锚固边坡稳定性分析有限元模型及锚固效应的探讨

锚固边坡具有锚固结构与土体变形协调的特点,而用条分法分析边坡稳定性时因土体刚体假设无法考虑结构与土体共同作用的本质,存在低估锚固效应的问题。提出了一种有限元法分析锚固边坡的方法,考虑在有限元模型中采用点锚式和全长粘结式杆单元模拟实际锚固结构的自由段和锚固段,注浆加固体采用接触单元,在土体和结构共同作用和接触变形协调的应力计算的基础上,结合条分法稳定性系数概念,对锚固结构考虑粘结强度或抗拉强度,对土体考虑剪切破坏强度,可得出工程分析所需的锚固边坡稳定性系数。研究结果表明:有限元法所得滑动面深度较条分法更深,稳定性系数更大,其有效锚固长度也存在一定的差异。

FEM modeling method for anchored slope stability analysis and discussions on anchoring effect

Soil and anchor structure are under the condition of deformation compatibility in anchored slopes.The nature of the combined action between soil and anchor structure can not be considered by the slice method due to the rigid body assumption of soil.Thus,the results by slice method often underestimates the anchorage effect.A stability assessment method for anchored soil slope was proposed using FEM.In FEM modeling,point anchored truss elements and full-length bond truss elements were used to simulate the substantial reinforcement effect according to different parts of anchorage,namely,free part and anchored part.Based on the stress field given by FEM analysis with the reinforcement effect contained,unfavorable slip surface of anchored slopes could be obtained utilizing the safety factor concept of slice method where the ultimate shear strength of soil and anchor structure were considered.The unfavorable slip surface given by the method was deeper than that of the slice method and the safety factor was increased.The characteristics of the difference of effective anchorage length between the slice method and the proposed FEM-based method were studied.