基于Hoek-Brown强度准则的高应力判据理论分析

Theoretical analysis of high stress criterion based on the Hoek-Brown criterion

如何评价工程岩体中赋存的应力状态一直是工程设计人员所要面对的基本问题之一。应力状态评价需综合考虑岩体强度和岩体中赋存的应力两个要素,其评价结果反映了地下结构围岩在二次应力场作用下满足岩体强度准则时可能的变形破坏响应。通过对前人研究成果的分析,总结出高应力作用下地下结构的基本变形破坏规律。利用Hoek-Brown强度准则分析岩体强度与岩体质量分级参数和岩石单轴抗压强度的关系,得出多数情况下岩体强度与岩石单轴抗压强度的比值都小于0.5,进一步确认了利用岩体强度和应力之比作为高应力判据的可靠性。通过综合分析Hoek-Brown强度准则和岩石剪切破坏的摩擦理论,推导出在不同摩擦系数下岩体强度与岩体中赋存的最大主应力在破坏时的基本关系。根据这一基本关系,再结合地下空间二次应力场的调整规律,从岩石力学的角度证明了新的高应力判据。将该高应力判据应用于国内外的各种已建成的工程实例,发现评价效果良好。最后给出了应用该高应力判据进行应力状态评价的一般步骤,同时也指出所需要注意的问题。

How to evaluate the stress state in an engineering rock mass is one of the most fundamental problems that all the underground structure designers have to be faced with.Evaluating the stress state needs considering both sides of this problem,rock mass strength and stresses in the rock mass.The evaluation results reflect the deformation and failure responses of surrounding rock masses under the actions of secondary stresses when they observe a rock mass strength criterion.Most research findings in the past on high stress criterion are summarized to infer a general deformation and failure law for underground structures under the impact of high stresses.By analyzing the relation between the rock mass strength and the rock mass rating parameters and the uniaxial compressive strength（UCS） of rock specimens according to the Hoek-Brown criterion,a conclusion is come to that the ratio of the rock mass strength to the UCS should be less than 0.5 in most situations.With respect to the new high stress criterion put forward by the authors in 2009,basic relationships at different frictional coefficients between the rock mass strength and the maximum principal stresses present in the rock mass are obtained by analyzing the Hoek-Brown strength criterion and rock friction theory comprehensively;based on this relationship and the redistribution law of secondary stress field around an underground opening,the new high stress evaluation criterion is verified from the aspect of rock mechanics.The application of this criterion to some engineering practices all over the world proves that this new high stress evaluation criterion works very well.Finally,the authors put forward the general rules and procedures for how to use this new criterion,and some concerns that should be careful of.