Compression Index of Cohesive Soils and Its Prediction
Soumi Dey, Bikash Chandra Chattopadhay
Compression Index (Cc), Index Properties, Alluvial Soils, Settlement.
For cost effective and safe constructions of foundations at sites having deposits of fine grained soils within the zone of influence due to new construction, evaluation of consolidation settlement assumes great importance. The Compression Index (Cc) of the affected soils within the zone of influence need to be known for such evaluation. Such estimation are made generally on the basis of results of consolidation tests made on undisturbed soil samples collected from specified depths at the site. Collections of such soil samples require high cost, and complex sampling device which requires high skilled operator, time and proper care for the device. The degree of disturbances created during sampling, transportation from field to laboratory and preparation of sample for test, are also unknown. Further soils in general and alluvial soils in particular are very erratic and only limited number of boring in the field and corresponding limited number of consolidation tests may not provide sufficient information to the designer for mapping variation in the consolidation characteristics of the soils. As a result from a long period of time, several attempts have been made in past to predict the Cc using index properties, which are relatively easier to determine taking lesser time to test in laboratory. In this work, attempts have been made to check the efficacy of available correlations in literature by comparing predicted values with experimental test results on soils collected from different locations around Kolkata on two sides of Hooghly River in South Bengal. This work highlights the need for establishing more reliable correlation for Compression Index.