高地应力硬脆性围岩破坏影响因素分析

地应力对硬脆性岩体稳定性具有极为重要作用,已有研究主要集中于脆性破坏方式及其是否发生的预测上,而对地应力、洞形等因素与脆性破坏深度间关系的研究较为少见。基于硬脆性岩体脆性破坏准则,利用Examine2D软件,分析不同地应力环境及洞形时围岩脆性破坏深度d_f变化情况。结果表明:最小主应力量值较低时,破坏深度d_f与主应力比k近似为直线关系,较高时则为非线性增长;随着k值增加,屈服范围逐渐偏离最小主应力方向45°夹角发展;洞室断面长宽相近时,主应力方向较主应力量值对d_f的影响小,相同应力量值不同主应力方向,破坏位置不同,深度变化较小。洞形不同应力集中系数不同,选择长短轴长度之比与应力比k相接近的椭圆形谐洞,可有效降低破坏深度。

Influence of Different Factors on Hard Rock Brittle Failure in High In-situ Stress

The in-situ stress is obviously important to the stability of the underground opening in brittle hard rock. Previous researches generally focused on the brittle failure fashion and its prediction, the relation of the in-situ stress and the depth of brittle failure is extremely insufficient. In the paper, based on the brittle failure criterion, the relationship between the different in-situ stress environment,opening shape and the depth of brittle failure d5 have been analyzed by Examine2D soft- ware. Conclusions can be drawn as follows：with the increase of principal stress ratio k value,dr shows increase trend in the form of line in the low minimum principal in-situ stress, in the form of non-line in the high minimum principal in-situ stress and damaged region diverge the direction of the minimum principal stress to the angle of 45~ between the minimum in-situ stress. The in- fluence of the direction of principal stress is lower than the value of the principal stress when tunnel＇s length similar to width. The site of brittle failure is different with different tunnel shape in the identical in-situ principal stress environment, but the depth of brittle failure is minor. Stress concentration factor in different excavation shape is different. The depth of brittle failure effectively reduced when the prolate axis vs minor axis equal to the k in ellipse cavern.