库水位升降对典型堆积层滑坡的加卸载动力作用规律研究

Study on the Load and unload effect law of reservoir water level fluctuation to typical debris landslide

以三峡库区为背景,利用有限元软件对库水位在145 m与175 m之间波动时岸坡稳定性系数的变化进行数值模拟,探讨库水位波动时的加卸载动力作用规律,以及水位变化速率、渗透性系数和坡体形状等因素对加卸载过程的影响。研究表明:库水位升降速率大于渗透性系数时,库水位上升稳定性系数增大,对边坡来说是卸载作用;库水位下降稳定性系数减小,对边坡是加载作用。渗透性较小的岸坡,其安全系数与水位的变化呈正比,也即水位上升时相当于对岸坡进行了卸载,水位下降时相当于对岸坡进行了加载;当渗透性较大时,在水位上升或下降时,都分别存在加载过程与卸载过程。坡体厚度、长度及坡角的变化不会影响库水位升降对边坡的加卸载作用过程的划分。

With the Three Gorges Reservoir Region as the background,the numerical simulation for the variation of bank slope stability coefficient when the reservoir water level fluctuates between 145 m and 175 m was made using the finite element software,the loading and unloading law of the landslide under the reservoir water level fluctuation,and the effects of such factors as of the rate of reservoir water level change,the water permeability coefficient and slope shape etc.on the loading and unloading process were discussed.The research indicates that,if the rate of level fluctuation is greater than the permeability coefficient,the rise stability coefficient of reservoir water level increases and it is unloading action to the slope when the water level rises;it is an action of loading to the slope when the reservoir water level declines.For the slope with smaller permeability,its safety factor is proportional to the water level changes,that is,the bank slope is unloaded when the water level rises,and the slope is loaded when the water level drops.When permeability is high,the water level rises or falls,there are both processes of loading and unloading to slope.The changes of slope length,thickness and slope angle will not affect the division of the process of loading and unloading in the reservoir water level fluctuation to slope.