Seismic Response Analysis Of Buried Pipeline

In the process of urban modernization, buried pipeline, one major part of urban lifeline system, is playing an increasingly important role. Disasters, especially earthquakes have great harm to the safety of buried pipeline.Thus, researching the failure law of buried pipelines in earthquake and improving its seismic performance has become an important subject for urban disaster prevention and mitigation. Due to surrounding soil, the vibration characteristics of buried pipelines are different from those of overground structures, and the seismic analysis of buried pipelines has its own characteristics.Based on the domestic and overseas earthquake materials, this paper summarized the damage form of buried pipelines and the main factors. With the theory of underground structure seismic analysis and finite element method, applying large general FEM software of ANSYS, finite element model is set up to analyze the buried water supply pipeline with changing directions.According to the design of water supply pipeline, static analyses of pipelines under permanent load and variable loads are made to conclude the displacement and stress value of the pipelines. Then make modal analysis on pipelines to get the natural frequency and period, and summarizes the characteristics of vibration mode. Apply seismic response spectrum theory in analyzing the dynamic response of the pipelines. Select four nodes respectively on the axial surface and section ring of one end. Under the conditions of three soil types (â… ,â…¡,â…¢) and the intensity of 7, 8 and 9 degrees, stress and displacement response rule can be concluded. At the same site (I), the bigger the earthquake intensity is, the bigger the axial displacement of the pipeline will be. The axial displacement value of end section nodes is smaller than that of axial surface nodes. At the same site, with the increase of seismic intensity, the lateral displacement value is far smaller than that of the axial displacement, and the change is stable, not very drastic as axial displacement. At the same earthquake intensity (8 degree), the softer the site soil is, the bigger the axial displacement will be. The axial displacement of end section node is smaller than that of axial node. In the same soil, the stress response is growing with the increase of the intensity. Under the same intensity, the stress response is growing as the site soil gradually becomes softer. To ensure the normal use of the concrete pipeline, in soil I, at the earthquake intensity of 9 degree, the pipeline damage occurs; in soil II and III, damage occurs at the earthquake intensity of 8 degree or above.Under the same conditions and by the comparison of time-history method, results show that conclusions from the two analyzing methods are consistent. Seismic response spectrum analysis method is simple in calculation and thus feasible. Finally, based on the analysis results and relevant pipeline construction data, some suggestions are proposed on the earthquake resisting techniques of buried pipelines.