Evaluation Method of Maximum Shear Modulus of Cohesionless Soil Based on State Parameters from Piezocone Penteration Test

The maximum shear modulus of soil is an important parameter for dynamic design of foundations and response analysis of seismic sites. At present, this parameter is mainly determined through laboratory tests, but such tests cannot represent the real situation in the field. Thus, in situ testing technologies have attracted much attention. The Suqian-Xinji Expressway was regarded as the engineering background and seismic piezocone test (SCPTU) was conducted at the site. Based on the summary of research results for existing methods used to determine the maximum shear modulus, the relationship between the piezocone penetration test (CPTU) parameters and the maximum shear modulus was studied in terms of the reference value of the maximum shear modulus calculated using the measured shear wave velocity. The relationship between the joint CPTU parameters, state parameters, and maximum shear modulus was also analysed. The results show a good correlation between the maximum shear modulus and CPTU parameters. The maximum shear modulus value can be approximated by cone tip resistance and pore pressure parameters. The state parameter can serve as an effective alternative parameter for void ratio or pore pressure parameter ratio, and the dual factors of confining pressure and void ratio can be considered simultaneously. The estimated maximum shear modulus is the same as the reference value. Therefore, the in situ state parameters of CPTU can be used as a new method to evaluate the maximum shear modulus of cohesionless soil.