Research On The Creep Characteristic Of Saturated Soft Clay

Based on the project of HuNan Zhucheng highway construction, this paper has studied the special creep characteristic of soft clay. Firstly, triaxial consolidation creep tests under different confining pressures and different loading grades are carried out on the soft clay samples. Then, according to the creep test curves, a new empirical creep model is presented, in which the power function is used for shear stress-strain behavior and hyperbolic function for strain-time behavior. Thirdly, the new creep model is insetted to the traditional layer-wise summation method and the settlement-time curve is developed. Finally, the mechanism of deformation of embankment is analyzed. The main work are as follows:(1) Based on a series of laboratory tests, the strength and deformation characteristics of soft clay are studied. One-dimensional consolidation creep tests under different consolidation stresses and triaxial consolidation creep tests under different confining pressures and different loading grades are carried out on soft clay, and the full-process creep test curves have been achieved, which can reveal the special creep mechanism of soft clay. The creep curves, equal-time stress-strain curves and stain rate-deviator curves have been analyzed detailedly in this paper."Chen loading method"is applied in processing these curves.(2) On the basis of the triaxial creep tests data, the famous empirical creep models of Singh-Mitchell model, Mesri model and the relative revised models are applied respectively to predict and simulate the test results. However, there are obvious differences between the actual test results and the simulating results in terms of models mentioned above. Therefore, in this paper, a new empirical creep model is presented, in which the power function is used for shear stress-strain behavior and hyperbolic function for strain-time behavior. This model has few parameters and the simulation results of creep tests on the soft clay in Zhucheng highway has been remarkably improved.(3) The traditional layer-wise summation method is improved based on the new empirical creep model. The main advantage of the improved method lies in not only the final settlement, but also the settlement-time curve can be achieved according to the improved layer-wise summation method.(4) The widely used FEM analysis progam-Plaxis is adopted in the paper to study the deformation character at different phases of the embankment construction. Both the post-construction settlement and the mechanism of deformation during the process are revealed using the soft soil creep model.