Abstract
This paper describes the effect of gravel content on mechanical properties of gravelly softrocks. Experimental study is conducted by using artificial specimens in which have marble as hard gravel and welded tuff as soft gravel. The following results were obtained. Fundamentally stress-strain relationships under shearing depend on the properties of matrix material. The equivalent modulus of deformation can be derived from gravel content, deformational modulus of gravel and that of matrix. Strength relation is nonlinear and it can be expressed by power function. Peak strength of gravelly rocks which take with strain-softening is smaller than peak strength of matrix. Strength relation of gravelly soft rocks can be estimated by gravel content, peak strength of matrix and residual strength of matrix.
