Analysis Of The Settlement Stability Of High-Speed Railway Subgrade On Soft Ground And Its Prediction Of The Post-Construction Settlement

The high speed running of train needs a smooth and stable foundation. The subgrade which is the foundation of track system must maintain the designing parameters of track within a standard under the operating condition, and this means that a high quality of stability for the settlement of subgrade is needed. Therefore, the predicting and effective controlling of post-construction settlement is the key point of designing and construction of high-speed railway subgrade.In this thesis, the post-construction settlement of high-speed railway subgrade on soft soil was studied both by experiential method and by finite element method (FEM), and gray theory was used in the prediction of the post-construction settlement.Given different filling height and different thickness of soft ground , lots of calculation and analysis is carried out about the corresponding post-construction settlement by using the two diffirent treatments of soil foundation(sand drains and CFG piles). Accorrding to the various value reasonable safe conditions can be selected for the high railway on the basis of the settlement control. Meanwhile, the value calculated also can provide a numerial reference for the designing and construction of high-speed railway.Based on the method of composite module, a seepage-coupling model was established in ABAQUS and successfully used to analyze the behavior of composite foundation, such as the distribution of the pore pressure and deformation in reinforced regions and substratum.Gray theory is used to predict the settlement of subgrade on soft ground of high-speed railway, and comparison is conducted with the traditional predict methods. The conclusion shows that the prediction based on gray theory is better than the value gained by traditional methods. Based on the model GM(1,1), the unequal time-interval prediction modle of recent information of identical dimension for subgrade settlement is established, and buffered softening arithmetic is used to eliminate in infinite increase of gray prediction model. By using this modle, a more better precision will be got.The work presented herein not only reveals the settlement stability conditions of high-speed railway subgrade on soft ground, but also discuss the FEM andprediction method for post-construction settlement analysis, and thus supplys a better reference both in data and technique for the design and construction of high-speed railway.