地铁隧道新型初期支护结构支护参数敏感性正交数值模拟试验

为研究喷混等级、波纹钢板厚度、砂浆锚杆长度和间距4 种主要因素对隧道围岩稳定性的影响程度,以广州市轨道交通22 号线横沥站至番禺广场站暗挖区间隧道工程为研究背景,把正交试验法与地下工程有限元法结合应用于隧道支护参数的优化,并设计了9 种试验工况,通过极差分析优化锚喷支护参数和波纹钢板厚度,利用结构内力验算安全系数确保其满足设计要求。研究结果表明: 针对广州地区典型的上软下硬地层,分析了不同支护参数组合下的围岩及支护结构受力变形规律,得出了优化后的支护参数;通过极差分析得到混凝土等级为重要影响因素,在很大程度上影响了围岩的稳定性,而波纹钢板、锚杆长度和间距为次要影响因素。

Orthogonal Numerical Simulation Experiment on Structural Parameter Sensitivity of New Type of Primary Support of Metro Tunnel

The orthogonal experiment method combined with finite element method is applized to the optimization of support parameters of a mined tunnel section on Hengli Station-Panyu Square Station of Guangzhou Rail Transit Line No. 22, and 9 experiment conditions are designed to study the influences of shoctcrete grade, corrugated steel plate thickness, mortar anchor length and spacing on the stability of tunnel surrounding rock. And then the parameters of boltshotcrete support and the thickness of corrugated steel plate are further optimized by range analysis, and the safety factor is checked by the structural internal force to meet relevant design requirements. The study results show that: (1) The optimized support parameters for typical upper soft and lower hard strata in Guangzhou area are obtained by analyzing the stress and deformation laws of surrounding rock and supporting structure under different combinations of supporting parameters. (2) The range analytical results indicate that the concrete grade is an important influencing factor greatly affects the stability of the surrounding rock, while the corrugated steel plate thickness, mortar anchor length and spacing are the secondaries.