高水头作用下水工压力隧洞的水力劈裂分析

ANALYSIS OF HYDRAULIC FRACTURING IN HYDRAULIC TUNNELS UNDER HIGH WATER PRESSURE

以前研究均认为水力劈裂的必要条件是岩体中发生Ⅰ型张拉破坏。实际上,在众多岩体工程中,其断裂破坏型式多属压剪破坏。本文根据断裂力学原理对高水头作用下水工压力隧洞的水力劈裂作用进行了研究,首先研究水工压力隧洞围岩区各种类型裂纹的I型应力强度因子的计算方法,讨论分析张开型复合型裂纹发生水力劈裂的理论判据。然后研究压剪断裂的力学机理,分析有水压力作用的压剪断裂应力强度应力的计算及其断裂判据。最后将以上理论应用于某水电工程引水发电隧洞的高压竖井的水力劈裂安全性分析中。

The previous on hydraulic fracturing generally assume that tensile cracking is the essential mode of hydraulic fracturing in rocks. In reality, however, the mode of fracturing is combined with compression and shearing, as observed in many rock engineering. In this paper, the effect of hydraulic fracturing on deep-lying hydraulic tunnels under high water pressure is studied on the principles of fracture mechanics. Firstly, the analysis method of stress intensity factor of crack of model I in many complex conditions in the surrounding rock masses of tunnels is presented. Then, the criteria of hydraulic fracturing of different tensile cracks are discussed. The mechanism and formula for stress intensity factor are put forward. Finally, by using the above theory, the hydraulic fracturing analysis of under-lying hydraulic tunnels of a hydropower project is performed, which shows that the method presented is reliable.