裂隙岩体水力劈裂的颗粒离散元数值模拟

利用颗粒离散元软件PFC2D从细观角度初步模拟裂隙岩体水力劈裂的发展过程,并分析影响水力劈裂的部分因素。研究结果表明,以初始裂缝尖端处的接触黏结破坏作为水力劈裂发生的标志,可以较真实地模拟裂隙岩体水力劈裂时裂缝的产生和扩展过程。数值模拟结果表明,初始裂缝的相对长度、岩体的渗透性以及水压力的加载速率等因素均对水力劈裂的起裂压力有较大影响。起裂压力随着岩体初始裂缝长度的增加、水压加载速率的加快而降低,随着岩体渗透性的增加而有较明显提高。这些规律与现有的理论和研究结果是一致的,从而验证了采用颗粒离散元模拟裂隙岩体水力劈裂的可行性。

Simulation of Hydraulic Fracturing of Fractured Rock Mass by PFC2D

In this paper, the initiation and development of hydraulic fractures is simulated using the Particle Flow Code (PFC2D) from the meso-prospective, and some influencing factors are analyzed. Results show that the generation and propagation of crack can be simulated practically. The hydraulic fracturing would occur if contact bonds lying between the particles fail around the initial crack tip. It also illustrates that the value of initiation pressure is influenced by the relative length of initial crack, permeability of rock mass and the loading rates of water pressure. With the increasing of initial crack length, the initiation pressure decreases. And it would increase significantly if the permeability of rock mass increases. As water pressure loading rates accelerate, the initiation pressure would be reduced. These conclusions are in good agreement with theories and it shows the feasibility of simulating the hydraulic fracturing of fractured rock mass with particle discrete element method.