基于应变软化模型的桩锚支护过程稳定性分析

Process Stability Analysis of Pile-Anchor Supporting Based on Strain Softening Model

为了研究深基坑在桩锚支护过程中的稳定性变化规律,利用FLAC^3D软件对深基坑进行数值模拟,采用应变软化模型对基坑在开挖过程中的支护桩变形、锚索受力、稳定性以及塑性区变化进行计算,结合实测数据进行计算分析,并与Mohr-Coulomb模型进行对比.研究结果表明：FLAC3D应变软化模型数值模拟结果与实际监测结果基本吻合,且优于Mohr-Coulomb模型,并能较好地反映软岩土体的变形特性;随着基坑开挖的进行,支护桩身最大水平位移点位置随着开挖步的不断增加呈现出逐渐下降趋势;在基坑开挖过程中,锚索锚固力逐渐增大,并沿索体呈现出先增大后减小的变化趋势,且最大值出现在剪切滑动面位置处;开挖过程中,基坑张拉、剪切塑性区域主要集中分布在开挖面及开挖面3-7m深度内.

In order to study the change law of stability during deep foundation pit pile-anchor supporting process,deformation of pile,anchor cable force,changes of safety coefficient and plastic zone distribution were calculated and analyzed by taking FLAC3 Dsoftware based on strain softening model during the deep foundation pit excavation process,and compared with the Mohr-Coulomb model,and analyzes the results combining with the measured data.The results show that the strain softening model results are in substantially the same with the actual monitoring results,which is better than Mohr-Coulomb model,and the strain softening model can reflect the strain softening properties of soft rock better.During foundation pit excavation process,the maximum horizontal displacement of supporting pile showed a gradual downward trend with the increasing of excavation step.Along with the excavation,the overall anchor force increases gradually,which causes the anchoring force to first increase and then decrease,and the maximum anchor force appeared in the shear slip surface.The distribution of slope shear and tension plastic zone mainly concentrate on the foundation pit surface layer within 3-7m.