Calculation And Prediction Of Settlement After-construction For Embankment In Soft Clay

Many highway construction have to be built on thick soft clay foundation .the soft foundation has large settlement under load. Because the high pore-water ratio,lower strength,high compression all are the characteristics for the soft foundation. Therefore,per-loading technique is usually adopted to get rid of most deformation due to primary and secondary consolidation before construction. Even so,the foundation settlement after construction will exist for a long period. And in this paper,the prediction method of the foundation settlement after construction is discussed.Firstly,two-dimensional formulas of Biot's consolidation FEM base on nonlinear hyperbolic model and Merchant's model are presented to calculate settlement of saturated soft clay ground. Form the observation date obtained during construction,the geological parameters may reasonably be determined by direct optimal method such as Powell so that it minimizes the squares of differences between calculated and measured quantities (objective function). Adopting FEM and the roadbed settlement after construction is calculated. Then a back analysis program of FEM for soil is given. The back analysis was performed for two highways based on the program and the results were obtained.In addition,the application of the date process in foundation settlement prediction is presented at the end of this paper. Based on the exponential method,hyperbolic method,GM method,the idea to select calculating model automatically in the light of least deviation is raised. Base on this idea,a forecast program is developed. The actual detection data show that the program is effective and practical.