DETERMINING RELATIVE DENSITY OF SANDS FROM CPT USING FUZZY-SETS

Significant discrepancy exists among the available correlations that a re commonly used for determining relative density using cone penetrati on test (CPT) data. These correlations recognize the difference in san d compressibility and its effect on CPT data. Experience has indicated that compressibility is not a well-defined parameter. Current knowled ge on the subject of sand compressibility and its effect on CPT data i s limited and qualitative. A new approach that aggregates some of the available correlations for the determination of relative density using CPT data is developed. The new approach uses a weighting scheme that relates the compressibility, measured by friction ratio and expressed as a fuzzy number, to the base correlations. Field CPT data are used t o examine and demonstrate the new approach. Results of the limited cas es studied show that relative density can be determined reliably from CPT data using the proposed model.