Research On Constitutive Model And Its Calculation Method Of High-filled Embankment Rheological Settlement

Along with the streth of China's highway gradually forwards the central-western regions of multihilllock and multimound in China where in highway building would appear unavoidably a large number of high-filling subgrades whose fill-cutting height is about 10~30 meters. How to calculate and predict efficiently the settlement of the high-filling embankment after establishment so as to eliminate the harm brought by the embankment settlement has become an important topic in the field of scientific technology of highway construction in the central-western regions. Based on the viscoelastic rheological theory, staring with the constitutive model of rheological settlement of subgrade, this paper unfolds the following researches:Combining the practical examples of built and underbuilding high-filling engineerings, the deep analysis is carried out on these problems of the reason caused by high-filling, the manifestation and the factors leading to its rheological settlement, and the indoor experiment research is unfolded on the rheological property of the subgrade filling, which is from the design of rheological experiment device, the formulation of experimental scheme to implementation of rheological experiment, so one integrated indoor rheological regulation of geotechnical materials is formed, and a series of test data have been obtained, which provide one reference for the calculation of high-filling subgrade settlement.The establishment of the rheological constitutive model of geotechnical material has been deeply explored at the base of the rheological experiment, comparing the merit and shortcoming of the existing rheological constitutive model, in this paper, the rheological constitutive model based on fractional order infinitesimal analysis was selected at last and the dimension problems existing generally in this kind of model have been explored. By introducing the nominal relaxation time, not only the dimension problem in the constitutive relation was resolved, but also combining Deborah number in rheology, and the time scale effect in the experiment of geotechnical rheology has been revealed profoundly, and based on the fractional order infinitesimal analysis theory and Millay-Leffler function, the three-parameter and four-parameter type Kelvin-Voigt rheological constitutive model have been built, by adoping the area decision function containing weight value and the means of pointwise searching, the automatic identifying of the constitutive model parameter has been realized.On the base of the built constitutive model of rheology, the problems of settlement deformation of high-filling embankment in filling and after building have been abstracted with mechanics model, using Boussineq and Flamant analytic solution of the elasticity half-space in the stress distribution of load action, according to the corresponding principle of elasticity-viscoelasticity, and adopting the rheological constitution based on the fractional order infinitesimal analysis, the stress distribution at the semi-infinite viscoelastic space and the analytic approximate solution of displacement variation have been obtained, and then, its own stress distribution of the high-filling embankment and the analytic approximate solution of its deformation have been researched, at last, the compatibly complete simplified calculation formula of the high-filling embankment in rheological settlement has been obtained.Based on the viscoelastic finite element method, with the aid of ADINA, the large-scale universal non-linear finite-element software, adopting the model of viscoelastic material, and utilizing the element living-death technology, the rheological performance of the high-filling embankment in the condition of complex three-dimension boundary has been explored emphatically, and the influence of these factors, the topography, the reclamation speed and the embankment slope on its rheological settlement quantity have been simulated.