Secondary Compression of Clay Soils

In this thesis, the behavior of secondary compression of a selected clay soil from Famagusta is assessed by conducting series of one-dimensional consolidation tests on samples prepared with various initial void ratios and water contents. The testing program consists of standard oedometer tests (SOT) and long term creep tests (CT) where the samples are subjected to preconsolidation stress prior to application of a sustained effective stress for a period of seven days. The analysis of the test results indicated that, the coefficient of secondary compression for soft samples increases up to an effective stress of 50 kPa and then gradually decreases and becomes approximately constant with increasing effective stress. The coefficient of secondary compression for compacted samples is observed to increase with increasing vertical effective stress up to an effective stress of approximately 2.5 times preconsolidation stress, staying approximately constant with respect to further increase in effective stress. For overconsolidated samples, the coefficient of secondary compression increased with reduction in the degree of overconsolidation. The rate of secondary compression decreased with log time for all samples. The maximum value of the coefficient of secondary compression occurred in the Log time range of 100 min to1000 min for all samples. A creep function, previously proposed by (Yin, 1999) is applied on the measured creep curves, the function indicated a good fit to the measured creep curves for all samples.