In situ observation of spalling process of intact rock mass at large cavern excavation
In situ observation of spalling process of intact rock mass at large cavern excavation
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DOI：
10.1016/j.enggeo.2017.05.012
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发表时间：
2017-08-30
影响因子：
7.4
通讯作者：
Li, Shaojun
中科院分区：
文献类型：
--
作者：
Liu, Guofeng;Feng, Xia-Ting;Li, Shaojun
本文介绍了一座跨度34m、高88.7m的大型地下厂房，在历时两年多的分层开挖过程中，对岩体剥落过程的现场观测结果。建立了一种利用数字钻孔摄像机在预制钻孔中对岩片剥落过程进行现场观测的方法。观测结果清晰地显示了岩石破裂及伴随的层裂破坏的全过程。不仅可以捕捉到沿洞室轴线沿着分步开挖影响下的岩石破裂和剥落的发展情况，而且可以观察到后续分层开挖对先前岩石破裂和剥落区域的影响。通过观测结果可以更好地了解大型洞室围岩的破坏机制，这涉及复杂的开挖顺序。讨论了大型洞室与小型隧洞围岩片裂行为的差异。分析了地应力、地质构造、岩石力学性质、分层开挖等因素对岩石剥落过程的影响。研究成果对类似大型地下洞室群的开挖与支护设计具有一定的指导意义，对高地应力条件下大型洞室群施工过程中开挖方案的动态调整和支护优化具有一定的指导意义。
This paper presents the results of in situ observation of rock spalling process of a large underground powerhouse, with 34 m in span and 88.7 m in height, during excavation layer by layer over two years. A method for in situ observation of rock spalling process has been established in pre-installed boreholes by using digital borehole camera. Observation results clearly show the whole process of rock fracturing and the associated spalling failure. Not only could the development of rock fracturing and spalling affected by the step-by-step excavations along the cavern's axis be captured, but also could the effect of the subsequent excavation layer by layer on the previous rock fracturing and spalling area be observed. The failure mechanism of rock mass surrounding the large cavern, which involves complex excavation sequences, could be better understood through the observation results. The difference of rock spalling behavior between large cavern and small tunnel is discussed. Influence of geostress, geological structures, rock mechanical properties, and layered excavation process on rock spalling process has been analyzed. The results in this study is instructive for rethinking the engineering design including the excavation and support at similar large underground caverns, as well as for the dynamic adjustment of excavation schemes and support optimization during the construction of a large cavern subjected to high geostress.