Back-Calculation of Elastic Modulus of High Liquid Limit Clay Subgrades Based on Viscoelastic Theory and Multipopulation Genetic Algorithm

This paper presents a new model for modulus back-calculation for high liquid limit clay subgrades. In this model, the viscoelasticity theory is employed to describe the displacement hysteresis, and the multipopulation genetic algorithm (MPGA) is used to iterate the optimal results. The reliability and precision of the proposed back-calculation model are confirmed by finite element (FE) simulations and in situ tests. Based on the new method, 12 sets of results from FE simulations show that the correlation coefficient between the time-history curve of displacement and the real curve can be >= 0.99, where the calculation error is < 4%. Further, through comparative studies, it is found that the new calculation method works better in convergence speed and adaptability than the traditional method and plays a very useful role in subgrade design and construction quality control.