Consolidation: Critical Appraisal of Settlement Versus Rate of Settlement (SRS) Approach with Fuzzy Logic

Analysis of time dependent behavior of clayey soils in vertical consolidation is carried out by plotting the experimental settlement, δ, with its differential (with respect to experimental time, t) dδ/dt. This is called the settlement versus rate of settlement (SRS) approach. A fastest rapid loading method is suggested that gives the coefficient of consolidation, c_v values very close to true c_v and also shows how near the calculated, and true c_v values are by fuzzy logic. The merits and demerits are compared with popular methods. The SRS methods work even when the settlement-time-pressure data at the beginning of load increment is not known. The simple procedure for quantitative isolation of secondary consolidation and creep (from primary consolidation) is suggested. Six phases of consolidation are quantitatively identified instead of three (initial, primary, and secondary). Terzaghi’s one-dimensional consolidation equation is resolved in three parts; (1) parabolic 0–40%U, (2) transition 40–60%U, and (3) exponential 60–100%U, where U is the degree of consolidation. It is shown that the SRS plot is a very powerful and useful tool for consolidation analysis.