Prediction of Swelling Behavior of Addis Ababa Expansive Soil Using Simple Mathematical Model

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Addis Ababa University


Damage due to soil swelling is very noticeable in wide spectrum of structures such as roads, buildings, canal linings, landfill liners, etc. To evaluate severity of swelling and to design for the best and most economical stabilization strategy, an accurate assessment of the swell potential is required. The main reason of swelling behavior is water absorption of soil mass in time. And the time required for completion of swelling is relatively long. In view of that several attempts have been made by researchers to obtain time-swell relationships for expansive soils. Some progress has been made toward characterizing swelling characteristics, despite the complexity of the behavior. In this study a simple hyperbolic mathematical model is used to predict the swelling behavior of an expansive soil from Addis Ababa. The formula was first proposed by Richard and Abbot, 1975. The model was formed in one equation with many parameters. The main advantage of this model is that only one parameter is needed to run the model. The main parameters that are needed to run the model are the applied pressure and initial dry density. The other parameters of the model including the initial slope of the swell-time curve, the final slope, the reference swell, and the peak swell were investigated experimentally. Based on the experimental results, empirical relationships were developed for determination of these parameters as functions of the applied pressure and initial dry density. The model prediction were compared with the experimental results and showed good agreements for all levels of applied pressure and initial dry density of the tested soil.