Mohr-Coulomb与Hoek-Brown强度准则在浅埋偏压隧道数值模拟中的对比

Comparison of Mohr-Coulomb and Hoek-Brown Criteria in Numerical Simulation of Shallow Unsymmetrial Loading Tunnel

在隧道建设中,因地形限制,常常遇到浅埋偏压等复杂情况,若再加上隧道围岩破碎、围岩条件较差,则会使隧道的施工设计难度大大增加。在对该类隧道进行数值模拟时,强度准则的选择对模拟结果的影响至关重要。Mohr-Coulomb(M-C)强度准则和Hoek-Brown(H-B)强度准则是隧道数值模拟研究中较为常用的两种强度准则。为了对这两种强度准则进行数值模拟对比研究,以贵阳市黔春大道七冲村二号隧道为工程背景,分别基于M-C强度准则和H-B强度准则,运用FLAC3D5.0建立三维模型,结合现场监测数据,从位移、应力两方面对模拟结果进行对比分析。结果表明:由于H-B强度准则将围岩视为非连续介质,反映了岩体非线性破坏的特点,考虑了岩体中的结构面等因素对强度的影响。因此,相比基于M-C强度准则的模拟结果,基于H-B强度准则的模拟结果的位移、应力值更大,且受到偏压的影响也更大,位移矢量及主应力迹线的偏转角度更大;但是在低应力状态下,M-C强度准则的适用性仍较好,因此在浅埋段中,基于两种强度准则的模拟结果在变形的发展趋势上以及应力重分布的情况都大致吻合;与现场监测数据相对比,两种模拟结果的水平位移变化与监测结果的趋势大致相同,但基于H-B强度准则的模拟结果相关性更好。

In the numerical simulation of this kind of tunnel, the choice of strength criterion is very important to the result. Mohr-Coulomb （M-C） and Hoek-Brown （H-B） strength criteria are the 2 most commonly used strength criteria in numerical simulation study of tunnel. In order to compare the numerical simulations of the 2 strength criteria, on the background of the project of Tunnel No. 2 in Qichong Village of Qianchun Road in Guiyang, we compared and analyzed the numerical simulation results from the aspects of displacement and stress by established 3D model using FLAC3D5.0 based on M-C and H-B strength criteria and monitoring data. The result shows that （1） Due to surrounding rock is regarded as discontinuous medium in H-B strength criterion, which reflects the characteristics of rock mass＂s nonlinear failure and considers the influence of structural plane and other factors on the strength. Therefore, comparing with the simulation result based on M-C strength criterion, the simulated displacement and stress based on H-B strength criterion are larger. They are more affected by the unsymmetrial loading, and the deflection angles of displacement vector and the trace of main stress are greater. （2） However, under low stress condition, the applicability of M-C strength criterion is still good. Therefore, in shallow buried section, the simulation results of deformation development trend and stress redistribution based on 2 strength criteria agree roughly. Compared with the field monitoring data, the trends of horizontal displacement of the 2 simulation results is approximately the same as that of the monitoring result. But the correlation of simulation result based on H-B strength criterion is better.