

[0012] Step S2: planning several water reservoir locations in an area of ​​the open-pit mine where the geological structure is stable, the groundwater level is low, and there are no adverse geological bodies;

[0013] Step S3: Design the volume, depth, and anti-seepage measures of the water reservoir, excavate the water reservoir to form a water reservoir body that meets the design, lay HDPE anti-seepage membrane or concrete lining, and complete the anti-seepage treatment of the pool bottom and pool wall;

[0014] Step S4: Install a drainage system consisting of a water collection well and drainage pipes, and lay out water diversion pipes to drain rainwater and mine water; configure the water reservoir with a pH sensor and a turbidity meter to form an automatic water quality monitoring system, and monitor changes in the water quality of the reservoir;

[0015] Step S5: Establish a regular inspection mechanism for the surface water storage system, clean the sediment in the storage tank and inspect the anti-seepage system.

[0016] Preferably, the specific construction steps of the pit bottom water storage system in step 3 are:

[0017] Step L1: Determine the water accumulation area and estimated water volume at the bottom of the open pit, and design the shape and volume of the water reservoir;

[0018] Step L2: Excavate an open pit-bottom water storage tank, ensure the stability of the water storage tank bottom and surrounding rocks, and use grouting technology to reinforce the water storage tank bottom plate to prevent settlement and leakage; lay HDPE anti-seepage membrane or concrete lining, and complete the anti-seepage layer construction with double-layer waterproof concrete sandwiching the anti-seepage membrane;

[0019] Step L3: Lay out a water circulation system consisting of water diversion pipes and drainage pipes to drain rainwater and mine water; install a fully automatic water level monitor in the reservoir to track the water level in real time;

[0020] Step L4: Establish a regular inspection mechanism for the pit bottom water storage system, clean the sediment in the water storage tank and inspect the anti-seepage system.

[0021] Preferably, the specific construction steps of the dump site reconstruction ecological aquifer water storage system in step 3 are:

[0022] Step M1: Conduct a damage assessment of the thickness, lithology, permeability, and strength of the original aquifer and aquiclude of the open pit, as well as the scope and extent of damage to the open pit. Obtain the hydrogeological parameters of the original aquifer and aquiclude of the open pit through geological exploration, borehole sampling, and indoor testing.

[0023] Step M2: Establish a relationship curve between groundwater depth and vegetation coverage in the open-pit mining area. Based on the relationship curve, design an artificial reconstruction of aquifer thickness and aquiclude depth to maintain ecological water use on the surface of the dump site.

[0024] Step M3: Utilize the clay or bentonite natural materials existing in the mining area in combination with polymer synthetic materials to form a composite aquiclude material with good construction performance as a reconstructed aquiclude. The thickness of the reconstructed aquiclude should be greater than or equal to the thickness of the original aquiclude and connected to the original aquiclude.

[0025] Step M4: Utilize the Quaternary gravel and rock blocks removed from the mining area as aquifer materials. Use grouting pumps and rollers to construct a reconstructed aquifer in the inner dump using the grouting and compaction methods. The thickness of the reconstructed ecological aquifer in the dump should be less than or equal to the thickness of the original aquifer and should be connected to the original aquifer. Ensure that the construction process can effectively fill the voids and cracks in the aquifer.

[0026] Step M5: Construct a phased pile hole press-in type anti-seepage wall or a trench pouring type waterproof wall to prevent the lateral loss of the restored shallow water. The horizontal aquiclude is constructed when the open pit mine is closed;

[0027] Step M6: Carry out quantitative evaluation of parameters and calculation of recharge water volume of the reconstructed ecological aquifer of the spoil dump under different recharge conditions, use GMS numerical simulation software to simulate and calculate the water mixing ratio, runoff velocity and runoff time of the groundwater in the reconstructed ecological aquifer of the spoil dump, study the hydrodynamic field and migration and diffusion laws of characteristic components under the recharge conditions of the reconstructed ecological aquifer of the spoil dump, and carry out slope stability, recharge environmental impact assessment and safe mining impact assessment under the recharge conditions of the reconstructed ecological aquifer of the spoil dump.

[0028] Preferably, after the reconstruction of the ecological aquifer in the spoil dump is completed in step M4, grouting is performed in the slope area to form a reinforced slope to ensure slope stability. The width of the grouting reinforcement area is calculated using the empirical formula for preventing water-blocking coal pillars in water-bearing or water-conducting faults:

[0029] ;

[0030] In the above formula, L is the width of the grouting reinforcement area / m; K is the safety factor, which ranges from 2 to 5; M is the thickness of the ecological aquifer reconstructed by the dump / m; p is the actual head value of the ecological aquifer reconstructed by the dump at the maximum water storage capacity / MPa; K p is the tensile strength of the rock-concrete composite in the grouting reinforcement section / MPa.

[0031] Preferably, the specific steps for constructing the Quaternary loose aquifer water storage system in step 3 are:

[0032] Step N1: Conduct hydrogeological exploration and pumping tests of the shallow Quaternary aquifer in the coal seam roof of the open-pit mine area to identify the hydrogeological parameters and groundwater runoff characteristics of typical recharge areas;

[0033] Step N2: Select an area downstream of the open-pit mine in the direction of groundwater runoff and with high stratum permeability for dewatering water recharge. Construct several recharge wells in the recharge area as injection wells and observation wells. Install automatic groundwater monitoring instruments in the observation wells to conduct online testing of the water level, water temperature, and electrical conductivity of the Quaternary loose aquifer and monitor the water level and water quality during the recharge process. A total of seven injection wells and observation wells are included, with Well No. 1 serving as the injection well and the other six serving as observation wells. The six observation wells are arranged behind the injection well in the form of vertices and midpoints of the sides of an equilateral triangle.

[0034] Step N3: sampling the groundwater of the Quaternary unconsolidated aquifer during the recharge process, and testing the suspended solids, organic matter, microorganisms, and special indicator components of mine water in the water sample;

[0035] Step N4: Conduct quantitative evaluation of parameters under native hydrogeological conditions and different recharge conditions and calculate the recharge water volume. Use GMS numerical simulation software to simulate and calculate the water mixing ratio, runoff velocity, runoff time, and discharge water volume of the Quaternary loose aquifer groundwater. Study the hydrodynamic field and migration and diffusion laws of characteristic components under the recharge conditions of the Quaternary loose aquifer. Conduct environmental impact assessment and safe mining impact assessment of the Quaternary loose aquifer recharge.

[0036] Preferably, the specific steps for constructing the water storage system of the deep bedrock aquifer in the coal seam floor in step 3 are:

[0037] Step M1: Based on the on-site water pressure test phase and past monitoring and testing data, select a location for constructing the ground recharge hole that is convenient for ground water and power supply, close to the reservoir, avoids land acquisition costs, is easy to maintain, and has good permeability in the recharge target layer;

[0038] Step M2: Carry out quantitative evaluation of parameters under original hydrogeological conditions and different reinjection conditions and calculate reinjection water volume. Use GMS numerical simulation software to simulate and calculate the water mixing ratio, runoff velocity, runoff time, and discharge volume of deep groundwater in the coal seam floor. Study the hydrodynamic field and migration and diffusion laws of characteristic components under reinjection conditions of deep aquifers in the coal seam floor. Carry out environmental impact assessment, water inrush hazard classification, and safe mining impact assessment under deep reinjection conditions of the coal seam floor.

[0039] Preferably, the water use in step 4 includes production water in the mining area, ecological water in the mining area, domestic water around the mining area, agricultural water around the mining area, and ecological water around the mining area; the water use principle is to give priority to ensuring production and ecological water in the mining area, and secondly to ensuring domestic water, agricultural water, and ecological water around the mining area.

[0040] Preferably, in step 4, the water storage principle is determined based on the amount of water that can be stored in the mining area, the water use route and the water use principle. During drainage and operation in the open pit, surface water reservoirs and pit bottom water reservoirs are preferentially used for temporary water storage, and used for production and ecological water in the mining area, as well as for living and agricultural water in the surrounding areas of the mining area.

[0041] Secondly, in combination with the different hydrogeological conditions of the open-pit mining area, the construction spoil dump is used to reconstruct the ecological aquifer, the Quaternary loose aquifer and the deep bedrock aquifer in the coal seam floor for recharge and water storage; during the drainage and operation in the open-pit mine, the spoil dump is used to reconstruct the ecological aquifer for water storage, and used as ecological water for the mining area; water is stored through the Quaternary loose aquifer injection wells and the deep aquifer injection wells in the coal seam floor, and used as domestic water, agricultural water and ecological water around the mining area.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] 1. The method for constructing a three-dimensional storage system of the present invention comprehensively considers the geological conditions, hydrogeological conditions, and environmental protection requirements of the mining area to establish an advanced three-dimensional storage system. This system can effectively manage and utilize water resources in open-pit mines, reduce negative impacts on the environment, improve water resource recycling efficiency, and replenish groundwater resources to achieve groundwater resource protection and restoration.

[0044] 2. The three-dimensional storage system of the present invention fully utilizes the surface and pit bottom water storage facilities in the mining area, and combines the ecological aquifer reconstruction in the spoil dump with the shallow aquifer in the coal seam roof and the recharge method of the deep aquifer to form a coordinated system for three-dimensional mine water storage and groundwater resource protection. This can significantly increase the utilization rate of mine water and further maintain the properties of mine water resources. It solves the current problems of single mine water storage methods, susceptibility to pollution, low utilization rate, and difficulty in long-term storage.

[0045] 3. The surface water reservoirs and pit bottom water reservoirs in the mining area of ​​this three-dimensional storage system can temporarily store the open-pit mine water and allocate it at any time for ecological water production in the mining area and water for living and agriculture in the surrounding areas. The ecological aquifer is reconstructed in the spoil dump within the mining area, which is conducive to the reconstruction of damaged strata, optimization of spoil disposal plans and environmental restoration. The recharge of Quaternary groundwater can raise the groundwater level and realize the protection of aquifers and water resources. The recharge of the coal seam floor aquifer provides a deep restoration path for the storage, protection and utilization of water resources in open-pit coal mines.

[0046] 4. The three-dimensional storage system of the present invention helps to improve the safety and stability of mine water storage, reduce the negative impact of open-pit mine water inrush on the ecological environment, improve the storage efficiency of open-pit mine water resources, and realize efficient and multi-channel mine water resource utilization;

[0047] 5. The three-dimensional storage system of the present invention combines the topography and hydrogeological parameters of the mining area, comprehensively plans and utilizes a multi-mode integrated water storage system, effectively reducing the loss of groundwater resources, the area of ​​the drop funnel, and the depth of the water level in open-pit mining, thereby ensuring the long-term management and effective utilization of water resources in open-pit mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a flow chart of the three-dimensional storage method for open pit water of the present invention;

[0049] Figure 2 This is a schematic cross-sectional view of a three-dimensional storage system for open pit water according to the present invention;

[0050] Figure 3 This is a schematic diagram of the layout of water storage and recharging wells and monitoring wells in the Quaternary loose aquifer and the deep bedrock aquifer in the coal seam floor of the present invention;

[0051] Figure 4 Schematic diagram of groundwater flow field in recharge storage of Quaternary loose aquifer.

[0052] Figure numerals: 1. open pit; 2. overburden; 3. original aquifer; 4. original impermeable layer; 5. bedrock; 6. coal seam; 7. surface water storage system; 8. pit bottom water storage system; 9. spoil dump reconstruction ecological aquifer storage system; 10. Quaternary loose aquifer storage system; 11. deep bedrock aquifer storage system in the coal seam floor; 12. recharge well; 13. reinforced slope; 14. reconstructed impermeable layer; 15. Quaternary groundwater flow line; 16. Quaternary loose aquifer recharge well; 17. water cut-off curtain. DETAILED DESCRIPTION

[0053] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following Figures 1 to 4The technical solutions of the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0054] like Figure 2 As shown, open-pit mining of coal mines is a process of excavating shallow coal seams by open-pit mining and forming an open-pit mine 1 at the excavation point. The geological section of the open-pit mine area generally includes, from top to bottom, a covering layer 2, an original aquifer 3, an original impermeable layer 4, bedrock 5, a coal seam 6, and a bedrock aquifer deep in the coal seam floor. In the process of open-pit mining of coal mines, an open-pit mine area will first be formed and the original mined soil and rock will be transferred outside the mining area. As the mining area of ​​the open-pit mine 1 increases and the cost of earthwork transportation is reduced, the working face area opposite to the mining direction of the open-pit mine 1 is used as an internal dumping ground for storing Quaternary gravel and rock blocks stripped from the mining area of ​​the mine, thereby reducing the cost of earthwork transportation and gradually realizing the ecological restoration of the mining area.

[0055] like Figures 1 and 2 As shown, the present invention discloses a three-dimensional storage method suitable for open-pit mine water, which includes the following steps:

[0056] 1. Conduct regional geological and hydrogeological surveys of the open-pit mining area to obtain regional topographic and geomorphological parameters of the open-pit mining area, as well as hydrogeological parameters of the dump, Quaternary aquifer, and bedrock aquifer deep within the coal seam floor. Hydrogeological parameters include aquifer water level, aquifer permeability, aquifer water storage coefficient, mine water inflow, mine water inflow points, mine excavation plan, dump size, and dump permeability. Regional topographic and geomorphological maps of the mining area will be inspected using remote sensing technology to obtain regional topographic and geomorphological maps and stratigraphic histograms. Groundwater level contour maps of the shallow Quaternary aquifer in the coal seam roof, water level contour maps of the deep sandstone confined aquifer in the coal seam floor, and parameters such as mine water inflow and mine water inflow points will be obtained through construction survey drilling.

[0057] Second, determine the water inflow and water quality characteristics of the open pit mine 1, and establish a dynamic monitoring system and data collection mechanism for the mine water inflow. Determine the water quality standards for the mine water inflow and the water quality standards for the five storage systems: surface water storage system 7, pit bottom water storage system 8, waste dump reconstructed ecological aquifer storage system 9, Quaternary unconsolidated aquifer storage system 10, and deep bedrock aquifer storage system 11. Based on the mine water inflow, determine the water storage capacity of each of the five storage systems.

[0058] The following is an example of an open-pit mine in Inner Mongolia:

[0059] A large amount of mine water gushed out during mining at an open-pit mine in Inner Mongolia. Limited water storage locations and imperfect water storage methods resulted in a significant amount of water wasted. Simultaneously, large amounts of drainage caused the groundwater level in the predominantly water-filled Quaternary loose aquifer within 5 km of the mine to drop by more than 30 meters. Furthermore, severe water leakage from the mine's spoil dump, due to stripping deposits, made ecological restoration of the dump difficult. To alleviate water use issues in the mine and surrounding areas during production, as well as ecological restoration of the spoil dump and groundwater levels in the Quaternary aquifer after mine closure, the present invention employed a method for constructing a three-dimensional storage system for an open-pit mine, achieving safe and efficient storage and utilization of mine water resources.

[0060] The mine water inflow is about 84,000m 3 / d, and established a dynamic monitoring system for mine water inflow, and determined the water quality characteristics of mine water inflow as shown in Table 1.

[0061] Table 1 Water quality characteristics of mine water inflow:

[0062] .

[0063] 3. Plan a three-dimensional storage system for open-pit mine water and carry out construction according to the process requirements of the three-dimensional storage system.

[0064] The three-dimensional storage system includes five storage systems: surface water storage system 7, pit bottom water storage system 8, spoil dump reconstruction ecological aquifer water storage system 9, Quaternary loose aquifer water storage system 10 and coal seam floor deep bedrock aquifer water storage system 11. Combined with the water inflow of the open-pit mine 1, the corresponding water quality standards and storable water volume of the five storage systems are determined.

[0065] Surface water storage system 7 and pit-bottom water storage systems have no additional requirements for stored water quality. The primary source of mine water inflow is the Quaternary aquifer. Therefore, both the reconstructed ecological aquifer in the spoil dump and the Quaternary unconsolidated aquifer can be used to store mine water. Mine water quality is superior to that of the coal seam floor aquifer, so the deep bedrock aquifer beneath the coal seam floor can also be used to store mine water. The mine water inflow volume of open pit 1 was used to determine the storage capacity of each of the five storage systems.

[0066] 1. Specific construction steps of surface water storage system 7.

[0067] Conduct geological surveys of the open-pit mine area to obtain soil type and groundwater level parameters, plan multiple reservoir locations in the eastern wing of the open-pit mine area, where the geological structure is stable, the groundwater level is low, and there are no adverse geological bodies; and design the volume, depth, and anti-seepage measures of the reservoirs.

[0068] The surface water storage system 7 has three water storage tanks, each with a length, width and height of 70m, 20m and 2m respectively, with a capacity of about 2800m3 Excavate the water reservoir to form a water reservoir body that meets the design, lay HDPE anti-seepage membrane or concrete lining, and complete the anti-seepage treatment of the pool bottom and pool wall.

[0069] Install a drainage system consisting of collection wells and drainage pipes, and lay water diversion pipes to divert rainwater and mine water. Install an automatic water quality monitoring system with pH sensors and turbidity meters in the reservoirs to monitor changes in water quality. Establish a regular inspection mechanism for the surface water storage system, clean out sediment in the reservoirs, and inspect the anti-seepage system.

[0070] 2. Specific construction steps of the pit bottom water storage system 8.

[0071] Determine the water accumulation area and estimated water volume at the bottom of open pit 1, and design the shape and volume of the reservoir. Excavate the open pit reservoir, ensuring the stability of the reservoir bottom and surrounding rock. Use grouting to reinforce the reservoir floor to prevent subsidence and leakage. Lay an HDPE impermeable membrane or concrete lining, using a double layer of waterproof concrete sandwiched between the impermeable membrane, to complete the anti-seepage layer. Lay a water circulation system consisting of diversion pipes and drainage pipes to drain rainwater and mine water. Install a fully automatic water level monitor in the reservoir to track the water level in real time. Establish a regular inspection mechanism for the pit reservoir system, clean the reservoir of sediment, and inspect the anti-seepage system.

[0072] 3. Specific construction steps for the reconstruction of the ecological aquifer water storage system 9 of the spoil dump.

[0073] A damage assessment is conducted on the thickness, lithology, permeability, strength of the original aquifer and original aquiclude of the open pit 1, as well as the scope and extent of damage to the open pit 1. The hydrogeological parameters of the original aquifer 3 and original aquiclude 4 of the open pit 1 are obtained through geological exploration, drilling sampling, and indoor testing.

[0074] A relationship curve between the groundwater level depth and vegetation coverage in the open-pit mining area was established. Based on the relationship curve, the thickness of the artificially reconstructed aquifer and the depth of the aquiclude were designed to determine that the groundwater level should be less than 1.5m deep and the aquiclude should be within 1.5m of the surface of the dumping site to maintain ecological water use on the surface of the dumping site.

[0075] The reconstructed aquiclude 14 is formed by combining natural clay or bentonite materials in the mining area with polymer synthetic materials to form a composite aquiclude material with good construction performance. The thickness of the reconstructed aquiclude 14 should be greater than or equal to the thickness of the original aquiclude and connected to the original aquiclude.

[0076] The Quaternary gravel and rock blocks removed from the mining area are used as aquifer materials. Grouting pumps and rollers are used to construct the dump site reconstructed aquifer in the inner dump site by grouting and compaction methods. The thickness of the ecological aquifer reconstructed in the dump site should be less than or equal to the thickness of the original aquifer and connected to the original aquifer. The construction process should ensure that the gaps and cracks in the aquifer are effectively filled. After the construction of the ecological aquifer reconstructed in the dump site is completed, grouting is performed in the slope area to form a reinforced slope 13 to ensure slope stability. The width of the grouting reinforcement area is calculated using the empirical formula for water-bearing or water-conducting fault anti-water-blocking coal (rock) pillars:

[0077] .

[0078] In a specific embodiment, L is the width of the grouting reinforcement area / m; K is the safety factor, which is 5; M is the thickness of the ecological aquifer reconstructed in the spoil dump / m, which is 60m; p is the actual head value at the maximum water storage capacity of the ecological aquifer reconstructed in the spoil dump / MPa, which is 0.6MPa; Kp is the tensile strength of the rock-concrete composite in the grouting reinforcement section / MPa, which is 4.0MPa. The construction width of the slope grouting reinforcement area for the ecological aquifer reconstructed in the spoil dump is 100.6m.

[0079] Construct phased pile-hole pressure-type anti-seepage walls or trench-filled waterproof walls to prevent lateral loss of restored shallow water. The horizontal aquiclude is completed when the open-pit mine is closed. Quantitative evaluation of parameters and calculation of recharge water volume are conducted for the reconstructed ecological aquifer in the spoil dump under different recharge conditions. GMS numerical simulation software is used to simulate and calculate the water mixing ratio, runoff velocity, and runoff time of the groundwater in the reconstructed ecological aquifer in the spoil dump. The hydrodynamic field and migration and diffusion patterns of characteristic components in the reconstructed ecological aquifer under recharge conditions are studied. Slope stability, recharge environmental impact assessment, and safe mining impact assessment are conducted under recharge conditions for the reconstructed ecological aquifer in the spoil dump.

[0080] 4. Specific construction steps of the Quaternary loose aquifer water storage system 10.

[0081] Conduct hydrogeological exploration and pumping tests of the shallow Quaternary aquifers in the coal seam roof of the open-pit mine area to identify the hydrogeological parameters and groundwater runoff characteristics of typical recharge areas;

[0082] The east side of the open pit 1, which is located downstream of the open pit mine and has strong stratum permeability, was selected to carry out drainage water recharge. Multiple recharge wells 12 were constructed in the recharge area as injection wells and observation wells. Automatic groundwater monitoring instruments were installed in the observation wells to conduct online testing of the water level, water temperature, and electrical conductivity data of the Quaternary loose aquifer, and to carry out water level and water quality monitoring during the recharge process. Figure 3 As shown, there are 7 wells in total, including injection wells and observation wells. Well No. 1 is used as an injection well, and the recharge water volume can reach 200m3 / h, and the other 6 wells are observation wells, and the 6 observation wells are arranged on the rear side of the injection well in the form of vertices and midpoints of the sides of an equilateral triangle; the full diameter of the injection well is Φ450mm, and a Φ273mm diameter casing and a Φ273mm diameter filter tube are inserted; the full diameter of the monitoring well is Φ330mm, and a Φ108mm diameter casing and a Φ108mm diameter filter tube are inserted.

[0083] During the recharge process of the Quaternary loose aquifer, samples of the aquifer groundwater were taken to test the suspended matter, organic matter, microorganisms, and special indicator components of mine water in the water samples. The overall water quality of the Quaternary drainage was better than that of the mine water, which confirmed that the Quaternary drainage could be used for "raw water recharge" during the Quaternary recharge.

[0084] like Figure 4 The schematic diagram of the groundwater flow field of the Quaternary loose aquifer recharge storage is shown in the figure. The original hydrogeological conditions and the quantitative evaluation of the parameters under different recharge conditions and the recharge water volume calculation are carried out. The water mixing ratio, runoff velocity, runoff time and discharge volume of the Quaternary loose aquifer groundwater are simulated and calculated using the GMS numerical simulation software. The hydrodynamic field and the migration and diffusion laws of the characteristic components under the recharge conditions of the Quaternary loose aquifer are studied. It is determined that a single well of 200m is carried out downstream of the overall groundwater flow direction, that is, outside the water cut-off curtain 17 on the east side of the open pit 1. 3 The Quaternary loose aquifer water storage system 10 with a recharge volume of / d, the Quaternary loose aquifer recharge well 16 and the Quaternary groundwater flow line 15 are as follows Figure 4 Carry out the environmental impact assessment of the Quaternary loose aquifer recharge and the impact assessment of safe mining, with a single well of 200m 3 The / d recharge scheme has little impact on the drainage of open pit 1.

[0085] 5. Specific construction steps of the deep bedrock aquifer water storage system 11 in the coal seam floor.

[0086] Based on the on-site water pressure test phase and past monitoring and inspection data, the ground recharge hole was constructed in the east wall area of ​​open-pit mine 1, which is convenient for ground water and power supply, close to the water reservoir, avoids land acquisition costs, is easy to maintain, and has good permeability of the recharge target layer.

[0087] Carry out quantitative evaluation of parameters under original hydrogeological conditions and different reinjection conditions and calculate reinjection water volume. Use GMS numerical simulation software to simulate and calculate the water mixing ratio, runoff velocity, runoff time and discharge volume of deep groundwater in the coal seam floor. Study the hydrodynamic field and migration and diffusion laws of characteristic components under the reinjection conditions of deep aquifers in the coal seam floor. Carry out environmental impact assessment, water inrush hazard classification and safe mining impact assessment under the conditions of deep reinjection of the coal seam floor.

[0088] 4. Determine the water use channels and principles for the open-pit mine area. Based on the operation plan of the open-pit mine 1, utilize the surface water storage system 7, the pit bottom water storage system 8, the spoil dump reconstructed ecological aquifer water storage system 9, the Quaternary loose aquifer water storage system 10, and the coal seam floor deep bedrock aquifer water storage system 11 to dynamically store and use water, thereby completing the three-dimensional storage and resource utilization of water resources in the open-pit mine area.

[0089] Water use channels include production water in the mining area, ecological water in the mining area, domestic water in the mining area, agricultural water in the mining area, and ecological water in the mining area. The water use principle prioritizes production and ecological water in the mining area, followed by domestic water, agricultural water, and ecological water in the mining area.

[0090] The water storage principle is determined based on the amount of water that can be stored in the mining area, the water use route, and the water use principle. During the drainage and operation period in the open pit 1, surface water reservoirs and pit bottom water reservoirs are preferentially used for temporary water storage, and the water is used for production and ecological use in the mining area, as well as for domestic and agricultural use in the surrounding areas. Secondly, in combination with the different hydrogeological conditions of the open pit mining area, the ecological aquifer, the Quaternary loose aquifer, and the deep bedrock aquifer in the coal seam floor are reconstructed using the construction spoil dump for recharge and storage; during the drainage and operation period in the open pit 1, the ecological aquifer is reconstructed using the spoil dump for storage, and the water is used for ecological use in the mining area; water is stored through the Quaternary loose aquifer injection well and the deep aquifer injection well in the coal seam floor, and the water is used for domestic, agricultural, and ecological use in the surrounding areas.

[0091] The three-dimensional storage system constructed by the present invention can effectively restore the aquifers and impermeable layers destroyed by open-pit mining operations, and establish hydraulic connections with the original aquifers. The rapid recovery of Quaternary groundwater after replenishment can raise the groundwater level, thereby improving the three-dimensional storage efficiency of open-pit mine water, effectively reducing the loss of groundwater resources, the area of ​​the drop funnel and the depth of the water level drop in open-pit mining, and realizing high-efficiency, multi-channel and long-term utilization of mine water resources.

[0092] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A three-dimensional storage method for open pit water, characterized in that: The three-dimensional storage method comprises the following steps: Step 1: Conduct regional geological and hydrogeological surveys of the open-pit mine area to obtain the topographic and geomorphological parameters of the open-pit mine area, as well as the hydrogeological parameters of the spoil dump, Quaternary aquifer, and bedrock aquifer deep within the coal seam floor; Step 2: Determine the water inflow and water quality characteristics of the open pit (1), and establish a dynamic monitoring system for the water inflow and a data collection mechanism; Step 3: Plan a three-dimensional storage system for open pit water. The three-dimensional storage system includes five types of storage systems: surface water storage system (7), pit bottom water storage system (8), spoil dump reconstruction ecological aquifer water storage system (9), Quaternary loose aquifer water storage system (10), and coal seam floor deep bedrock aquifer water storage system (11). Combined with the water inflow of the open pit (1), determine the corresponding water quality standards and storable water volume of the five storage systems, and carry out construction according to the process requirements of the three-dimensional storage system. Step 4: Determine the water use pathways and principles in the open-pit mine area. Based on the operation plan of the open-pit mine (1), use the surface water storage system (7), pit bottom water storage system (8), spoil dump reconstruction ecological aquifer water storage system (9), Quaternary loose aquifer water storage system (10) and coal seam floor deep bedrock aquifer water storage system (11) to dynamically store and use water, thus completing the three-dimensional storage and resource utilization of water resources in the open-pit mine area.

2. The three-dimensional storage method for open-pit mine water according to claim 1, characterized in that: The hydrogeological parameters in step 1 include aquifer water level, aquifer permeability, aquifer water storage coefficient, mine water inflow, mine water inflow point, mine mining plan, spoil dump size and spoil dump permeability.

3. The three-dimensional storage method for open-pit mine water according to claim 2, characterized in that: Specific construction steps of the surface water storage system (7) in step 3: Step S1: Conducting geological survey of the open-pit mine area to obtain soil type and groundwater level parameters; Step S2: planning several water reservoir locations in an area of ​​the open-pit mine where the geological structure is stable, the groundwater level is low, and there are no adverse geological bodies; Step S3: Design the volume, depth, and anti-seepage measures of the water reservoir, excavate the water reservoir to form a water reservoir body that meets the design, lay HDPE anti-seepage membrane or concrete lining, and complete the anti-seepage treatment of the pool bottom and pool wall; Step S4: Install a drainage system consisting of a water collection well and drainage pipes, and lay out water diversion pipes to drain rainwater and mine water; configure the water reservoir with a pH sensor and a turbidity meter to form an automatic water quality monitoring system, and monitor changes in the water quality of the reservoir; Step S5: Establish a regular inspection mechanism for the surface water storage system (7), clean the sediment in the storage tank and inspect the anti-seepage system.

4. The three-dimensional storage method for open-pit mine water according to claim 3, characterized in that: The specific construction steps of the pit bottom water storage system (8) in step 3 are: Step L1: Determine the water accumulation area and estimated water volume at the bottom of the open pit (1), and design the shape and volume of the water reservoir; Step L2: Excavate an open pit-bottom water storage tank, ensure the stability of the water storage tank bottom and surrounding rocks, and use grouting technology to reinforce the water storage tank bottom plate to prevent settlement and leakage; lay HDPE anti-seepage membrane or concrete lining, and complete the anti-seepage layer construction with double-layer waterproof concrete sandwiching the anti-seepage membrane; Step L3: Lay out a water circulation system consisting of water diversion pipes and drainage pipes to drain rainwater and mine water; install a fully automatic water level monitor in the reservoir to track the water level in real time; Step L4: Establish a regular inspection mechanism for the pit bottom water storage system, clean the sediment in the water storage tank and inspect the anti-seepage system.

5. The three-dimensional storage method for open-pit mine water according to claim 4, characterized in that: The specific construction steps of the ecological aquifer water storage system (9) of the dump in step 3 are as follows: Step M1: Conduct damage assessment on the thickness, lithology, permeability, strength of the original aquifer and the original aquiclude of the open pit (1), as well as the scope and extent of damage to the open pit (1), and obtain the hydrogeological parameters of the original aquifer (3) and the original aquiclude (4) of the open pit (1) through geological exploration, drilling sampling, and indoor testing; Step M2: Establish a relationship curve between groundwater depth and vegetation coverage in the open-pit mining area. Based on the relationship curve, design an artificial reconstruction of aquifer thickness and aquiclude depth to maintain ecological water use on the surface of the dump site. Step M3: using clay or bentonite natural materials existing in the mining area in combination with polymer synthetic materials to form a composite aquiclude material with good construction performance as a reconstructed aquiclude (14). The thickness of the reconstructed aquiclude (14) should be greater than or equal to the thickness of the original aquiclude and connected to the original aquiclude; Step M4: Utilize the Quaternary gravel and rock blocks removed from the mining area as aquifer materials. Use grouting pumps and rollers to construct a reconstructed aquifer in the inner dump using the grouting and compaction methods. The thickness of the reconstructed ecological aquifer in the dump should be less than or equal to the thickness of the original aquifer and should be connected to the original aquifer. Ensure that the construction process can effectively fill the voids and cracks in the aquifer. Step M5: Construct a phased pile hole press-in type anti-seepage wall or a trench pouring type waterproof wall to prevent the lateral loss of the restored shallow water. The horizontal aquiclude is constructed when the open pit mine is closed; Step M6: Carry out quantitative evaluation of parameters and calculation of recharge water volume of the reconstructed ecological aquifer of the spoil dump under different recharge conditions, use GMS numerical simulation software to simulate and calculate the water mixing ratio, runoff velocity and runoff time of the groundwater in the reconstructed ecological aquifer of the spoil dump, study the hydrodynamic field and migration and diffusion laws of characteristic components under the recharge conditions of the reconstructed ecological aquifer of the spoil dump, and carry out slope stability, recharge environmental impact assessment and safe mining impact assessment under the recharge conditions of the reconstructed ecological aquifer of the spoil dump.

6. The three-dimensional storage method for open-pit mine water according to claim 5, characterized in that: After the reconstruction of the ecological aquifer in the spoil dump is completed in step M4, grouting is performed in the slope area to form a reinforced slope (13) to ensure the stability of the slope. The width of the grouting reinforcement area is calculated using the empirical formula for preventing water-blocking coal pillars in water-bearing or water-conducting faults: ； In the above formula, L is the width of the grouting reinforcement area / m; K is the safety factor, which ranges from 2 to 5; M is the thickness of the ecological aquifer reconstructed by the dump / m; p is the actual head value of the ecological aquifer reconstructed by the dump at the maximum water storage capacity / MPa; K p is the tensile strength of the rock-concrete composite in the grouting reinforcement section / MPa.

7. The three-dimensional storage method for open-pit mine water according to claim 1, characterized in that: The specific construction steps of the Quaternary loose aquifer water storage system (10) in step 3 are: Step N1: Conduct hydrogeological exploration and pumping tests of the shallow Quaternary aquifer in the coal seam roof of the open-pit mine area to identify the hydrogeological parameters and groundwater runoff characteristics of typical recharge areas; step N2: Select an area downstream of the open-pit mine in the direction of groundwater runoff and with high stratum permeability to carry out drainage water recharge. In the recharge area, construct several recharge wells (12) as injection wells and observation wells. Install groundwater automatic monitoring instruments in the observation wells to test the water level, water temperature, and electrical conductivity of the Quaternary loose aquifer online and carry out water level and water quality monitoring during the recharge process. Among them, there are a total of 7 wells for injection and observation. Well No. 1 is used as an injection well, and the other 6 wells are observation wells. The 6 observation wells are arranged behind the injection well in the form of vertices and midpoints of the sides of an equilateral triangle. Step N3: sampling the groundwater of the Quaternary unconsolidated aquifer during the recharge process, and testing the suspended solids, organic matter, microorganisms, and special indicator components of mine water in the water sample; Step N4: Conduct quantitative evaluation of parameters under native hydrogeological conditions and different recharge conditions and calculate the recharge water volume. Use GMS numerical simulation software to simulate and calculate the water mixing ratio, runoff velocity, runoff time, and discharge water volume of the Quaternary loose aquifer groundwater. Study the hydrodynamic field and migration and diffusion laws of characteristic components under the recharge conditions of the Quaternary loose aquifer. Conduct environmental impact assessment and safe mining impact assessment of the Quaternary loose aquifer recharge.

8. The three-dimensional storage method for open-pit mine water according to claim 1, characterized in that: The specific construction steps of the deep bedrock aquifer water storage system (11) in the coal seam floor in step 3 are: Step M1: Based on the on-site water pressure test phase and past monitoring and testing data, select a location for constructing the ground recharge hole that is convenient for ground water and power supply, close to the reservoir, avoids land acquisition costs, is easy to maintain, and has good permeability in the recharge target layer; Step M2: Carry out quantitative evaluation of parameters under original hydrogeological conditions and different reinjection conditions and calculate reinjection water volume. Use GMS numerical simulation software to simulate and calculate the water mixing ratio, runoff velocity, runoff time, and discharge volume of deep groundwater in the coal seam floor. Study the hydrodynamic field and migration and diffusion laws of characteristic components under reinjection conditions of deep aquifers in the coal seam floor. Carry out environmental impact assessment, water inrush hazard classification, and safe mining impact assessment under deep reinjection conditions of the coal seam floor.

9. The three-dimensional storage method for open-pit mine water according to any one of claims 1 to 8, characterized in that: The water use channels in step 4 include production water in the mining area, ecological water in the mining area, domestic water around the mining area, agricultural water around the mining area, and ecological water around the mining area; the water use principle is to give priority to ensuring production and ecological water in the mining area, and secondly to ensuring domestic water, agricultural water, and ecological water around the mining area.

10. The three-dimensional storage method for open-pit mine water according to claim 9, characterized in that: In step 4, the water storage principle is determined based on the amount of water that can be stored in the mining area, the water use route and the water use principle. During the drainage and operation period of the open pit (1), surface water reservoirs and pit bottom water reservoirs are preferably used for temporary water storage, and used for production and ecological water in the mining area, as well as for living and agricultural water in the surrounding areas of the mining area. Secondly, in combination with the different hydrogeological conditions of the open-pit mine area, the ecological aquifer, the Quaternary loose aquifer and the deep bedrock aquifer of the coal seam floor are reconstructed by using the spoil dump during construction to recharge and store water; the ecological aquifer is reconstructed by using the spoil dump during the drainage and operation of the open-pit mine (1) and used as ecological water for the mining area; water is stored through the injection wells of the Quaternary loose aquifer and the deep aquifer of the coal seam floor, and used as domestic water, agricultural water and ecological water around the mining area.

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