An Application Of The Soil-Cenment Pile In The Roadbed Of Railway

Although composite foundation has widely used in engineering during recent years, the research on the mechanical behavior has lagged behind the engineering applications。In the first chapter, the main research studies are about the situations of the soil-cement pile in the country。In the second chapter, by an example of application, the main research studies are the function and the construction techniques, In the last, it emphasize that the characteristic of the soil-cement pile and the problem of it。In the third chapter, firstly, in the soil-cement pile, the soil-cement plays an important role in strengthen the vertical substance. Its intensity determined the bearing capacity of the composite foundation, So it is necessary to study the physics character of the soil-cement, also the size of the energy has a determine influence on the soil-cement pile, According to the unconfined compression tests on the cement and the sand soil cement with different cement ratio and different curing time, and studying on rules of the unconfined compression and modulus, and summarizing of the characteristic of stress-strain diagram of soil cement, this dissertation analyzes the influence of cement ratio and curing time and characteristic of soil on unconfined compressive strength, and study the mechanicbehaviors of sand soil cement on the condition of soaking or dryness. The tests provide some data to the application of these two kinds of soil cementThe basic theory and some computations of FEM for composite foundation are discussed in the four chapter. The element types of soil and pile, models of soil and pile and calculation steps in FEM are focused on. Some notes are mentioned when nonlinear characteristics are applied. In the four chapter, the establishment of 3D FEM models, the selection of elements and meshing are discussed. Further analysis on the numerical result is presented, and then some contrasts are made with the test data. The conclusion is drawn that the selection of model and parameters are reasonable. The contrasts also supply a base for further analysis. And the stress and displacement of the composite group piles, two-layer foundation are computed respectively when varying modulus in the last. It's concluded that the method based on two-layer foundation does not fit to computing the displacement of composite foundation, and it causes to in security if applied to engineeringBy an example of application of the soil-cement pile in collapsible loess foundation treatment in ZhengZhou-Xi'an passenger dedicated railway line (in LingBao) the paper analyses and discusses the theory of the soil-cement pile, and make the field test, field quality control。And the Goodman interface elements were defined to contribute a nonlinear numerical model for the coupling finite elements and interface elements the interaction of a pile-soil system analyzed by ANSYS, case studies showed the results are fairly well consistent with the field observation, so it is so vivid that the soil-cement pile treat with collapsible loess foundation.