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在高应力作用下,岩爆、钻孔崩落、片帮都是地下空间硬脆围岩中常见的破坏现象,这三类现象本质上均可归于完整岩体的脆性破坏,它们分别反映了高应力作用下完整岩体不同的破坏程度。通过对前人关于岩爆判据、钻孔崩落判据和片帮应力强度比判据研究成果的类比分析可知,这些脆性破坏现象在破坏时具备相同的应力背景条件。脆性破坏的应力条件可以用地下空间周边切向最大应力与岩石单轴抗压强度之比(σθmax/σci)或者工程区最大主应力与岩石单轴抗压强度之比(σ1/σci)来描述,两种指标本质上反映了相同的应力背景条件。对于σθmax/σci,σθmax/σci=0.4±0.1是发生脆性破坏的应力临界条件;对于σ1/σci,σ1/σci=0.15±0.05是发生脆性破坏的应力临界条件。大量的工程实例和基于Hoek-Brown强度准则的力学分析也证明了这一背景条件的正确性。这里两种指标都取了一个范围,主要是由于不同的岩体分级、岩性和工程地质条件会对指标的界定产生较为显著的影响。
Under the action of high stress, rockburst, borehole caving and sheet caving are all common failure phenomena in hard and brittle surrounding rock of underground space, and these three kinds of phenomena can all be attributed to brittle failure of intact rock mass in essence, which respectively reflect high Different damage degree of complete rock mass under stress. Through the analogy analysis of the predecessors’ research results about the criteria of rockburst, the criterion of drilling cavern and the criterion of stress intensity ratio, we can see that these brittle failure phenomena have the same stress background conditions when they are damaged. The stress conditions for brittle failure can be described by the ratio of the maximum stress in the perimeter of the subsurface to the uniaxial compressive strength of the rock (σθmax / σci) or the ratio of the maximum principal stress to the uniaxial compressive strength of the rock (σ1 / σci) , The two indicators essentially reflect the same stress background conditions. For σθmax / σci, σθmax / σci = 0.4 ± 0.1 is the stress critical condition for brittle failure; for σ1 / σci, σ1 / σci = 0.15 ± 0.05 is the stress critical condition for brittle failure. A large number of engineering examples and mechanics analysis based on Hoek-Brown strength criterion also prove the correctness of this background condition. Both of these two indicators have taken a range, mainly due to different rock mass grading, lithology and engineering geological conditions will have a more significant impact on the definition of indicators.