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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 existing in the engineering rock mass has always been one of the basic problems that the engineering designers should face. The evaluation of stress state needs to consider both the strength of rock mass and the stress existing in the rock mass. The evaluation results reflect the possible deformation and failure response of the surrounding rock of underground structure when it meets the rock mass strength criterion under the secondary stress field. Through the analysis of previous research results, the basic rules of deformation and failure of underground structures under high stress are summarized. The Hoek-Brown strength criterion is used to analyze the relationship between rock mass strength and rock mass grading parameters and the rock uniaxial compressive strength. It is concluded that the ratio of rock mass strength to uniaxial compressive strength of rock mass is less than 0.5 in most cases. Use the ratio of rock mass strength and stress as the criterion of high stress. Through the comprehensive analysis of the Hoek-Brown strength criterion and the friction theory of rock shear failure, the basic relationship between the rock mass strength and the maximum principal stress existing in the rock under different friction coefficients is deduced. According to this basic relationship, combined with the adjustment rule of secondary stress field in underground space, new high stress criterion is proved from the perspective of rock mechanics. Applying the criterion of high stress to various completed engineering cases at home and abroad, we find that the evaluation results are good. Finally, the general procedure of stress state evaluation applying this high stress criterion is given, and the problems that need to be noticed are also pointed out.