The maximum shear modulus is a fundamental parameter related to the mechanical behavior used for analysis of dynamic behavior and aseismatic design of geotechnical structures of soft clays. The previous methods to get the maximum shear modulus in China are generally from the laboratory test which is of time consuming and lower accuracy. This paper performed the measurements of shear wave velocity using the downhole and seismic piezocone tests on the background of expressway engineering of the Quaternary Lixiahe ages-old lagoon facies soft soils in North Jiangsu. Based on the shear wave velocity test data from the downhole and seismic piezocone tests

empirical correlations between the maximum shear modulus Gmax and parameters derived from piezocone measurements are developed. It is shown that the piezocone tip resistance and pore pressure parameter can be used for a preliminary estimate of the maximum shear modulus Gmax of soft soils.