库水位上升诱发边坡失稳机理研究

Study on mechanism of slope instability due to reservoir water level rise

库水位上升有可能诱发边坡失稳破坏,湖北省秭归县三峡库区的千将坪高速滑坡即是一例。库水位上升对边坡稳定性的影响主要表现在孔隙水压力作用和滑动面强度参数的弱化上,采用Mohr-Coulomb强度准则描述了孔隙水压力对土体应力状态的影响,土体浸水后,在孔隙水压力作用下Mohr应力圆变小而向左移动并相对远离强度曲线。边坡稳定性分析表明,在库水位由坡脚上升到坡顶的过程中,孔隙水压力作用使边坡的稳定性先降低后增加。指出水库蓄水初期,由于孔隙水压力使边坡的稳定性降低,加上滑动面强度参数的弱化给边坡稳定性带来的不利影响,若边坡的安全储备强度不够,很可能发生滑坡。

Reservoir water level rise may result in instability of a slope. Qianjiangping landslide, situated on the Three Geoges, Zigui County, Hubei Province, is a right example. Effects of reservoir water level on slope stability include the action of interspace water pressure and the weakening of strength parameters of slide interface. Using Mohr-Coulomb strength principle, effect of interspace water pressure on soil stresses is analyzed. After slope soil is soaked, the Mohr circle diminishes and moves to the left apart from the strength curve. Results of slope stability analysis show that slope stability firstly decreases and then increases due to interspace water pressure when reservoir water level rises from the foot to the top of the slope. It is also pointed out that the slope will probably lose its stability because of the disadvantageous action of interspace water pressure during the initial stage of water level rising and the weakening of strength parameters of slide interface.