不平衡推力法的弹塑性有限元改进

结合杭金衢高速公路K111碎石土滑坡工程实例,研究如何使极限平衡法与有限元法有机结合应用于边坡稳定性计算和分析中,以及碎石土边坡稳定性系数与滑动面抗剪强度发挥程度的关系。研究结果表明,可以采用弹塑性有限元边坡稳定性极限分析法,得到边坡接近破坏状态时滑坡体的塑性变形破坏区,然后据此确定边坡的滑动面;通过野外工程地质勘探揭示,该法确定的潜在滑动面与实际滑动面基本相符;可根据极限状态下塑性应变值的大小确定滑面带上不同抗剪强度取值段,采用全面考虑滑面上岩土体抗剪强度不同发挥程度的不平衡推力法计算碎石土边坡的稳定性系数;采用该方法进行碎石土边坡稳定性分析能更加真实地反映边坡所处的实际状态。

ELASTOPLASTIC FINITE ELEMENT IMPROVEMENT OF IMBALANCED THRUST FORCE METHOD

Connected with concrete engineering example of K111 debris landslide in Hangjinqu Expressway,it was investigated that how to combine mutually limit equilibrium method with FEM to be applied to analyzing slope stability and calculation of stability factor.Meanwhile,relationship between stability factor of slope and utilization degrees of the shear strength of sliding plane was also studied.The results are shown as follows:(1) the zone of plastic deformation and failure of slip-mass under approaching failure state can be obtained by the limit analysis method of elastoplastic FEM of slope stability;and then according to it,sliding plane of slope is determined;(2) it is shown that the sliding plane of slope determined by elastoplastic finite element limit analysis corresponds basically to the actual one revealed by field engineering geologic prospecting;(3) sections with different utilization degrees of shear strength are determined on the basis of plastic strain value under limit state of slope;(4),it can calculate more accurately the stability factor of debris slope with imbalanced thrust method that comprehensively thinks over the different utilization degrees of shear strength of soil and rock on sliding plane;(5) it is proven by analyzing concrete example that to combine elastoplastic finite element with limit equilibrium method may be very well used to analyze the stability of debris slope and calculate its stability factor;it can reflect the actual state of slope more accurately.Therefore,it provides a reference to the stability analysis,evaluation and forecast of this kind of landslides.