一种斜向大断面拱座单桩基础隧道式CRD法开挖三维数值分析

3-D Numerical Simulation Analysis of A Single Pile Skewback Foundation with Large Inclined Section Using CRD Tunnel Excavation Method

某大桥拱座基础为斜向大断面单桩基础,具有大型基坑和隧道受力的特点,空间受力复杂,很有必要研究其力学行为。采用摩尔库伦屈服准则,考虑材料的弹塑性,通过MIDAS GTS软件建立三维整体模型,计算分析了CRD法开挖施工过程中围岩、初支、中隔壁、横撑应力、变形的情况,归纳出随着开挖步施进初支最大主拉、压应力的分布曲线和位移曲线图。结果表明该施工方案初支拉、压应力及变形均较小,开挖至距离基础底约8米处为变形和应力最大处,对施工方案的制定和施工监测有重要的参考作用。

A form of single pile foundation with oblique large cross section is applied in an arch bridge abutment founda-tion .With the characteristics of large foundation pit and tunneling excavation ,the foundation is under complex mechani-cal stress .So it is necessary to study and discuss its mechanical behavior .Considering the elastic-plasticity of the materi-als by using Mohr-Coulomb criterion ,the three-dimensional integrated model was established by Midas-Gts software to calculate the situation of the primary support ,surrounding rocks ,medium septum ,transverse bracing and deformation during the CRD excavation .And then with the progress of the excavation ,the distribution and displacement curves of the maximum principal tensile and compressive stress of the primary support were concluded .The results suggest that the ten-sile and compressive stress of the primary support as well as the deformation are all smaller by the CRD excavation method ,and the maximum value of the stress occurrs when the foundation base is about 8 meters deep .The research re-sults have some referential significance to the planning of the construction scheme and the monitoring of the construction progress .