As a man-made engineering hazard, it is widely accepted that rockburst is the result of energy release. Previous studies regarded the unloading of in-situ stress resulted from deep tunnel excavation as a quasi-static process, whereas the transient stress variation during excavation is received much less attention. In this research, rockbursts happened during conduction of diversion tunnels at Jinping II hydropower station were introduced at first. Then, the brittle-ductile-plastic (BDP) transition property of Jinping marble was numerically described by the Hoek-Brown strength criterion, and the dynamic energy release process derived from the transient unloading of in-situ stress was studied using an index, local energy release rate. Studies have shown that, due to transient unloading, the strain energy of the surrounding rock mass goes through a dynamic process of decreasing at first, increasing at second, next reducing and stabilizing at last. Moreover, the first decreasing of strain energy results from elastic unloading wave and does not cause brittle failure in rock masses, which is consistent with the elastic condition. But the secondary reducing of strain energy owes to that the accumulated strain energy in rock masses exceeds the storage limit, and inevitably triggers off the brittle failure in the rock mass. Thus, the shorter distance to tunnel wall means the bigger and intenser energy release. Finally, a relationship between the average value of local energy release rate and the rockburst intensity was established to assess the rockburst risk induced by excavation of a deep tunnel by blasting.

中文翻译：

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能量释放视角下的岩爆预测——以锦屏二级水电站引水隧洞为例

作为一种人为工程危害，岩爆是能量释放的结果已被广泛接受。以往的研究认为，深部隧道开挖产生的地应力卸载是一个准静态过程，而开挖过程中的瞬态应力变化却很少受到关注。本研究首先介绍了锦屏二级水电站引水隧洞导流过程中发生的岩爆。然后，利用Hoek-Brown强度准则数值描述锦屏大理岩的脆-韧-塑性(BDP)转变特性，并利用指数、局部应力研究了地应力瞬态卸载产生的动态能量释放过程。能量释放率。研究表明，由于瞬态卸载，围岩的应变能经历了一个先减小，后增大，再减小，最后稳定的动态过程。此外，应变能的首次下降是由弹性卸载波引起的，不会引起岩体的脆性破坏，这与弹性条件是一致的。但应变能的二次降低是由于岩体中累积的应变能超过了储存极限，不可避免地引发了岩体的脆性破坏。因此，到隧道壁的距离越短意味着能量释放越大越强烈。最后，建立局部能量释放率平均值与岩爆强度之间的关系，以评估深部隧道爆破开挖的岩爆风险。