Numerical Simulations of Compressive Tests on Bimrock

The paper deals with the mechanical behaviour of “bimrock” (block in matrix rock), characterized by a heterogeneous structure, constituted by rock blocks included in a small-grained, well-cemented material (matrix) with lower mechanical characteristics. The bimrock is a very peculiar material that may give rise to serious problems in engineering applications. To properly model this kind of problems it is necessary to suitably characterize the bimrock. In order to contribute to the understanding of the bimrock mechanical behaviour and to individuate strength and deformability laws suitable for the bimrock as an equivalent continuum, a number of unconfined or laterally confined tests on bimrock specimens have been numerically simulated. The finite difference and the finite element methods, implemented in the FLAC 2D and the ADINA 2D and 3D codes, respectively, have been used to investigate possible model-dependent responses. Novel approaches have been used, in which the size, orientation and position of rock blocks contained in a two and three-dimensional specimen are generated according to a random process that produces representative samples of block populations with assigned statistical properties. Different volumetric proportions and aspect ratios of the blocks have been considered and the effects on the strength and deformability of bimrock are presented. The numerical results from both 2D and 3D analyses show the influence of the volume proportion of the blocks on the strength and deformability of bimrock. Furthermore, the results suggest that the interfaces between the blocks and the matrix play an important role, and may have an influence on the mechanical behaviour of bimrock.