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随着大量深埋越岭隧道的修建,高地应力问题对于围岩分级的影响越来越大。公路隧道设计规范中的围岩分级BQ法对于初始地应力影响的折减系数K3仅从高地应力和极高地应力两个方面进行考虑,而对于高地应力情况下影响围岩稳定的岩爆和大变形情况未加以区分和细化,从而造成BQ法在高地应力段特别是岩爆和大变形段的分级适应性较差。本文针对BQ法对于初始地应力折减系数K3该方面考虑不足的缺点,将高地应力情况的岩爆和大变形对围岩质量的影响引入围岩分级中,采用强度应力比值将岩爆烈度分为四个等级、大变形分为三个等级,各个等级对应相应的折减值,从而形成岩爆段和非岩爆段的初始地应力折减系数值K31,以及大变形段和非大变形段的初始地应力折减系数值K32,再以BQ法为基础建立了高地应力条件下的围岩分级BQ-hg法。通过对BQ-hg法进行围岩分级应用检验,其分级准确率较高,适应性较好,值得进一步完善和推广。
With the construction of a large number of deep buried tunnels, the impact of the problem of high ground stress on the classification of surrounding rock is more and more significant. The reduction coefficient K3 of the surrounding rock classification BQ method in the design specifications of highway tunnels for initial geostress is only considered from two aspects of high geostress and very high geostress. For rockburst and large rock mass which affect the stability of surrounding rock in high ground stress The deformation has not been distinguished and refined, resulting in poor grading adaptability of the BQ method in the high-stress stage, especially in the rock burst and the large deformation section. In this paper, the BQ method for the initial stress reduction factor K3 this aspect to consider the shortcomings of high rock stress and the large deformation of the surrounding rock quality into rock classification, the use of intensity and stress ratio will rock burst intensity points For the four grades, the large deformation is divided into three grades, and each grade corresponds to the corresponding reduction value to form the initial stress reduction coefficient K31 of the rock burst section and the non-rock burst section, as well as the large deformation section and the non-large deformation section Section of the initial stress reduction factor K32, and then based on the BQ method established under the conditions of high rock stress classification BQ-hg method. Through the application of BQ-hg method to the surrounding rock grading, the grading accuracy rate is higher and the adaptability is better, which deserves further improvement and promotion.