ABSTRACT
This chapter aims to investigate the macro–meso geomechanical behaviors of bimsoils (block-in-matrix soils) under shear and compression stress states. The shear testing was conducted by using a specially designed variable-angle shear testing device, and the uniaxial compressive strength experiments at a medium strain rate were conducted to characterize the rate effects and the macro–meso failure mechanism of a bimsoil with different rock block percentages using a servo-hydraulic variable frequency dynamic machine. Macroscopic deformation analysis combined with the mesoscopic 3-D laser technique was used to reveal the internal failure mechanism of bimsoils. An index of fractal dimension was used to establish the relationship between block size and shear strength parameters; it suggests that the fractal dimension of the fracture surface is large for the samples having a larger block size, and the shear strength of bimsoil is strongly related to the morphology of fracture surface. The improvement of shear strength for bimsoils was the result of interactions between the soil matrix and rock blocks, and induced by the intrinsic shear fracture mechanism. The result of the uniaxial compression testing indicated that the cumulative fracture width and surface toughness were dependent on the loading rate.
