基于收敛-约束法的隧道围岩安全性评价

Evaluation of Tunnel Surrounding Rock Safety Based on Convergence-constraint Method

以Hoek-Brown弹塑性模型及应变软化模型为基础,采用FLAC3D数值模拟软件,构建三维数值模型,计算深埋隧道不同开挖方式下的围岩特征曲线,并对隧道围岩及支护结构稳定性进行评价。研究结果表明:采用Hoek-Brown弹塑性模型计算所得的隧道围岩安全系数要低于应变软化模型所计算得到的安全系数,表明采用弹塑性模型进行支护结构设计时,支护结构安全性较低,设计中可能会导致支护材料费用的增加,而考虑应变软化条件下的围岩安全系数更加接近工程实际;采用不同开挖形式所获得的隧道围岩安全系数并不相同,采用全断面法开挖所获得的安全系数要明显低于七步开挖法,采用收敛约束法计算隧道围岩稳定性更加直观。

Based on Hoek-Brown elastic-plastic model and strain softening model, by using FLAC^3D numerical simulation software, a 3D numerical model is built to calculate the surrounding rock characteristic curve of deep buried tunnel under different excavation conditions, and the stability of tunnel surrounding rock and support structure are evaluated. The results show that （ 1 ） the safety factor of tunnel surrounding rock calculated by Hoek-Brown elastic-plastic model is lower than that calculated by strain-softening model, indicating that when using elastic-plastic model for supporting structure design, the safety of supporting structure is poor, the design of which may increase the supporting material cost, while considering the safety factor of surrounding rock under strain softening condition is closer to actual engineering; （2） different forms of tunnel excavation modes result in different safety factors of surrounding rock, the safety factor obtained by full section excavation method is significantly lower than that obtained by 7-step excavation method, and the rock stability calculated by convergence-constraint method is more intuitive.