基于敏感性分析的地铁车站矩形深通风竖井支护参数优化

Supporting Parameters Optimization of Rectangular Deep Ventilation Shaft for Subway Stations Based on Sensitivity Analysis

为分析不同的喷射混凝土厚度、锚杆长度、锚杆间距和工字钢横向支撑间距对重庆某地铁车站矩形通风竖井围岩位移的影响,采用有限元数值模拟和敏感性分析方法,对竖井短边(X方向)、长边(Y方向)水平位移的敏感度系数进行分析。计算结果表明:1)竖井水平位移与支护结构参数的敏感性顺序依次为喷射混凝土厚度>工字钢间距>锚杆间距>锚杆长度;2)X、Y方向6 m深度处支护结构参数的敏感度系数比60 m深度处支护结构参数的敏感度系数均略大。结合工程实际,提出了优化横向支撑支护参数,且优化后的围岩变形和喷射混凝土的应力、弯矩及锚杆轴力均有所增大,但仍符合规范中位移限值及支护结构容许应力的要求,明显提高了施工进度,为岩石地层矩形深通风竖井支护结构设计提供参考。

In order to analyze the influence of different shotcrete thickness,anchor length,anchor spacing and different lateral support spacing of I-steel on the surrounding rock displacement of rectangular ventilation shaft,in a subway station of Chongqing Rail Transit,finite element numerical simulation and sensitivity analysis methods are used to analyze the sensitivity coefficients of horizontal displacement on the short side(X direction)and long side(Y direction)of the shaft.The results show that:1)the sensitivity of vertical shaft horizontal displacement and supporting structure parameters is in the order of shotcrete thickness>I-beam spacing>bolt spacing>bolt length,and the sensitivity coefficient of supporting structure parameters at a depth of 6 m in the X and Y directions;2)the sensitivity coefficients of the support structure parameters at a depth of 60 m are slightly larger.Based on the actual project,the optimized lateral support parameters are proposed.After optimization,although the deformation of the surrounding rock and the stress,bending moment and bolt axial force of the shotcrete have been increased,it still meets the requirements of the displacement limit and the allowable stress of the supporting structure in the specification,which significantly improves the construction schedule.It provides reference for the design of rectangular deep ventilation shaft supporting structure in rock formations.