CORRELATION BETWEEN CBR VALUES AND INDEX PROPERTIES OF SUBGRADE SOILS: IN THE CASE OF BODITI TOWN

construction Technology and Management

The suitability and stability of soil is usually evaluated before its use in construction of pavement. Proper analysis is necessary to ensure that Civil engineering infrastructures such as roads, buildings, rails, dams, etc. remain safe and free to withstand settlement and collapse. This paper presents the results of the correlation between California Bearing Ratio (CBR) and index properties of sub-grade soils in the Boditi town. CBR (California Bearing Ratio) test is performed to evaluate stiffness modulus and shear strength of subgrade soils. However, CBR test is laborious and time consuming, particularly when soil is highly plastic. In order to solve this limitation, it may be appropriate to correlate CBR value of soil with its index properties like grain size analysis, Atterberg limits, and compaction characteristics such as MDD (Maximum Dry Density) and OMC (Optimum Moisture Content). SLRA (Single Linear Regression Analysis) and MLRA (Multiple Linear Regression) based Models were utilized. It is seen that MLRA gave better correlations up to R2 of about 0.984. It is observed that the Soaked CBR value can be predicted with confidence from LL (Liquid Limit), PI (Plasticity Index) and percent finer while un-soaked CBR value can be obtained from LL, plasticity index and MDD. Laboratory tests were carried out to determine soaked CBR, LL, PL, PI, MDD and OMC on soil samples collected from different parts of town. A correlation relationship between CBR and soil index properties were developed using non-linear and multiple linear regression analysis. Standard Minitab 16 and Microsoft Excel 2019 software package were used for the analysis.

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.