金沙江下游金坪子Ⅱ区低速滑坡活动机理初探  

PRELIMINARY STUDY OF THE CREEP MECHANISM OF JINPINGZI ZONE Ⅱ SLOW MOVING LANDSLIDE IN LOWER REACHES OF JINSHA RIVER

作　　者：蒋树 王义锋 唐川[3] 潘洪月 王坤 

机构地区：[1]中国长江三峡集团公司博士后工作站,北京100038 [2]中国三峡建设管理有限公司乌东德工程建设部,成都610041 [3]地质灾害防治与地质环境保护国家重点实验室(成都理工大学),成都610059

出　　处：《工程地质学报》2017年第6期1547-1556,共10页Journal of Engineering Geology

摘　　要：金坪子滑坡是金沙江下游乌东德水电站下游方向距离大坝最近的一处巨型深厚崩坡积碎屑土古滑坡,以Ⅱ区活动部分为研究对象,在大量勘察试验成果以及长达11a的精确监测基础上,分析滑坡岩土体的物理力学性质以及滑坡的长期动态特征,特别是滑坡与降雨和地下水的动态响应关系,并基于Green-Ampt降雨入渗模型研究了降雨直接入渗补给地下水的可能性,利用极限平衡法探讨了理想刚塑性条件下该滑坡所受力的平衡关系,进而分析滑坡的活动机理。研究结果表明,滑坡的长期持续活动是滑带土黏性流变特征的表现,地表和深部位移均表现为牵引活动模式,地表自2005~2016年的平均位移速率为0.19~0.87mm·d^(-1),深部以基底滑动为主,不同部位具有不同程度的内部变形。降雨是影响滑坡动态的最主要因素,在理想情况下,降雨很难直接入渗补给滑区地下水,地下水动态变化缓慢,与滑坡活动有一定正相关关系,但作用并不显著。与一些动态特征直接受地下水位影响的浅层低速滑坡不同,金坪子Ⅱ区的活动机理更可能是降雨在滑坡上部一定深度范围内形成暂态饱和区,滑体容重和渗透作用的变化影响了滑坡的动态。Jinpingzi landslide is the nearest deep-seated colluvial debris landslide to the arch dam of Wudongde hydropower station in the downstream direction in lower reaches of Jinsha River. Its active zone II was studied. Based on geotechnical investigation and long-term monitoring, the physical and mechanical property of the landslide materials and the long-term kinematics, especially the relationships among the landslide movement, rainfall and the groundwater were analysed. The response of the groundwater regime to the precipitation was further analyzed under different initial water content conditions based on the Green-Ampt infiltration model. Relationships between resisting forces and driving forces were discussed by limit equilibrium method assuming rigid-plastic frictional slip. Results showed that the long-term continuous movement was mostly due to the viscous component of the slip zone. Surfaceand subsurface displacement both showed a retrogressive type with average surface displacement rate 0？ 19 ？ 0. 87mm＊d 1 from 2005 to 2016. Basal sliding accounted for most of the deformation with different degrees of internal deformation in different parts. Rainfall was the predominant factor affecting the landslide activity but it is hard for rainfall water infiltrating to the deeply buried groundwater regime. Unlike some shallow landslides, the mechanism of Jinpingzi zone II slow moving landslide was more likely to be the formation of transient saturated zone in shallow depth. The change of unit weight of the sliding mass and the effect of seepage affected the kinematics of the landslide.

关 键 词：低速滑坡 滑坡动态 抗剪强度 降雨入渗 黏性流变 

分 类 号：P642.22[天文地球—工程地质学]