ISSN 1000-3665 CN 11-2202/P

    基于InSAR技术的缓倾煤层开采诱发顺层岩体地表变形模式研究

    A study of deformation mode and formation mechanism of abedding landslide induced by mining of gently inclined coal seam based on InSAR technology

    • 摘要: 贵州贞丰县某煤矿开采煤层以向斜缓倾的三叠系上统火把冲组(T3h)为主,与贵州省大部分煤矿开采的背斜反倾煤层不同,其采矿活动诱发的地面沉降和滑坡风险亦表现出不同的变形破坏模式(背斜反倾煤层易诱发倾倒崩塌、顺层缓倾煤层易诱发地面塌陷与滑坡)。论文利用升、降轨观测的共15期3 m空间分辨率L波段PALSAR -2 SAR为数据源,开展了多期地表变形D -InSAR测量,确定出变形发生的位置、范围与滞后时间。经实地调查验证,InSAR解算结果较好地吻合了矿区开采范围和地表破坏情况,证实了InSAR在煤矿区识别时序性地表形变的准确性。进而分解计算了地表三维变形,并通过与地下开采范围和过程的相关性分析,深化了对该地区缓倾煤层地下开采诱发的顺层滑坡变形模式的认识:(1)InSAR可以识别计算出采矿区地表变形的范围与沉降量,矿区变形在干涉影像中表现为以采空区地表为中心向四周扩散的圆环状变形条纹;(2)地表变形区域覆盖地下采空区上方及附近地表区域,根据地表变形情况与地下采空区范围计算出该地区上山边界角约70°、下山边界角约58°;(3)地下采空与地表沉降变形存在约30 d的时间滞后;(4)顺层地下采空引发的地表水平移动方向受地层产状、地表坡向共同作用,水平向为沿层面的顺层滑移与向沉降中心汇聚的合成运动结果;(5)沿层面的顺层滑移与地表坡度因素叠加造成采空区地表上山侧岩石受拉产生拉裂缝,下山侧则易产生塌陷坑及裂缝。

       

      Abstract: The coal seam of a coal mine in Zhenfeng county in Guizhou Province is dominated by the synclinal gently dipping Upper Triassic Torch Group (T3h), which is different from the anticlinal gently dipping coal seam of the most coal mines in Guizhou. The ground subsidence and landslide risks induced by mining activities also show different deformation and failure modes. In this paper, PALSAR -2 SAR with a total spatial resolution of 3 m and L -band in 15 periods of orbit ascending and descending observations is used as the data source to carry out D -InSAR measurements of surface deformation in multiple periods, and the location, range and lag time of deformation are determined. Through field investigation and verification, the InSAR calculation results are well consistent with the mining area and the surface damage situation, confirming the accuracy of InSAR in identifying temporal surface deformation in the coal mine area. Furthermore, the 3D surface deformation is decomposed and calculated, and the correlation analysis with the underground mining scope and process deepens the understanding of the bedding landslide deformation mode and formation mechanism induced by the underground mining of gently inclined coal seam in this area. The results show that (1) InSAR can identify and calculate the surface deformation range and settlement of the mining area, and the deformation of the mining area is shown in the interference image as a circular ring deformation fringe with the surface of the goaf as the center and spreading around. (2) The surface deformation area covered the region above the underground mined -out area and areas near the surface, and according to the scope of the surface deformation condition and underground mined -out area in the region the mountain border angle is calculated as about 70°, and the mountain border angle, about 58°. (3) There is a time lag of about 30 d between the underground mining and surface subsidence deformation. (4) The horizontal movement direction of the surface caused by underground mining in bedding strata is affected by the occurrence of strata and the direction of surface slope, and the horizontal direction is the resultant movement result of bedding slip along the bedding strata and convergence to the settlement center. (5) The overlying bedding slip along the plane and surface slope factors results in the tension fracture of the rock on the surface of the goaf on the uphill side, while the subsidence pit and fracture are not easy to occur on the downhill side.

       

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