Analysis of one-dimensional nonlinear consolidation of a saturated lumpy porous clay layer

In reclamation projects, excavated clay is dumped without any compaction to form a landfill with a heterogeneous pore structure. In this clay, interlump fissures is several orders of magnitude larger than intralump pores, forming lumpy porous clay with double porosity. In this study, a nonlinear consolidation model is proposed for lumpy porous clay based on double porosity concept and mixture theory. The analysis follows these steps: in step 1, a representative saturated lumpy porous clay is considered as a 3-part composition, i.e., solid, fissure fluid and pore fluid, and the volume fractions are defined; in step 2, the decomposition equation is given for each part's strain, and the homogenization relation of mixture theory is used to provide the stress relation inside the saturated lumpy porous clay; in step 3, the energy balance equation is derived in terms of the energy conjugation; in step 4, according to the energy conjugation pairs, new nonlinear constitutive equations are proposed for saturated lumpy porous clay; and in step 5, using Darcy's law, the consolidation control equations are given. The model calculations are compared with experimental data, indicating that the proposed model can effectively simulate the consolidation curves of the clay observed in the laboratory.