基于正交试验法的重力锚基坑岩土参数敏感性分析

Sensitivity Analysis of Rock-Soil Parameters of a Gravity Anchor Excavation Based on Orthogonal Experiment Method

为了探究重力锚基坑变形过程中的岩土参数敏感性,以重庆万州驸马长江大桥北岸重力锚基坑作为研究对象,首先基于正交试验法设计计算方案,采用有限差分软件FLAC^(3D)对基坑开挖变形进行数值计算。然后对计算结果进行极差分析和方差分析。结果表明:极差分析和方差分析识别出的影响基坑开挖变形的主要岩土参数均为全风化层的弹性模量E_1、泊松比μ_1、黏聚力c_1、内摩擦角φ_1以及强风化层的弹性模量E_2;结合基坑开挖试算结果综合确定的反演目标参数为全、强风化层的弹性模量E_1和E_2。研究结果为后续的位移反分析奠定了基础,以及为控制基坑开挖变形提供了施工指导建议,同时还为类似工程的敏感性分析问题提供了借鉴方法。

In the aim of investigating the sensitivity of rock-soil parameters during the deformation of gravity anchor excavation,FLAC^(3D) was employed to simulate the deformation based on orthogonal experiment design,and range analysis and variance analysis were conducted for the simulation results. The gravity anchor excavation of Fuma Yangtze River Brideg in Wanzhou District,Chongqing City,was selected as the research object. Results of range analysis and variance analysis both suggest that elastic modulus E_1,poisson's ratio μ_1,cohesion c_1,and internal friction angle φ_1 of completely-weathered layer and elastic modulus E_2 of strongly-weathered sandy mudstone were identified as the dominant geotechnical parameters that affect the deformation of excavation. Furthermore in association with trial calculation results,E_1 and E_2 were determined as the target parameters of inversion analysis. The research results laid a foundation for subsequent displacement back analysis,provided guiding suggestion for controlling the deformation of excavation,and offered a reference for sensitivity analysis of similar engineering as well.