基于Hoek-Brown强度折减法的隧道开挖面稳定分析

Stability Analysis of Tunnel Excavated Surface Based on Hoek-BrownStrength Reduction Method

在隧道开挖过程中,当泥水盾构通过岩层时刀盘磨损加快,需定点开舱检查及更换刀具,此时开挖面的稳定情况对工程安全至关重要。依托南京市江宁区新济洲供水管线廊道工程,采用PLAXIS~(3D)有限元软件建立数值模型,并与现场监测结果进行对比,基于霍克布朗(H-B,Hoek-Brown)准则的强度折减法,计算不同支护应力下隧道开挖面的安全系数,得到各工况下的破坏模式。结果表明:在该工程中,开挖面在各工况下均处于稳定状态,常压开舱安全系数2.9,带压开舱最大安全系数17.2,可优先选择常压开舱;开舱点开挖面附近岩土体破坏模式分为4类:中心内侵型、两侧内侵型、滑落型和外侵型;随着支护压力的增大,安全系数先增大后减小,最大安全系数对应支护压力约为1.35倍的开挖面水土压力。

In the process of tunnel excavation,it is needed to check or replace the cutter at some suitable locations.Currently,the stability of the excavation surface is crucial to the safety of the project.Based on the Xinjizhou water supply pipeline corridor project in Nanjing City,this paper establishes a numerical model,and compares the numerical results with the field monitoring results.The safety factors of tunnel excavation surface under different supporting pressure are calculated based on strength reduction method of Hoek-Brown criterion,and the failure modes under various working conditions are obtained.The results show that the failure modes of rock mass near the excavation surface are divided into four types:central inward invasion,bilateral inward invasion,sliding and outward invasion.With the increase of support pressure,the safety factor increases first and then decrease sharply,and the maximum safety factor corresponds to 1.35 times of original stress of excavation face.