土钉与土体相互作用的仿真试验分析

The simulation test for the interaction between soil nailing and soil mass

运用快速拉格朗日元(FLAC3D)数值法,考虑土钉的加固作用及土钉与土体的相互作用,模拟土钉支护施工过程。选择能够反映开挖特点的土的本构关系、开挖支护模拟过程及双弹簧土钉单元,建立数值分析模型。分析了基底、基坑壁土体的变形响应及土钉在开挖、使用阶段的力学响应。结果表明:①开挖引起基坑壁变形,并导致拉伸与剪切破坏;对于拉伸破坏,应使土钉长度超过滑移面;对于剪切破坏,可增大土钉在剪出口位置的密度;②开挖完毕后,各层土钉轴力沿长度方向的分布不均匀,土钉轴力最大值位置可表征潜在滑动面的位置。FLAC3D能够对基坑分步开挖及支护进行模拟,建立的数值模型能够反映土钉支护基坑的真实情况,为基坑土钉支护技术的设计与施工提供指导。

The numerical simulation technique of fast lagrangian analysis of continua （FLAG^3D） are used to simulate the construction process of excavation in foundation with soil nailing, which considering the function of soil nailing and the interaction law between soil and soil nailing. The constitutive law of soil which can reflect the excavation characteristic of soil, the process of excavation and reinforcement simulation, and the double-spring soil nailing elements are chosen to found a numerical calculation model. Deformation responses of foundation bottom and side-wall soil mass are analyzed as well as the mechanical response of soil nailing during and after excavation. The analysis results show that,① the process of excavation lead to the deformation of soil mass in foundation, which is the reasons of tensile failure and shear failure; for tensile failure areas, the length of soil nailing should be set over the slip plane ; for shear failure areas, the density of soil nailing can be set large at the place of shear opening. ② after excavation, the axial stress distributes different along the axial length, the location of maximum axial stress in the soil nailing can indicate the location of potential slip plane. Conclusion FLAC^3D can simulate the excavation and reinforcement of foundation reasonably. The analytical model built in this paper can reflect real situation for the foundation reinforced by soil nailing during and after excavation, which can give guidance for design and construction of soil nailing reinforcement technique in foundation.