Wing crack propagation model under high hydraulic pressure in compressive-shear stress state

Abstract

A new wing crack model subjected to hydraulic pressure and far-field stresses was proposed considering the effect of hydraulic pressure in wing crack and the connected part of the main crack on the stress intensity factor at the wing crack tip. With the equivalent crack length leq of the wing crack introduced, the stress intensity factor KI at the wing crack tip was assumed to the sum of two terms: on one hand a component KI(1) for a single isolated straight wing crack of length 2l, and subjected to hydraulic pressure in the wing crack and far-field stresses; on the other hand a component KI(2) due to the effective shear stress induced by the presence of the equivalent main crack. The lateral tensile stress and hydraulic high pressure are the key factors that induce crack propagation unsteadily. The new wing crack theoretical model proposed can supply references for the study on hydraulic fracture in fractured masses, hydraulic fracturing in rock masses.