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1.
Seismic analysis of deep tunnels in near fault conditions: a case study in Southern Italy 总被引：1，自引：0，他引：1
Mirko Corigliano Laura Scandella Carlo G. Lai Roberto Paolucci 《Bulletin of Earthquake Engineering》2011,9(4):975-995
The importance of underground structures in transportation and utility networks makes their vulnerability to earthquakes a
sensitive issue. Underground facilities are usually less vulnerable to earthquakes compared to above-ground structures, but
the associated risk may be relevant, since even a low level of damage may affect the serviceability of a wide network. Seismic
analysis of tunnels close to seismogenic faults is a complex problem, which is often neglected at the design stage for the
lack of specific codes or guidelines for the design of underground structures in seismic conditions and also because, as mentioned
above, underground structures are considered less vulnerable to earthquake loading. This paper investigates the seismic response
of deep tunnels focusing on the required steps for a proper design under both static and dynamic loading. The study aims at
contributing to improve the methods currently used for the seismic analysis of underground structures. At this purpose, the
seismic response of a deep tunnel in Southern Italy has been investigated along the transversal direction. The infrastructure
is part of the railway switch line connecting Caserta to Foggia in the Southern Apennines which is one of the most active
seismic regions in Italy. The seismic response in the transversal direction has been analysed by using the pseudo-static approach
as well as through advanced numerical modeling using the spectral element method coupled with a kinematic approach for finite
fault simulations. The pseudo-static approach has been implemented using a closed-form analytical solution. The results obtained
from advanced numerical modeling and the pseudo-static method have been compared to assess their validity and limitations. 相似文献
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在地下结构抗震设计简化分析方法中，强制反应位移法将土层变形施加在有限元模型侧边界模拟地震作用，反应加速度法将土层加速度施加到整个有限元模型上模拟地震作用，此外还有仅将土层加速度施加到土层模型上模拟地震作用的方法。上述方法均规避了反应位移法中关于弹簧刚度的取值问题，提高了计算效率。本文以1个双跨箱形结构为例，用动力时程分析的计算结果作为校核，分析了强制反应位移法、反应加速度法和仅将土层加速度施加到土体中的简化分析方法在不同侧边距条件下的计算精度，再结合常用的反应位移法，对比分析了4种简化分析方法的误差。分析结果表明:使用强制反应位移法时，侧边距取为1倍结构宽度导致的误差最小，反应加速度法和仅在土体施加加速度的简化方法对侧边距取值不敏感，反应位移法在角点造成的误差最大。 相似文献
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复杂场地的土层地震反应分析对结构的地震反应计算及抗震安全性评价有重要意义。采用直接有限元法对土层进行三维建模,可使系统的计算力学模型更加符合实际情况。但由此带来的计算量之大,使得传统的计算方法难以胜任。在此背景下,本文利用静力子结构方法推导了在多点输入模式下进行土层地震反应分析时拟静力位移的求解步骤,并通过均匀土层算例验证了行波输入下利用约束子结构模态综合法进行复杂场地地震反应分析的可行性。 相似文献
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对地下结构抗震Pushover分析方法进行了改进,采用自由场局部变形峰值作为目标位移,局部变形峰值时刻对应的土层水平加速度作为等效惯性加速度输入。给出了局部变形峰值和等效惯性加速度确定方式,详细介绍了基于自由场局部变形的地下结构抗震Pushover分析方法实施步骤、使用方法和功能特点。该方法更有针对性地考虑了强地震作用下不同埋深地下结构与土体的非线性特征以及两者之间的相互作用,通过分析变形和受力情况可以得到完整的能力曲线,更好地评估地下结构抗震性能。使用本文方法对3种埋深的地下结构进行计算,并与动力非线性分析结果进行对比研究。结果表明:本方法在计算稳定性和模拟精度方面优于基于自由场整体变形的Pushover方法;对于不同的输入地震波,能力曲线的吻合程度更高;在强震和罕遇地震情况下,对于深埋地下结构,计算结果略大于动力非线性结果,对实际工程而言更加安全。 相似文献
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《地震研究进展（英文）》2022,2(4):100118
The pushover method for underground structures is a seismic analysis method featured by high calculation accuracy and a simple implementation process. The method has been widely used in seismic design and other related scientific research; however, the influence of different soil-structure flexibility ratios on the accuracy of this method is still not well understood. In this study, we select the cross-section structures beneath the Daikai subway station as the research object and establish 12 finite element analysis models with different soil-structure flexibility ratios using ABAQUS. All models are computed by the dynamic time-history method or the pushover method. Furthermore, the dynamic time-history solution result is taken as the standard solution, and the precision and application of the pushover analysis method are discussed based on the parameters of peak interlayer displacement and peak internal force of the middle column section. The results show that the soil-structure flexibility ratio has a significant influence on the calculation accuracy of the pushover method, and the calculation accuracy of this method is the most ideal when the soil-structure flexibility is equal to 1. The research results can provide significant references for the seismic design of underground structures or the improvement of simplified seismic analysis methods. 相似文献
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The dynamic stability analysis of slopes is often conducted by the traditional method of slices, using pseudo-static calculations. However, the response of a geotechnical structure subjected to seismic loads can be studied through a dynamic finite element analysis, which can be considered one of the most complete available tools, as information about the stress distribution and the deformations can be obtained. The dynamic analysis of the stability of San Pedro cliff at the Alhambra in Granada is studied in this paper. The results have been compared with pseudo-static calculations worked out with the method of slices. Real accelerograms have been selected for the dynamic tests. Thorough in situ and laboratory tests have been conducted in order to properly characterize the cliff. The soil constitutive model is also explained in this paper. Finally, the influence of the sources of energy dissipation has been studied through the material damping, the integration scheme and the boundary conditions. 相似文献
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针对地下结构抗震分析中应用广泛的波动方法与振动方法,从物理方程和有限元格式出发,明确了两种方法的区别与联系。通过标准数值试验,证明了振动方法是波动方法采用下卧刚性基岩假设和地层水平无限延伸假设,仅考虑SV波垂直向上入射的一种特例。采用波动方法模拟弹性地基,对比振动方法结果,表明弹性地基和刚性地基上地表位移响应和隧道结构内力响应均有显著差异。建议应根据具体场地条件,选择振动或波动方法进行地下结构抗震设计研究。 相似文献
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历史震害表明,填充墙与框架的连接刚度对框架结构的抗震性能有重要影响。我国《建筑抗震设计规范》(2010)建议"框架结构中的砌体填充墙,宜与柱脱开或采用柔性连接",但对二者的具体连接刚度,规范并没有做出明确规定。运用ABAQUS软件,对前人开展的考虑填充墙与框架连接影响的框架结构拟静力试验进行数值模拟,对比分析填充墙框架结构破坏特征及滞回曲线等抗震性能指标,验证了有限元模型的可靠性。基于某典型框架结构,建立不考虑填充墙、考虑填充墙与框架不同连接刚度的框架结构有限元模型。模态分析表明,连接刚度对框架结构的频率影响较小,结构的动力特性趋于一致;多遇地震和罕遇地震作用下的弹塑性时程分析表明,合适的连接刚度可以提高结构的抗震性能。研究可为框架结构的抗震设计提供参考。 相似文献
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随着城市轨道交通工程抗震性能越来越受到关注,反应位移法作为一种简捷的抗震设计方法被大量应用于地下结构抗震设计中。地基弹簧系数的确定方法是反应位移法抗震设计中最为重要的因素之一,本文选取试验法、李英民法、MIDAS法和有限元法,结合北京典型地层,对比分析这四种方法地基弹簧系数取值对地下结构的弯矩、轴力和剪力的影响规律。结果表明:(1)在反应位移法计算中,地基弹簧系数取值对结构内力响应具有重要影响,对结构轴力和剪力的影响较大,而对于弯矩的影响相对较小;(2)地基弹簧系数获取方法优选试验法,在无地勘资料情况下,经验公式和有限元法可作为备选方法;(3)综合考虑四种不同地基弹簧系数确定方法对结构内力影响程度,为保证结构设计的安全性,可对试验法下结构内力进行系数修正,修正系数建议值为1.10。 相似文献
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首先基于地震作用下地下结构的变形受周围地基土变形控制这一相互作用特征,在反应位移法的基础上讨论两种简化分析方法:一种是将土层变形施加在模型边界模拟地震作用;另一种是将土层加速度施加到整个模型上模拟地震作用。这两种简化分析方法都避免了反应位移法中弹簧刚度的取值问题,提高了计算效率。其次分析不同地震动强度、不同侧边距的计算结果,并用动力时程分析的计算结果校核,分析两种简化计算方法的精度。结果表明:随着地震动强度的增加两种简化分析方法的计算结果都令人满意,使用强制反应位移法时建议侧边距取两倍结构宽度,使用反应加速度法时建议侧边距取三倍以上结构宽度。 相似文献
13.
Mahendra P. Singh 《Soil Dynamics and Earthquake Engineering》1986,5(4):226-233
The paper describes the development of a mode accleration-based response spectrum approach for calculating the seismic design response of the nonclassically damped structures. The response is divided into a pseudo-static part and a dynamic part. The pseudo-static part is calculated by a simple static analysis of the structure for the inertial forces, induced by a unit ground acceleration, applied statically. The dynamic part, of course, pends upon the dynamic characteritics of the structure which are defined in terms of the complex-valued modal characteristics. The correlation between the pseudo-static and dynamic components is properly considered. The design ground input in this approach is defined in terms of the relative acceleration and relative velocity response spectra. The proposed approach has the desired attribute of the mode acceleration approach as the response can be accurately calculated even if only a first few modes are used in the analysis. The approach is computationally more efficient than the convenionally used mode displacement approach. The applicability of the approach is verified by numerical simulation results. 相似文献
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The seismic response characteristics of underground structures in saturated soils are investigated. A fully fluid-solid coupling dynamic model is developed and implemented into ABAQUS with a user-defined element to simulate the dynamic behavior of saturated soils. The accuracy of the model is validated using a classic example in literature. The performance of the model is verified by its application on simulating the seismic response characteristics of a subway station built in saturated soils. The merits of the model are demonstrated by comparing the difference of the seismic response of an underground structure in saturated soils between using the fully coupling model and a single-phase medium model. The study finds that the fully coupling model developed herein can simulate the dynamic response characteristics of the underground structures in saturated soils with high accuracy. The seismic response of the underground structure tends to be underestimated by using the single-phase medium model compared with using the fully coupling model, which provides a weaker confining action to the underground structure. 相似文献
15.
Nonlinear earthquake response analysis and energy calculation for seismic slit shear wall structures
Based on the concept of structural passive control, a new type of slit shear wall, with improved seismic performance when
compared to an ordinary solid shear wall, was proposed by the authors in 1996. The idea has been verified by a series of pseudo-static
and dynamic tests. In this paper a macro numerical model is developed for the wall element and the energy dissipation device.
Then, nonlinear time history analysis is carried out for a 10-story slit shear wall model tested on a shaking table. Furthermore,
the seismic input energy and the individual energy dissipated by the components are calculated by a method based on Newmark-β
assumptions for this shear wall model, and the advantages of this shear wall are further demonstrated by the calculation results
from the viewpoint of energy. Finally, according to the seismic damage criterion on the basis of plastic accumulative energy
and maximum response, the optimal analysis is carried out to select design parameters for the energy dissipation device. 相似文献
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关于埋深对地下结构地震反应的影响的研究对象多见于地下隧道,对地铁车站地震反应受埋深影响变化规律缺乏深入研究。本文基于ANSYS有限元软件,采用改进的简化方法建立三种不同埋深的地铁车站结构有限元模型,以两种基岩波的水平向和竖向地震动作为激励,求解各模型中地铁车站结构重要部位的地震反应。分析不同埋深时地铁车站结构惯性作用、侧面土体和上部土体三个因素对地铁车站地震反应的影响情况。分析结果表明:在双向地震作用下,地铁车站侧壁弯矩、剪力、轴力和中柱轴力随埋深的增加而增加,中柱剪力和弯矩随埋深增加而减少。埋深越深,侧面土体对地铁车站地震反应影响越大;上部土体使中柱轴力不断增加;结构自身的惯性作用对其地震反应的贡献逐渐减小。 相似文献
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离散单元法在框架结构地震反应分析中的应用 总被引：1，自引：0，他引：1
将离散单元法应用于框架结构的地震反应分析,并建立了框架结构的离散单元计算模型。在数值求解过程中,本文采用同步动态松弛法确立与求解结构单元平衡关系,避免了动态松弛法由于路径相关性所造成的误差。本文编制了框架结构地震反应时程分析程序,并以一实际结构为例,进行了时程分析。算例表明,本文所提出的方法简单、有效,为工程结构地震反应分析提供了新的思路与方法。 相似文献
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黄土地区地铁地下结构抗震研究综述 总被引：2，自引：2，他引：0
介绍了地铁地下结构抗震研究的发展历史、研究现状及黄土地区地铁地下结构抗震的相关研究,总结归纳出地震作用下地铁地下结构的地震破坏形式与地震反应特征;对地铁地下结构的不同抗震研究方法进行对比研究,指出各种研究方法的优缺点与适用情况。针对我国黄土地区地铁地下结构抗震分析理论研究不足,基础资料积累欠缺,抗震设计尚无可靠依据的实际情况,探讨了黄土动力本构模型、黄土与结构动力相互作用、离心机振动台试验研究及抗震分析方法等因素对黄土地区地铁地下结构抗震研究可靠性的影响,提出黄土地区地铁地下结构地震动力反应分析、地震破坏机理分析、抗震性能分析及抗震设计中需要深入研究的关键问题。 相似文献
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通过梳理轨道交通地下结构抗震设计流程,明确抗震设计方法选择的原则和依据。在阐明反应加速度法基本原理基础上,引出土层地震反应分析的一维等效线性化法,并对影响土层地震反应计算结果关键参数进行讨论。针对一维土层地震反应得到的加速度时程提出合理拟合抛物线型二阶基线方程,可以消除加速度时程长周期随机分量引起的漂移问题,经自然积分可以得到消除基线漂移的位移时程;同时阐明数值分析软件Origin Pro有效解决积分得到位移时程的基线漂移问题并得到合理位移分布的途径和方法。以北京地铁3号线体育中心站为例,详细说明反应加速度法相关各个技术环节实现的方法和结果,并指出反应加速度法或位移法所依据的土层地震反应分析和位移时程的确定具有较强专业性,应做专项咨询分析工作;只有一维土层地震反应分析获得的加速度反应谱及时程客观合理,有限元计算所需相应地震动水平的等效剪切模量才可信;积分得到的位移时程需要有效消除基线漂移影响。只有上述相关结果真实客观可信,有限元计算结果才能模拟真实的土层-地下结构地震反应。 相似文献
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为提高大型复杂结构体系的计算效率,在深入分析约束模态综合法原理的基础上,论述了非比例阻尼体系中约束模态综合法对阻尼矩阵的处理方法,并探讨了如何缩减对接界面自由度的问题。同时,通过算例详细说明了该方法在高层建筑结构动力时程分析中的应用。计算结果表明,在利用约束模态综合法求解非比例阻尼体系的动力问题时,文中所采用的阻尼矩阵的处理方法是有效的,与有限元直接法相比具有很好的精度。对于地基土-高层建筑结构体系的地震响应分析问题而言,缩减对接界面自由度的约束模态综合法可达到很好的计算精度,能够更大程度的提高计算效率,为大型复杂结构的动力时程分析研究和工程应用提供了一定的依据和方便。 相似文献