Study On The Rheology Of Clay And Its Applications In The Evaluation Of Long-term Stability Of Bridge's Pile Foundations

With the development of the infrastructure construction in China, there are increasing projects of road, railway, bridge, housing, airport and seaport that are under construction or to be constructed on the soft clay in the coastal and lakeside areas as well as the middle-and-lower reaches of rivers. Therefore, more and more attentions have been paid to the long-term deformation of the pile foundation on soft clay. Numbers of engineering experiences and researching results have showed that the long-term deformation on the soft clay could last a long period after the bridge being put into operation. The rheology of soft clay will produce notable, no matter for a long-term or a short-term, impacts on the geotechnical characteristics of the foundation. So, for the thick soft clay layers, the rheology makes the soil deformation continue to increase with the time should be regarded as one of the major reasons causing the failure of the bridge on the soft clay area. According to the theory of time-dependent behavior of soils, it is of great significance to study the pile foundation's long-term deformation of the bridge on the soft clay area when exerting horizontal loads. In this paper, based on a viscoelastic constitutive model of clay which reflects the influence of time on the soil strength and deformation as well as the laboratory testing data of rheology of clays, finite element method is adopted to simulate the long-term deformation of the pile foundations. The major contents of this study are as follows:1) The time-dependent behavior of soft clays in strength and deformation is the primary reason that affects the stability of long-term deformation of bridge constructed in the soft clay area. Theoretical analysis has been made in this paper on the Theological phenomena, constitutive model and parameter identification. In order to make use of the viscoelastic constitutive model in the numerical analysing, the one-dimensional differential type of burgers model is deduced into three dimensions, and the equivalence between the above model and the three-dimensional integral type of rheological constitutive model (presented as the Prony series) is demonstrated in...