Long term cyclic behavior of saturated soft clay under different drainage conditions

Abstract

An alarming settlement has been observed during the operation of transport infrastructures built on soft clay areas. Considering the long duration of traffic load, analyzing the long-term cyclic behavior of saturated soft clay considering different drainage conditions is of considerable significance. In this study, a series of cyclic triaxial tests were conducted on undisturbed soft clay from Wenzhou under the partially drained and undrained conditions, respectively. The test results reveal that: (a) more permanent strain was generated of the soft clay specimen under partially drainage condition, which is due to the volume change caused by both the decrease of void ratio and the shape deformation of specimens; (b) under partially drained condition, the resilient strain and hysteretic loops both exhibit a sudden increase in strain due to transient softening induced by excess pore water generated in the early stage followed by a reduction until a steady value is attained; (c) it is obvious that the allowable cyclic stress ratio (CSR) under undrained condition is larger than that under partially drained condition, indicating that considering partially drained condition is necessary in practical engineering design.