Research Of Settlement Calculation And Prediction Method Of Soft Soil Roadbed On Jia-Shao Highway

The soft soil is widely distributed in China, particularly in coastal areas of Jiangsu and Zhejiang. With the rapid development of highway construction, it is inevitable that a large number of roadbeds pass through the soft soil areas. Properties of soft soil ground are often poor, such as slow consolidation, low intensity, and large deformation and so on. Stability and deformation are often encountered in expressway construction on the soft clay ground. Therefore, it is of great academic value and social benefit to improve the existing foundation settlement calculation and forecast method, so that the numerical solution of settlement is close to the measured data.This paper takes engineering as the background, i.e. the south bank connecting line of cross river channel form Jiaxing to Shaoxing, and the main work and achievements are as follows:(1) The roadbed monitoring data was compared and analyzed. The result shows: the settlement is larger in the middle of embankment than sides; The fill section and construction have influence on the settlement and lateral displacement of roadbed; the preceding loading influence more on settlement of roadbed than the later loading. The cumulative settlement of the prestressed pipe pile foundation was obviously less than the foundation of plastic drain board.(2) The one-dimensional large strain consolidation model CS2was improved, FORTRAN programming package was used to implement the computation of the model. With the improved CS2model which simulates embankment settlement of roadbed consolidation process, the calculation results show that the numerical solution of settlement was agreement with the measured data.(3) The finite element analysis software MIDAS/GTS was used to analyse the settlement deformation of the general roadbed and the roadbed nearby bridge. Research shows that:the largest settlement of the general roadbed occurred in the center of the top surface of the first layer of soil, the maximum value of roadbed lateral displacement appeared in the soil whose property is poor below the embankment edge. The settlement and lateral displacement of the roadbed nearby bridge are greatly reduced, and the lateral displacement mainly occurs in the soil where the prestressed pipe piles were not reached.(4) According to the test data, the SEP program and the hyperbolic model was used to forecast the roadbed settlement, and the predicted values were compared with the measured values. Research shows that:the SEP calculation program and hyperbolic prediction model can predict settlement; in contrast, the SEP calculation program is more accurate to forecast settlement than the hyperbolic model.