Empirical Model for Estimating Compression Index from Physical Properties of Weathered Birimian Phyllites
Dr. CFA Akayuli, Bernard Ofosu
CSIR-Building and Road Research Institute
Geotechnical Engineering Division P.O.Box 40, KNUST-Kumasi, Gh
Geotechnical investigation is required for the determination of ground parameters for safe and economic design of civil engineering structures. Compression index is one of the soil parameters that are required for calculation of foundation settlements, however, the determination of compression index is expensive, cumbersome, time consuming and required a lot of experience for obtaining undisturbed soil samples from the field. In order to mitigate these complexities, equations have been developed by many researchers in the past to predict compression index using index properties of soil which are relatively easier to conduct in the laboratory. Linear regression analysis was used to established empirical models relating compression index and index properties of sixty weathered Birimian phyllites samples in the Kumasi area. Based on the analysis, the liquid limit resulted in the model with the highest coefficient of determination compared to the moisture content, plasticity index, and plastic limit. The resulting model was used to predict the compression index of about thirty samples that were not used in the regression analysis; the results showed that, the model is able to predict the compression index with less error. The empirical model (Cc = 0.004LL – 0.03) involving the liquid limit is recommended for prediction of compression index for preliminary design and verification of the laboratory tests soils in Kumasi within the Birimian phyllites.
Keywords: Compression index, Liquid limit, linear regression Birimian Phyllites.
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