深部隧洞掘进开挖瞬时卸荷动态破坏研究

Study on Dynamic Failure by Instantaneous Unloading under Tunneling Excavation in Deep Tunnel

摘要:

瞬时卸荷是岩体开挖形成的瞬时岩体应力释放和调整。针对高应力区隧洞岩体开挖瞬时卸荷过程，通过能量守恒推导出了瞬时卸荷位移公式；基于Kachanov准则对构件的脆性破坏理论推导出隧洞侧壁围岩卸荷的初始破裂时间和完全破裂时间，并得出完全破裂时间等于岩体开挖卸荷完成时间；通过锦屏二级水电站某隧洞瞬时卸荷分析得出岩体在开挖瞬时卸荷条件下会产生岩爆，并且卸荷岩体的初始破裂时间较完全破裂时间短，但破裂却已很明显。

关键词:隧道工程;卸荷位移;破裂时间;隧洞岩体

Abstract:

Instantaneous unloading is instantaneous rock mass stress release and adjustment caused by rock mass excavation. According to the instantaneous unloading process of tunnel rock mass excavation in high stress zone, the instantaneous unloading displacement formula was deduced through the energy conservation; the initial fracture and the complete rupture time of tunnel wall rock mass unloading were deduced based on brittle failure theory of Kachanov criterion, and it was obtained that the complete rupture time is equal to the completion time of rock mass excavation unloading. By the analysis on the instantaneous unloading of a tunnel in Jinping Ⅱ hydropower station, it was concluded that rock blasting would be caused under instantaneous excavation unloading conditions and the initial fracture time was shorter than the complete rupture time, but the fracture has been very clear at that time.

Key words:tunnel engineering; unloading displacement; fractue time; tunnel rock mass