Sandy pebble soil is a special coarse-grained soil whose strength and deformation characteristics are one of the key concerns in engineering field. The comprehensive mechanical properties of sandy pebble soil were examined via triaxial shear test,interfacial shear test and rheological test,and appropriate constitutive relationships were selected to describe the stress-strain relationships of sandy pebble soil. In addition,the corresponding model parameters were summarized. Tests results reveal that the shear strength of unsaturated sand pebble soil was remarkably larger than that of saturated samples. Under low confining pressure,unsaturated samples and saturated samples displayed shear shrinkage characteristics and dilatancy characteristics,respectively,while under high confining pressure,obvious shear shrinkage characteristics could both be observed. The shear stress and displacement on the interface between sandy pebble soil and concrete face show a good hyperbola relationship,and the shear strength and normal stress show a good linear relationship. The relationship between rheological deformation and time of sandy pebble soil is linear in logarithmic coordinates. A rheological model of sandy pebble soil with eleven parameters was proposed to better reflect the rheological properties of sandy pebble soil. The research results provide theoretical support for the research of strength and deformation characteristics and settlement prediction of sandy pebble soil foundation.