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以广梧高速公路牛车顶隧道为工程背景,探讨岩体流变情况下隧道二衬支护时机确定的理论和数值计算方法。对比理论方法预测拱顶下沉时程曲线与现场实测结果,建立数值计算模型,分析隧道围岩应力释放系数对围岩稳定性的影响表明,理论方法预测拱顶下沉时程曲线与现场实测表现出相同的发展规律,并且二者得到的二衬支护时间基本相同,验证了理论方法的正确性。围岩应力随着掌子面推进而不断释放,III级围岩应力释放比较缓慢,空间效应比较明显;当开挖释放应力系数大于或等于60%时,整个围岩的松动区都大于锚喷加固范围,最终确定出二衬的合理支护时机,为工程实践提供参考。
Based on the engineering background of the cow roof tunnel of Guang-Wu Expressway, the theoretical and numerical methods for determining the timing of tunnel lining support under rheological conditions are discussed. Contrast theory method is used to predict the time course of vault sinking and the field test results. The numerical calculation model is established to analyze the influence of the stress release coefficient of surrounding rock on the stability of surrounding rock. The theoretical method is used to predict the time course of vault sinking and the field measurement Showing the same law of development, and the two lining support time is basically the same, verify the correctness of the theoretical method. The stress of surrounding rock is released continuously with the progress of the face of the rock. The stress release of Grade III surrounding rock is relatively slow and the space effect is obvious. When the releasing stress coefficient of excavation is greater than or equal to 60%, the rock loosening area of the whole rock is larger than that of anchor spray Strengthen the scope of the final determination of the second lining of the reasonable timing of support for engineering practice to provide a reference.