A Study Of Roadbed Deformation Laws And Expressway Diseases Concerning Fill Embankment Of Special Structure

Two types of expressway diseases, vehicle bump at bridge-head and the fill and excavation roadbed problem, have often appeared in course of expressway construction. And they are still difficult harness problems at present.The new concept of the fill embankment of special structure is put forward in this thesis, and it means two kinds of transitional sections of expressway - the transitional section between the fill embankment behind bridge abutment and a bridge, and the transitional section between the slope after excavation and the fill embankment along one side of it. On the basis of this cognition, according to the construction example of Guangzhou - Zhaoqing expressway in Guangdong province, the deformation laws of the fill embankment behind bridge abutment and the roadbed consisting of the fill and the slope after excavation, and these two types of expressway diseases concerning them are discussed in detail. The research pays attention to the settlement patterns of the fill embankment behind bridge abutment for vehicle bump at bridge-head, and the formation reasons of it and the behavior and mechanism of reinforced roadbed consisting of the slope after excavation, the fill embankment and geogrid under loads are analyzed for the fill and excavation roadbed problem. This paper includes the studies at four aspects - the study of indoor structure model test, the analysis of flexibility theories, the analysis for these models and the engineering sites by non-linear finite element method(FEM) and diseases forecast, and suggestion of harness countermeasures. By means of model test, the deformation characteristics of roadbed in the engineering sites are predicted on the basis of the study of the displacement regulations of model soil elements. According to the FEM analysis for these models, the suitable calculating model and parameters are obtained. And some representative engineering sites are calculated and analyzed to research the characteristics of these diseases and effects under different harness methods. Moreover limit equilibrium methods of stability analysis of soil slope are used for evaluating integral stability of roadbed.In this paper a lot of hidden trouble in this project is pointed out, and some advices of solving these problem are also given. Therefore, the result of this thesis can be effectively used in the engineering design and engineering execution of Guangzhou - Zhaoqing expressway. All of these works provides scientific basis and gains experience for the future study about them.