川西岷江河谷典型大型—巨型古滑坡特征物探解译分析

在遥感解译、野外调查的基础上,采用高密度电法和电阻率测深法,并结合钻探对川西岷江河谷发育的尕米寺滑坡、俄寨村滑坡、格机寨滑坡等典型大型—巨型古滑坡的空间结构进行了勘探分析,有效确定了古滑坡的空间结构和滑带特征,并认为古滑坡的滑动面多具有高低阻相间的不稳定电性层,且滑坡前缘多位于不稳定电性层变薄收敛的地方。其中,俄寨村滑坡高低阻相间的不稳定电性层厚约0~45 m,为滑坡堆积层,古滑动面紧贴基岩面,滑动面平均埋深约30 m,弱风化基岩面埋深约5.6~61 m,强风化层厚约为3~12 m;尕米寺滑坡高低阻相间的不稳定电性层厚约2.5~43 m,为滑坡堆积层,沿剖面古滑动面平均埋深约35 m,在滑坡中部存在一圈闭的低阻异常体,推测为古河道,并与钻探结果相吻合,其埋深约56~96 m,弱风化基岩面埋深13.3~100 m,强风化及岩溶综合层厚一般约为5~20 m。基于古滑坡的地球物理勘探数据和解译结果,统计分析了川西岷江河谷地区大型—巨型古滑坡空间岩土体的地球物理物性参数,对指导该区滑坡调查分析具有重要的指导意义。

GEOPHYSICAL EXPLORATION AND SLIDING SURFACE DISCRIMINANT ANALYSIS OF LARGE-GIANT ANCIENT LANDSLIDES IN MINJIANG RIVER VALLEY, WESTERN SICHUAN

High density resistivity method and conventional resistivity sounding method are applied in the exploration analysis of the space structure of a series of typical large-giant ancient landslides such as the Gamisi landslide, the Ezhaicun landslide and the Gejizhai landslide. The survey results show that the slip surfaces of ancient landslides are unstable and have low resistance electrical layers. Also the fronts of the landslides are mostly located in the convergence area of the unstable electrically thin layers. Among them, the unstable electrical layer thickness of the Ezhaicun landslide of high and low resistance is about 0~45 m, and it is the landslide accumulation layer. The sliding surface is close to the bedrock surface with the burial depth of about 30 m. The burial depth of weakly weathered bedrock surface is about 5.6~61 m, and the thickness of strong weathered layer is about 3~12 m. The unstable electrical layer thickness of the Gamisi landslide of high and low resistance is about 2.5~43 m, and it is the landslide accumulation layer. The average burial depth of ancient sliding surface along the profile is about 35 m. In the middle of the landslide there is a circle of closed low resistance anomaly bodies, which are speculated as the paleo-channels with the burial depth of about 56~96 m. The burial depth of weakly weathered bedrock surface is about 13.3~100 m, and the thickness of strong weathered and karst complex layer is about 5~20 m. Based on the geophysical exploration data and interpretation results of ancient landslides, the geophysical parameters of spatial rock-soil bodies of large-giant ancient landslides in the Minjiang River Valley were analyzed, which are of great significance to guide the investigation and analysis of landslides in this area.