桥基荷载作用下斜坡稳定性评价的三维有限元法

Three-dimensional FEM of Slope Stability Evaluation with Bridge Pile Foundation Load Effect

基于强度折减法,采用弹塑性有限元方法以三维实体单元模拟桥基荷载作用下的斜坡,利用逐步改变步长的搜索法求解出桥基荷载作用下边坡的安全系数,将强度折减法从二维平面问题引申到三维空间问题,避免了二维方法中桩基计算宽度的确定,更好地得出边坡应力应变分布情况,提出将塑性区是否贯通作为求解边坡安全系数的标准,为复杂边界下求解边坡稳定性分析评价提供了新的思路和方法。以湖南湘西印家溪大桥为工程实例,计算分析了该桥边坡在桥基荷载作用下的稳定安全系数,计算结果表明了本文方法的有效性。

Based on strength reduction method, by use of elasto-plastic finite element method, the slope with bridge pile foundation load effect is modeled by three-dimensional solid element, where the slope safety factor is obtained by use the technique of searching the slip surface where the strength reduction coefficient is changed progressively. The strength reduction method is extended from two-dimensional plane problem to the three-dimensional space problem, where the definition of calculation width of pile foundation is avoided and the distribution of stress and strain of the slope can be obtained more exactly. Then a criterion to gain the safety factor by differentiating the plastic area is whether or not penetrated is presented. The present method provides a new clue and means for analyzing slope safety problem. Numerical examples of applying the method to obtain the slope stability factor with bridge pile foundation load effect are given by use of Yinjiaxi bridge in Hunan western area as engineering instance, which demonstrate that the present method is efficient and reliable.