A 1D thermomechanical model for saturated clay and its optimisation-based parameter identification

Abstract

This paper proposes a one-dimensional (1D) thermomechanical model for clays and its optimisation method for identifying the parameters from only limited laboratory tests. First, a new thermomechanical model accounting for the volumetric expansion and shrinkage behaviour under heating–cooling cycle is proposed for test simulations. Then, the optimisation-based parameter identification is proposed. A newly developed mutation is adopted to enhance the original Nelder–Mead differential evolution algorithm (NMDE). In the optimisation, the laboratory tests on Bangkok clay are selected as objective, with two temperature-controlled oedometer tests and three heating–cooling cycle tests under different overconsolidation ratios (OCRs). The sensitivity of model parameters is analysed by a sensitivity analysis method. Five state-of-the-art optimisation algorithms are chosen as comparison to highlight the effectiveness and efficiency of the proposed NMDE. Finally, the optimal parameters are verified by comparing with other experimental results and predictions on two other clays. All comparisons show that a reliable solution can be acquired by the proposed optimisation together with the thermomechanical model, which is practically useful with a reduction in testing costs.