Evaluation of Aseismic Resistance of Pipeline Strucure Subjected to Large Ground Deformation

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Objects of this study are to clarify the non-linearly behavior characteristics of buried pipeline subjected to large ground deformations and to evaluate the aseismic resistent force of the pipelines during liquefaction environment for the effective aseismic design model. Particularly we focussed on the large ground deformations induced by soil liquefaction during strong ground motion and performmed laboratory test for the large ground displacement of liquefied soil and built up the analytical method for seismic response of buried pipeline including its joints. Liquefaction tests using the model pipeline in sand box on the shaking table are performed. From the results of shear strains, pore pressures and accelerations the non-linearly characteristics of restorning forces of pipeline-ground system during soil liquefaction are investigated. Experiment for the lateral flow induced by soil liquefaction is also performed. Analytical method for the lateral flow induced by liquefaction was developed based on the potential head method of the ground by 2 dimensional FEM.Numerical computations for the large ground displacements of the several surface layers models and the responses of the displacements and internal forces of the buried pipelines with joints subjected to such ground deformations are performed including the countermeasure method of the sand compaction piles and sheet piles. Accuracy of these analytical methods is confirmed by comparing the analytical results with the experimental or measured results. The relations between the important parameters for aseismic design of pipelines, such as the inclined angle and the thickness of the surface layer, the parameters of the pipeline and the joints, the conditions of the ground improvements and the large ground diformations, are evaluated and the useful results were obtained.