CPTU Interpretation for Silty Sand in Binh Dai Offshore Wind Farm

Abstract

Geotechnical engineering parameters are of significant effect on foundation design. In-situ tests such as piezocone penetration test (CPTU) are widely used for estimate of effective internal friction angle of sand. How to choose appropriate interpretation method for CPTU is a big problem for geotechnical design. As a case study, the laboratory test results and CPTU results of two Phases (Phase 2 and Phase 3) in Binh Dai offshore wind farm of Vietnam were analysed to establish the correlation between effective internal friction angle φ' and corrected tip resistance qt. The effective internal friction angles of the four sand layers in Binh Dai are found to be linear dependent on the soil depth. Meanwhile, linear expressions between effective internal friction angle φ' and corrected tip resistance qt are proposed, which have high quality in prediction of effective internal friction angle φ' for silty sand in Binh Dai. It worth noting that direct use of CPTU method established by other site’s data without any site specific experience would lead to misestimate at offshore wind farm in Vietnam. New correlations should be established by using site specific data cautiously.