不同降雨条件下对山区公路弃土场稳定性影响分析

Stability Analysis of Spoil Ground in Mountain Highway Under Different Rainfall Conditions into Account

降雨是诱发山区公路弃土场失稳的重要原因之一。为研究不同降雨条件下弃土场失稳破坏机理,提出了一种同时考虑弃土场填料饱和度、孔隙水压力及软化效应的稳定性计算方法,通过Geo-Studio有限元seep模块建立降雨入渗模型,分析不同降雨条件下弃土体内部孔隙水压力和饱和度的变化规律,结合弃土场暂态饱和区域内软化效应,将降雨渗流结果与slope稳定性模块进行耦合,分析不同降雨类型下弃土场稳定性变化规律。研究结果表明:降雨入渗阶段,暂态饱和区首先在弃土场坡脚处和表层逐渐发育,并指向斜坡深层土体延伸,导致部分填料负孔隙水压力随着降雨历时增加逐渐增大,在孔隙水压力、重度及软化效应共同作用下,弃土场由稳定削弱至欠稳定,该影响具有一定的滞后性。安全系数受降雨类型影响不同,弃土场边坡稳定性影响顺序为:前锋型>中锋型>等强型>后锋型。

Rainfall is one of the important reasons for the instability of road spoil grourd in mountainous areas.In order to study the instability and failure mechanism of spoil ground under different rainfall conditions,a stability calculation method is proposed,which simultaneously considers the filling saturation,pore water pressure and softening effect in spoil ground,the rainfall infiltration model was established by the Geo-Studio finite element seep module,and the changes law of pore water pressure and saturation in the spoil ground under different rainfall conditions were analyzed,combined with softening effect in transient saturation region in spoil ground,coupling rainfall seepage results with the slope stability module:analysis of the change law of spoil ground stability under different rainfall types.The research results show that:during the rainfall infiltration stage,the transient saturation zone first develops gradually at the toe of the spoil ground and on the surface of the ground,and extends toward the deep soil body on the slope,resulting in the gradual increase of negative pore water pressure in some soil bodies with the increase of rainfall,under the combined action of pore water pressure,severity and softening effects,the spoil ground is weakened from stable to unstable.This effect has a certain hysteresis.The safety factor is affected by the rainfall pattern differently,and the spoil ground is relatively cheap,the order of influence on the stability of the spoil ground is as follows:striker typecenter typeequal strength typerear striker type.