Deformation and strength characteristics of graded gravel by large-scale triaxial tests

Graded gravel is known as one of the most common construction materials applied in railroad foundation. The in situ condition and the engineering behavior of graded gravel have important influence on the stability and performance of the supper structure. This paper presents the results of experimental investigation carried out in triaxial test with low confining pressures on graded gravel used to construct high-speed railway ballastless track. The exponential formulation to illustrate the relationship between deviator stress and axial strain was proposed. In addition, the analyses on the shear strength and deformation characteristics indicate that undrained samples have strain-softening characteristic while drained samples have strain-hardening characteristic. It is found from the deformation analysis that the dilation strain of graded gravel tends to occur in case of low confining pressures. Also, the data indicated that changes in moisture have significant effects on shear strength and deformation properties, especially in the saturation condition with the reduction by 25% of cohesion, which may result in road bed damage. © 2015 ejge.