Confining pressure effects on stress intensity factors : a 3D finite element analysis

Abstract FRE

At great depths of earth, fracture in rock masses occurs under the influence of confining pressure.

However, most of the previous rock fracture studies deal only with ambient conditions and ignore the effects of multiaxial stresses induced because of applying the confining pressure.

In this paper, the influence of confining pressure on the mixed mode stress intensity factors (KI and KII) is investigated for a test specimen.

A large number of 3D finite element models were analyzed for investigating the effect of various confining pressure levels on the fracture behaviour of brazilian disc specimen.

In the finite element models a uniformly distributed confining pressure in the range of 0 MPa to 20 MPa is applied to all sides of the test specimen.

It is shown that the confining pressure has a significant effect on the mode I stress intensity factor, but the mode II stress intensity factor is completely independent of the applied confining pressure.

A comparison between the confined and unconfined conditions shows that the effective mixed mode stress intensity factor increases by increasing the value of confining pressure for all mode mixities.