Characteristics and Aseismic Design Model of Non-Linearly Behavior of Conduit-Ground System During Strong Seismic Motion

本文的研究目的是阐明普通公用管道在地震或大变形作用下的非线性行为特征，并对管道有效抗震设计模型中土壤弹簧或接头弹簧等重要参数进行评价。重点研究了强地震动过程中土壤液化引起的地面大变形，对土壤弹簧进行了室内试验，建立了包括管道节点在内的管道地震反应分析方法。以模型管道为管道模型，在振动台砂箱中进行了液化试验。从剪切应变、孔隙压力和加速度的计算结果出发，研究了土壤液化过程中管道-地基系统恢复力的非线性特征。还进行了土体液化引起的侧向流动试验。开发了基于二维有限元法的土体液化及侧向流动数值分析程序。通过将分析结果与实验或测量结果进行比较，证实了这些方法的准确性。以弹性地基梁为基础，分析了管道在土壤液化环境下的受力特性。以改进传递矩阵法为分析工具，对管道及节点的位移和内力进行了数值计算，并对管道抗震设计的重要参数进行了评价。

Objects of this study are to clarify the non-linearly behavior characteristics of common utility conduit subjected to seismic ground motions or large ground deformations and to evaluate the important parameters such as soil spring or joint spring for the effective aseismic design model for the conduit. Particularly we focussed on the large ground deformations induced by soil liquefaction during strong groundmotion and performmed laboratory test for the soil springs and build up the analytical method for seismic response of conduit including its joints. Liquefaction tests using the the model pipeline as the conduit model in sand box on shaking table are performed. From the results of shear strains, pore pressures and accelerations the non-linearly characteristics of restorning forces of conduit-ground system during soil liquefaction are investigated. Experiment for the lateral flow induced by soil liquefaction is also performed.Numerical analysis programs for soil liquefaction and lateral flow induced by it are deveroped based on 2 dimensional FEM.Accuracy of these methods is confirmed by comparing the analytical results with the experimental or measured results. Behavior of conduit in soil liquefaction environment is analyzed, which is based on a beam on an elastic foundation. Using modified transfer matrix method as analytical tool, numerical computations are performed for displacements and internal forces of conduit and joints, and important parameters for aseismic design of conduit are evaluated.