Research Of The Method To Predict Settlement On Soft-soil Ground In Expressway

For effectually controlling unitary stabilization and settlement of soft-soil ground, dynamic control for settlement distortion should be done in process of construction to reach the purpose of validating and optimizing design, shortening time, reducing cost and improving quality for project. So it becomes one of the key techniques on dynamic control for settlement distortion that how to back-analyze parameters of ground in time base on field test data. The problem, a large number of test sections did not display resilience but keep up subsiding after uninstalling loads, was found in analyzing field test data. Which arouses think in the change of effective stress during uninstalling loads. As the problem is concerned, two-direction load, which differences from the usual load process, is presented. From analyzing the change of effective stress in the process of one-direction to two-direction load, it is founded that the evanescing process of pore water pressure proposed in the paper shows a better agreement to fact. And four constitutive models are established, which are hyperbolic model, half-logarithm model, exponential model and Poisson model. Combined with the analysis of the change of effective stress, the iteration formulations of settlement calculation are provided. Through comparing field data with the calculated results by the program designed by optimization algorithm, the result shows that the method is correct and reliable. Various previous methods are summarized and classified into two categories: semi-math methods and pure-math methods. Based on discussion of the common and difference among these methods, multiple-exponential model is presented. Using the new method to predict settlement of some sections in SU-JIA-HANG expressway, the result indicates that the new method can accurately predict settlement and has practical value. In the end, through comparing the solution of FEM to Biot concretion theory with the result of predict method in this paper, the superiority of the method presented in the paper is further testified.