黄土斜坡动力响应特征分析   总被引：2，自引：1，他引：1       下载免费PDF全文

夏坤  董林  李璐 《地震工程学报》2019,41(3):694-701

斜坡动力响应特征与斜坡形态密切相关,若入射地震波主频接近斜坡卓越频率就会放大斜坡动力响应,甚至造成斜坡失稳。汶川地震对远离震中的黄土地区造成了较为严重的破坏,局部场地震害和地震动放大效应显著。选取汶川地震典型黄土斜坡场地,利用地形台阵流动观测和数值模拟计算相结合的方法,系统开展强震动作用下黄土斜坡场地动力响应特征研究。结果表明:坡顶卓越频率最小,其PGA放大系数甚至达到坡底的1.98,这种现象可能与斜坡高差和入射波波长之比密切相关,比值0.2时坡顶放大效应达到最大。随斜坡坡度增加,放大效应增强,坡顶反应谱卓越周期放大系数可达5,说明斜坡地形对强震地面运动有显著影响。数值计算结果与实际强震观测基本吻合,其结果对黄土地区建设工程抗震设防具有重要的科学与实际意义。  相似文献   

THE EFFECT OF HARD INTERLAYER THICKNESS ONTHE SITE SEISMIC RESPONSE          下载免费PDF全文

ZHOU Zheng-hua  LI Yu-ping  ZHOU You  LI Xiao-jun  CHEN Liu  SU Jie  DONG Qing  WANG Ya-fei 《地震地质》2019,41(5):1254-1265

Studies on the effect of near-surface overburden soil layers on seismic motion have shown that the overburden soil layers have a significant impact on the seismic effect of the site due to the formation age, genetic type, thickness difference, structure, and dynamic characteristics of the soil layers. In this paper, the one-dimensional seismic response analysis of a nuclear power plant site containing a thick hard interlayer was conducted to discuss the influence of the hard interlayer thickness on the site seismic response, so as to provide a basis for determining the seismic motion parameters for seismic design of similar sites. Based on the engineering geological data of a nuclear power plant site, five models of one-dimensional soil-layer seismic response analysis were built, and the equivalent linear method of the one-dimensional site seismic response was applied to analyze the effect of the interlayer thickness on the peak acceleration and the acceleration response spectra of the site seismic response. The seismic response characteristics of the site and influence rules of the hard interlayer thickness are summarized as follows:1)Under different input seismic motion levels, the peak acceleration at the top of the hard interlayer was less than the input peak acceleration, and the peak acceleration at the ground surface of site was greater than the input peak acceleration. 2)Under the same input seismic motion, the ratios of the peak accelerations at the top of hard interlayer to the input peak accelerations were smaller than the ratios of the peak accelerations at the ground surface to the input peak acceleration, and these ratios first decreased and then increased gradually with the increase of the hard interlayer thickness; while for the same hard interlayer thickness, these ratios gradually decreased as the input peak acceleration increasing. 3)For the same input seismic motion, the ratios of the peak accelerations at the ground surface of site to those at the top of the hard interlayer increased gradually as the hard interlayer thickness increased; however, corresponding to different hard interlayer thicknesses, the variation characteristics of ratios which are the peak accelerations at the ground surface of site to those at the top of the hard interlayer were inconsistent with the increase of the input peak acceleration. 4)The hard interlayer had a significant influence on the short-period acceleration response spectrum and the thicker the hard interlayer was, the wider the influence frequency band would be; while for a special hard interlayer thickness, the influence frequency band is certain, and the hard interlayer had little effect on the acceleration response spectrum coordinates outside this frequency band, the longer the period is, the less the influence of the hard interlayer on the acceleration response spectrum coordinates. The seismic response characteristics of the site and influence rules of the hard interlayer thickness indicate that the hard interlayer thickness has a significant impact on the peak acceleration and the acceleration response spectra of the site seismic response, and the hard interlayer has obvious isolation effect at the seismic motion, and the increase of its thickness reduces the nonlinear effect of the site and leads to the wider influence frequency band. Meanwhile, the higher the input peak acceleration is, the stronger the nonlinear effect of the site, and it's remarkable that the soft layer overlying the hard interlayer has a significant amplification effect on the seismic motion.  相似文献   

近场水平地震动选取原则及脉冲型水平地震动弹性谱特性研究     

王海东  刘巴黎  蔡长丰 《地震工程与工程振动》2019,39(1):222-230

以近40年来世界范围内发生的20次地震总计800条水平地震记录为基础,从加速度反应谱入手,研究震中距、PGV/PGA比值及震级对水平加速度反应谱特性的影响,提出了一种同时考虑震中距、PGV/PGA比值及震级3个指标的近场地震动选取方法。然后对选取的脉冲型水平地震记录作加速度反应谱研究场地类别、震级、PGV/PGA比值等因素对脉冲型水平地震动反应谱特性的影响。研究表明:(1)PGV/PGA>0.2、震中距D<20 km、6.50.2、震中距207.0作为中远场脉冲型地震动的选择原则需要进一步研究。(3)震级M_w>7.0时脉冲型地震动反应谱谱值在中长周期范围内明显增大。(4)PGV/PGA>0.2时脉冲型地震动平均谱谱值在中长周期范围内明显增大。  相似文献   

Estimating flood quantiles at ungauged sites using nonparametric regression methods with spatial components     

Martin Durocher  Donald H. Burn  Shabnam Mostofi Zadeh  Fahim Ashkar 《水文科学杂志》2019,64(9):1056-1070

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可液化场地大直径扩底桩的动力p-y曲线特征研究          下载免费PDF全文

高盟  尹诗  徐晓  陈高鹏 《地震工程学报》2019,41(4):916-924

可液化场地大直径扩底桩-土动力相互作用p-y曲线研究对扩底桩抗震设计具有重要意义。基于有限差分程序FLAC~(3D),分别建立扩底桩和等直径桩的三维有限差分模型,通过在模型底部输入正弦波,得到可液化场地中不同埋深下扩底桩与等直径桩的桩-土动力相互作用p-y曲线,对两者的动力p-y曲线特征进行对比分析。结果表明:正弦波输入下扩底桩动力p-y曲线多呈倒"S"形,随着埋深增加,动力p-y曲线滞回圈面积及面积增长速度逐渐减小,斜率逐渐增大;扩底桩与等直径桩动力p-y曲线所围成的图形相似,两者动力p-y曲线斜率均随埋深增加逐渐增大,扩底桩动力p-y曲线滞回圈面积及面积增长速度在各埋深处均大于等直径桩,利于能量耗散,抗震性能更好。  相似文献   

天津简易烈度计地震预警试验区建设   总被引：1，自引：1，他引：0  

许可  郭巍  高也  柳艳丽  刘瑞瑞 《震灾防御技术》2019,14(2):456-463

通过建设80个简易烈度计观测点,与天津行政区内具备实时传输能力的测震台站和强震动台站共同组建了天津地震预警观测网络,初步实现了地震预警功能,提升了天津行政区的防震减灾能力,同时开展地震预警信息服务试验,为政府和社会提供地震预警信息。本文介绍了天津简易烈度计地震预警试验区的建设情况、台站分布情况、仪器性能指标、数据处理及数据记录情况,并探讨了简易烈度计在预警台网中的应用,获得了初步认识。  相似文献   

激光跟踪仪分段积分测距改正模型研究与分析     

潘国荣  张春涛  周志  王穗辉 《大地测量与地球动力学》2019,39(4):377-381

针对装配现场难以实现恒温测量的情况,以对测距影响较大的温度因子为研究对象,提出激光跟踪仪分段积分测距改正方法,建立分段积分测距改正模型。基于Radian激光跟踪仪进行单测线温度测距改正实验,结果表明,该方法能够有效地减弱温度梯度的影响,为装配现场的测距温度梯度改正提供理论支撑,有助于提高飞机等装配制造的精度。  相似文献   

世界遗产地乡村聚落功能转型与空间重构——以汤口、寨西和山岔为例   总被引：2，自引：1，他引：1  

杨兴柱  杨周  朱跃 《地理研究》2020,39(10):2214-2232

作为新兴的重要发展力量,旅游业发展深刻地改变着社会经济形态和空间格局。一方面,世界遗产地乡村聚落承载传统功能（如居住功能、生产功能等）,另一方面,旅游消费给予乡村聚落新的发展活力,文化传承、休闲旅游等潜在功能逐步被挖掘。旅游发展进程中世界遗产地乡村聚落功能转型与人类适应性的科学研究,是亟待深入研究的重要前沿课题,对于指明世界遗产地乡村聚落转型发展方向和促进世界遗产地可持续发展具有重要指导价值。采取参与式农村评估方法、GIS空间分析和高清遥感影像相结合的方法,以黄山世界遗产地汤口、寨西和山岔3个聚落为案例研究对象,解析了3个聚落功能转型与空间重构的特征与模式,分析了聚落转型发展的影响因素与机制。3个聚落在功能转型与空间重构上,存在不同的特征与模式：汤口呈功能耗散式转型与空间破碎化分异、寨西呈功能模块化融合与空间协同性演替、山岔呈功能自组织适应与空间核域式集聚,并相应形成“原地生长型”“就地重建型”“景村共生型”三种转型发展模式。内外因素的相互作用、多元主体的能动性与旅游市场需求为世界遗产地3个聚落转型发展的支撑力、行动力与驱动力,推动着聚落的转型发展。  相似文献   

基于数值模拟的射电望远镜台址测风塔位置优选方法研究          下载免费PDF全文

何飞龙  许谦  王娜  朱春花 《天文学报》2020,61(5):57

射电望远镜天线结构设计和观测任务的正常进行都需要台址风场信息.随着望远镜性能要求的提高,天线结构设计越来越复杂,风载荷对天线观测时造成的指向影响也越发明显,如何在设计时保证结构刚度和强度,在观测时提高有效观测时间,都需要准确的风场数据.由于传统台址测风塔布置方法无法对测风塔拟设点的可靠性做出定量化评估,因此提出一种基于数值模拟优化测风塔位置的方法.数值模拟基于规范参数设置边界条件,与实测数据比较,整体趋势吻合,满足精度需求.对试验台址设置了4个测风塔位置,经分析P2点与天线位置的风速均方根误差值(root-mean-square error, RMSE)最小,测得的数据更能表征天线区域的风场特性.  相似文献   

Luminescence dating of reticulated red clay buried in Lanshanmiao Paleolithic site in Zhejiang Province,southern China   总被引：1，自引：1，他引：0  

Lu  Ying  Sun  Xuefeng  Xu  Xinmin  Liu  Yalin  Yi  Shuangwen 《地理学报(英文版)》2020,30(9):1436-1450

The Lanshanmiao(LSM) Palaeolithic site,which was excavated in the summer of 2017 by the Zhejiang Provincial Institute of Cultural Relics and Archaeology,is the only excavated palaeolithic site in central Zhejiang Province to date.Luminescence dating methods,including optical stimulated luminescence(OSL) and thermal transfer OSL(TT-OSL) for quartz and post-infrared(IR) stimulated luminescence(p IRIR290) for feldspar,were used to determine the age of the LSM site.The results showed that the LSM section developed before 145.5 ± 12.5 ka and ended after 17.1 ± 1.0 ka.The TT-OSL dating of samples NJU2576 and NJU2615 showed that palaeolithic artifact-bearing layer was between 150 and 100 ka in age.The age range of the palaeolithic layer mainly corresponded to the transition between Marine Isotope Stage(MIS) 6 and MIS5.Our study showed that hominins prominently occupied the LSM site during the glacial and interglacial stages,when it exhibited a floodplain environment.  相似文献