Dynamic characteristics of overconsolidated remolded red clay in Southwest China: an experimental study

Red clay is a typical subgrade filler, but it always leads to uneven settlement of roadbeds because of its engineering characteristics such as fracture, expansion, shrinkage, and nonuniformity of distribution. This paper studied the dynamic characteristics of overconsolidated remolded red clay in the railway special line project of the Southwest Anning Refinery. Its dynamic properties with various overconsolidation ratios, confining pressures, and dynamic stress amplitudes were obtained by a series of dynamic triaxial tests under cyclic loading. The critical dynamic stress increases linearly with the overconsolidation ratio and the confining pressures under the cyclic pure compressive force. The empirical estimation formula of the critical dynamic stress for the region is obtained by regression analysis. Then, the parametric study shows that the dynamic strength of the overconsolidated remodeled red clay is proportional to the overconsolidation ratio, confining pressures, and cyclic pressure. The number of cyclic load vibrations has a negligible effect on the dynamic internal friction angle of the overconsolidated red clay. In contrast, it has a significant effect on dynamic cohesion. The experimental results can be used as a basis for the study of permanent deformation control measures of the roadbed in this area.