基于围岩动态分级的隧道底部支护优化与稳定性研究

徐东强 邢亮 曹富兴

摘要 在对以往隧道工程进行调研的基础上，确定合适的围岩动态分级方法后，采用围岩分级后的岩石力学参数在承赤高速进行现场试验与监测得出平底隧道支护符合稳定要求。并根据霍克布朗准则，通过FLAC3D有限差分软件对比不同隧道底部模型的拱顶沉降、拱底隆起和二衬应力得出：Ⅳ1级围岩下隧道两个模型的竖向位移变形值相差不超1 mm，平底隧道的二衬与仰拱隧道二衬在承载应力上差距较小。故Ⅳ1级围岩下取消仰拱，采用平底隧道的形式具有可行性。其他类似工程可借鉴于此研究成果。

关 键 词 围岩动态分级;岩石力学参数;霍克布朗准则;有限差分软件;可行性

中图分类号 U451     文献标志码 A

Support optimization and stability of tunnel bottom based on dynamic classification of surrounding rock

XU Dongqiang， XING Liang， CAO Fuxing

（School of Civil Engineering and Transportation， Hebei University of Technology， Tianjin 300401， China）

Abstract On the basis of previous tunnel projects' investigation， suitable dynamic classification method of surrounding rock is determined. The field test and monitoring of rock mechanics parameters after surrounding rock classification at Chengchi Expressway show that the flat bottom tunnel supports meets the stability requirements. According to the rule of Hoek-Brown， through FLAC3D finite difference software contrast different model at the bottom of the tunnel vault subsidence， arch bottom uplift and the secondary lining， can conclude that the vertical displacement of each tunnel model differs by no more than 1 mm in controlling settlement for IV1 surrounding rock and there was a small difference in bearing stress between the secondary lining of flat bottom tunnel and that of invert tunnel. It verifies the feasibility of using flat-bottom tunnel to substitute invert arch for IV1 surrounding rock.Other similar projects can draw on the results of this research.

Key words dynamic classification of surrounding rock; rock mechanics parameters; rule of Hoek-Brown; finite difference software; feasibility

0 引言

現代隧道建设中通过支护结构调动围岩承载能力的观念深入人心，然而隧道开挖是一个动态过程，围岩状况也不是一成不变的，如何根据工程需要确定合理的围岩参数，是隧道修建过程中需要考虑的问题[1-2]。并且，在围岩性质不良的隧道中，仰拱作为公路隧道衬砌的结构设计中的一部分，能够有效的控制围岩变形。王可意[3]细化了岩体的完整性系数与岩石的风化程度对岩石强度指标的影响。石志龙等[4]通过监测数据及时调整围岩级别，控制施工参数取得了较好的经济效益。实际围岩力学行为较为复杂，具有明显的时空效应，随施工过程而变化[5]。进行现场监控量测能够及时了解隧道结构的实际受力情况，是衡量隧道稳定性的标准[6-7]。……