Numerical Simulation Analysis Of Buried Pipeline Crossing Fault

The key point of problem that response of buried pipeline crossing fault is the lasting displacement of soil which makes the pipeline damaged. This kind seismic hazard is one of the main damages, and also, one of the great task in the field of lifeline earthquake engineering need to be researched. Since the California earthquake taken in 1971, the theory came into being which is based on the plentiful earthquake data and numerical method, combined with theory analysis and experimental analysis, then give the foundation to aseismic design for buried pipeline when crossing fault. In the thesis two parts are included. In the first part several fundamental aspects concerning the response of buried pipeline when crossing fault are described. Chapter 1 give an overview of the state-of-the-art of study on the earthquake response of buried pipeline crossing fault, including development of theoretical analysis, experimental study. Besides, the article demonstrates proper analysis methods should be adopted to solve different problems. The system of reaction between pipeline and soil is suggested in Chapter 2, including the material modal of soil and fault, the modal of reaction between pipeline and soil, the modal of pipeline buckling and effective calculation region. Chapter 3 is devoted to the introduce the application of numerical method which reappear the movement of buried pipeline when crossing active fault ,and give introduction of the True Grid technique that can improve the precision. In the second part principals, basic relationship and parameter developed in the first part are applied to numerical examples for FEM simulation. Given the modal of beam on elastic foundation a number of influential factors are observed during the analysis in Chpter 4 . The common laws of the movement of buried pipeline acrossing fault are given by large quantities of comparative analysis. In Chapter 5 the shell modal is used to analysis the final data about many factors having influence on the pipeline. Chapt 6 illustrates the whole process of buried pipeline damaged by means of numerical simulation. The study in this part get some conclusions: the dangerous section firstly appear at the position about 0.5 meters away from the fault-plane; some part of soil will be stiffened when buried pipeline was damaged; several sensitive factors such as displacement of fault, Diameter-Thickness Ratio,crossing angle, friction coefficient between pipeline and soil and the character of soil are found in the analysis. Pipeline is easy damaged at the position about 0.5 meter away from the fault-plane in the clay, however , in the rock, the dangerous will be found near the fault-plane; the main stress of dangerous point increase with the main strain at slowly speed when the buried pipeline has inelastic behavior,then there are cracks appear on the surface of pipeline and that will extend to the two sides with the crack made more big, at last, the pipeline damaged at the position 1-5 meters away from the fault-plane.