Abstract: The modified Cam-Clay model is improved to facilitate the use of soil constitutive model and reduce the selection of geotechnical parameters in the calculation of offshore wind power pile foundation. Firstly, according to the characteristics of K₀ consolidated saturated soil in ocean engineering, the yield surface function suitable for dilatant soil is derived by introducing phase change parameters based on the modified Cam-Clay model. Furthermore, referring to the research concept of the unified hardening model, the dissipative work is introduced as hardening parameter to improve the thermodynamic soil model of Collins in association with the traditional elastic-plastic theory. A new unified modified Cam-Clay model suitable for both sand and clay is proposed. Finally, case analysis is carried out to verify the model. Results demonstrate that the constitutive model proposed in this paper needs few calculation parameters, and is of high accuracy and clear physical meaning.

Key words: marine soil, K₀ consolidation, dissipated work, hardening parameters, unified modified Cam-Clay model