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Consolidation Characteristics Determination for Phosphatic Clays. Volume 2: User Manual for Computer Program SICTA

02-084-104-v2Final

Introduction

This manual describes the theory and numerical implementation of the seepage induced consolidation test analysis. The computer program SICTA (Seepage Induced-Consolidation Test Analysis) determines the model parameters for soft soil consolidation characteristics from the results of a seepage induced-consolidation test. The analysis procedure includes an optimization scheme for solving the non-linear inverse problem.

It is difficult to design a testing program which will provide directly the compressibility and permeability functions for soft soils and a parameter estimation algorithm is needed. Such algorithm requires the numerical simulation of a test performed on a soft soil sample. This algorithm will minimize the difference between the experimentally obtained results and the numerically calculated values.

A testing technique based on the concept of hydraulic consolidation is adopted as a method to provide a reliable experimental data for the need of the parameter estimation analysis. This technique originally proposed by Imai (1981) is modified to obtain more reliable results by performing the test with a constant flux through a soil sample. In this experiment, the soil slurry is poured into the testing apparatus and a constant flow rate is imposed through the sample. The imposed seepage force triggers the consolidation process in the sample during which the sample surface settles and the induced pressure difference across the sample increases. Ultimately, the process reaches the steady state when the settlement and pressure change seize. The ultimate height and pressure difference at steady state are used in the analysis.