固废基土质覆盖层水气响应与隔氧性能:从土柱试验到现场示范

    Hydraulic response and oxygen barrier performance of earthen cover constructed with solid wastes: from soil column test to field demonstration

    • 摘要: 酸性废水削减对矿山与尾矿堆场生态修复至关重要,研发固废基土质覆盖层对于防渗、隔氧与酸性废水源头削减具有重要的科学与工程价值。采用典型固废构建毛细阻滞复合防渗型土质覆盖层,通过土柱试验与现场示范研究其防渗隔氧性能。室内试验表明42 d干旱条件下此覆盖层的氧气通量仅为0.48 mol/(m2·a),低于北美控制标准2 mol/(m2·a);在施加的华南湿润区50 a一遇的暴雨下,底部未渗漏。后续在金矿酸性固废堆场开展了国内首个30 m×40 m大尺寸现场示范,1 a的监测期内总降雨量1193.2 mm,覆盖层底部累计渗漏量20.0 mm/a,满足北美控制标准30 mm/a;期间的年均氧气通量为0.75 mol/(m2·a);试验区域植被复绿度100%。这表明固废基土质覆盖层在中国酸性固废场地防渗隔氧与酸性废水源头削减的应用前景广阔。

       

      Abstract: Reducing the source of acid mine drainage is very important for the ecological restoration of acid mines and tailings dumps, the research and development of earthen cover constructed with solid wastes is of great scientific and engineering value for achieving seepage prevention, oxygen barrier and reducing generation of acidic mine drainage. In this paper, typical solid wastes are used to construct a composite earthen cover, and its performances in reducing water percolation and oxygen entry are also studied through soil column test and field demonstration. Soil column test results show that the oxygen flux of this earthen cover is 0.48 mol/(m2·a); no bottom leakage is found in the cover after applying an extreme rainfall with 50-year return period in the humid area of southern China. Thereafter, the first full-scale test of earthen cover constructed using solid wastes is built in acid mining dumps. During the one-year monitoring period, the total rainfall is 1193.2 mm, and the cumulative leakage is 20.0 mm. The oxygen flux during monitoring is 0.75 mol/(m2·a). The revegetation in the experimental area is 100%. These results show that the earthen cover constructed with solid wastes has broad application prospects in reducing water percolation and oxygen entry at the base of the cover in acid solid waste dumps, leading to a significant reduction of acid mine drainage.

       

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