摘要
为准确评价围岩稳定性,通常利用FLAC3D中的遍布节理模型,并采用Mohr-Coulomb强度准则开展模拟计算,但由于其本质上是将层状岩体视为各向同性,因此模拟结果与现场监测值相比误差较大。基于修正的Hoek-Brown准则,将其在I_(1)-√J_(2)平面与Mohr-Coulomb强度准则分别进行瞬时等效、最佳一次逼近,推导出相应的等效强度公式。利用该公式计算得到不同倾角岩体的等效强度参数,并导入FLAC3D遍布节理模型,研究渝湘高速共和隧道段围岩稳定性。结果表明:1)采用2种方法对岩体参数进行修正,隧道开挖后关键点变形均大于修正前,更接近实测值;2)瞬时等效修正所得偏应力σ_(1)-σ_(3)值小于修正前,而最佳一次逼近修正所得σ_(1)-σ_(3)值始终大于修正前,且随倾角变化趋势与修正前相同;3)2种修正法均可用于岩体参数修正,经过对比分析认为最佳一次逼近修正效果更佳。
Generally,the pervasive joint model in FLAC3D and the simulation calculation using Mohr-Coulomb strength criterion are used to evaluate the stability of rock accurately.However,the layered rock mass is essentially regarded as isotropic,leading to a large error between simulated results and monitoring values.Based on a revised Hoek-Brown criterion,the instantaneous equivalent and best one-time approximation are performed on the I_(1)-√J_(2)plane and Mohr-Coulomb strength criterion,respectively,and the corresponding equivalent strength formula is derived.The formula is used to calculate the equivalent strength parameters of rock masses with different inclination angles,and the FLAC3D pervasive joint model is imported to study the stability of the surrounding rock in the Gonghe tunnel of the Chongqing-Hunan expressway.The results show the following.(1)The methods are used for modifying the rock mass parameters.The deformation of key points after the tunnel excavation is greater than that before the modification,which is closer to the measured value.(2)The value of deviatoric stressσ_(1)-σ_(3)obtained from the instantaneous equivalent modification is smaller than that before the modification.The value ofσ_(1)-σ_(3)obtained from the best one-time approximation modification is greater than that before the modification,and the change in trend with inclination is the same as that before modification.(3)The instantaneous equivalent modification and best one-time approximation modification methods can be used for rock mass parameter modification;the latter one has a better effect.
作者
胡其志
刘倩
丁志刚
包文成
HU Qizhi;LIU Qian;DING Zhigang;BAO Wencheng(School of Civil Engineering,Architecture and Environment,Hubei University of Technology,Wuhan 430068,Hubei,China;CCCC Road and Bridge Southern Engineering Co.,Ltd.,Beijing 101149,China)
出处
《隧道建设（中英文）》
CSCD
北大核心
2021年第10期1662-1671,共10页
Tunnel Construction
基金
国家自然科学基金(51979100)。
