Characterization of large strain consolidation parameters of soft materials with time-variant compressibility at low effective stress

Abstract

The one-dimensional (1D) large strain consolidation (LSC) of saturated soft materials that are deposited at very low-density usually exhibit time-variant compressibility (void ratio vs vertical effective stress (e-σv′)) relation. The 1D column-like model test serves as an effective approach for characterizing this consolidation characteristic if all the physical parameters (including the settlement rate, pore pressure and density) are measured. Unfortunately, the density measurement is not always realistic due to its high cost (e.g., with X-rays) and the time-effect must be roughly neglected by using an average compressibility relation. This can further lead to erroneous estimations of the materials’ permeability (k) relation (permeability vs void ratio (k-e)) in the LSC analysis. This paper presents two modifications on two conventional equations for compressibility and permeability, respectively. The first one describes the compressibility curve’s movement in the lne-lnσv′ plane, and the other quantifies the ratio between the permeability calibrated by neglecting time-effect and its true value. These modifications originate from deep comparative analyses of several physical parameters between the column test and numerical prediction. Meanwhile, a simple hand-calculation procedure is proposed to estimate the new constants.