隧道对地表地震动放大作用的研究

场地条件对地震波传播有较大的影响,浅埋隧道改变了近地表的场地条件,势必会对地面地震动产生一定的影响,进而影响临近地面结构的地震响应。文章选取Ricker小波作为输入动力时程,利用数值方法研究了均匀弹性场地中圆形隧道对地表水平向峰值加速度的影响,分析了不同隧道埋深和入射波频率时地表水平向加速度的变化规律。结果表明,随着隧道埋深的增大,其对地表加速度峰值的影响变小,但影响范围近似线性增大,主要集中在5倍的隧道半径范围内;无量纲周期λ/D在6～8左右时,隧道对地表PGA的放大作用最为显著;λ/D10时,隧道对地表地震动的影响基本可以忽略。     

自锚式双塔悬索桥在近场与远场地震作用的动力响应

为探究近场、远场、脉冲和非脉冲四种地震作用下自锚式双塔悬索桥的地震响应,首先基于sap2000建立某自锚式双塔悬索桥三维空间有限元模型,其次依据该桥场地条件从PEER中选取近场、远场、脉冲和非脉冲地震动,最后将该四种地震动作为有限元模型的激励源,以此探究自锚式双塔悬索桥的地震响应.研究表明:近场脉冲地震动产生的位移响应...     

近断层脉冲型地震下桥梁基础减隔震支座减震性能研究

文章为研究近断层脉冲型地震动下桥梁基础减隔震支座的减震性能,设计一种桥梁基础减隔震支座,在选取近断层脉冲型地震动和非脉冲型地震动下进行地震响应分析。结果表明:在脉冲型地震动激励下,支座及梁端位移响应大于非脉冲型地震动下位移响应,近断层区域桥梁抗震设计时应将脉冲型地震动效应作为重点设计;在近断层脉冲型地震动作用下,设计桥梁基础减隔震支座能够较大幅降低桥墩基础底部的弯矩内力效应,起到有效的减隔震效果。     

中庭式地铁车站结构地震动力响应机制分析北大核心CSCD

随着建筑功能需求的多样化,出现了中庭式地铁车站结构型式。为引入自然光,中庭式地铁车站结构顶板、中板的中部去除,设置横梁代替;并且为了扩大空间,地下一层不设柱,地下二层设置扁柱,这些特征使中庭式车站地震动力响应异于传统车站。文章通过中庭式地铁车站土-结构1/30缩尺模型振动台试验研究,探究不同峰值、频谱地震动作用下场地土体的放大衰减效应、结构的加速度、动力应变响应,并分析地震动力效应对结构内力的影响,为中庭式车站结构抗震设计提供参考依据。     

中庭式地铁车站结构地震动力响应机制分析

随着建筑功能需求的多样化,出现了中庭式地铁车站结构型式。为引入自然光,中庭式地铁车站结构顶板、中板的中部去除,设置横梁代替;并且为了扩大空间,地下一层不设柱,地下二层设置扁柱,这些特征使中庭式车站地震动力响应异于传统车站。文章通过中庭式地铁车站土-结构1/30缩尺模型振动台试验研究,探究不同峰值、频谱地震动作用下场地土体的放大衰减效应、结构的加速度、动力应变响应,并分析地震动力效应对结构内力的影响,为中庭式车站结构抗震设计提供参考依据。     

铁山港跨海特大桥地震安全性评价研究

文章结合铁山港跨海特大桥工程实例,通过开展桥梁近场区地震地质、工程地质等相关勘测,研究地震危险性概率和设计地震动参数,并对工程场地地质灾害进行了评价。研究成果为桥梁工程抗震设计提供了参考数据。     

阿李公路黑城河特大桥施工阶段地震反应分析

为了研究桩—土效应对大跨连续刚构桥施工阶段地震响应的影响,以青海省黑城河特大桥为例建立有限元模型,采用动态时程分析法对施工过程中考虑桩土效应和不考虑桩—土效应的各个施工阶段地震响应进行分析对比.结果表明连续刚构桥建造过程中,考虑桩—土效应对悬臂端位移、主梁根部弯矩及桥墩底部弯矩变化较大.研究结果可以对大跨径连续刚构桥施工阶段抗震分析提供一些有意义的建议.     

桩土效应对桩柱式桥墩地震响应的影响分析

文章以桩柱式桥墩为研究对象,建立桥墩有限元动力分析模型,采用反应谱法计算分析考虑桩土效应和不考虑桩土效应时桥墩地震响应的差异,并以土体性质和桩长为参数,分析土弹簧刚度及桩长的变化对地震响应的影响。研究结果表明:桩土效应对桥墩地震响应的影响不可忽略,不考虑桩土效应时,墩底的内力偏安全,墩顶位移偏危险;随着桩长的增加,墩底横向剪力和弯矩减小,变化幅度随土体比例系数m值及墩高的增大而减小。     

下穿引水隧洞对铁路隧道地震效应的影响研究

结合云南省盐津县白水江三级电站下穿内昆铁路手扒岩隧道的实际工程,采用LS-DYNA显式动力分析程序对既有铁路隧道地震效应受下穿引水隧洞的影响进行了研究。研究结果表明:在单个方向地震波作用时,震动速度、加速度响应的最大方向与加载方向一致;在3个方向地震波同时作用下,既有隧道最大响应发生在边墙处;新建下穿隧道建成后,相当于减震洞的形成,既有隧道结构上震动速度、加速度及主应力均有不同程度的减小,使既有隧道交叉段的地震响应得到改善。     

高速铁路交叉隧道动力学问题研究综述

文章针对高速铁路交叉隧道的分类和组合型式进行划分,分别阐述了其存在的关键动力学问题,并通过广泛的相关文献调研,总结了高速铁路交叉隧道在列车振动、空气动力效应以及地震震动等方面的研究现状与不足;指出了今后的研究重点:(1)考虑隧道结构、地层参数以及邻近交叉隧道的结构特征,建立高速列车-轨道-交叉隧道为一体的三维精细化分析模型,并用其开展定量安全评价;(2)开展车隧气动结构效应研究,提出保障隧道结构安全的工程措施,进而建立考虑列车气动荷载与其他动力荷载叠加作用下交叉隧道的安全性评估方法;(3)进行全方位的高速铁路交叉隧道地震动力响应研究,揭示交叉隧道结构本身的动力特性,提出相适应的抗震设计方法;(4)引入混凝土和岩石动力损伤本构关系,建立能考虑材料动态损伤的计算模型,以对结构在长期反复动力作用下的动力响应特性及其累积损伤效应开展深入研究。     

锚固系统对地震边坡动力响应的影响研究

文章利用有限差分程序FLAC2D6.0,从单元屈服状态和剪应变增量、应力场、动力稳定性等方面对比分析了自然边坡和锚固边坡在地震作用下的动力响应情况。结果表明：在地震作用下,土坡产生不可恢复的累积变形,其大小与输入的地震波峰值有关,而锚固边坡较自然边坡有更好的延性;锚固系统能在一定程度上限制坡顶拉破坏的产生和很好的控制坡脚剪切破坏的发展;锚杆轴力沿全长呈不均匀分布,且在滑移面附近变化幅度最大。     

强震对路基边坡毁灭性破坏的演化机理分析

强震产生的地震波会对路基边坡造成巨大的破坏,严重摧毁道路、阻碍救援。文章阐述了强震动作用对路基边坡的破坏机理,分析了强震作用下产生的＂地震波效应-地震力作用于边坡体-坡体破坏＂波动袭击链的链式效应。     

Seismic Dynamic Response of an Atrium-type Subway Station北大核心CSCD

Atrium-type subway stations have been utilized for multifunctional demands. For natural lighting, the middle parts of slabs are replaced by beams. And to expand space, no columns are set for the 1st floor underground, while flat columns are set for the 2nd floor. These characteristics make the seismic response of the atrium-type subway station differ from the traditional station. In this paper, by a shaking table test of soil-structure 1/30 scale model of the atrium-type subway station, the amplification and attenuation effect of soils to the ground motion, as well as the acceleration and the strain response of the structure are analyzed when the model is subjected to lateral ground motions with different PGA and frequency contents. Subsequently, the seismic dynamic effect on the structural internal force distribution is discussed to improve the seismic design of the atrium-type subway station. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

路基不同压实度下地震动力响应分析

为了了解填土路基在地震作用时的动力响应及路基提高压实度对抵抗地震破坏的效果,文章利用软件FLAC3D建立半路基模型,输入一段实测汶川地震波,模拟计算路基不同压实度在地震剪切波作用下的动力响应,以分析路肩处动力响应与路基趾部的比值随压实度增加的变化趋势,得到压实度对路基水平和竖直方向地震动力响应的影响方式。     

瑞利波作用下隧道洞口段的抗震设防长度

隧道洞口段是隧道抗震设计的薄弱部位,文章从瑞利波动方程出发,推导了洞口段地层在瑞利波作用下的峰值位移、峰值加速度和地层曲率的计算公式,并探讨了洞口段抗震设防长度。分析结果表明:在瑞利波作用下,地层位移、曲率和加速度随隧道埋深的增大而迅速减小,因此当洞口埋深达到一定程度后,地层对隧道的强加位移已很小,无需再设防;现行隧道设计规范规定的洞口段抗震设防长度偏短,应延长。最后,结合汶川地震隧道洞口段破坏长度,进行了分析验证,分析结论可供隧道抗震设计、灾后重建和今后有关规范修订参考。     

Integrated optimal eco-driving on rolling terrain for hybrid electric vehicle with vehicle-infrastructure communication

This research presents an integrated optimal controller to maximize the fuel efficiency of a Hybrid Electric Vehicle (HEV) traveling on rolling terrain. The controller optimizes both the vehicle acceleration and the hybrid powertrain operation. It takes advantage of the emerging Connected Vehicle (CV) technology and utilizes present and future information as optimization input, which includes road topography, and dynamic speed limit. The optimal control problem was solved using Pontryagin’s Minimum Principle (PMP). Efforts were made to reduce the computational burden of the optimization process. The evaluation shows that the benefit of the proposed optimal controller is significant compared to regular HEV cruising at the speed limit on rolling terrain. The benefit ranges from 5.0% to 8.9% on mild slopes and from 15.7% to 16.9% on steep slopes. The variation is caused by the change of hilly road density.     

Using Seismic Tomography and Holography Ground Imaging to Investigate Ground Conditions

Unforeseen, variable subsurface ground conditions present the greatest challenge to the heavy construction and civil engineering industry in the design, construction, and maintenance of large projects. A detailed, accurate site investigation will reduce project risk, improve construction performance and safety, prolong the life of the tunnel or structure,and prevent waste in over - design. Presently, site characterization and geotechnical engineering are limited by the inability to adequately describe these subsurface ground conditions.NSA Geotechnical Services has successfully applied seismic tomography and holography ground imaging technologies on tunneling and heavy civil excavations worldwide. Seismic signal waveforms traveling through a complex medium consist of various arrivals from refractions, reflections, scattering, and dispersion. Tomography and holography are proven inversion technologies for estimating location and extent of material property variations causing changes in signal waveforms.ent attenuation rates and velocities. Seismic waves will travel faster through competent material and be generally less attenuated than through broken/fractured ground or voids.encounters an interface between ground zones possessing different seismic properties. Most geologic structures, anomalies,and changes in lithology provide detectable seismic reflections if they are within a reasonable distance of the seismic source.This paper will present various applications of these technologies, illustrating how seismic imaging can provide accurate information regarding ground conditions associated with tunneling projects. With this information, engineers can complete projects safely, within time and budget constraints.     

水平地震作用下土工格栅填土边坡动力研究

文章基于三维拉格朗日有限差分的原理,用拟静力法和动力法来分析土工格栅填土边坡的动力特性和抗震性能。研究结果表明土工格栅能很好地提高填土体的强度和抗震性能;动力法计算结果比拟静立法计算结果更为安全,且只有动力法才能分析出填土边坡失稳的主因。     

Analysis of the Stability of the Shield Tunnel Excavation Face Considering Fluid-Solid Coupling Effect北大核心CSCD

In order to study the impacts of the transient seepage on the stability of tunnel excavation face during the installation of lining segments, the fluid-solid coupling effect based numerical model of the tunnel excavation face was developed by the finite element software PLAXIS. With adoption of the variablecontrolling approach, the influences of the depth/diameter ratio (the ratio of the buried depth to diameter of the tunnel) and the support pressure ratio (the ratio of the face support pressure to water and soil pressures ahead of the excavation face) on the face stability and ground settlement were investigated, respectively. At same time, the failure modes of the excavation face under the fluid-solid coupling analysis were also discussed. The results show that:1) the transient seepage leads to the development of the soil arching at the front of the excavation face, in which the smaller deformation at the excavation face is achieved, and so less support pressure for the face stability is allowed. While for the plastic analysis without taking into account the effect of transient seepage, a higher support pressure is required to maintain the stability of the excavation face; 2) in the fluid-solid coupling analysis, the depth/diameter ratio has less impacts on the stability of the excavation surface, but has larger impacts on the ground settlement. The larger the depth/diameter ratio, the larger the ground surface settlement and the settlement profile; 3) however, with the combination of the decrease of the support pressure and the impact of transient seepage on the settlement of ground surface, the soil arching effect in front of the excavation face is gradually reduced. The deformation zone at the ground surface is then connected with the deformed part ahead of the tunnel face to form a wedge-shaped soil sliding zone. It is also observed that the wedge-shaped body tends to have a larger funnel-shaped failure mode than that in the plastic analysis without considering the transient seepage. The results show that the transient seepage has a great impact on the stability of tunnel excavation face in the soil condition with high permeability ratio. The fluid-solid coupling analysis should be adopted to evaluate the deformation of excavation face and ground settlement. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

山区高速公路桥隧连接段直立高陡边坡防护

本文主要高以山区高速公路桥隧连接段直立高陡边坡防护施工技术方案的论证及比选,桥隧连接段的位置大多都所处地形地貌与地质状况相对比较薄弱环节,位于这种地形位置的边坡防护要求较高,且要满足该类型边坡防护的效果。根据工程实际因素,需要进一步加强和深化高陡坡隧道洞口与桥梁相接位置的安全防护勘察工作,经现场勘察及几种防护方案的必选与论证,试图从山区高速公路桥隧连接段直立高陡边坡防护方案优化设计的角度降低防护施工难度及成本。鉴于桥隧连接段及隧道洞口现状直立高陡边坡整体基本处于稳定状态,加接延长隧道洞口明洞工程,并采用SNS主洞防护网与被动防护网相结合的防护方案合理可行,该防护方案的施工工艺简单,易操作,施工成本与施工安全风险低。