Study On Fracture Properties Of Rocks Under Compressive Loading

With the aid of the Muskhelishvili's complex potentials theory, boundary conditions on the crack faces and the single value condition of displacement, the problem of a plate under compressive loading is turned into Hilbert problem and the fundamental solution for cracks with different surface forms under concentrated pseudo-tractions are given. Detail analysis on the values and distribution condition of the shear stress are made for different surface form, and a new compute mode are build up. With the aid of the "pseudo-traction" method , the superposition technique and the arrived fundamental solution, a method for getting the stress intensity factor(SIF) for material such as rock with center inclined crack under compressive loading are given.By using the arrived fundamental solution, combined with the "pseudo-traction" method and the boundary collocation, the stress intensity factor for crack in a finite plate under compressive loading are solved, the effects of crack direction and boundary condition on the stress intensity factor are analyzed, and the varying curves of the SIF along with the width are given. Former fracture mode is based on the crack surface with free boundary condition, but in view of the shear stress on the fracture surface under compressive loading, a new fracture mode is reached. This mode is more accurate and coincides with nature.Based on the fundamental solution, the "pseudo-traction" method and the superposition technique, the multiple crack interaction modes are arrived, the interaction question is solved. Interactions between different cracks and the stress intensity factors for different crack surface forms are calculated, and theeffect of the distance and the angle on the stress intensity factor is analyzed.The study indicate that the surface form has no effect on Kl, but has obvious effect on Kll , and will affect the breaking angle and mode; In finite plate, the boundary condition has effect on the SIF and the K is bigger than in infinite plate; the effect of the distance and the angle between cracks are all have obvious effects on the multiple crack interaction, and the interactions between cracks also have obvious effects on the SIF, which can be neglect only when the distance is bigger enough.