Revisiting the CPT-based characterizations of a highway subgrade

ABSTRACT

This paper revisits the cone penetration test (CPT) based characterizations derived from small strain shear modulus (G₀) and seismic shear wave velocity (V_s). The need for this study is demonstrated through comparisons with existing CPT-V_s/CPT – G₀ models. Among the literary correlations considered in the present study, some of them showed better performance. The previous correlations show an error margin ranging between −140% and +440% in estimating the G₀, whereas the predicted V_s was underestimated by 16% or overestimated by 109%. The CPT-G₀ correlations utilizing the proposed compressibility index (I_cc) denotes the higher regression coefficient value which designates the advantageous stress normalization. It is found that there is a good agreement between the measured and predicted V_s with expected error limits of ± 4%. Moreover, the proposed correlations in this study might be applicable to site-specific conditions due to the limitation of data points pertinent to organic silts and clays category based on the unified soil classification system.

KEYWORDS:

• Cone penetration test
• relative density
• small strain shear modulus
• shear wave velocity

Acknowledgments

The authors are grateful to Techniplan S.P.A private limited located in capital city Addis Ababa of Ethiopia for their cooperation in providing the raw data.

Disclosure statement

No potential conflict of interest was reported by the authors.