Effects of hanging wall and forward directivity in the 1999 Chi-Chi earthquake on inelastic displacement response of structures

The characteristics of the inelastic response of structures affected by hanging wall and forward directivity in the 1999 Chi-Chi earthquake are investigated. Inelastic displacement ratios (IDRs) for ground motions impacted by these near- field effects are evaluated and comprehensively compared to far-field ground motions. In addition, the inelastic displacement responses to hanging wall and footwall ground motions are compared. It is concluded that the inelastic displacement response is significantly affected in the short period range by hanging wall and in the long period range by footwall. Although high peak ground acceleration was observed at hanging wall stations, the IDRs for structures on hanging wall sites are only larger than footwall sites in the very long period range. Forward directivity effects result in larger IDRs for periods longer than about 0.5s. Adopting statistical relationships for IDRs established using far-field ground motions may lead to either overestimation or underestimation in the seismic evaluation of existing structures located in near-field regions, depending on their fundamental vibration periods.     

河西走廊早新生代红层次生剩磁及其对原生剩磁影响评价

系统研究了河西走廊火烧沟组陆相红层200个采点岩石的热退磁行为和17个代表性样品的岩石磁学特征,结果表明有102个采点可以分离出A、B、C三个剩磁分量,有82个采点只有一个分量(C分量),16个采点只能分离出A、B分量.A、B分量分别由针铁矿和磁赤铁矿携带,C分量在砂岩中由磁铁矿携带,在泥质砂岩和泥岩中由磁铁矿和赤铁矿共同携带.A、B分量剩磁方向随机分布,不能获得置信水平的古地磁平均方向,为次生剩磁.它们的存在并不影响岩石原生剩磁的分离,也不影响原生剩磁信号的稳定性和获得的古地磁数据的可靠性.16个砂岩采点中不能分离出C分量,是由于后生的赤铁矿彻底改变了由磁铁矿携带的原生剩磁组分,在高密度采样的情况下剔除这些采点并不影响古地磁极性柱的构建和解释.     

郯庐断裂带宿迁段合欢路土壤氡分布特征与迁移特征的数值模拟

沿郯庐断裂带宿迁段合欢路布设土壤氡测线并对测得的数据进行分析研究,结果表明研究区域内土壤氡探测结果对断裂带位置、断层类型和特征有较好的指示性.在已知场地地质构造参数、地层岩性特征的基础上,建立土壤氡迁移模型.建立模型时识别了断裂类型和覆盖层分层特征,并讨论了断层内部结构与氡浓度取值,使模型与实际情况相等.数值模拟结果印...     

四川泸州地区测震台网地震监测能力研究

为加强川南泸州区域的地震监测能力,新建15个流动测震台站,与泸州和荣昌2个固定台站形成泸州台网.根据《地震震级的规定GB 17740-2017》,计算了泸州台网的震级监测能力,并通过实际地震事件的统计分析,验证了震级监测能力计算结果的准确性和合理性.基于D值理论,计算了泸州台网在研究区域的震中定位误差和震源深度定位误差...     

Does Foreign Direct Investment Affect SO_2 Emissions in the Yangtze River Delta? A Spatial Econometric Analysis

As the major source of air pollution, sulfur dioxide(SO_2) emissions have become the focus of global attention. However, existing studies rarely consider spatial effects when discussing the relationship between foreign direct investment(FDI) and SO_2 emissions. This study took the Yangtze River Delta as the research area and used the spatial panel data of 26 cities in this region for2004–2017. The study investigated the spatial agglomeration effects and dynamics at work in FDI and SO_2 emissions by using global and local measures of spatial autocorrelation. Then, based on regression analysis using a results of traditional ordinary least squares(OLS) model and a spatial econometric model, the spatial Durbin model(SDM) with spatial-time effects was adopted to quantify the impact of FDI on SO_2 emissions, so as to avoid the regression results bias caused by ignoring the spatial effects. The results revealed a significant spatial autocorrelation between FDI and SO_2 emissions, both of which displayed obvious path dependence characteristics in their geographical distribution. A series of agglomeration regions were observed on the spatial scale. The estimation results of the SDM showed that FDI inflow promoted SO_2 emissions, which supports the pollution haven hypothesis. The findings of this study are significant in the prevention and control of air pollution in the Yangtze River Delta.     

Propagation of internal waves up continental slope and shelf

In a two-dimensional and linear framework, a transformation was developed to derive eigensolutions of internal waves over a subcritical hyperbolic slope and to approximate the continental slope and shelf. The transformation converts a hyperbolic slope in physical space into a flat bottom in transform space while the governing equations of internal waves remain hyperbolic. The eigensolutions are further used to study the evolution of linear internal waves as it propagates to subcritical continental slope and shelf. The stream function, velocity, and vertical shear of velocity induced by internal wave at the hyperbolic slope are analytically expressed by superposition of the obtained eigensolutions. The velocity and velocity shear increase as the internal wave propagates to a hyperbolic slope. They become very large especially when the slope of internal wave rays approaches the topographic slope, which is consistent with the previous studies.     

南海高分辨率岩石圈有效弹性厚度及其影响因素分析

南海构造环境复杂,海盆内海山规模不一,为了探究南海岩石圈强度的影响因素及其与海山演化的联系,本文利用Parker-Oldenburg法计算得到地壳密度分布并结合基于小波变换的导纳法计算南海岩石圈有效弹性厚度(简称T_e),提高了计算结果的准确度和分辨率。南海大洋岩石圈T_e整体较小,分布在0～16 km范围内。南海T_e与居里点深度和热流点相关性高,说明岩石圈强度受温度结构影响强烈,海山T_e值与海山加载时岩石圈年龄未表现出相关性,表明岩浆活动等热异常会削弱岩石圈强度。     

近场问题的研究现状与发展方向

在过去的20年里,近场问题受到了地震学家和土木工程师的共同关注,一方面原因旨在阐明地震本身的机理,解释新现象;另一方面是由于地震动作为一种主要的输入荷载,在某些情况下将对整个结构设计的最终结果起到控制作用. 同时试验和评估等其它领域的相关研究也均以指定的荷载形式为前提,荷载形式的变化直接影响了土木工程中的诸多方面,所以希望研究这种荷载的规律并获得其与结构反应之间的关系. 本文回顾了近场问题研究的历史,介绍了近年来国内外针对近场地震动所展开的相关研究工作,其中包括近场地震动本身的特性与近场地震动对土木工程结构的影响等方面,指出了目前存在的问题和进一步应该研究的方向,对于近场问题的深入研究具有一定的参考价值.      

条斑紫菜质粒状DNA的提取与富集

以细胞为材料,用异硫氰酸胍一十二烷基肌氨酸钠作裂解液,在条斑紫菜总ＤＮＡ中直接提取到了质粒状ＤＮＡ,但其含量明显地低于高分子量的主带ＬＮＡ。总ＤＮＡ经Ｗｉｚａｒｄ树脂处理后,在低温洗 脱物的电泳图谱上质粒状ＤＮＡ带的亮度高于主带,质粒状ＤＮＡ得到了明显的富集。本文为条斑紫菜质粒状ＤＮＡ的研究提供了简便,有效的提取与富集方法。     

应用RAPD技术对裙带菜七个配子体克隆的遗传分析

对裙带菜７个单克隆进行了ＲＡＰＤ分析,从２０个引物中筛选出１６个能产生稳定的扩增片段的引物,共产６４条扩增片段,其中５６条呈现多态,多态位点比例高达８７．５％,根据这些引物扩增的指纹图谱,计算了各材料之间的遗传距离（Ｄ）,并由此进行了聚类分析,结果显示,各品系之间的遗传距离在０．４４１９－０．７４２之间,裙带菜种内遗传变异丰富,其遗传距离与地理分布没有必然的联系。