Development of Evaluation Method of Life Cycle Risk for Underground Structures based on Characteristics of Ground Motion

本研究的目的是探讨基于场地效应分析的强震作用下结构表层损伤评估方法。选用科比地基的八个实际断面作为表层模型，利用二维有限元有效应力分析程序进行了分析。结果表明，场地效应主要表现为空间不均匀分层引起的加速度反应集中与地面应变反应增大的非线性耦合。反应加速度和地应变的分布与建筑物和埋地管道的实际损伤分布基本吻合。其次，提出了地震时与医院相连的救生索的抗震可靠性和造价的评估方法。采用基于蒙特卡罗法的生命线管网可靠性分析方法，对八代市供水管网的虚拟模型和真实的模型进行了可靠性分析。对不同地基和管道条件下的模型进行了数值计算。因此，在地震烈度为6度的情况下，除了改善地面或管道条件的方法外，还需要另一种方法来准备地震。最后，将费用的不均衡视为风险，通过管理风险进行规划，使其变小，在本研究中，我们开发了一个自来水厂业务的风险管理系统，其中有必要进行适当的维护。

Objects of this study is to investigate the estimation method of the structural damages, which is based on the site effects analysis of the surface layers for the strong earthquake. The two dimensional finite element effective-stress analysis program is used for the analysis of the eight actual cross sections of Kobe ground chosen as the surface layer models. Results show that the site effects are characterized mainly as the nonlinear coupling of the concentration of acceleration response due to the non-uniform layering in space and the increased ground strain response. The spread of response acceleration and ground strain mostly agree well with the actual damage distributions of building and buried pipelines. Nextly we develop the evaluating method for for seismic reliability and costs of a lifesaving lifeline connecting to a hospital during earthquake. By using reliability analysis method for lifeline network based on Monte Carlo method reliability of a virtual model and a real one of Yatsushiro-city water supply pipeline network is evaluated. Numerical computations are performed for models with various conditions of ground and pipes. As a result, in a case of seismic intensity 6, another method preparing for earthquakes are needed except improving method of conditions of grounds or pipes. Finally, regarding unevenness of expense as a risk and planning by managing the risk so that it becomes small, in this study, we develop a risk management system in waterworks business, in which it is necessary to perform appropriate maintenance.