水平旋喷组合结构中管棚受力特点数值分析

Properties of pipe roof in horizontal jetgrouting pile composite pre-reinforcement structure

为研究隧道预加固管棚水平旋喷桩组合结构中管棚的力学行为、管棚搭接处的受力特点,采用三维弹塑性有限元方法,对比分析在开挖过程中,管棚水平旋喷桩组合结构和超前管棚注浆结构中管棚的轴应力、剪应力、弯矩分布特点。结果表明:管棚水平旋喷桩组合结构中,钢管所受弯矩和剪应力约为超前管棚注浆结构的10%,所受轴应力约为超前管棚注浆结构的40%;钢管的受力特点与超前管棚注浆结构存在较大差异。2种结构的管棚搭接处的力学行为均较为特殊,在分析管棚水平旋喷桩组合结构中钢管的受力情况,或对超前管棚注浆结构考虑管棚搭接效应进行受力分析时,应将现有受力简化模型进行修正。

To investigate the mechanical behaviors of pipe roof inside horizontal jet-grouting pile composite structure and the pipe mechanical characteristics in overlapping area,3D elastic-plastic finite element method was used to comparativly analyze the axial stress,the shear stress and the bending moment distribution characteristics of steel pipes in horizontal jet-grouting pile composite structure and pipe roof structure,in the process of the excavation.The results indicate that there are large gaps on the mechanical characteristics of steel pipes for horizontal jet-grouting pile composite structure and steel pipe roof structure.In the horizontal jet-grouting pile composite structure,steel pipes bear only 10% bending moment and shear stress and 40% axial stress of that of the steel pipe roof structure.The steel pipe mechanical behavior changes in the overlapping area as well.The existing simplified mechanical model of steel pipes should be modified when mechanical characters are investigated for either the steel pipe in jet-grouting composite structure or in the pipe roof structure considering the overlapping effect.