高土石围堰施工-运行过程边坡稳定性分析

Slope stability analysis of high earth-rock cofferdam considering construction and working processing

高土石围堰边坡稳定性与堰体材料的力学性质密切相关.在围堰施工及运行过程中,随着结构应力和渗流状态的变化,堰体材料力学参数也发生持续性变化.基于围堰施工过程中堰体应力及渗流状态变化规律分析和土石材料力学非线性理论,建立考虑施工过程的土石围堰边坡稳定分析模型;在此基础上,进行高土石围堰施工-运行过程边坡稳定特性分析,结果表明堰体边坡稳定的最不利工况出现在基坑开挖后的堰前水位下降期,最危险滑动面位置随着水位下降速率的增加由背水面转向迎水面;当水位下降速率一定时,堰坡稳定安全系数呈先减小后增加趋势,最小值及其出现时间与水位下降速率相关.

Slope stability of high rock-fill cofferdam is closely associated with mechanical parameters of earth and rock;and the mechanical parameters vary with the change of stress and transfusion state of cofferdam during its construction and working process.The slope stability analysis model of high earth-rock cofferdam considering construction process was established based on material nonlinearity theory and the analysis of stress and seepage during cofferdam construction and working process.The slope stability analysis of a high earth-rock cofferdam with this model indicated that the most dangerous condition appeared in the period of upstream water level falling after foundation pit excavation finished.With the increase of water level falling speed,the dangerous sliding surface shifted from downstream slope to upstream slope.When the water level fell with determinate speed,the slope safety factor appeared decreased firstly and increased finally,and the minimum slope safety factor and the critical time was related with the water level falling speed.