高水压下岩体裂纹扩展的渗流-断裂耦合机制与数值实现

Seepage-fracture coupling mechanism of rock masses cracking propagation under high hydraulic pressure and numerical verification

采用渗流力学、断裂力学理论结合Monte Carlo方法描述岩体裂纹的随机分布,研究高水压作用下岩体原生裂纹的变形和翼形裂纹的萌生、扩展、贯通的渗流-断裂耦合作用机制,建立高水压作用下岩体裂纹的渗流-断裂耦合数学模型,给出该数学模型的求解策略与方法,在Fortran95平台下开发高水压下岩体裂纹扩展的渗流-断裂耦合分析程序HWFSC.for。高水压下岩体裂纹扩展的渗流-断裂耦合体现在岩体裂纹网络和渗流初始条件都随渗流时步变化。对高压注水岩体裂纹扩展过程进行渗流-断裂耦合分析。结果表明,高压注水条件下,岩体裂纹扩展存在起动水压力,当水压力大于起动水压力时,裂纹尖端开始萌生翼形裂纹,随着裂纹水压力的增加,翼形裂纹扩展,进而与其他裂纹搭接贯通,停止扩展。渗流-断裂耦合分析考虑了裂纹动、静水压力对裂纹产生的法向扩张效应及翼形裂纹的扩展而形成新的渗流通道两方面的影响,连通裂纹数随渗流的发展而增加。岩体裂纹的渗流-断裂耦合分析,能较真实地再现岩体裂纹的水力劈裂现象,描述岩体裂纹的扩展、贯通过程及与之相耦合的渗流响应。

With the theory of fluid mechanics and fracturing mechanics combined with Monte Carlo method to describe random distribution of rock cracks, seepage-fracture coupling mechanism involving deformation of primary crack, initiation, propagation and coalescence of wing cracks under high hydraulic pressure was studied. The mathematical model of seepage-fracture coupling of rock masses cracks propagation was established. The solving strategies and methods were proposed, as well as developing the analysis program HWFSC.for for seepage-fracture coupling of cracks propagation under high hydraulic pressure on the Fortran95 platform. The fact that crack networks and seepage initial condition vary with seepage conditions embodies in seepage-fracture coupling of cracking propagation under high hydraulic pressure. Coupling analysis of the process of rock cracking propagation during high pressure water injection process comes to the conclusion： starting water pressure has been shown to reside in rock cracking propagation under high hydraulic pressure, when the water pressure is more than the starting water pressure, the wing crack is born on the crack tips, as water pressure on the crack tips increases, the wing cracks propagate, and then coalesce with other cracks, finally stop propagating . The analysis of seepage-fracture coupling considers the influence of the dynamic and static water pressure of the cracks on the cracks normal expansionary and the wing cracks propagation, and the number of connected cracks increases as the seepage develops. Analysis of seepage-fracture coupling analysis of rock cracks can re-create the phenomenon of hydraulic fracturing, describe the process of rock cracks propagation, the rock bridge coalescence and inter-coupling response of seepage in fractured rock masses.