Stress-strain behavior of soil-rock mixture at medium strain rates - Response to seismic dynamic loading

This paper aims to investigate the seismic dynamic responses of soil-rock mixtures (SRM) at medium loading strain rates. A total of 130 SRM specimens with four rock block percentage (RBP) of 20%, 30%, 40% and 50% were produced to conduct the uniaxial compressive strength test, at strain rates of 1x10(-5) s(-1), 5x10(-4) s(-1), 1x10(-3) s(-1), 5x10(-3) s(-1), and 1x10(-2) s(-1). From the experimental results, SRM presents particular rate dependence characteristics that are different from each soil and rock material, the peak stress and peak strain first increase and then decrease with the increase of strain rate. The inflection points of rate-dependence are different for specimens with different RBP. The rate-dependence characteristic of SRM is strongly influenced by the rock blocks in the SRM specimen. In addition, crack initiation stress level crci/af and crack damage stress level sigma(cd)/sigma(f) do not change with the increases of strain rate. What is more, the experimental results also show that the failure pattern of SRM performs as a spitting failure, shear failure, and conical failure at various strain rates. All the test results proved the particular seismic dynamic responses of SRM, and the interactions between the rock blocks and the soil matrix are the primary factor determining the dynamic response.