上海地区第四承压含水层沉积环境及结构特征

上海地区第四承压含水层是地下水开发利用的主要层次,对其沉积环境、成因、结构特征进行深入研究有利于更好地开展地下水资源开发利用及地质环境保护工作.本文在对上海地区大量钻孔资料深入分析的基础上,对第四承压含水层形成时期即早更新世中、晚期沉积环境及含水层的成因进行了深入剖析,对含水层结构特征进行了详细刻画,为三维地质结构的建立奠定了基础.     

小型煤矿矿井涌水量预测方法探讨

矿坑涌水量的大小是反映一定充水条件下,矿坑充水程度的定量指标,该指标将做为矿山开采设计中制定防治水方案的依据.以河南省安阳县铜冶二矿为例,分别采用比拟法和解释法两种方法对该煤矿技术改造设计新井落底标高(-95 m)进行涌水量预测,对结果进行综合分析,参考该矿周边的生产情况,推荐矿设计新井落底水平(-95 m)矿井正常涌水量为60.22 m3/h,最大矿井涌水量为84.31 m3/h,并提出了建议.     

川西义敦古火山弧的火山建造

义敦古火山弧是松潘-甘孜造山带地质演化中极其重要的地质构造单元,本文对构成义敦古火山弧主体的海相火山建造进行了系统分析.按岩石地层单位的划分原则,重新厘定了火山地层的界线.这套火山建造主要由玄武岩、安山岩、流纹岩、粗面岩组成,并出现了特殊的钾玄岩组合.火山岩序列经历了由晚二叠世至早中三叠世初始裂谷的亚碱性岩系拉斑系列、碱性岩系钠质系列,到晚三叠世早期不成熟岛弧的亚碱性岩系拉斑系列、钙碱系列,再到晚三叠世晚期成熟岛弧的亚碱性岩系钙碱系列、碱性岩系钾质系列的演化过程.按照地层结构和火山喷发的自旋回单位,成熟岛弧期的火山建造可分为三个大旋回、四个大的韵律,并建立了火山岩地层模型.尝试利用层序地层学原理,把该套火山-沉积地层分为两个层序、五个准层序组,反映了海平面相对升降及沉积速率的变化.按变质矿物组合,该套火山地层的变质作用可分为三期:火山期后热液及成岩变质;区域动力变质;晚期热液及矿化热液蚀变.岩石地球化学分析表明,该火山建造总体属同源岩浆演化系列,母源有可能是石榴石或尖晶石二辉橄榄岩,并经历了早期熔融分离及围岩的长期交换.     

Population landscape: a geometric approach to studying spatial patterns of the US urban hierarchy

We present a geometric and graphic approach to studying spatial patterns of urban hierarchy in the US. The multiplicatively weighted Voronoi diagram is found to be effective for visualizing theoretical regions delineated by socio‐economic variables. The population landscape of the continental US demonstrates overall and stepwise patterns reflecting population, neighborhood and distance, with overwhelming influence from huge metropolitan areas. Stepwise exploration and cluster analysis of the spatial pattern reveal an urban hierarchy. Attributes and arrangement are the two important factors of urban hierarchy, with attribute having a stronger local influence and arrangement having a stronger global influence. The study also presents a variation of Zipf's law to visualize the rank‐size distribution from tabular and statistical space to map space.     

洛阳地震台面波震级的偏差研究

利用洛阳地震台1985 ～ 2003 年记录的1755 个地震的面波资料,采用与国家地震台网中心相同的面波震级公式,研究了该台测定的面波震级与国家地震台网中心测定面波震级之间的偏差。结果表明,洛阳地震台测定面波震级的偏差与震中距之间有明显的相关性,在1°≤Δ≤130°范围内面波震级由偏小0. 1 逐渐变化到偏大,Δ≥20°时偏大0. 2 ～ 0. 3;在130° ＜ Δ≤180°范围内偏大0. 2。     

基于SEEW-SVM的结构损伤在线识别

在增量式特征向量加权支持向量机(WEVLS-SVM)结构损伤在线识别方法的基础上,提出了自适应特征向量指数加权向量机(SEEW-SVM)识别方法,该方法通过增加样本与修剪算法更新样本,并根据样本贡献量的大小对特征向量自适应进行指数加权。以剪切型结构为例进行了数值模拟分析,结果表明SEEW-SVM方法与WEVLS-SVM方法相比,不仅提高了识别精度,而且大大提高了识别效率,更适用于对结构的时变参数进行在线识别。     

Study of the seismic response of a recycled aggregate concrete frame structure

Based on six-degree-of-freedom three-dimensional shaking table tests, the seismic response of a recycled aggregate concrete （RAC） frame was obtained. The analysis results indicate that the maximum story shear force and overturning moment reduce proportionally along the height of the model under the same earthquake wave. The story shear force, base shear coefficient and overturning moment of the structure increase progressively as the acceleration amplitude increases. The base shear coefficient is primarily controlled by the peak ground acceleration （PGA）. The relationships between the PGA and the shear coefficient as well as between the PGA and the dynamic amplification factor are obtained by mathematical fitting. The dynamic amplification factor decreases rapidly at the elastic-plastic stage, but decreases slowly with the development of the elastic-plasticity stage. The results show that the RAC frame structure has reasonable deformability when compared with natural aggregate concrete frame structures. The maximum inter-story drift ratios of the RAC frame model under frequent and rare intensity 8 test phases are 1/266 and 1/29, respectively, which are larger than the allowable value of 1/500 and 1/50 according to Chinese seismic design requirements. Nevertheless, the RAC frame structure does not collapse under base excitations with PGAs from 0.066 g up to 1.170 g.     

A study on the seismic performance of steel‐reinforced concrete frame‐concrete core wall high‐rise mixed structure by large‐scale shaking table tests and numerical simulations

This paper reports a study for the seismic performance of one large‐scaled (1/15) model of 30‐story steel‐reinforced concrete frame‐concrete core wall mixed structure. The study was implemented by both shaking table tests, in which the similarity ratio for lateral and gravitational accelerations was kept to 1:1, and numerical nonlinear dynamic analysis. The test observations presented herein include story displacement, interstory drift, natural vibration periods, and final failure mode. The numerical analysis was performed to simulate the shaking table test procedure, and the numerically obtained responses were verified by the test results. On the basis of the numerical results, the progressions of structural stiffness, base shear, and overturning moment were investigated, and the distributions of base shear and overturning moment between frame and core wall were also discussed. The test demonstrates the seismic performance of the steel‐reinforced concrete frame‐core wall mixed structure and reveals the potential overturning failure mode for high rise structures. The nonlinear analysis results indicate that the peripheral frames could take more shear forces after core wall damaged under severe earthquakes. Copyright © 2013 John Wiley & Sons, Ltd.