Analysis of the Evolution Law of Hysteresis Curve Morphological Characteristics of Polyurethane-Bonded Rubber Particle-Sand Mixture under Cyclic Loading

A new composite material of polyurethane-bonded rubber particle-sand mixture (PolyBRuS) is presented here. A series of cyclic triaxial tests were carried out the hysteresis curves under different confining pressures, temperatures, and freeze–thaw cycles, and then the morphological characteristics and evolution law of hysteresis curves under low-temperature conditions were analyzed. The results indicate that the dynamic strain amplitude, temperature, and number of freeze–thaw cycles have a great influence on the hysteresis curve, while the confining pressure has little influence on the hysteresis curve. While the temperature (T) is −15°C and the number of freeze–thaw cycles (N) is 25, the long-axis slope K, i.e., the elastic properties and stiffness of the PolyBRuS material, decreases with increasing dynamic strain amplitude, tends to increase with higher confinement pressures. While N = 25 and the confining pressures (σ3) is 25 kPa, the distance between the center point of the adjacent hysteresis curve d, i.e., fine microscopic damage of the PolyBRuS material, grows with increasing dynamic strain amplitude, rises with lower temperature. While T = −10°C and σ3 = 25 kPa, hysteresis curve area S, i.e., energy dissipation of the PolyBRuS material, increases non-linearly in relation to the dynamic strain, and reduces with the enlarge of the number of freeze–thaw cycles, however, this reduction is negligible. Further research should focus on the quantitative analysis of the morphological characteristics and evolution law of hysteresis curves.