Abstract: To understand the deformation and mechanical behavior of soil-rock aggregate mixture, a series of large-scale triaxial tests is conducted under different stress paths (conventional, constant stress ratio and constant p paths). The experimental results indicate that the strain softening of soil-rock aggregate mixture is insignificant under the low-confining pressure condition; the soil cohesion is generally low and the internal friction angle is relatively high. The internal friction angle and deformation modulus increase as the rock content increases from 25% to 70%. The stress-strain curves of soil-rock aggregate mixture are similar under the conventional stress path and the constant p path. Their shear strength indices are also similar. However, the form and development process of stress-strain curves under constant stress ratio path are significantly different. The specimen presents dilatation under low confining pressure and shrinkage at high confining pressure under conventional stress path. The higher the rock content, the more significant the dilatation under low confining pressure is. Conversely, the more significant the shear shrinkage under high confining pressure is. The relationship of volumetric strain and axial strain is linear under constant stress ratio path, and its slope decreases with the increase of stress ratio (q/p). The soil-rock aggregate mixture generally exhibits dilatation in constant p path tests, which is especially significant under low average principal stress.

Key words: soil-rock aggregate mixture, stress path, large-scale triaxial test, rock content, shear strength, volumetric strain characteristics