Compression and Creep Indices of Organic Clayey Soil

Abstract

For construction of structures on soft clay layers, engineers must have to consider the consolidation behaviours of such soil. Due to the viscosity of clayey soils, their organic content strongly influences on consolidation behaviours as well effecting on vertical stress. Laboratory studies on soft soil have offered better understanding and thus better prognosis of these behaviour, and several related tests are performed and presented in this research. Two odometer tests were done, the first being a conventional odometer test for three soil types to find their compressibility parameters, while the second consisted of a series of long term odometer tests to find the creep coefficient for each type of soil. Seven incremental consolidation pressures were applied to each soil sample with different organic content (25 kPa, 50 kPa, 100 kPa, 200 kPa, 400 kPa, 800 kPa and 1600 kPa). A detailed study of the results obtained from this incremental loading was then undertaken. From the consolidation test, the values of different parameters such as the compression index (Cc) and secondary compression index (Cα) were obtained, and it was found that Cc and Cα values increased with increased organic content in the soil. The study also found that, generally, Cα decreases with incremental loading.