中文摘要：

利用FLAC3D软件模拟锦屏二级水电站施工排水洞典型洞室断面围岩开挖应力调整过程,通过关键点应力监测分析洞壁不同深度围岩应力变化过程特征及岩爆潜在动力源分布情况,同时,据自洞壁围岩应力释放率分析研究岩爆滞后性特征。研究结果表明：洞壁浅表层围岩最大、最小主应力皆为降低过程,发生应力降低型屈服却不易积聚弹性应变能;距洞壁一定距离处围岩发生塑性屈服并积聚较高弹性应变能,形成岩爆潜在动力源,随围岩屈服过程不同程度地释放能量,对浅表层屈服围岩的稳定产生影响进而发生岩爆灾害;深部弹性区围岩亦聚集较高的应变能,会进一步加剧岩爆的等级及破坏性;围岩应力释放率较低时不会发生岩爆灾害,应力释放率逐渐变大,围岩弹性应变能及塑性应变能分布特征逐渐变化,释放率达到70%～80%时围岩将发生岩爆灾害。

英文摘要：

The stress distribution process in surrounding rock mass near excavation surface of typical cross-section in Jinping Ⅱ hydropower station drainage-hole during excavation was simulated using the FLAC3D numerical software.The characteristics of stress alteration in different depths of the surrounding rock and the potential rock burst energy source were analyzed by the key point stresses monitoring.Based on the hypothesis of rock mass stress release rate around the wall,the delay characteristic of the rock burst was researched from the angle of rock mass stress release rate.The results show that the major and minor principal stresses of the shallow surrounding rock reduce during excavation,and the rock mass in this region yields in stress-reduce way which is not easy to accumulate elastic strain energy.Surrounding rock mass of a certain distance from the tunnel wall yields in plastic way and accumulates considerable elastic strain energy,which becomes the rock burst energy source,while the rock yields,the energy releases,which affects the stability of shallow stress-reduce yield rock mass and eventually leads to rock burst.The deep rock mass which is in elastic state also accumulates great stain energy,aggravates the degree of rock burst and damage.The rock burst will not occur when the stress release is low;as the stress release rate gradually increases,the distribution of the elastic strain energy and plastic strain energy change and the risk of rock burst obviously increases;rock burst happens when stress release rate reaches 70%-80%.