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Long-term mechanical and acoustic emission characteristics of creep in deeply buried jinping marble considering excavation disturbance
International Journal of Rock Mechanics and Mining Sciences ( IF 7.0 ) Pub Date : 2021-01-22 , DOI: 10.1016/j.ijrmms.2020.104603
Ersheng Zha , Zetian Zhang , Ru Zhang , Shiyong Wu , Cunbao Li , Li Ren , Mingzhong Gao , Jifang Zhou

To obtain a complete understanding of the stability of deep caverns after excavation disturbance, a laboratory simulation method for testing surrounding rock under excavation disturbance was systematically proposed. The rock creep mechanical behavior considering excavation disturbance was compared with that of rock without excavation disturbance, and the results show that the long-term rock strength considering excavation disturbance is significantly lower than that without excavation disturbance at a 2400 m depth. Based on this method, a step-loading triaxial creep and associated acoustic emission (AE) test was carried out with a single-stage loading time of 5 days and a total loading time of approximately 50 days. The results show that with an increase in stress level, the transient strain of the deep rock increases nearly linearly, while the axial creep strain rate increases exponentially. The AE monitoring results demonstrate that when the rock creep transforms from the initial creep stage to the steady-state creep stage, and from the steady-state creep stage to the accelerating stage, the AE amplitude will clearly exhibit a band-shaped distribution, and the AE count rate and AE energy rate will show a single peak or multiple peaks. Multistage AE data can be used to determine the long-term strength of rock. In addition, with an increase in the stress level, the microcracks of the deep rock under excavation disturbance transform from closed primary microcracks to initiating, propagating and coalescence secondary microcracks, which ultimately leads to macroscopic shear failure. The above research results can provide a reference for deep resource exploitation and deep cavern stability evaluation.



中文翻译:

考虑开挖扰动的深埋锦屏大理石的蠕变的长期力学和声发射特性

为了全面了解开挖扰动后深洞的稳定性,系统地提出了一种在开挖扰动下测试围岩的实验室模拟方法。比较了考虑开挖扰动的岩石蠕变力学行为和不考虑开挖扰动的岩石蠕变力学行为,结果表明,在2400 m的深度下,考虑开挖扰动的长期岩石强度明显低于不考虑开挖扰动的岩石。基于此方法,进行了一步加载三轴蠕变和相关声发射(AE)测试,其中单阶段加载时间为5天,总加载时间为大约50天。结果表明,随着应力水平的提高,深层岩石的瞬态应变几乎呈线性增加,而轴向蠕变应变率呈指数增长。AE监测结果表明,当岩石蠕变从初始蠕变阶段过渡到稳态蠕变阶段,并且从稳态蠕变阶段过渡到加速阶段时,AE振幅将明显呈现出带状分布,并且AE计数率和AE能量率将显示一个或多个峰。多阶段AE数据可用于确定岩石的长期强度。另外,随着应力水平的增加,开挖扰动下的深部岩石的微裂纹从封闭的初级微裂纹转变为初始,扩展和合并的次级微裂纹,最终导致宏观剪切破坏。

更新日期:2021-01-22
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