库水位骤降偶遇地震作用的土石坝稳定分析  

Stability Analysis of Earth Dam Caused by Sudden Earthquake During Rapid Drawdown of Reservoir Water Level

作　　者：戴维 任旭华[1] 张继勋[1] 黄丹雏 DAI Wei;REN Xuhua;ZHANG Jixun;HUANG Danchu(School of Water Conservancy&Hydropower Engineering,Hohai Univ.,Nanjing 210098,China)

机构地区：[1]河海大学水利水电学院,南京210098

出　　处：《三峡大学学报（自然科学版）》2021年第3期6-11,共6页Journal of China Three Gorges University：Natural Sciences

基　　金：国家自然科学重点基金项目(U1765204);江苏省水利科技资助项目(2017074)。

摘　　要：正常运行过程中库水位是不断变化的,当库水位降落后,坝体内部的孔隙水压力和渗流场会发生变化,过快的下降速率会导致坝体内的孔隙水压力不能及时消散,在渗流的作用下上游坝坡产生浮起或下滑的趋势,若在库水位骤降时期发生地震,则对土石坝的坝坡稳定更加不利.为研究某混凝土心墙土石坝在库水骤降偶遇地震情况下瞬态渗流场特性及坝坡稳定性规律,基于非饱和渗流原理,采用Geo-Studio有限元软件进行数值模拟,得到了不同骤降速率下坝体内部浸润线及上下游坝坡安全系数的变化规律,并研究了不同骤降速率下偶遇地震作用和不同骤降时刻发生地震时的上下游坝坡安全系数,最终对所得到的规律进行公式总结.结果表明:坝体浸润线在库水位骤降过程中会出现向上凸起的现象,骤降速率越大凸起越明显;在地震作用下,坝坡上游安全系数值减小幅度较大,下游坝坡安全系数变化不大;在库水位骤降初期发生地震最危险;库水位骤降至死水位时的最大速率不应超过2 m·d~(-1).During the normal operation,the reservoir water level is constantly changing.When the reservoir water level falls,the pore water pressure and seepage field inside the dam will change.Too fast decline rate will lead to the pore water pressure in the dam can't be dissipated in time,under the action of seepage,the upstream dam slope has a tendency to rise or fall.If an earthquake occurs in the period of reservoir water level drop,it is more unfavorable to the stability of the dam slope.In order to study the characteristics of transient seepage field and the stability law of dam slope of a concrete core-wall earth-rock dam under the occasional earthquake of sudden drawdown of reservoir water,based on the principle of unsaturated seepage,the numerical simulation was carried out by using Geo-Studio finite element software,and the variation laws of the internal saturation line of the dam body and the safety factor of the upstream and downstream dam slope under different sudden drawdown rates were obtained.The safety factor of the upstream and downstream dam slope under the occasional earthquake action under different sudden drawdown rates and the earthquakes at different sudden drawdown moments were studied.Finally,the obtained laws were summarized by formulas.The results show that the saturation line of dam body will appear upward bulge in the process of sudden drop of reservoir water level,and the larger the sudden drop rate is,the more obvious the bulge is;under the action of earthquake,the safety factor of upstream dam slope decreases greatly,and the safety factor of downstream dam slope has no obvious change;earthquakes are most dangerous in the early stage of reservoir water level collapse;the maximum rate should not exceed 2m·d-1 when the reservoir water level drops to the dead water level.

关 键 词：土石坝 库水位骤降 地震作用 

分 类 号：TV641[水利工程—水利水电工程]