| Peat soils are characterized by their high compressibility and long-term settlement. The purpose of this thesis is to develop a model to represent the whole range of peat compression including primary, secondary, and tertiary compressions. Experimental results from two different types of consolidation tests, constant stress and constant rate of strain tests, indicate that the unique effective stress-void ratio-rate of void ratio change ($sigmaspprime$-e- e) concept is valid for peat consolidation. Based on a modified form of Hardin's model, a unique $sigmaspprime$-e- e model incorporating the finite strain consolidation theory of Gibson, England, and Hussey is developed for one-dimensional compression of peat. Only three model parameters, which can be easily obtained by graphical methods from the deformation-time data of the conventional multiple-stage-load increment tests, are needed along with hydraulic conductivity for the proposed model. The e-log t curves of the model are in good agreement with the experimental curves obtained in the laboratory tests and reflect the different shapes of these curves based on the unique $sigmaprime$-e- e concept. Limited number of field case studies give support to the model and its ability to predict field settlement-time curves based on the model parameters obtained directly from the laboratory tests.;Expedient constant rate of strain tests can be performed to obtain the model parameters which can be used to predict long-term compression behavior under constant stress condition. Experimental results indicate that the compression parameters obtained from the constant rate of strain tests are in close agreement with those obtained from the conventional tests. The proposed model allows, for the first time, use of compression parameters obtained from constant rate of strain tests in the prediction of compression in its entire range; i.e. from primary to tertiary compression under constant stress. However, because of the sensitivity of the model parameters at high stress levels, the parameters obtained from constant rate of strain tests have to be used with caution. |
