New limit states for the seismic fragility assessment of circular tunnels: Application in case of tunnels in clayey soil deposits

IF 6.7 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Tunnelling and Underground Space Technology Pub Date : 2024-10-14 DOI:10.1016/j.tust.2024.106129

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引用次数: 0

Abstract

This paper introduces a novel framework to define limit states for the seismic fragility assessment of circular tunnels in soil. A numerical framework is developed for this purpose, focusing on the response of tunnels subjected to ground seismic shaking in the transverse direction. New limit states are defined based on the ovaling deformation of the tunnel, corresponding to different levels of liner stiffness degradation caused by seismic shaking. The latter is evaluated via nonlinear static pushover analyses of the examined ground-tunnel configurations. Nonlinear dynamic analyses are performed to evaluate the demand of examined tunnels and develop Probabilistic Seismic Demand Models (PSDMs). The uncertainties related with the definitions of capacity and demand are thoroughly evaluated based on the results of the nonlinear static pushover and dynamic analyses, respectively. The proposed framework is applied to a 6 m diameter circular tunnel embedded in uniform clayey soil deposit at a burial depth of 15 m. Various assumptions are made regarding the thickness and mechanical properties of the liner and the soil, leading to the investigation of 27 ground-tunnel configurations. A suite of ground motions is selected to perform dynamic analyses of each examined configuration. Based on the results of the analyses new PSDMs and PGA-based fragility functions are derived. Comparisons of the proposed fragility curves with existing, empirical, and analytical fragility curves for tunnels, reveal differences, which in some cases are significant and are mainly attributed to the different definitions of Engineering Demand Parameters (EDPs) and limit states between the compared curves, as well as to different assumptions in the analytical frameworks proposed by various studies. The proposed framework may be applied to other ground-tunnel configurations to develop fragility functions for a more rigorous risk and resilience assessment of these types of systems.

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圆形隧道地震脆性评估的新极限状态：在粘性土隧道中的应用

本文介绍了一种新的框架，用于定义土壤中圆形隧道地震脆性评估的极限状态。为此，本文开发了一个数值框架，重点关注隧道在横向地震动下的响应。根据隧道的椭圆形变形定义了新的极限状态，与地震震动引起的不同程度的衬砌刚度退化相对应。后者是通过对所考察的地面隧道配置进行非线性静态推移分析来评估的。非线性动态分析用于评估受检隧道的需求，并建立概率地震需求模型（PSDM）。根据非线性静态推移分析和动态分析的结果，分别对与容量和需求定义相关的不确定性进行了全面评估。提出的框架适用于一个直径 6 米、埋深 15 米、嵌入均匀粘土沉积层的圆形隧道。对衬砌和土壤的厚度及机械性能做了各种假设，从而对 27 种地面隧道配置进行了研究。我们选择了一套地动图，对每种检查过的构造进行动态分析。根据分析结果，得出了新的 PSDM 和基于 PGA 的脆性函数。将所提出的脆性曲线与现有的、经验的和分析的隧道脆性曲线进行比较，发现两者之间存在差异，在某些情况下差异很大，这主要归因于所比较的曲线之间工程需求参数（EDPs）和极限状态的定义不同，以及各种研究提出的分析框架中的假设不同。建议的框架可用于其他地面隧道配置，以开发脆性函数，对这些类型的系统进行更严格的风险和复原力评估。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Tunnelling and Underground Space Technology 工程技术-工程：土木

CiteScore

11.90

自引率

18.80%

发文量

454

审稿时长

10.8 months

期刊介绍： Tunnelling and Underground Space Technology is an international journal which publishes authoritative articles encompassing the development of innovative uses of underground space and the results of high quality research into improved, more cost-effective techniques for the planning, geo-investigation, design, construction, operation and maintenance of underground and earth-sheltered structures. The journal provides an effective vehicle for the improved worldwide exchange of information on developments in underground technology - and the experience gained from its use - and is strongly committed to publishing papers on the interdisciplinary aspects of creating, planning, and regulating underground space.