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

本研究的目的是阐明地面大变形作用下埋地管道的非线性行为特征，并评估液化环境下管道的抗震抗力，以建立有效的抗震设计模型。特别是针对强地震动作用下土壤液化引起的地面大变形问题，进行了液化土壤地面大变形的室内试验研究，建立了含接头的埋地管道地震反应分析方法。在振动台砂箱中进行了管道模型的液化试验。根据土的剪应变、孔隙水压力和加速度的测试结果，研究了液化过程中管道-地面系统的地震力的非线性特性。对液化引起的侧流进行了试验研究。基于二维有限单元地基势头法，建立了液化侧流分析方法，并对几种表层模型的大位移及含接头埋地管道在大位移作用下的位移和内力响应进行了数值计算，包括挤密砂桩和挤密砂板的对策桩通过将分析结果与实验或测量结果进行比较，确认这些分析方法的准确性。对管线抗震设计中的重要参数，如倾斜角度、表层厚度、管线参数、接头参数、地基处理条件、大变形等之间的关系进行了分析，得出了有益的结论。

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.