考虑土体剪胀特性的土质边坡稳定性极限分析

Limit analysis of stability for soil slope considering dilatancy

剪胀特性是土体的重要特性之一,然而,经典的塑性力学理论高估了土体的剪胀性质,从而使土体强度背离实际情况。通过等效内摩擦角的方法,对原有的土体抗剪强度进行修正,反映出土体剪胀性对土体强度的影响。通过构建对数螺旋形式的破坏机构,推导出相应的内能耗散和外力功率表达式,结合极限分析理论和强度折减方法,建立边坡安全系数的求解方法。结果表明,该方法的计算结果是合理的。随着剪胀角的不断增大,边坡安全系数增大的速度变慢,这种变化趋势是非线性的。针对不同的土质特性,提出相应的剪胀角取值建议。

The shear dilatancy is one of the important features of soil.However,it has been overestimated by the classic plastic mechanics,thereby causing the deviation of soil strength from practice.We modify the shear strength parameters of Mohr-Coulomb criterion by the using of equivalent internal friction angle,which reflects the influence of dilatancy on soil strength.Based on the failure mechanism with a logarithmic spiral shape,we use the equations to calculate the internal dissipation,derive external work of slopes,and establish a method to evaluate the safety factor of slop by the theories of limit analysis and of strength reduction.The results show that the results computed by numerical modeling test are reasonable.The safety factor increases more slowly with the increasing of the dilatancy angle,and the trend is non-linear.The recommendations of the values of dilatancy angle are given in practice work.