Abstract: Soft clay is characterized by high water content, large compressibility and Poisson's ratio. For thick soft soil foundation, it is difficult to ensure that the lateral deformation remains zero under vertical loading. The condition of flexible constraints with proper consideration of lateral deformation is more realistic with engineering practices. Therefore, in this paper, a consolidation test with flexible lateral constraints was conducted on the undisturbed and remodeled soils. The influences of the lateral constraints on the settlement characteristics and deformation parameters of soft clay were investigated. The results show that both the primary and secondary consolidation deformations of the soil under flexible constraints are greater than those under the K0 lateral confining conditions, as well as performing a shorter consolidation time and more nonlinear isochronous curves. The theory of non-Darcy flow was introduced to modify the Terzaghi’s consolidation theory, so that nonlinear governing equations considering the certain lateral deformation effect were deduced. Furthermore, the parameters of the calculated model were obtained from the flexible lateral restraints consolidation tests. Finally, the validity of the proposed model was verified by the laboratory test results.

Key words: soft clay, flexible geometric confined, consolidation test, ε-lgp curve, non-linear model