甘肃岷县阳坡村大型古滑坡发育特征与稳定性评价

Developmental characteristics and stability simulation ofYangpo Village large-scale ancient landslides in Minxian County,Gansu Province

青藏高原东北缘地质环境条件复杂,在内外动力耦合作用下发育一系列大型—特大型古滑坡,滑坡具有规模大、危害大、复活频繁等特点。位于甘肃岷县的阳坡村滑坡为一大型黄土-泥岩滑坡,该滑坡空间结构复杂、变形强烈。通过野外地质调查、遥感解译、无人机航测、钻探、数值模拟等研究方法,对阳坡村滑坡空间结构和变形特征进行分析,阐明了滑坡变形机制及影响因素。阳坡村滑坡的拉张裂缝等变形集中分布在3个强变形区(I_(1)、I_(2)、I_(3));钻探揭露阳坡村滑坡体发育两级滑带,其中钻孔ZK1揭露滑带位置为9.7~10.5 m和22.0~25.0 m,ZK3揭露滑带位置为10.0~12.3 m和36.0~37.0 m,滑坡体积约465×10^(4)m^(3);数值模拟结果表明,滑坡在一般工况下滑体位移变形量较小,稳定性较好;在暴雨工况下滑坡前缘强变形区产生局部变形,大范围变形可能牵引后部堆积体发生滑动;在地震工况下滑坡复活变形范围与大小较一般工况有明显增大,同时出现多个潜在滑动面,坡体产生多处变形。研究结果为阳坡村滑坡防治提供有效参考,对大型黄土-泥岩滑坡稳定性评价具有一定理论和实际意义。

The northeast edge of the Qinghai−Xizang Plateau has complex geological and environmental conditions,and a series oflarge and very large landslides have been developed in the region under the coupling of internal and external dynamics,which arecharacterised by their large scale,high hazards,and frequent recurrence and resurrection.The landslide in Yangpo Village,MinxianCounty,Gansu Province,is a large loess−mudstone landslide with complex spatial structure characteristics and strong deformation.This paper analyses and reveals the geometric spatial structure and deformation characteristics of the landslide in Yangpo Villag through field geological investigation,remote sensing interpretation,unmanned aerial surveying,drilling,and numerical simulation,andelucidates its deformation and destabilisation mechanism and influencing factors.The results of the study show that;the deformation oftensile cracks and other deformations of the landslide in Yangpo Village is concentrated in three strong deformation zones(I_(1),I_(2),I_(3)).The drilling reveals that the landslide body in Yangpo village develops two levels of slip zones,in which borehole ZK1 reveals slipzones of 9.7~10.5 m and 22.0~25.0 m,and ZK3 reveals slip zones of 10.0~12.3m and 36.0~37.0m,with the volume of the landslide ofabout 465×10^(4)m^(3).Numerical simulation results show that the slide displacement and deformation under the general conditions aresmall,and the stability is relatively good;Under heavy rainfall conditions,the strong deformation area at the leading edge of thelandslide shows obvious signs of local deformation,which may result in unstable sliding,and a wide range of deformation may pull theback of the pile to slide;under seismic conditions,the resurrection deformation range and displacement size of the landslide increasesignificantly compared with the general conditions,and at the same time there are several potential sliding surfaces,which may result inmultiple deformation and multilevel activities of the slope body.The results of the study provide an effective reference for theprevention and control of landslides in Yangpo Village,and have certain theoretical and practical significance for the evaluation of thestability of large loess−mudstone landslides.