大型深厚缓坡细粒土堆积体水库坍岸机理研究  

Study on Collapse Mechanism of Large-Scaled Reservoir Bank in Accumulation of Fine-sized Soil with Deep and Gentle Slope

作　　者：方力[1] 胡卸文[1] FANG Li;HU Xiewen(Southwest Jiaotong University, Chengdu, Sichuan, 611756)

机构地区：[1]西南交通大学,四川成都611756

出　　处：《四川水力发电》2021年第4期120-125,共6页Sichuan Hydropower

基　　金：国家重点研发计划(No.2018YFC1505401)资助。

摘　　要：四川宝兴河硗碛水电站库区自水库蓄水以来,库区岸坡坍岸发育,其中位于蚂蟥沟内的蚂堆5号堆积体属于早期冻融堆积细粒土,地形坡度在10°左右。该类土按水下稳定坡角分析认为应该处于稳定状态,但是该大型堆积体在每年的库水变化过程中,坍岸变形严重且规模大,严重威胁库区环湖公路运营安全。结合野外勘察及钻孔揭露,查明了蚂堆5号堆积体地质结构,构建了相应地质模型。采用饱和-非饱和渗流有限元算法全过程模拟其在水库运营期间地下水渗流场的动态变化过程,以此为基础分析堆积体坍岸变形和稳定性演化特点。研究表明:该堆积体坍岸变形主要发生在库水位下降期间,且呈明显的牵引式失稳模式,变形趋势与监测点实测数据相符。堆积体坍岸变形破坏及强烈与否主要受库水位变动条件下的坡体内地下水渗流场动态变化控制。Since the reservoir was impounded,the bank slope of Qiaoqi Hydropower Station on Baoxing River in Sichuan has been developing,and among which Madui No.5 accumulation in Mayinggou belongs to early freeze-thaw accumulation of fine-sized soil,and the terrain slope is about 10°.According to the analysis of the underwater stable slope angle,this type of soil should be considered to be in a stable state.However,serious bank collapse and large-scale deformation occurs at the large-scale accumulation each year when water level of the reservoir changes,which seriously threatens the safe operation of the highway around the lake in the reservoir area.Through field survey and drilling exposure,the author ascertains the geological structure of Madui No.5 accumulation and sets up a corresponding geological model.The whole process of saturated-unsaturated seepage finite element algorithm is used to simulate the dynamic change process of the groundwater seepage field during the operation of the reservoir,and on this basis,the characteristics of bank collapse deformation and stability evolution of the accumulation are analyzed.This study shows that the bank collapse deformation of the accumulation mainly occurs when water level declines,the deformation is in an obvious traction-type instability mode and the trend was consistent with the measured data at the monitoring point.The deformation and failure of bank collapse and its intensity are mainly controlled by the dynamic changes of the groundwater seepage field in the slope under the condition of fluctuation of water level.

关 键 词：水库坍岸 细粒土 缓坡堆积体 稳定性 演化规律 

分 类 号：P343.3[天文地球—水文科学] A715[天文地球—地球物理学]