深埋隧洞围岩在高水压力作用下可能会发生水力劈裂，尤其是断层及其影响带岩体。某抽水蓄能电站高压岔管区断层及影响带岩体灌浆前后的试验结果表明，灌浆后岩体的水力劈裂压力明显增加，但仍有17%试段岩体的水力劈裂压力值小于或等于引水水道内的静水压力。充水试验结果表明岩体没有发生水力劈裂，其原因可能有三个：一是不能依据压力增加的绝对值来判断岩体是否发生劈裂，应根据压力增加的相对大小来判断；二是尽管水道内的水压力很高，但水道内的水流通过钢筋混凝土渗漏到围岩灌浆圈时，会损失一部分水头，实际的水压力比水道内的静水压力要低；三是与岩体的二次劈裂压力有关。

Hydraulic fracture may occur in the surrounding rock of deep-buried tunnel under high water pressure, especially in the fault and its influencing zones The results of high water pressure test before and after the grouting in the fault and its influencing zones of a pumped storage power station showed that the pressure of hydraulic fracture increases obviously after the grouting, but the hydraulic fracture pressure value of about 17% of test section rock mass is less than or equal to the hydrostatic pressure in the diversion penstock. However, the results of water-filling test indicated that there is no hydraulic fracture in the fault and its influencing zones, which may be due to that: (1) the absolute values of increased pressure may not be appropriate to determine the occurrence of hydraulic fracture, and the relative values of increased pressure should be used; (2) although the water pressure is high in the pipe, there is head loss when water leaks from reinforced concrete into wall rock grouting zone, resulting in lower water pressure than the hydrostatic pressure in the pipe; and (3) the secondary hydraulic fracture of rock mass.