汉中地区变电设施在汶川大地震中的表现及其分析

"5.12"汶川大地震中,陕西省的电力系统受到了不同程度的震害,汉中地区的震害尤其严重。根据震后对汉中地区变电站系统的震害调查,本文描述了在这次地震中汉中地区变电设施的震害情况和地震表现,对震害情况进行了破坏原因的分析,并对今后的变电站抗震设计提出了一些建议。     

疲劳动剪应变门槛与武广高铁无碴轨道路堑基床长期动力稳定

针对武广高铁无碴轨道红黏土路堑基床长期动力稳定性问题,利用改造后的应力控制式动三轴仪代替国内尚无的剪应变控制式共振柱仪,测试土体疲劳动剪应变门槛值,提出了一套完整的试验方案和数据处理方法,为疲劳动剪应变门槛的确定开辟了新的试验途径。通过疲劳动三轴试验,获得了9种试验条件下红黏土疲劳动剪应变门槛值。按曲线走势特征,红黏土 - 曲线可分为稳定型、临界型、破坏型3类,且不同试验条件下同类型的曲线具有相似的走势特征;探讨了含水比、围压对红黏土疲劳动剪应变门槛的影响,给出了简单实用的疲劳动剪应变门槛经验估算公式;基于室内试验及现场动响应测试成果,采用动剪应变法初步评价了武广高铁无碴轨道红黏土路堑基床的动力稳定性,给出了不同物理状态下红黏土基床最小换填厚度建议值。研究成果为我国高速铁路无碴轨道土质路基动力稳定性评价及路堑基床换填厚度的确定提出了新的思路,也为红黏土疲劳特性的深入研究提供了宝贵的第一手资料。     

邻近既有隧道的新建大断面隧道施工参数优化分析

结合大帽山隧道Ⅴ级围岩段施工参数优化的试验,通过爆破震动速度、岩体声波波速和围岩内部位移的现场监控量测工作,研究既有隧道旁新建大断面隧道双侧壁导坑法施工时岩体的损伤程度和范围,进而优化导洞的单循环进尺、爆破参数等施工参数。研究表明：推进式往复爆破作业的双侧壁导坑法开挖的隧道必然导致围岩产生一定程度的损伤、破坏,尤其是小净距隧道间的中夹岩岩墙;双侧壁导坑法开挖的大断面隧道,控制岩体的损伤程度和损伤范围是相互矛盾的,通过减少单循环开挖进尺来减少爆破震动速度,只能控制岩体的损伤范围,多次的重复爆破导致损伤岩体的损伤程度更大,极大影响围岩稳定;相反,通过适当加大单循环开挖进尺来控制损伤程度的同时,过大的爆破震动速度导致损伤范围更大,极大影响邻近既有隧道的安全运行。利用现场监测数据,通过在UDEC软件中实现的岩体各向异性爆破损伤模型,计算导洞推进式开挖全过程围岩压力的变化和既有隧道支护结构的状态,综合考虑各种因素,优化得到折中的单循环进尺。     

Post-earthquake building damage assessment in Yushu using airborne SAR imagery

The synthetic aperture radar (SAR) plays an important role in earthquake emergency response because of its all-time and all-weather imaging capabilities. On April 14, 2010, an MS7.1 earthquake occurred in Yushu county, Qinghai province of China, causing a lot of buildings collapsed. In this paper, the building damage in Yushu city due to the earthquake was assessed quantitatively using high-resolution X-band airborne SAR image. The features of the buildings with different damage levels (collapsed, partial collapsed, non-collapsed) in the SAR image were analyzed first. Based on these building features, we interpreted the individual building damage in Yushu city block by block and got the numbers of the collapsed, partial collapsed and non-collapsed buildings separately for each block, referring to pre-earthquake QuickBird image when necessary. Let the damage index of individual collapsed, partial collapsed, non-collapsed building be 1, 0.5, 0 respectively, the remote sensing damage index of each block was then calculated through remote sensing damage index equation. Finally, the preliminary quantitative relationship between the remote sensing damage index interpreted from the SAR image and that interpreted from the optical image was built up. It can be concluded that a desirable damage assessment result can be derived from high-resolution airborne SAR imagery.     

大型电气设备瓷套管地震易损性分析

通过对电气设备进行增量动力分析(IDA),得出在不同地震波作用下瓷套管根部的应力值,回归分析得出瓷套管应强比(RSS)与地震峰值加速度(PGA)的关系式.以瓷套管应强比作为整体性能指标,进行地震易损性分析,得出瓷套管在不同破坏状态下的应强比值区间,给出瓷套管地震失效概率与地震峰值加速度之间的计算公式,并绘制瓷套管在不同...     

Tropical cyclone risk perceptions in Darwin,Australia: a comparison of different residential groups

Different individuals and groups perceive risk differently. This can significantly affect risk management and mitigation practices and requirements. This paper presents findings from a study of tropical cyclone risk perceptions in the city of Darwin in the Northern Territory of Australia. Primary in-depth interview data and other secondary data are analysed, focussing in particular on wind damage, storm surge and life safety risk perceptions of residents since Cyclone Tracy, which impacted in 1974, and perceptions of future climate change as it relates to tropical cyclone risk. The analysis reveals that a number of perceptions prevail. In particular, the study reveals a wide difference of perceptions between short-term residents (Group 1) and long-term and expert residents (Group 2) in relation to wind damage, storm surge and life safety risk. It also reveals a large division between laypersons (Group 3) and expert residents’ (Group 4) perceptions of climate change risk as it relates to tropical cyclone risk. The author recommends that flexible, multiple and integrative management and mitigation approaches are required to deal with such different perceptions and divisions in the resident population.     

兴文岩溶区地质灾害的危害与防治

兴文岩溶区位于兴文县中南部地区,该区拥有丰富的地质旅游资源,在带动地方经济发展上起着不可替代的作用。但复杂的地质背景使得该区的地质灾害呈现出多样性,这不仅会对该区的旅游资源造成不可恢复的损失,而且还会给当地人民的生命财产带来巨大的损失,在一定程度上制约了社会和区域经济的发展。因此,对兴文岩溶区地质灾害的危害进行研究具有十分重要的意义。在分析了该区地质灾害分布和特点的基础上,研究了该区地质灾害的影响因素,并针对其危害提出了可行的防治对策,为兴文地质灾害的防治规划提供参考。     

Effects of excitation frequency on detection accuracy of orthogonal wavelet decomposition for structural health monitoring

Accurate estimation of stiffness loss is a challenging problem in structural health monitoring. In this study orthogonal wavelet decomposition is used for identifying the stiffness loss in a single degree of freedom spring-mass-damper system. The effects of excitation frequency on accuracy of damage detection is investigated. Results show that pseudo-alias effects caused by the orthogonal wavelet decomposition (OWD), affect damage detectability. It is demonstrated that theproposed approach is sunable for damage detection when the excitation frequency is relatively low. This study shows how a priori knowledge about the signal and ability to control the sampling frequency can enhance damage detectability.     

汶川地震对建筑结构设计的启示

汶川大地震造成了大量房屋建筑的破坏。本文通过对钢筋混凝土结构和砌体结构的震害研究、非结构构件的震害分析以及典型震害进行的调查归类分析,探讨了此次地震对建筑结构抗震设计的启示,总结了经验并给出了以下相关的建议：（1）适当提高抗震设防标准。（2）房屋建筑设计要更好实现“强柱弱梁”机制：改进加强楼梯间设计：进一步研究非结构构件与主体结构的连接。（3）进一步推广隔震技术。     

汶川地震框架柱震害的初步分析

按照框架结构抗震概念设计的要求,结构应具有多道抗震防线,其中一个原则是“强柱弱梁”。但是在汶川地震中,框架结构柱的破坏明显重于梁,柱端与节点的破坏较为突出,即所谓的“强梁弱柱”结构很普遍。在对地震破坏区实地考察的基础上,对框架结构梁柱节点处的破坏以及柱顶、柱脚和柱身的震害进行分类,分析了各种震害的原因,总结了框架结构中框架柱的破坏特点,从期为将来框架柱的抗震设计提供震害经验。