基于Hoek-Brown准则等效强度参数的工程应用

Application of Equivalent Strength Parameters based on Hoek-Brown Criterion in Deep-Buried Tunnels

为研究重庆至长沙省际公路共和隧道层状围岩稳定性,减小模拟值与实测值误差,并充分考虑倾角效应、静水压力效应和罗德角效应,将适用于层状岩体的修正Hoek-Brown(H-B)准则在I_(1)-√J_(2)平面与Mohr-Coulomb(M-C)准则进行瞬时等效,推导出用于层状岩体的等效强度参数公式,计算得到不同倾角下砂质页岩等效c、φ值,然后输入FLAC^(3D)遍布节理模型中对原岩体参数进行修正。结果表明:1)修正岩体参数法所得关键点位移变化规律与修正前一致,且位移量大于修正前,但当倾角大于60°后,该法适用性有所降低;2)修正后围岩各关键点偏应力(σ_(1)-σ_(3))始终大于修正前,且二者塑性区随倾角变化趋势一致;3)当岩体内摩擦角小于节理内摩擦角时,围岩塑性区面积较大;反之,当岩体内摩擦角大于节理内摩擦角时,塑性区面积较小。

In order to reduce the error between the simulated value and the measured value and to fully consider the dip effect,hydrostatic pressure effect,and Rod angle effect,the revised Hoek-Brown(HB)criterion for layered rock masses was applied to the I_(1)-√J_(2)plane and Mohr-Coulomb(MC)criterion performs instantaneous equivalence,derived the equivalent strength parameter formula for layered rock mass,calculated the equivalent c andφvalues of sandy shale under different dip angles,and then entered them to Ubiquitous-Joint model in FLAC^(3D).The original rock mass parameters were revised,and the stability of the layered surrounding rock of the Gonghe Tunnel of the Chongqing-Changsha Interprovincial Highway was studied.The results showed that:1)The change law of the key point displacement obtained by the modified rock mass parameter method is the same as that before the modification,and the displacement is larger than that before the modification,but when the inclination angle is greater than 60°,the applicability of the method is reduced;2)The deviator stress at the key point(σ_(1)-σ_(3))is always greater than before correction,and the plastic zone of the two has the same tendency with the dip angle;3)When the friction angle in the rock body is less than the internal friction angle of the joint,the plastic zone area of the surrounding rock is larger;When the friction angle in the rock body is greater than the internal friction angle of the joint,the area of the plastic zone is smaller.