EVALUATION OF RESILIENT MODULUS OF SUBGRADE SOIL IN SELECTED LOCATIONS OF BANGLADESH

Abstract

In this thesis the study on the prediction of resilient modulus of subgrade soil based on index properties and moisture content is described. The study was mainly concerned with the effects of the variables such as percentage of silt and clay, maximum dry density, CBR and moisture content on resilient modulus. Several tests such as such as modified proctor compaction test, California bearing ratio test, Atterberg limit test, Grain size analysis and Specific Gravity tests were conducted on three types of subgrade soils. Three well-known resilient modulus prediction models were used to obtain resilient modulus for three selected subgrade soil samples. The test results indicated that the variables influence the resilient modulus are percentage of silt and clay, CBR, maximum dry density and optimum moisture content. Resilient modulus is increasing significantly with the increase in both CBR value and maximum dry density. However, it is ominously decreasing with the increase in both percentage of silt and clay and moisture content. Models that used for prediction of each subgrade soils fitted reasonably resilient modulus data with accuracy in terms of R2. An empirical analysis was done for predicting resilient modulus that agreed with the experimental findings.