长大竖井围岩稳定性有限元分析

Stability Analysis for the Surrounding Rockmass of a Long Shaft by FEM

对以混凝土为内衬支护结构的长大竖井井筒,采用理想弹塑性材料本构关系及Drucker-Prager屈服准则建立三维有限元模型,对围岩受力及变形特征进行分析,给出围岩的应力与位移分布特征、竖井周边特征点的变形(位移)大小及破坏区的范围;对比讨论了现浇混凝土支护结构不同支护厚度对围岩稳定性的影响,分析计算结果表明围岩稳定性良好,竖井的初步设计是合理的,改变支护厚度对纵向及总位移影响较大,随支护厚度的增加围岩应力分布更均匀。按一定深度建立竖井水平剖面的二维模型对井筒的稳定性进行分析,将二维与三维分析结果进行对比分析,其结果表明二维分析存在较大误差,说明了二维简化分析的不合理性。

Based on the vertical shaft with supporting structures of concrete interred lining, the ideal elasto-plastic constitutive model and Drunker-Prager yiehl criterion are employed to establish the FEM model. The behavior of stress and displacement,the size ofdeformation and yield zone of the surrounding roekmass are analyzed. Meanwhile, the impact of different thickness of east-in-situ concrete support is compared and discussed. It can be clearly shown that the stability of surrounding roekmass is quite well, which manifests that the initial design of shaft is reasonable. The vertical and total deformation is greatly impacted with the change of thickness of supporting structure, the stress distribution is more uniform as the thickness increases. A 2D model is set up on certain depth of tbe shaft to analyze the shaft stability, the results of 2D model test are compared with those of the 3d analysis. Big errors exist in the 2D analysis, which embodies that the simplified 2D analysis is irrational.