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Shear wave velocity as function of cone penetration resistance and grain size for Holocene-age uncemented soils: a new perspective

ABSTRACT

              For feasibility studies and preliminary design estimates, field measurements of shear wave velocity, V
                       s, may not be economically adequate and empirical correlations between V
                       s and more available penetration measurements such as cone penetration test, CPT, data turn out to be potentially valuable at least for initial evaluation of the small-strain stiffness of soils. These types of correlations between geophysical (Vs) and geotechnical (N-SPT, q
                       c-CPT) measurements are also of utmost importance where a great precision in the calculation of the deposit response is required such as in liquefaction evaluation or earthquake ground response analyses. In this study, the stress-normalized shear wave velocity V
                       s1 (in m/s) is defined as statistical functions of the normalized dimensionless resistance, Q
                       tn-CPT, and the mean effective diameter, D
                       50 (in mm), using a data set of different uncemented soils of Holocene age accumulated at various sites in North America, Europe, and Asia. The V
                       s1–Q
                       tn data exhibit different trends with respect to grain sizes. For soils with mean grain size (D
                       50) < 0.2 mm, the V
                       s1/Q

                  tn
                  0.25
                 ratio undergoes a significant reduction with the increase in D
                       50 of the soil. This trend is completely reversed with further increase in D
                       50 (D
                       50 > 0.2 mm). These results corroborate earlier results that stressed the use of different CPT-based correlations with different soil types, and those emphasized the need to impose particle-size limits on the validity of the majority of available correlations. For feasibility studies and preliminary design estimates, field measurements of shear wave velocity, V
                       s, may not be economically adequate and empirical correlations between V
                       s and more available penetration measurements such as cone penetration test, CPT, data turn out to be potentially valuable at least for initial evaluation of the small-strain stiffness of soils. These types of correlations between geophysical (Vs) and geotechnical (N-SPT, q
                       c-CPT) measurements are also of utmost importance where a great precision in the calculation of the deposit response is required such as in liquefaction evaluation or earthquake ground response analyses. In this study, the stress-normalized shear wave velocity V
                       s1 (in m/s) is defined as statistical functions of the normalized dimensionless resistance, Q
                       tn-CPT, and the mean effective diameter, D
                       50 (in mm), using a data set of different uncemented soils of Holocene age accumulated at various sites in North America, Europe, and Asia. The V
                       s1–Q
                       tn data exhibit different trends with respect to grain sizes. For soils with mean grain size (D
                       50) < 0.2 mm, the V
                       s1/Q

                  tn
                  0.25
                 ratio undergoes a significant reduction with the increase in D
                       50 of the soil. This trend is completely reversed with further increase in D
                       50 (D
                       50 > 0.2 mm). These results corroborate earlier results that stressed the use of different CPT-based correlations with different soil types, and those emphasized the need to impose particle-size limits on the validity of the majority of available correlations.VsVsVsNqcVs1QtnD50Vs1QtnD50Vs1Q
                  tn
                  0.25
                tn0.25D50D50D50