基于新《电力设施抗震设计规范》的地震动随机模型参数研究          下载免费PDF全文

田利  高国栋  盖霞 《地震工程学报》2018,40(6):1206-1210

根据新《电力设施抗震设计规范》(GB50260-2013)对随机地震动功率谱参数的取值进行分析。介绍新《电力设施抗震设计规范》中设计反应谱,推导设计谱到功率谱的转换过程。选取常用的Clough-Penzien修正过滤白噪声模型作为拟合函数,通过功率谱参数拟合,得到不同场地类别、不同抗震设防烈度下的地震动模型参数。该研究成果可为电力工程抗震设计分析提供参考。  相似文献   

Character and origin of De Geer moraines in the Seacoast region of New Hampshire,USA          下载免费PDF全文

Samantha N. Sinclair  Joseph M. Licciardi  Seth W. Campbell  Brian M. Madore 《第四纪科学杂志》2018,33(2):225-237

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Evaluation of ASCE 7 equations for designing acceleration‐sensitive nonstructural components using data from instrumented buildings     

Hamidreza Anajafi  Ricardo A. Medina 《地震工程与结构动力学》2018,47(4):1075-1094

This study uses instrumented buildings and models of code‐based designed buildings to validate the results of previous studies that highlighted the need to revise the ASCE 7 F_p equation for designing nonstructural components (NSCs) through utilizing oversimplified linear and nonlinear models. The evaluation of floor response spectra of a large number of instrumented buildings illustrates that, unlike the ASCE 7 approach, the in‐structure and the component amplification factors are a function of the ratio of NSC period to the supporting building modal periods, the ground motion intensity, and the NSC location. It is also shown that the recorded ground motions at the base of instrumented buildings in most cases are significantly lower than design earthquake (DE) ground motions. Because ASCE 7 is meant to provide demands at a DE level, for a more reliable evaluation of the F_p equation, 2 representative archetype buildings are designed based on the ASCE 7‐16 seismic provisions and exposed to various ground motion intensity levels (including those consistent with the ones experienced by instrumented buildings and the DE). Simulation results of the archetype buildings, consistent with previous numerical studies, illustrate the tendency of the ASCE 7 in‐structure amplification factor, [1 + 2(z/h)] , to significantly overestimate demands at all floor levels and the ASCE 7 limit of to in many cases underestimate the calculated NSC amplification factors. Furthermore, the product of these 2 amplification factors (that represents the normalized peak NSC acceleration) in some cases exceeds the ASCE 7 equation by a factor up to 1.50.  相似文献   

黄土高填方场地地震动参数特性分析   总被引：2，自引：0，他引：2       下载免费PDF全文

来春景  朱彦鹏  王春青  马天忠 《地震工程学报》2018,40(6):1168-1173,1223

削山造地后形成的黄土高填方场地对地震动参数特性影响较大。以实际工程项目为研究对象,构造不同填土高度的计算剖面,采用一维等效线性化方法计算土层地震动参数,分析基岩地震动输入参数和填土高度对场地地表放大效应的影响。研究表明:场地地震放大系数随填土层的高度增加呈递减趋势。在多遇地震动和基本地震动作用下,场地地震放大系数递减速度比罕遇地震动和极罕遇地震动作用下要大。当填土高度达到一定程度后放大效应趋于平稳;填土高度的变化,会改变地表加速度反应谱的形状。填土高度越大,地表反应谱长周期的频谱成分越显著,反应谱曲线向后移,反应谱峰值点均明显向长周期移动,并出现多个峰值点,反应谱特征周期值变大;下伏基岩的刚度越大,地表峰值加速度的放大效应越大。地表加速度反应谱特征值相比变小。当填土高度增大到一定程度时,下伏基岩的种类对地表地震动特性影响则不明显。该研究成果对高填方场地的地震安全评价和结构抗震设计提供参考。  相似文献   

Mapping cropland fallow areas in myanmar to scale up sustainable intensification of pulse crops in the farming system     

Murali Krishna Gumma  Prasad S Thenkabail  Kumara Charyulu Deevi  Irshad A Mohammed  Pardhasaradhi Teluguntla  Adam Oliphant 《地理信息系统科学与遥感》2018,55(6):926-949

Cropland fallows are the next best-bet for intensification and extensification, leading to increased food production and adding to the nutritional basket. The agronomical suitability of these lands can decide the extent of usage of these lands. Myanmar’s agricultural land (over 13.8 Mha) has the potential to expand by another 50% into additional fallow areas. These areas may be used to grow short-duration pulses, which are economically important and nutritionally rich, and constitute the diets of millions of people as well as provide an important source of livestock feed throughout Asia. Intensifying rice fallows will not only improve the productivity of the land but also increase the income of the smallholder farmers. The enhanced cultivation of pulses will help improve nutritional security in Myanmar and also help conserve natural resources and reduce environmental degradation. The objectives of this study was to use remote sensing methods to identify croplands in Myanmar and cropland fallow areas in two important agro-ecological regions, delta and coastal region and the dry zone. The study used moderate-resolution imaging spectroradiometer (MODIS) 250-m, 16-day normalized difference vegetation index (NDVI) maximum value composite (MVC), and land surface water index (LSWI) for one 1 year (1 June 2012–31 May 2013) along with seasonal field-plot level information and spectral matching techniques to derive croplands versus cropland fallows for each of the three seasons: the monsoon period between June and October; winter period between November and February; and summer period between March and May. The study showed that Myanmar had total net cropland area (TNCA) of 13.8 Mha. Cropland fallows during the monsoon season account for a meagre 2.4% of TNCA. However, in the winter season, 56.5% of TNCA (or 7.8 Mha) were classified as cropland fallows and during the summer season, 82.7% of TNCA (11.4 Mha) were cropland fallows. The producer’s accuracy of the cropland fallow class varied between 92 and 98% (errors of omission of 2 to 8%) and user’s accuracy varied between 82 and 92% (errors of commission of 8 to 18%) for winter and summer, respectively. Overall, the study estimated 19.2 Mha cropland fallows from the two major seasons (winter and summer). Out of this, 10.08 Mha has sufficient moisture (either from rainfall or stored soil water content) to grow short-season pulse crops. This potential with an estimated income of US$ 300 per hectare, if exploited sustainably, is estimated to bring an additional net income of about US$ 1.5 billion to Myanmar per year if at least half (5.04 Mha) of the total cropland fallows (10.08 Mha) is covered with short season pulses.  相似文献   

形态参数下地表采动裂缝三维建模及可视化方法     

戴华阳  王祥  李军  郭俊廷  阎跃观 《测绘通报》2018,(2):148-153

实现对地表采动裂缝的三维建模及可视化能促进裂缝的形状、成因研究,并为开采沉陷监测和生态环境恢复提供科学支持。目前三维建模方法和软件主要面向建筑物、管道、地质体等地物地貌,若直接应用于地表裂缝的建模与表达会存在野外测绘工作量大、形态规律表达不准确、呈现不逼真等问题。本文结合三维地形建模、分形、空间插值等理论,提出了基于几何形态参数的地表裂缝三维建模方法,并利用ArcEngine平台实现了对裂缝的三维可视化;选取甘肃省东峡矿区为试验区,根据裂缝分布与形态预计参数,实现了对区域内裂缝的模拟,并通过与实测数据和高分辨率影像进行对比,验证了该方法能真实逼真呈现裂缝的形态、延伸与细节信息。  相似文献   

深空探测科学仪器研究进展     

高震宇  王民建  黄帆  宋爱国  朱利丰 《南京气象学院学报》2021,13(3):257-268

深空探测是对宇宙中地球以外的行星、卫星、小行星和彗星等星体或空间环境的探测活动.合理选择深空探测科学仪器,了解被测星体的物理及化学性质、地表地貌、动态特性以及有机物和水的存在,对人类了解地外水和生命信息、认识太阳系的起源和演化有着重要意义,是深空探测的重要任务.本文总结了深空探测的科学目标,介绍了近50年来典型深空探测任务中探测器所搭载的科学仪器及其特点,包括质谱仪、光谱仪、探地雷达和磁力计等,整理了其性能参数及面向的探测功能任务,最后讨论了深空探测科学仪器目前呈现出的小型化、低功耗、更强的环境适应能力和多仪器联合使用的发展趋势.  相似文献   

高速公路通道下沉开裂治理实践          下载免费PDF全文

张锦灵  豆敬峰  李金刚 《探矿工程》2018,45(6):75-80

河南省省道323线登封市大冶镇一段公路软弱地基以及路面出现不均匀沉降,通道箱涵开裂,边坡为欠稳定边坡。将事故路段分为4个区域进行加固治理。通过采用注浆加固路基基础、设置坡面排水系统、提高地基的承载能力等治理措施,保证了道路的通行能力。  相似文献   

郑州市地面沉降监测基岩标施工技术   总被引：3，自引：2，他引：1       下载免费PDF全文

王刚  李莹  黄烜  于丽 《探矿工程》2018,45(4):82-86

根据区域地质条件,郑州市地面沉降监测网基岩标建标场地选择在淮河西路与西三环交叉口东南600 m的河南省地质环境监测院内,建标深度为732 m。地质鉴别孔孔深780 m,孔径108 mm,全孔取心钻进,施工的重点是保证岩心采取率,采用泥浆护壁回转钻进,根据钻进层位的岩性不同配置不同特性的泥浆;基岩标标孔孔深780 m,孔径311 mm,施工的控制目标是孔身质量和垂直度。采用三牙轮钻头宝塔式钻具组合不取心钻进施工工艺。取得了较好的施工质量,创造了良好的效益。  相似文献   

地质雷达电磁干扰分析及在隧洞岩溶探测中的应用   总被引：2，自引：2，他引：0  

李俊杰  朱红雷  赵国军  夏志强  郭佳豪 《中国岩溶》2018,37(2):286-293

将地质雷达用于千岛湖配水工程某隧洞岩溶探测,分析了倾斜状电磁干扰异常与溶洞雷达异常差异,通过雷达剖面及疑似异常区单道时间-频率谱的分析,推断了隧底岩溶的性质及空间分布特征,含水溶洞在雷达剖面反映为同相轴错断,强振幅及能量高衰减的特性,高频干扰波振幅幅值较异常区小且能量不满足随时间推移逐渐衰减的规律,雷达成果为隧洞安全施工提供了准确的参考。   相似文献