Abstract: In order to further clarify the effect of particle breakage on strength and deformation of soft rock coarse aggregates, consolidation drained triaxial shear tests of two groups of different initial dry densities of sericite schist coarse aggregates are carried out. The law of particle breakage and its influence on mechanical properties of sercite schist coarse aggregates are discussed. The result shows that the relative particle breakage index of sercite schist coarse aggregates increases with confining pressure. But the growth rate of particle breakage is greatly influenced by the initial dry density. The relationship between particle breakage and confining pressure might be described by a linear function. The particle breakage of high density samples is significantly higher than low density samples under the same stress level because of the influence of the initial porosity. So influence of particle breakage on shear strength decrease under the high density is higher than the influence of low density samples; this might cause stress strain curve of two different dry densities to intersect somewhere. Finally, the shear strength of low density is greater than the high density samples. The porosity of high density sample is small and its dilatancy factor always stay near 1.The porosity of low density sample is larger and the particle breakage and dilatancy delay the impact on its dilatancy factor. So the lower density of samples, the larger volume change is. However, the volume change is very small because of the influence of particle breakage and dilatancy of sericite schist coarse aggregates.

Key words: scricite schist, relative particle breakage rate, different dry densities, shear strength, dilatancy factor