堰塞坝溃口斜坡失稳概率分布函数参数确定及影响因素分析

Determination of parameters in probability distribution function of breach slope stability losing of barrier dam and analysis of influencing factor

为确定堰塞坝溃口斜坡在水流侵蚀作用下的失稳概率分布函数,掌握函数变化规律,明确不同因素对稳定性影响强弱程度,开展了数值分析.结果表明:随着侵蚀发展,平均主应力逐渐减小,剪应力逐渐增大,处于破坏面上的剪应力到达峰值点后逐渐减小.概率密度分布函数中参数a随溃口高度和斜坡坡度的增大先增大后减小,随侵蚀深宽比的增大先增大后趋于稳定.随着斜坡坡高的增大,安全系数对小坡高较敏感,斜坡坡度和容重影响下的安全系数具有相同的规律.随着黏聚力的增大,安全系数对小黏聚力较敏感,当黏聚力增大到一定程度,黏聚力的变化对安全系数的变化不敏感.安全系数关于内摩擦角的灵敏度随内摩擦角的增大先减小后增大,侵蚀深宽比对安全系数的影响具有相同规律.

In order to determine the probability distribution function of stability losing of breach slope of barrier dam subjected to water flow erosion,grasp the rule of function variation,and clear the degree of influence of different factors on stability,numerical simulation test was carried out.The result shows that average principal stress will degrease with erosion progression while the shear stress will gradually increase,and the shear stress on the destructional surface will gradually decrease after reaching its peak value.The parameter ain probability density distribution function will increase at first and then decrease with the increase of the depth and slope of the breach,and it will increase at first and then become stable with the increase of depth-to-width ratio of the erosion.The safety factor will be sensitive to small depth of breach and with the increase of slope height,it will have identical variation rule under the influence of the breach slope and soil density.The sensitivity of safety factor to small cohesion will be higher;with the increase of cohesion up to certain extent,the safety factor will not sensitive to the variation of the cohesion.The sensitivity of safety factor to inner friction angle will decrease at first and then increase with the increase of the inner friction angle and the influence of depth-to-width ratio of erosion on safety factor will have an identical pattern.