Based on the finite-strain coupling model of primary-secondary consolidation proposed by Ding et al.

a reduced small-strain coupling model is investigated with dimensionless analysis method. A new coupling coefficient of primary-secondary consolidation

is introduced into the reduced model. For the case of

the model could be equivalent to classic Terzaghi’s consolidation model. Finite difference method is used to analyze the variation of excess pore pressure predicted with the proposed model. The results show that: (1) when is greater than zero

the excess pore pressure at early stage of consolidation increases with the development of time especially for higher values of

which is similar to Mandel effect; (2) values of excess pore pressure predicted by Terzaghi’s primary consolidation theory are generally less than those by the proposed coupling model. The mechanism of the above phenomenon lies in the coupling effect of primary and secondary consolidation

which is analogous to the viscous effect using EVP model by Yin et al. According to the concept firstly presented by Mesri & Godlewski

a method to determine the value of for a given soil is put forward as well as a modified small-strain coupling model utilizing the concept. The presented coupling model can provide new and good reference with its simplicity and convenience for further study of primary-secondary coupling mechanism with application to engineering practice.