2015尼泊尔地震后加德满都谷地世界文化遗产破坏特征

2015尼泊尔地震对加德满都谷地的世界文化遗产造成不可估量的损失。为了探究谷地文化遗产震害整体分布特征,对谷地世界文化遗产建筑的震害状况开展实地调查,划分了三类文化遗产震害等级标准,形成了六处世界文化遗产的震害图并对其进行统计分析,加德满都、帕坦和巴德岗三处杜巴广场震后保存基本完好的文化遗产建筑占各自总数的39.5%、53.3%、50%,斯瓦扬布纳特寺、昌谷纳拉扬寺和博达哈大佛塔主体保存基本完好,附属建筑不同程度地破坏。加德满都、帕坦和巴德岗三处杜巴广场地层的松软沉积层放大地震效应使建筑严重破坏,斯瓦扬布纳特寺、昌谷纳拉扬寺震害主要受地形特征影响。考察成果为我国同类遗产建筑的抗震防护提供参考。     

白居塔塔体结构稳定性分析研究

在对白居塔建筑形制调查研究基础上,区分塔体内嵌高山体和内嵌低山体两种情况,确定重力作用以及重力和地震耦合作用两种工况。基于采用岩土摩尔—库伦本构模型的有限元分析技术,对白居塔和山体的耦合结构进行稳定性分析。得出以下结论:自重作用下,整体结构稳定性满足,且有较高的安全稳定系数;白居塔整体结构的刚度较大,整个结构体系属于抗震有利体系;白居寺整体结构基频模态以侧倾为主;在7°(基本加速度0.15 g)多遇地震作用下,两个模型整体结构的抗震稳定性较好,结构不会产生整体性失稳破坏;在8°(基本加速度0.3 g)多遇地震作用下,较高山体模型主体结构基本处于安全状态,较低山体模型主体结构不满足稳定要求;较高山体的模型相对于较低山体的模型,安全稳定性要高。     

Linked (im)mobilities and the relational politics of movement in post-earthquake Nepal

ABSTRACT

This article highlights the importance of various (im)mobilities that were induced by the massive 7.8-magnitude earthquake that struck Nepal on 25 April 2015. It analyzes over 120 news articles published in the immediate aftermath of the earthquake, arranging these into a mobility-centric narrative that highlights the politics of movement in the disaster’s wake. Drawing on the theoretical and methodological “mobilities turn”, I introduce the concept of linked (im)mobilities to demonstrate the complex dialectics structuring (im)mobilities after the disaster. More specifically, Nepal’s post-earthquake (im)mobilities intersected with one another and with a variety of geographic and political factors to produce a mutually constitutive web of contingent movements. Attending to these not only underscores the centrality of (im)mobilities themselves. By raising questions of scale, inequality, bordering, and “islanding”, the approach advanced here widens our analytical frame. It offers a conceptual architecture capable of encompassing more factors (beyond mobility), thereby facilitating a broader understanding of the disaster event and its various outcomes.     

Carbon dioxide controlled earthquake distribution pattern in the NW Bohemian swarm earthquake region,western Eger Rift,Czech Republic – gas migration in the crystalline basement

The ascent of magmatic carbon dioxide in the western Eger (Oh?e) Rift is interlinked with the fault systems of the Variscian basement. In the Cheb Basin, the minimum CO₂ flux is about 160 m³ h^?1, with a diminishing trend towards the north and ceasing in the main epicentral area of the Northwest Bohemian swarm earthquakes. The ascending CO₂ forms Ca‐Mg‐HCO₃ type waters by leaching of cations from the fault planes and creates clay minerals, such as kaolinite, as alteration products on affected fault planes. These mineral reactions result in fault weakness and in hydraulically interconnected fault network. This leads to a decrease in the friction coefficient of the Coulomb failure stress (CFS) and to fault creep as stress build‐up cannot occur in the weak segments. At the transition zone in the north of the Cheb Basin, between areas of weak, fluid conductive faults and areas of locked faults with frictional strength, fluid pressure can increase resulting in stress build‐up. This can trigger strike‐slip swarm earthquakes. Fault creep or movements in weak segments may support a stress build‐up in the transition area by transmitting fluid pressure pulses. Additionally to fluid‐driven triggering models, it is important to consider that fluids ascending along faults are CO₂‐supersaturated thus intensifying the effect of fluid flow. The enforced flow of CO₂‐supersaturated fluids in the transitional zone from high to low permeability segments through narrowings triggers gas exsolution and may generate pressure fluctuations. Phase separation starts according to the phase behaviour of CO₂‐H₂O systems in the seismically active depths of NW Bohemia and may explain the vertical distribution of the seismicity. Changes in the size of the fluid transport channels in the fault systems caused, or superimposed, by fault movements, can produce fluid pressure increases or pulses, which are the precondition for triggering fluid‐induced swarm earthquakes.     

汶川地震导致的古建筑震害

为了解汶川地震造成的古建筑震害及对古建筑的保护,根据古建筑震害资料,通过归纳方法,获得了古建筑不同的震害症状：对木结构而言,主要有地基破坏、柱底侧移、柱身倾斜、节点拔榫、装修开裂、梁架歪闪、瓦件掉落、填充墙破坏等;而砖石及砖木结构由于承重材料的抗拉、压、剪强度相对较差,容易产生倒塌等严重震害。在此基础上,通过勘查分析方法,获得了古建筑产生震害的主要原因：地震力过大、古建筑缺乏及时保养与加固、施工原因及砖石材料本身强度差的原因等。针对不同的震害原因,提出了相应的抗震加固建议。在上述工作基础上,得出如下结论：为提高古建筑的抗震性能,应加强对古建筑的维护与加固,及时清除各种隐患,将地震产生的破坏减小到最轻的程度。     

张衡地动仪的发明、失传与历史继承

地动仪的发明和失传存在深厚的社会背景.悬挂物对地震的良好反应是诞生科学思想的物质基础.地动仪是对天然验震器的发展,张衡不仅在利用物体惯性测震上,也在检测和记录地震微弱信号上有技术创新,成功测到公元134年12月13日陇西地震.天诫观念把自然现象与社会问题混为一谈,导致张衡晚年和地动仪的悲剧.仪器可能失传于东汉末年,当时发生了洛阳大火、毁铜铸钱、京师搬迁、人口剧减和灵台被毁等极端严重的社会混乱.张衡的科学思想和实践对现代地震学的起步发挥过思想启迪作用.对地动仪的研究需要开展科学实验,学术观点的统一只能建立在科学实验的基础上.     

玉树抗震救灾精神与社会主义核心价值

玉树抗震救灾精神就是大爱同心、众志成城的民族精神,就是坚韧不拔、百折不挠的革命英雄主义精神,就是挑战极限、全心全意为人民服务的精神,就是感恩奋进、自力更生、艰苦奋斗的精神。玉树抗震救灾精神是社会主义核心价值的时代表达,彰显了社会主义核心价值体系的现实要求。     

PROCEDURE AND SPECTRA FOR ANALYSIS OF RC STRUCTURES SUBJECTED TO STRONG VERTICAL EARTHQUAKE LOADS

Abstract

In view of the compendium of field evidence and supporting analysis work indicating the possible damaging effects of vertical earthquake ground motion, this paper addresses the problem of code-type vertical force calculation. In light of recent engineering seismology studies of the relationship between vertical and horizontal peak ground acceleration, the inadequacy of the 2/3-rule depicted by codes is highlighted. A simple piece-wise linear relationship is proposed and shown to represent existing strong-motion measurements adequately. Bilinear and inelastic spectra are derived and studied. It is demonstrated that net tensile forces and displacements may ensue, thus eroding the shear resistance of RC columns. A simple procedure is outlined whereby modal analysis may be employed to estimate conservatively vertical earthquake forces on buildings. Finally, areas of further exploration and refinement are identified.     

WHY IS THE MINARET SO SHORT? EVIDENCE FOR EARTHQUAKE DAMAGE ON MT ZION

Abstract

On top of King David's Sepulchre at Mt Zion there is an Ottoman minaret known as al-Nabi Da'ud. Compared with other minarets in Jerusalem, al-Nabi Da'ud seems to be somewhat shorter, and has a squat-like appearance. To track why it is shorter than other minarets, we inspected written historical sources, a sequence of old drawings dated between the mid-eighteenth and mid-nineteenth centuries and analysed the minaret's metric proportions. In drawings dated to and before 1833, the minaret is portrayed much higher than in drawings and photographs dated to and after 1838. Furthermore, comparative height-diameter ratio of various parts of the minaret does not fit those of its counterpart, the al-Qal'a minaret. Thus, we suggest that the minaret was originally built higher but damaged during the 1834 earthquake, and reconstructed to a lower height sometimes afterwards.