Evaluation of soil classification methods based on CPT data for soil in Nasiriyah, Iraq

Soils classification based on CPT data is depending on soil behavior in site which is very important for geotechnical engineers. Soil behavior is complicated since it related to the variation of the geological processes, therefore uncertainty in identifying soil stratigraphy is expected. In this paper, seven soil classification methods based on CPT data have been used for classifying the soil of the study site located in Nasiriyah city, south of Iraq. These methods have been presented with a description for each method. Four CPT soundings were tested and six boreholes were drilled at different locations next to CPT sounding locations at a depth (15-20) m. The results have been evaluated by comparing it with the results of (USCS) classification system after converting the results of SBT charts to USCS soil types groups. It has been found that Robertson chart 2010 and Eslami and Fellenius chart 1997 gave the best agreement with the results of the laboratory test with prediction ratios equal to (56, 88, 86 and 78) % for Robertson chart 2010 and (67, 75, 85 and 67) % for Eslami and Fellenius chart 1997 for CPT1, CPT2, CPT3, CPT4 respectively.