Experimental Study on Loading-Creep Coupling Effect in Rockfill Material

Abstract

Drained triaxial tests were performed to investigate the loading-creep coupling effect in a rockfill material using a modified triaxial apparatus. The modified apparatus can switch between stress-controlled and strain-controlled modes; thus, it enabled long-term multistage loading and creep. The test program was carefully designed to study two main concerns: (1) influence of creep on deforming characteristics under postcreep loading and (2) influence of loading history on creep characteristics. A strong coupling effect between loading and creep was observed in the tests. It was found that creeps change the deforming characteristics in the postcreep-loading stages through strain hardening, and the creep was influenced not only by the stress state but also by the precreep-loading pattern. The creeps after elastic and elastoplastic loadings showed different behaviors. It was further shown that the loading-creep coupling effect can be interpreted using the hardening plasticity theory.