万州安乐寺滑坡前缘松散堆积体成因与防治对策

Formation Mechanism and Slide Prevention Methods of Soil Deposits at the Toe of Anlesi Landslide in Wanzhou

逐一分析了安乐寺滑坡前缘西溪铺、农机技校松散堆积体的144个勘探钻孔,根据土体物质成分进行分层并对其因进行判断;对相邻钻孔的土层进行比较,将相同的土层连接起来,绘制工程地质剖面图;将工程地质剖面图进行综合对分析,探讨每一土层的连续性、延伸性.按照“钻孔-剖面-成层”的研究方法,对安乐寺滑坡前缘松散堆积体的特征及成进行详细的研究.研究结果表明:安乐寺滑坡前缘松散堆积体是以安乐寺滑坡前部的滑动解体作用为主,包括残积、坡积冲积等共同作用形成的.前缘松散堆积体中存在多个滑动面,滑动面平直、光滑,可以分为2种类型:一类是中深层滑动面数量较少,规模大;另一类是浅层滑动面,数量较多,规模小.滑动面的这种分布规律反映了前缘松散堆积体是一个长期不连续的变形体.最后,考虑松散堆积体下伏卵石砂土层地质结构,对松散堆积体防治措施进行了探讨,认为安乐寺前缘散堆积体采用抗滑桩支挡结合地表排水与护坡等措施进行治理是适宜的,但抗滑桩嵌固段必须深入到卵石砂土层以下定的基岩中,以避免抗滑桩随卵石砂土层产生整体位移.

The material of 144 boreholes of Xixipu and Nongjijixiao soil deposits at the toe of Anlesi landslide was analyzed, types of soil were classified and the formation mechanism was analyzed based on the properties of soil deposits in a single borehole. The same type of soil was connected to one layer in a profile with several boreholes. The continuity and extent of a soil layer was determined with profiles. The results show that most of the soil deposits at the toe of Anlesi landslide slipped from the foot of the landslide, and other soil deposits are residual, colluvial, talus and alluvial. The soil deposits were formed by co-action of gravity, running water, mechanical and chemical weathering. In the soil deposits, many sliding surfaces which are plane and smooth were found, and these can be classified into two kinds. There are a few large scale sliding surfaces, which are found at some depth, and many small sliding surfaces, which occur near the surface of the soil deposits. The distribution of sliding surfaces mentioned above indicates that the soil deposits have been deformed discontinuously for a long time. Slide prevention methods, considering the geological structure underlain by gravel sand, include driven piles, rip-rap and surface drainage as a means of stabilizing the soil deposits. The driven piles should be embedded in stable ground under the gravel sand to avoid being displaced.