مدل رياضي انتشار ترك هيدروليكي در سنگ شكننده با درنظرگرفتن اثر اندركنش (مضروبي) پارامترهاي اينرسي و گرانروي

Hydraulic Fracture Propagation in Brittle Rock: Considering Interaction Term between Fluid Inertia and Viscosity Parameters

در اين نوشتار، يك روش تحليلي براي حل مسيله‌ي شكست هيدروليكي در حالت كرنش صفحه براي سنگ شكننده‌ي نفوذناپذير و سختي زياد و تحت شرايط متقارن ارايه شده است. جريان سيال غيرقابل تراكم و آرام فرض شده و ترك در همه‌ي زمان‌ها كاملاً از سيال پر شده است. انتشار ترك در چارچوب مكانيك شكست خطي (LEFM) است. اين مسيله توسط گاراگاش در سال 2006 در مجله‌ي "Engineering Fracture Mechanics" بدون درنظرگرفتن اثر اندركنش پارامترهاي اينرسي و گرانروي بررسي شده است. در اين پژوهش با درنظرگرفتن اثر مذكور، بازشدگي، فشار داخلي سيال در ترك، و ميزان رشد ترك تحت تزريق سيال از روش اغتشاش تعيين و نتايج اين كار با اسناد موجود مقايسه و بررسي شده است.

Modeling of fluid-driven fractures, arguably one of the most challenging computational problems in geoengineering, has been the subject of numerous investigations. The thrust of these efforts has been directed, however, towards the mechanics of deep hydraulic cracks, with subsurface hydraulic fractures receiving comparatively little attention. Nonetheless, there are numerous circumstances when the propagation of a fluid driven fracture in a solid medium is influenced by the presence of a free surface: remediation of contaminated soils, excavation of hard rock by injection of fluids, preconditioning and cave inducement in mining, waste disposal, and fracture propagation in dams. Furthermore, there are also spectacular examples of geological processes that involve near-surface magma-driven fractures. Investigations have addressed various aspects of the problem, both analytically and numerically, for some further references. It is, however, only recently that there has been a rigorous effort to study the parametric dependence of a fluid-driven fracture and the corresponding different limiting regimes. An explicit solution for fracture propagation in the toughness-dominated regime has been constructed by Garagash [Engineering Fracture Mechanics, 2006], when the energy dissipated in the viscous fluid flow inside the fracture is negligibly small compared to the energy expended in fracturing the solid medium. It was also shown that the established method of asymptotic expansion in small parameters is equally applicable to study other small effects (e.g., fluid inertia) on the otherwise toughness-dominated solution. This paper represents an analytical method for solving the problem of plane-strain hydraulic fracture propagating in an impermeable brittle rock under large toughness and axisymmetric conditions. The flow of incompressible fluid in the fracture is unidirectional and laminar. Fracture propagation is described in the framework of linear elastic fracture mechanics (LEFM). The fracture is fully fluid-filled at all times. This problem has been examined by Garagash [Engineering Fracture Mechanics, 2006] without considering the interaction effect of inertia and viscosity parameters. In this work, the net pressure in the fracture, the crack opening, and the fracture half-length are obtained from the perturbation solution considering this interaction effect on the otherwise toughness-dominated solution. The results are compared with analytical reference solutions.