DETERMINING SOIL SHEAR STRENGTH PARAMETERS FROM CPT AND CPTu DATA

Determining the soil shear strength parameters, i. e., cohesion (C), internal friction angle (ϕ)is done by means of laboratory tests and the in situ testing data. The cone penetration test, cone penetrometer test (CPT) is not only quick and economical, but also is repeatable and shows continuous records of soil parameters with depth. The common approaches for shearing strength parameters determination from CPT data are on the basis of bearing capacity and cavity expansion theories. In this study, different methods of soil shear strength parameters determination from CPT and CPTu results, qc,fs anduwere reviewed and investigated. A new method is proposed for C, ϕprediction on the basis of all quantities, qc, u and fs from CPTu considering bearing capacity mechanism of failure. One advantage of this method is improvement accuracy in the case of erroneous data by using all three output of CPTu. The proposed, current and experimental test results of an information bank including 32 CPT and CPTu results were assessed in five sites. The comparison of predicted and measured C and ϕangle values indicates good consistency and low scatter for the proposed method. This can be led to more accurate and apply continuous soil parameters in optimized geotechnical design.