Orthogonal experimental study of soil–rock mixtures under the freeze–thaw cycle environment

Soil–rock mixtures is a special engineering geological material and often used as a roadbed filler. Based on the orthogonal experimental method, a series of large-scale triaxial tests of soil–rock mixtures under the freeze–thaw cycle environment was designed with five factors including rock content, compaction degree, moisture content, number of freeze–thaw cycles and freezing temperature at four experimental levels, respectively. Then, the effect of each orthogonal experimental factor and the effect of the confining pressure on the statics mechanical characteristics of the soil–rock mixtures were statistically investigated by range and variance analysis. Research results showed that the static stress of the soil–rock mixtures is linearly positively correlated with the confining pressure; for different confining pressures, the most crucial factors to affect the static stress are different; for the shear strength, the most crucial factors to affect the cohesive force and friction angle are correspondingly number of freeze–thaw cycles and rock content. The study of the crucial influence factors at different confining pressures after freeze–thaw cycles can provide guidance for design and protection of soil–rock mixtures under different environment.