Experimental study on the strength and deformation characteristics of sandy pebble soil foundation based on the equivalent density method

Abstract

With the rapid development of urban construction, many bridges and subways are built on sandy pebble soil foundation. As a special kind of soil, sandy pebble soil has the characteristics of large particle size, low compressibility, low cohesion, poor self-stability, large permeability coefficient, large friction coefficient, etc. The strength and deformation characteristics of the sandy pebble soil are one of the key concerns in engineering field. Due to the size limitation of the laboratory test equipment, scaling is necessary for sandy pebble soil. The equivalent density of coarse-grained material could be obtained by equivalent density method; large-scale triaxial and interface shear tests were performed to study the comprehensive mechanical characteristics. Furthermore, appropriate models were investigated to describe the stress-strain relationships of sandy pebble soil, and the corresponding model parameters were summarized. The tests results reveal that the saturated sand pebble soil show shear shrinkage characteristics under low confining pressure, conversely unsaturated samples show shear dilatancy characteristics under low confining pressure. Under high confining pressure, obvious shear shrinkage characteristics could be observed. The shear strength parameters of unsaturated samples are obviously larger than those of saturated samples. It shows a good hyperbolic relationship between shear stress and displacement on the interface of sandy pebble soil and concrete slab, and the shear strength and normal stress are in a good linear relationship. The research could provide strong support for engineering design in sandy pebble soil.