三峡库区典型滑坡地质与地球物理电性特征

Geological and Geophysical Electric Characteristics of Typical Landslides in Three Gorges Reservoir

滑坡属于地质灾害中的重要灾种之一,查明滑坡区的地质与地球物理特征,对分析滑坡形成机制、评价滑坡稳定性具有重要意义。鉴于此,本文将高密度电法引入三峡库区腹地万州区滑坡地质调查中,在区内四方碑滑坡、塘角1号滑坡和麻柳林滑坡进行地球物理探测工作,并结合钻孔资料对实测结果进行对比验证。实测结果表明:在地形复杂地区开展地球物理探测工作,通过数据反演与分析,可获取滑坡体地层结构及滑移面;结合相关地质资料,通过对比解译,可弥补单纯依靠钻孔信息来确定滑移面形态的不足;3个典型滑坡区地球物理实测资料揭露滑坡体和滑床地球物理电性特征表现为,由崩坡积物、第四系粉质黏土以及含水碎石块组成的滑坡体电阻率低于40Ω·m,而由砂岩与泥岩组成的滑床电阻率高于40Ω·m,高密度电法对基岩滑坡和土质滑坡都能获取较好的结果。

Landslide is one of the most important types of geological hazards.It is of great significance to find out the geological and geophysical characteristics of a landslide area for analyzing the formation mechanism of a landslide and evaluating its stability.In view of this,the high-density resistivity method was first introduced into the landslide geological survey of Wanzhou area in the hinterland of the Three Gorges Reservoir area,and the geophysical exploration of Sifangbei landslide,Tangjiao No.1 landslide,and Maliulin landslide was carried out in the area.The measured results were compared and verified with borehole data.Through data inversion and analysis,the stratum structure and slip surface of landslide bodies are obtained;By combining with the relevant geological data and comparative interpretation,it can make up for the deficiency of only relying on borehole information to determine the shape of slip surface;According to the measured data of the three typical landslide areas,the geophysical and electrical characteristics of landslide mass and sliding bed are as follows,resistivity of landslide mass composed of colluvium,quaternary silty clay and water bearing gravel block is less than 40Ω·m,while resistivity of sliding bed composed of sandstone and mudstone is more than 40Ω·m.It is proved that the high-density electrical method can get better results for both bedrock landslide and soil landslide.