露天坑排尾对采空区影响的数学预测及其稳定性

摘要

To reveal the impact of the height of the tailing dry stacked gangue (H) on the span of double gob area (D) and the roof thickness (h), the simulation software FLAC3D was used to simulate the excavation process of the double gob area of different spans during the tailing-backfilling process.The stress, plastic zones and the displacement of monitoring points of double gob area were analyzed by combining with the hyperbolic fitting equations, traditional failure criterion and the thickness reduction methods.When D is kept constant, tensile and compressive stress and the plastic zone area increase with the increase of H, and the displacement of all monitoring points increase significantly when the span is larger than 20 m.When H is kept constant, the displacement and the plastic zone area increase with the increase of D, and it can be quantitatively predicted that when the span is up to 26 m, the critical damage height of tailing dry stacked gangue is 182.44 and 189.85 m, respectively.When D and H are changed, the plastic zones of the double gob area take on a butterfly-shape, and the plastic zone area of the upper gob is greater than that of the lower part.A cutting-through failure will occur when the span exceeds 20 m and the tailing height exceeds 150 m.%为揭示露天坑干堆排尾堆高(H)对采空区跨度(D)与境界顶柱高(h)的影响,采用FLAC3D对不同跨度的双空区在尾砂回填过程中进行开挖模拟,并结合曲线拟合、传统破坏判据及厚度折减法,分别对地下双空区的受力、塑性区及关键点位移等特征进行分析及数学预测.研究表明:当D不变时,拉、压应力及塑性区面积均随H的增大而增加,且在D>20 m后位移变化率明显增大;当H不变时,监测位移和塑性区随D增大而增加,且定量预测出D=26 m时,上下空区临界破坏对应的H分别为182.44,189.85 m.当D与H均变化时,双空区的塑性区逐渐呈现"蝴蝶状",上部空区的塑性区域明显大于下部,且在D>20 m,H>150 m时,上部空区出现与露天坑底贯穿现象.