Modeling Triaxial Test on Intact Rock Using Discrete Element Method with Membrane Boundary

A new membrane boundary that applies realistic fluid confining pressure has been developed for modeling triaxial tests on intact rock by using the discrete element method. To realistically simulate the confining pressure, the new approach applies updated boundary force rather than a wall boundary. The applied forces only act on the boundary particles, which are identified and updated periodically. Comparisons between rigid-wall boundary and membrane boundary show that rigid-wall boundary can significantly alter the material response especially the material strength. The effect of confining pressures on the simulated results of triaxial tests is also investigated.