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With abundant mineral resources, many types of mining industry and many mines, mining development in China has led to the decline of groundwater level around the mines, waste of water resources, water quality pollution, surface collapse, land degradation, reduction of vegetation cover, and different degrees of impact on groundwater resources and ecological environment. In order to solve the problems of water waste and ecological damage caused by the lateral recharge of water from the strong seepage loose layer to the mine pit, we proposed a vertical curtain water interception technology with flexible magnetic suction membrane to protect the groundwater resources and ecological environment of coal mines. We firstly studied the performance of the suction membrane material, developed the magnetic absorption suction membrane connection process, and carried out indoor tests of different suction membrane connection processes, then we conducted a 1 369 m strong seepage loose layer water interception curtain field test application in the test mine. The research results show that the impermeable membrane has low permeability coefficient, dense structure, high flexibility, resistance to deformation and durability, and is a good material for water cut, pollution control and seepage control, which can meet the requirements of vertical curtain for the strong seepage loose layer of the mine. The self-developed magnetic suction joint material and connection process solved the problems of shallow laying depth, joint leakage and complicated operation of existing connection processes such as overlapping lap, joint lock and joint box, etc. The construction depth of suction membrane curtain connected by magnetic suction joint is not limited by the connection conditions, and the water interception effect of magnetic suction joint connection process is better than that of overlapping lap and joint lock (joint box) connection process. Through the test of making, laying, connecting and backfilling the curtain into a wall with 2 kinds of flexible magnetic absorbent impermeable membranes, the gap at the joint of the impermeable membrane was reduced from 5-20 cm to 0, and the two adjacent impermeable membranes were closely connected as an organic whole, which reduced the water passage of the interception curtain at the joint. Through the mine-field site test, it was found that the water catchment pits below the curtain which had been filled with strong seepage loose layer water leakage for a long time, had dried up, and the water level of strong seepage loose layer outside the curtain had increased by 5.55-9.12 m, and the water level inside the curtain had decreased by 3.21-5.84 m, so the protection of strong seepage loose layer water resources had achieved good results.

Underground water storage in goaf is one of the important means of water conservation and mining in the western ecologically fragile area. The stability of waterproof sealing wall is related to the safety of water storage in goaf. In view of the key problem that the stability of the waterproof sealing wall in the goaf is difficult to monitor and the water pressure resistance ability is difficult to predict, under the background of underground mining end sealing in Chahasu Coal Mine, by means of theoretical analysis, numerical simulation and field measurement, the mechanical properties of coal seam and roof and floor are tested, and the minimum compressive strength of coal body and roof and floor is obtained. Considering the stress characteristics of the sealing wall structure, the maximum bearing capacity of the waterproof closed wall without the influence of mining is calculated and deduced. The numerical model of waterproof sealing wall is established, and the stress state, deformation and damage of sealing wall under the influence of advanced mining and different water head heights (6, 9, 12 and 15 m) were analyzed. The stress and displacement monitoring systems of the waterproof sealing wall in the underground goaf has been developed. Based on the theoretical analysis, the monitoring points had been reasonably arranged and applied in the field. On this basis, combined with theoretical analysis and numerical simulation results, the maximum safe head height of the waterproof sealing wall and the head height of the warning water line are determined. The results showed that the advance mining has a certain impact on the damage of the waterproof sealing wall, and the water pressure increases the sliding range of the cracks between the sealing wall and the coal pillar contact surface. The maximum water head height borne by the waterproof sealing wall at the end of mining is 12 m, and the water head height of the warning water level line of the waterproof sealing wall is 9.6 m. The contact surface between the wall and the coal pillar as well as the top and bottom corners of the closed wall are structural weak surfaces, which are prone to damage. Attention should be paid to strengthening the monitoring or observation of the position of the sealing wall embedded in the coal and rock mass and the top and bottom corners of the sealing wall. If necessary, grouting and plugging can be used to reinforce the weak surface or leakage part of the structure. The research results can provide theoretical basis and application reference for stability monitoring and water pressure resistance evaluation of similar mine waterproof sealing walls.

Short-wall block backfill mining (SBBM) technology can effectively solve the problems of coal resources waste, water resources loss and gangue waste accumulation. However, after the long-term effect of mine water, the internal heavy metal ions in the gangue backfill materials may be leached, which have a certain potential impact on the groundwater environment in the mining area. Therefore, according to the technical characteristics of SBBM technology, comprehensive prevention of water resources loss and water resources pollution during SBBM was studied systematically. First, prevention and control of water resources loss in the mining area. Based on the combination relationship of “coal pillar, backfill body-barrier layer-aquifuge”, The development of water-conducting fractures in overlying strata under SBBM were analysed. The control mechanism of water resources protection under the evolution of overlying strata structure induced during SBBM was revealed. Secondly, prevention and control of water resources pollution in mining areas. The migration model of heavy metal ions in the gob was established. Then, the pollution mechanism of gangue backfill materials to water resources was revealed, the migration law of heavy metal ions in gangue backfill materials was analyzed, the comprehensive prevention and control technology of water resources destruction in mining area was summarized, the comprehensive prevention and control technology of water resources loss-pollution in mining area was summarized, and the design method of filling ratio based on water resources loss-pollution prevention was put forward. The results show that the gangue materials were filled into the gob as the backfill body, the gangue materials would be the permanent bearing body, which bore the load of the overlying strata accompanied with the protective coal pillar among the blocks, which could greatly prevents the collapse of the low-level stratum, restrict the water-conducting fractures to penetrate the barrier layer and protect the integrity of the high-level stratum. In addition, the heavy metal ions in gangue backfill materials were subjected to the coupled action of seepage, concentration, and stress and then driven by water head pressure and gravitational potential energy to migrate along the side of the coal pillar and below the floor stratum, during which mine water served as the carrier. The migration distance of heavy metal ions increased with increasing of the permeability of floor strata, leaching concentration of heavy metal ions/pollution source intensity, depth of floor breaks and water level heights, and decreases with the increase of gangue particle size and surrounding rock stress. Based on this, the comprehensive prevention and control technology of water resources loss-pollution in mining area was summarized, it included mining parameter control technology, backfill parameter control technology, pollution source control technology, transmission route control technology and in-situ water control technology. and the design method of filling ratio based on water resource loss-pollution prevention and control was put forward, which can realize the comprehensive prevention and control of water resource loss-pollution in mining area. This study will provide scientific theoretical basis and guidance for the comprehensive prevention and control of the water resources destruction problems caused by coal mining.