「Mine Pit · Treatment」

Curtain Water-Cutoff Technique‍

The curtain water-cutoff project at Yuanbaoshan Open-Pit Coal Mine, constructed with the participation of Shanghai Yuanyang, was successfully completed in 87 days. The project adopted the ultra-deep vertical impermeable membrane curtain water-cutoff technique, replacing the traditional extensive pumping and drainage scheme.

At present, the sump below the curtain location, which had long been filled with leakage water from the highly permeable loose layer, has dried up and contains no water. The water level in the highly permeable loose layer outside the curtain is 5.55–9.12 m higher than before the test, while the water level in the highly permeable loose layer inside the curtain is 3.21–5.84 m lower than before the test. The flexible magnetic-attraction impermeable membrane vertical curtain has achieved good application results in the Yuanbaoshan Open-Pit Coal Mine area [1]. The successful construction of the curtain water-cutoff project at Yuanbaoshan Open-Pit Coal Mine has greatly improved the ecological environment around the mining area and reduced the cost of drainage, delivering significant ecological, social, and economic benefits.‍

Curtain Water-Cutoff Project at Yuanbaoshan Open-Pit Coal Mine, 2022

To address the ecological deterioration and high pumping and drainage costs in the Yuanbaoshan mining area, after multiple rounds of bidding, China Coal Technology and Engineering Group Xi'an Research Institute Co., Ltd. selected Shanghai Yuanyang to construct a water-cutoff curtain to achieve permanent water cutoff and retention at the pit walls in the area, thereby reducing the waste of water resources, protecting the local ecological environment, and lowering the cost of mine pit drainage. Based on previous successful curtain water-cutoff construction experience at the Zhanihe Open-Pit Coal Mine, and through in-depth investigation and assessment of the geological conditions of the Yuanbaoshan mining area, our company formulated an HDPE impermeable membrane composite cutoff wall construction scheme after full exchange with technical personnel from the Wuhan Design and Research Institute of China Coal Technology and Engineering Group, supplemented by a practical and reasonable construction organization plan. Under the guidance of the scientific and reasonable construction scheme and organization plan, the Yuanbaoshan Open-Pit Coal Mine curtain water-cutoff project team completed 173 curtain wall panels in 87 days, with a total solid excavation volume of 67,109.68 m³ and an impermeable membrane laying area of 83,887.1 ㎡. To complete this important construction task with high quality, in addition to conventional large-scale foundation construction equipment such as trench cutters and trenching machines, our company also deployed self-developed membrane-laying equipment. The application of the membrane-laying equipment significantly improved membrane-laying efficiency.

During construction, to ensure flat membrane laying, reduce membrane wrinkles, and improve the adhesion between adjacent membrane panels, after multiple tests and demonstrations by the Yuanbaoshan project team and technical personnel from the Xi'an Research Institute of China Coal Technology and Engineering Group, the Yuanbaoshan Open-Pit Coal Mine curtain water-cutoff project team innovatively proposed an underwater magnetic-attraction connection technology for impermeable membranes, changing the natural-adhesion connection method of traditional technology. Its principle is to use male-female magnetic attraction to achieve self-adhesion at the overlapping parts of the impermeable membrane. It features tight connection, wrinkle resistance, and strong integrity [2], enabling the impermeable membrane to better perform its water-cutoff and seepage-prevention role. After the completion of the Yuanbaoshan Open-Pit Coal Mine curtain water-cutoff test project, the quality and water-cutoff effect of the curtain wall were verified by methods such as core sampling verification, flow field analysis, and flow rate changes. The results showed that the concrete pouring and filling were continuous and dense; the water level difference between the inside and outside of the wall had reached more than 15 m; the recharge flow of the blind ditch disappeared, and the water-cutoff effect was significant [3].

The successful construction of the curtain water-cutoff project at Yuanbaoshan Open-Pit Coal Mine not only solved the problems of water resource pollution and waste around the mining area and protected the local ecological environment, but also provided a new, efficient, and environmentally friendly solution for mine pit restoration and treatment, further enriching and improving the mine pit restoration and treatment system. Shanghai Yuanyang will continue to innovate processes and refine technologies, using solid construction strength to support the building of a Beautiful China and effectively improve people's quality of life.

References:

[1] Wang Hai, Huang Xuanming, Zhang Yan, Cao Haidong, Sun Hao, Miao Hechao, Tian Zenglin. Research on vertical curtain water-cutoff technology using flexible magnetic-attraction impermeable membranes in strongly permeable loose layers of mines [J/OL]. Coal Science and Technology: 1-10.

[2] Gao Sheng, Li Guozhi, Guo Yingjie, Tian Zenglin, Shao Dongmei, Zhu Hongjun. Application and effect evaluation of curtain water-cutoff technology in Yuanbaoshan Open-Pit Coal Mine [J]. Coal Geology & Exploration, 2022, 50(07): 28-35.

[3] Gao Sheng, Li Guozhi, Guo Yingjie, Tian Zenglin, Shao Dongmei, Zhu Hongjun. Application and effect evaluation of curtain water-cutoff technology in Yuanbaoshan Open-Pit Coal Mine [J]. Coal Geology & Exploration, 2022, 50(07): 28-35.