Detrmination of CBR Value by Correlation and Regression Analysis
Detrmination Of Cbr Value By Correlation And Regression Analysis The California Bearing Ratio (CBR) is the most utilised parameter for dimensioning flexible pavements in tropical countries. Often this test is expensive, laborious and time consuming, and to overcome this, some regression analysis (single and multiple) was considered between the soil’s index properties (liquid limit-LL, Plastic limit-PL and Plasticity index-PI), compaction characteristics (maximum dry density-MDD and optimum moisture content-OMC), percentage of particle sizes (gravel, sand and clay/silt) and CBR.
The study was carried out along an ongoing roadway construction project where thirty-three soil samples were collected and transported to the laboratory for analysis. Routine geotechnical tests were carried out and thereafter correlation and regression analysis were run on the obtained results to assess the relationship between these index properties, compaction characteristics and the experimental CBR obtained.
Following conclusions are drawn from above study
- CBR value of coarse grained soil bears significant correlation with Cu, MDD and OMC.
- CBR value decreases with increase in OMC but also increases with increase in MDD and grain size.
- From regression analysis the coefficient of variation (adjusted R2) for the CBR value is found to be 0.998.
- From the formula we can conclude that the correlation equation can be used for evaluating different values of CBR, but this research is limited for coarse grained soil only