A STUDY OF QUASI-PRECONSOLIDATION BEHAVIOUR OF CLAYS

Abstract

Long term consolidation tests were carried out on a highly plastic clay. The clay exhibited quasi-preconsolidation effect when the sample was consolidated uric . sustained loading. Consolidation tests wero also conducted with various consoli-dation-p essiuredurations-df loading and load-increment ratios. It was observed that quasiM-preconsolidation pressure increased with (1) decrease in load-increment ratio. (2) increase in the duration of sustained loading. (3) increase in the initial consolidation pressure. Effect of sample disturbance was further investigated which yielded a slightly low value of quasi-preconsolidation pressure. Secondary consolidation,logarithm of time curves showed that there was no general tendency for a linear rela-tionship except in initial stage. It was surprising to note stepping in later stages of the above curves. It was also found that secondary consolidation is higher for lower thick-ness of the specimen. In tests conducted on Belgium-type consolidometer, low values of secondary consolidation were obtained due to rusting and hence were not satisfactory. Tests were performed simultaneously to avoid the effect of temper-ature variation. Silicon grease and rubber membranes were used for reducing fr