桃舟古滑坡工程地质特性与稳定性分析

Engineering Geological Characteristics and Stability Analysis of Taozhou Ancient Landslide

古滑坡年代久远、成因复杂且不易查明,当工程活动经过时,由于人为扰动的影响,古滑坡极易复活,对工程带来严重危害。以桃舟古滑坡为例,采用钻探和物探相结合的方法对古滑坡进行工程地质勘察,获得了该地区的工程地质条件,该滑坡为中厚层巨型滑坡,成因为堆积体牵引式滑坡。根据勘察资料分析滑坡特征,识别了影响古滑坡稳定性的关键影响因素:物质组成及结构特征、地形条件、连续降雨和地下水以及人类工程活动。采用极限平衡法对古滑坡稳定性进行评价,计算结果表明该古滑坡整体处于基本稳定状态;然而由于滑坡体主要为松散堆积体,由局部稳定性计算结果可知古滑坡前缘会产生小型的堆积体滑坡。该计算结果与现场调查相一致,在滑坡前缘见到两处小型滑塌。综合分析研究结果,对公路选线以及滑坡前缘坍塌体的治理提供了一些建议。

The ancient landslide is of ancient origin,complex in cause,and difficult to locate.However,when engineering activities pass through,due to the impact of the human disturbance,ancient landslides are very prone to reactivation,posing a serious threat potential to the engineering projects.The Taozhou ancient landslide is presented in this paper as an example.The combination of the drilling and the geophysical exploration methods was used to conduct engineering geological investigations of the ancient landslide site,obtaining the engineering geological conditions of the area.The landslide site is a medium-thick layer large landslide body formed by accumulation and traction.Based on the nature and the characteristics of the landslide deformation,combined with survey data,key factors affecting the stability of the ancient landslide were identified:the material composition and the structural characteristics;topographic conditions;the continuous rainfall and the groundwater;and the human engineering activities.The limit equilibrium method was used to evaluate the stability of the ancient landslide.The analytical results indicate that the ancient landslide site is overall in a marginally stable state;however,since the landslide body is mainly loose accumulation,the results of local stability analysis show that the small-scale accumulation landslides will occur at the front of the ancient landslide.This analysis result is consistent with the on-site investigation,where two small collapses were observed at the front of the landslide.Finally,a comprehensive analysis of the above results provides some suggestions for the highway alignment and the treatment of the collapsed body at the front of the landslide.