Development of Fragility Curves for Problems in Geotechnical Earthquake Engineering

该研究项目的目标是建立岩土地震工程中各种问题的易损性曲线，特别是地基、斜坡和挡土墙的易损性曲线。易损性曲线提供了特定类型结构超过规定破坏水平(例如，轻微、中度、重大和完全)的概率，作为地震事件严重程度的函数。从工程应用的角度来看，脆弱性曲线具有极其重要的意义，因为实践工程师可以直接使用它们，而不必执行任何复杂的计算，因为它们构成了土木工程基础设施系统所有风险分析/损失估计/风险降低的基础。虽然已经建立了建筑物和桥梁等结构的易损性曲线，但还没有任何系统的努力来开发岩土结构(如基础、斜坡、挡土墙)的易损性曲线。这项任务尤其重要，因为在重大地震事件中，这些结构的破坏范围相当大。经验易损性曲线将使用最近发生的地震事件的可用破坏数据来计算，这些地震事件包括：北岭、日本神户、土耳其伊兹米特地震和台湾集集地震。在建立经验脆性曲线的同时，将使用蒙特卡罗模拟技术计算分析脆性曲线。其中一项重要的任务是比较“经验”和“分析”的易损性曲线，以提高其准确性和可靠性。将讨论与建立这类岩土结构的易损性曲线有关的几个问题，包括每种类型结构的不同破坏状态的定义和地震事件强度的测量。将考虑不同的机制对所考虑的岩土结构造成损害。将特别重视土壤液化、因超过抗剪强度而导致的斜坡破坏，以及地基和地基系统的倾斜。建立一系列岩土结构的易损性曲线，将成为这类结构在地震中的风险分析/损失估计/降低风险的基础。这些脆弱性曲线将使公共和私人组织能够对1)地震对民用基础设施系统的潜在破坏、2)翻新战略、3)保险费、以及4)引导应急管理团队识别高风险系统进行理性评估。

The objective of this research project is to develop fragility curves for a wide range of problems in geotechnical earthquake engineering; specifically, for foundations, slopes, and retaining walls.Fragility curves provide the probability of exceeding a prescribed damage level (e.g. minor, moderate, major, complete) for a certain type of structure, as a function of the severity of the seismic event. Fragility curves are extremely significant from the engineering applications point of view as practicing engineers can use them directly without having to perform any complex computations, and because they form the basis for all risk analysis/loss estimation/risk reduction of civil infrastructure systems. Although fragility curves have been established for structures such as buildings and bridges, there hasn't been any systematic effort to develop such curves for geotechnical structures (e.g. foundations, slopes, retaining walls). Such a task is particularly important, as damage to these structures is quite extensive during major earthquake events.Empirical fragility curves will be computed using available damage data from recent seismic events such as: the Loma Prieta, the Northridge, the Kobe, Japan, the Izmit, Turkey and the Chi-Chi, Taiwan earthquakes. In parallel with the task of establishing the empirical fragility curves, analytical fragility curves will be computed using Monte Carlo simulation techniques. One of the important tasks is to compare the "empirical" and "analytical" fragility curves so as to improve their accuracy and reliability. Several issues related to the establishment of fragility curves for such geotechnical structures will be addressed, including the definition of the different damage states for each type of structure and the measure of the intensity of the earthquake event. Different mechanisms will be considered to cause damage to the geotechnical structures considered. Particular emphasis will be given to soil liquefaction, to slope failure due to exceeding the shear strength, and to tilting of foundations and foundation systems.The establishment of fragility curves for a range of geotechnical structures will form the basis for the risk analysis/loss estimation/risk reduction of such structures, when subjected to earthquakes. These fragility curves will allow public and private organizations to make rational assessment of 1) the potential damage to civil infrastructure systems from earthquakes, 2) retrofitting strategies, 3) insurance premiums, and 4) guide emergency management teams to identify high-risk systems.This project involves a collaboration between researchers at Princeton University and the State University of New York at Buffalo.