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表层场地效应分析的强震结构损伤估计方法。采用二维有限元有效应力分析程序对神户地基选取的8个实际断面作为表面层模型进行了分析。结果表明：场地效应主要表现为空间非均匀分层引起的加速度响应集中与地面应变响应增加的非线性耦合；响应加速度和地面应变分布与建筑物和埋地管道的实际损伤分布基本吻合。接下来，我们开发了地震时连接到医院的救生生命线的地震可靠性和成本的评估方法。采用基于蒙特卡罗法的生命线网络可靠性分析方法，对矢津市供水管网的虚拟模型和真实模型的可靠性进行了评估。对不同地面和管道条件下的模型进行了数值计算。因此，在地震烈度较高的情况下，除了改善地基或管道条件的方法外，还需要另一种地震准备方法。最后，将费用不均视为一种风险，并通过管理风险进行规划，使其变小，在本研究中，我们开发了自来水企业的风险管理系统，其中需要进行适当的维护。

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.