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TBM(全断面隧道掘进机)施工和钻爆法是地下工程开挖的两种主要方法,不同施工方法导致围岩的扰动程度、变形破坏、自稳性、加固措施均不相同,要准确把握这些宏观特征,必须从微观上分析岩石的力学特征。本文以最大埋深2525m的锦屏二级水电站长大引水隧洞为研究对象,对不同开挖条件下的大理岩进行了声发射测试,分析了不同开挖条件下岩石的力学响应。试验结果表明:大理岩破坏过程是内部微裂纹产生和扩展过程的宏观反映,声发射信号与应力—应变曲线有良好的对应关系。在岩石破坏点的响应时间上,TBM开挖条件下的岩石应力—应变曲线在峰值强度附近表现得较为平坦,即在峰值荷载附近表现出较强的变形能力而不发生宏观破坏,同时TBM条件下的声发射振铃数比钻爆法响应要晚,表明TBM开挖条件下围岩的抗破坏能力更强一些。
TBM (Full-face Tunnel Boring Machine) construction and drilling and blasting methods are the two main methods of excavation of underground engineering, different construction methods lead to the disturbance of surrounding rock, deformation and failure, self-stability, reinforcement measures are not the same, to accurately grasp These macroscopic features must be analyzed microscopically from the mechanical characteristics of rocks. In this paper, the largest diversion tunnel of Jinping second stage hydropower station with a maximum depth of 2525m is taken as the research object. Acoustic emission tests are conducted on marble under different excavation conditions, and the mechanical response of rocks under different excavation conditions is analyzed. The experimental results show that the marble failure process is a macroscopic reflection of the internal microcracks generation and propagation process, and the acoustic emission signal has a good correspondence with the stress-strain curve. At the time of rock failure, the stress-strain curve of rock under TBM excavation is relatively flat near the peak intensity, that is, it shows strong deformability near the peak load without macroscopic failure, and the TBM condition The number of ringing of acoustic emission under the blasting method is later than that of the drilling and blasting method, which indicates that the rock surrounding the TBM is more resistant to destructive damage.