多点输入条件下的土质边坡地震反应     

景鹏旭  杨清逸 《华北地震科学》2021,39(1):17-22

以二维土质边坡模型为例,地震输入方式分别采取单点输入和多点输入,考虑其土层地震反应、主应力极值等特征,分析单点、多点输入的差异;在此基础之上,探讨单点输入与多点输入下坡高、坡角的变化对土质边坡模型安全系数的影响。结果显示,在地震工程抗震设计时采用多点输入比单点输入更加安全、更符合实际情况。  相似文献   

核电站抗震研究综述   总被引：6，自引：1，他引：5  

戚承志  钱七虎 《地震工程与工程振动》2000,20(3):76-86

核电站抗震性一直是核电站设计的主要问题之一。随着此问题各方面研究的深入和研究手段的进步,核电站的抗震计算理论也在不断发展,本文试图根据已有的资料,在核电站抗震问题的一些主要方面（地震输入参数的确定,抗震计算理论,结构与地基的相互作用,支加速度谱及反应谱的确定,建筑物及设备的抗震计算,地基,基础及地下建筑的抗震计算等）研究状况作一些综述,并在此基础上展望一下需要解决的问题。  相似文献   

某核电厂应急通道桥梁地震响应分析          下载免费PDF全文

周扬  邹德高  隋翊  龚涛  刘鑫 《地震工程学报》2020,42(2):318-325

某核电厂为满足建设、运营及特殊情况下的应急需求,拟建应急通道桥,其抗震安全十分重要。本文介绍了考虑桥-桩-地基的三维整体精细化模型的有限元动力时程分析方法,计算桥梁在SL-1(运行安全地震动)和SL-2(极限安全地震动)地震作用下地基典型断面、T梁以及墩柱的动力响应。结果表明该方法能直接处理土的非线性问题以及方便的考虑地基辐射阻尼作用,同时可以精细模拟T梁和盖梁间的支座接触。三维计算采用自主开发的GEODYNA高性能软件平台,计算效率较高。该方法可为核电厂桥梁抗震设计提供参考。  相似文献   

Rayleigh波场的数值模拟及其应用     

白建方  马立龙 《震灾防御技术》2019,14(2):328-340

本文总结了Rayleigh波场数值模拟的4种思路和各自特点,根据Lamb问题的理论分析成果提出了基于地表激振的Rayleigh波场数值模拟技术,论述了地表集中震源作用下引起地表波动场的特点及主要影响因素。在此基础上,利用Plaxis 2D有限元软件实现了Rayleigh波场的数值模拟,并结合算例验证了所提方法的可行性和结果的合理性。最后,针对多层建筑结构,研究了不同地震动输入模式下结构动力反应的特点。结果表明,Rayleigh波作用下结构的动力反应特性明显区别于在底部输入剪切波时的结果,不同地震动输入模式对结构的振动形态和破坏模式有着明显的影响。  相似文献   

Simulating monthly streamflow using a hybrid feature selection approach integrated with an intelligence model     

Zahra Alizadeh  Zaher Mundher Yaseen 《水文科学杂志》2020,65(8):1374-1384

ABSTRACT

Streamflow prediction is useful for robust water resources engineering and management. This paper introduces a new methodology to generate more effective features for streamflow prediction based on the concept of “interaction effect”. The new features (input variables) are derived from the original features in a process called feature generation. It is necessary to select the most efficient input variables for the modelling process. Two feature selection methods, least absolute shrinkage and selection operator (LASSO) and particle swarm optimization-artificial neural networks (PSO-ANN), are used to select the effective features. Principal components analysis (PCA) is used to reduce the dimensions of selected features. Then, optimized support vector regression (SVR) is used for monthly streamflow prediction at the Karaj River in Iran. The proposed method provided accurate prediction results with a root mean square error (RMSE) of 2.79 m³/s and determination coefficient (R² ) of 0.92.  相似文献   

Use of ACRU,a distributed hydrological model,to evaluate how errors from downscaled rainfall are propagated in simulated runoff in uMngeni catchment,South Africa     

Samuel Kusangaya  Michele Warburton  Emma Archer van Garderen 《水文科学杂志》2017,62(12):1995-2011

  相似文献   

Gridded climate data products are an alternative to instrumental measurements as inputs to rainfall–runoff models          下载免费PDF全文

José L.J. Ledesma  Martyn N. Futter 《水文研究》2017,31(18):3283-3293

Rainfall–runoff models are widely used to predict flows using observed (instrumental) time series of air temperature and precipitation as inputs. Poor model performance is often associated with difficulties in estimating catchment‐scale meteorological variables from point observations. Readily available gridded climate products are an underutilized source of temperature and precipitation time series for rainfall–runoff modelling, which may overcome some of the performance issues associated with poor‐quality instrumental data in small headwater monitoring catchments. Here we compare the performance of instrumental measured and E‐OBS gridded temperature and precipitation time series as inputs in the rainfall–runoff models “PERSiST” and “HBV” for flow prediction in six small Swedish catchments. For both models and most catchments, the gridded data produced statistically better simulations than did those obtained using instrumental measurements. Despite the high correspondence between instrumental and gridded temperature, both temperature and precipitation were responsible for the difference. We conclude that (a) gridded climate products such as the E‐OBS dataset could be more widely used as alternative input to rainfall–runoff models, even when instrumental measurements are available, and (b) the processing applied to gridded climate products appears to provide a more realistic approximation of small catchment‐scale temperature and precipitation patterns needed for flow simulations. Further research on this issue is needed and encouraged.  相似文献   

Mineralogical evidence for multiple dust sources in an early Triassic loessite     

Michael J. Wilson  Andrew Hurst  Anne D. Wilkins  Lyudmyla Wilson  Leon Bowen 《Sedimentology》2020,67(1):239-260

Loessite present in a borehole into the Smith Bank Formation (early Triassic age, Central North Sea) differentiates five coeval source terranes for aerosol dust, three long-distance sources and two local sources. All were active immediately following the end Permian mass extinction. Long-distance sources are sedimentary, basic magmatic and acid–intermediate volcanic. Although predominantly silt-sized and dominated by quartz with subordinate feldspars, muscovite and illite, evidence of basic and acid–intermediate magmatic/volcanic sources are pervasive. Baddeleyite is diagnostic of basic magmatism, an origin supported by enrichment of plagioclase relative to potassium feldspar. Deduction of acid–intermediate volcanism comes from the collective occurrence of irregular geometry quartz, volcanic shards, Ti-mineralization, euhedral biotite, sanidine, the co-occurrence of apatite and zircon, and the common occurrence of a tosuditic clay mineral. The tosuditic phase occurs as an unusual diagenetic dioctahedral chlorite/smectite formed at low temperature (<45°C), during very shallow burial by the decomposition of unstable rhyo-dacitic and andesitic grains in alkaline pore water from an adjacent lake that yielded pore fluids with a high Al : Si ratio. The Siberian Traps large igneous province is the likely source terrane for the magmatic and volcanic silt. Locally sourced clay pellets and kaolinite booklets formed from aeolian erosion of an adjacent, periodically desiccated lake-floor and a kaolinitic regolith, respectively. Inference of a prolonged harsh, arid climate leaves no evidence of any periods of sustained humidity or climatic fluctuation, such as pedogenesis. The association between the end Permian mass extinction, emplacement and aeolian erosion of the Siberian Traps large igneous province, and location of the Smith Bank Formation in a large lacustrine endorheic basin, combine to preserve a record of prolonged harsh climate in the early Triassic.  相似文献   

风应力输入到海洋中的能量的气候变率特征          下载免费PDF全文

谢泽林  王召民  武扬 《大气科学学报》2019,42(2):184-196

利用麻省理工学院海洋环流模式研究了风应力输入到海洋中的能量的气候变率特征。结果表明:风应力输入到海洋中的能量对气候变化有显著的响应。在北大西洋涛动(North Atlantic Oscillation,NAO)正位相的年份,风应力输入到海洋中的能量的大值区北移且加强,主要由于暴风路径的北移和天气尺度大气扰动的加强导致;同样,在南半球环状模(Southern Annular Mode,SAM)正位相年份输入到南大洋的能量大值区南移并加强,且输入到南极大陆沿岸流中的能量也有显著增加。经验正交函数分解分析结果表明:NAO主导了风应力输入到北大西洋区域的能量变化。SAM解释了南大洋区域风应力输入能量的第一模态,第二、三模态解释了受ENSO(El Niňo-Southern Oscillation)影响的情况。最近几十年,在南大洋区域,风应力及其输入能量的年代际变化都有所增强,而在北半球的中高纬度区域有所下降。  相似文献   

不同循环饥饿-投喂策略对珍珠龙胆石斑鱼生长和水质的影响     

王润  王晓龙  田相利  董双林  李志凌  韩笑冰 《海洋湖沼通报》2018,(4):66-73

研究了不同饥饿-投喂策略对珍珠龙胆石斑鱼(Epinephelus fuscoguttatus♀×Epinephelus lanceolatus♂)的生长和能量收支的影响。实验包括3个处理:C(持续投喂);S1R3(饥饿1d,投喂3d);S1R7(饥饿1d,投喂7d);S1R11(饥饿1d,投喂11d)。实验在生产性水泥养殖池中进行,养殖池规格为6m*6m,水深1.1m,日换水率为400%,珍珠龙胆石斑鱼的养殖密度为18.3ind·m-2。研究结果表明,处理组S1R7和S1R11石斑鱼末体重与对照差异不显著(P>0.05),而S1R3处理鱼末体重则显著低于对照(P<0.05);3个处理石斑鱼特定生长率变化趋势与末体重相似,处理组S1R7和S1R11石斑鱼与对照差异不显著(P>0.05),而S1R3处理则显著低于对照(P<0.05);处理组S1R7和S1R11石斑鱼摄食率与对照相比差异不显著(P>0.05),S1R3则显著低于对照组(P<0.05);处理组S1R7和S1R11石斑鱼饲料系数与对照相比差异不显著(P>0.05),S1R3则显著高于对照组(P<0.05);从各处理水质状况比较,S1R3和S1R7处理各指标浓度总体上要显著低于对照组(P<0.05),但S1R11处理与对照差异不大(P>0.05)。综合生长和水质指标可以看出,适宜的饥饿-投喂策略并不影响珍珠龙胆石斑鱼的正常生长。在本研究条件下,饥饿1天,投喂7d的循环投喂模式下,珍珠龙胆石斑鱼生长与对照相比差异不大,表现出完全补偿生长效应,水质指标则明显优于持续投喂。这一研究结果对于珍珠龙胆石斑鱼工厂化养殖技术与管理水平的提高具有一定的参考价值。  相似文献