中文摘要：

水力劈裂是石油开采、土石坝安全控制、原位地应力测试、隧洞突涌水防治等中的常见突出问题。首先,构建一维非稳定渗流模型,推导其解析解,并将水力劈裂关键因素水压力、水力梯度随时间的变化规律与有限元模拟结果进行对比,从而证明该理论解的正确性。其次,非稳定渗流结果与稳定渗流对比表明,在非稳定渗流状态下水压突增时刻,靠进水口处水力梯度最大,而趋于稳定状态时,水力梯度逐渐减小并最终达到稳定。同时,渗透性越小,高水力梯度作用时间越长,岩体发生水力劈裂的危险性越大。因此,采用非稳定渗流研究岩体水力劈裂作用机制是十分必要的。

英文摘要：

Hydraulic fracturing is a frequent problem in petroleum extraction, dam safety monitoring, in-situ geostress testing, tunnel-groundwater inrush prevention, etc. Firstly, a one-dimensional model considering unsteady seepage is established and its analytical solutions are derived. Comparing the calculated key factors （water pressure and hydraulic gradient） of hydraulic fracturing with the simulated result by finite element method, accuracy of these theoretical solutions is proved. Secondly, in terms of comparison with the result only considering steady status, it is presented that hydraulic gradient gets maximum as soon as water pressure increases in unsteady process. By contrast, hydraulic gradient gradually decreases and tends to be stable when reaching steady seepage status. Finally, the effect of rock permeability on hydraulic fracturing is also studied. The probability that hydraulic fracturing happens grows higher while the permeability is lower. In summary, it is essential to consider unsteady seepage status in mechanism study of hydraulic fracturing.