移动荷载作用下Kerr地基梁稳态响应解答

研究Kerr地基上的均质Euler-Bernoulli梁在移动集中荷载作用下的稳态响应,分析有无阻尼存在时列车速度、地基压缩刚度、剪切刚度对Kerr地基梁挠度曲线的影响。计算结果表明,地基阻尼的存在能明显减少移动荷载引起的地基梁挠度,地基梁的挠度受地基压缩刚度的影响比剪切刚度更为明显。     

基于MCI指数的福建省干旱气候特征

采用目前国家干旱监测业务实行的MCI指数,利用Morlet小波、经验正交函数（EOF）等方法,分析了福建省1961—2019年全省66个气象站MCI指数表征的干湿状况和干旱变化特征。结果表明：福建省存在明显的干湿气候特征,具有显著的6—8 a和22 a的周期振荡,内陆山区干湿变化周期比沿海长,在季节尺度上各季均存在多时间尺度和地域差异化的特点;其空间变化具有3种典型模态,反映了季风降水多寡和地形差异。MCI表征的干旱过程时空分布与历史干旱事件相吻合,秋季和冬季是福建省干旱发生频率最高的季节,春季和夏季是干旱强度最强的季节;闽江口以南沿海地区干旱发生率明显高于内陆地区,全省出现同步干旱的机率较小（12%）。     

气象服务在促进内蒙古政策性农业保险事业发展中的作用

文章在分析国内外农业保险发展现状的基础上,结合内蒙古农业气象观测站网建设和气象为农服务业务开展现状,阐述了气象服务在农业保险业务发展中的作用和优势,为我区各级气象部门开展政策性农业保险服务业务提供了思路。     

差异性风化岩石作为桩基持力层设计应注意的若干问题

基岩中存在软弱夹层为岩石的差异性风化的主要特征。在不均匀性地基土上选用该类地层作为钻孔灌注桩持力层时，它的存在将对桩长、单桩承载力、桩体沉降等带来不同程度的影响。以黄石电厂为例，指出在选用差异性风化岩石作为桩基持力层时应注意的若干问题。     

Relations between load and settlement of circular foundations on or in a dense sand expressed by a function of diameter and depth

When load acts on a circular foundation on or in a dense sand, average contact pressure on the lower surface of the foundation is q and settlement of the foundation is s. Diameter and depth of the foundation are B and D_f. When the sand, B and D_f are given, we can know the relation between q and s/B by, e.g. a loading test, i.e. the relation is determined by B and D_f for the sand. Using the results of numerical analyses, we express a relation between q and s/B up to s=0.1B by functions of a single variable which is a linear combination of B and D_f. Consequently when two foundations have different B's and different D_f's but have the same value of the variable, the relations are the same. Then we examine whether the functions can express the results of eleven tests of model foundations of wide range of B and/or D_f. In all the tests, the relations are expressed with sufficient accuracy. Copyright © 2005 John Wiley & Sons, Ltd.     

Displacement‐controlled method and its applications to material non‐linearity

For the analysis of non‐linear problems, the displacement‐controlled method (DCM) has a more extensive application scope and more powerful abilities than the load‐controlled method (LCM). However, difficulties of the DCM's procedure not amenable to most finite element implementations of the conventional LCM have restricted its applications in geomechanics. By means of Sherman–Morrison's theorem, the solution of DCM is improved. The improved procedure is characterized by high efficiency, good numerical stability and a programme structure similar to LCM. Two aspects of applications of DCM are illustrated. The first application is to compute the response of a structure under a given load level like the conventional finite element analysis. The second application is to trace the equilibrium path of a structure under a given load distribution type. A simple but effective algorithm is presented for automatically adjusting the step length in tracing the equilibrium path. Examples illustrate that the proposed procedures are suited for modelling complicated non‐linear problems in geomechanics. Copyright © 2005 John Wiley & Sons, Ltd.     

内约束方钢管混凝土柱抗震性能研究

由于方钢管对混凝土约束作用较弱,地震作用下方钢管混凝土柱底部钢管易出现屈曲,因此本文提出一种新型内约束方钢管混凝土柱。基于ABAQUS有限元软件,本文采用合理的材料本构模型建立内约束方钢管混凝土柱三维实体精细有限元模型,该模型能准确反应钢管、混凝土以及拉筋之间的相互作用,又能反应拟静力作用下混凝土的塑性损伤和钢材的循环硬化规律。有限元结果与试验结果吻合良好。首先,在此基础上笔选出最佳内约束形式,对拉箍筋方钢管混凝土柱的抗震性能明显优于圆环箍筋;其次,提出在不同轴压比下内约束方钢管混凝土柱的焊接拉筋最佳布置长度和合理体积配箍率;再次,探讨不同参数对内约束方钢管混凝土柱滞回性能的影响,结果表明:提高截面含钢率和长细比能有效改善组合柱的极限承载力,而轴压比在一定范围内有利于能提高柱的承载力;最后,讨论了约束措施对内约束方钢管混凝土柱耗能性能的影响。     

南京河西地区地面沉降成因分析

为了查明南京河西地区地面沉降的成因,笔者等在系统研究水文地质与工程地质条件的基础上,研究了地面沉降的分布特征和发展规律,以及地面沉降与地下水位、软土分布及建筑荷载之间的关系,进而揭示了南京河西地区地面沉降的成因。研究结果表明：南京河西地区不开采地下水,地面沉降与软土层厚度和建筑荷载分布关系密切,地面沉降主要受建筑工程影响,即建筑荷载和深基坑降水的作用。     

ISO2394:2015 Annex D (Reliability of Geotechnical Structures)

ISO2394:2015 contains a new informative Annex D on “Reliability of Geotechnical Structures”. The emphasis in Annex D is to identify and characterize critical elements of the geotechnical reliability-based design process, while respecting the diversity of geotechnical engineering practice. This paper highlights the main features of Annex D and gaps for future work.     

夏季湖北电网气象敏感负荷预测模型研究

利用2009-2010年湖北电网日用电负荷资料和气象资料,提出了基于电网负荷的分解算法,将电网日最大负荷分解为基础负荷与气象敏感负荷2个主要分量.其中,气象敏感负荷与气温、相对湿度及风速的综合气象敏感负荷条件指数相关.提出了基于权重指数的湖北省面平均气象敏感负荷条件指数的算法.利用相关比法,分析了湖北省气象敏感负荷与面均气象敏感负荷条件指数的非线性关系.基于均方偏差最小原理和非线性最小二乘法,建立了夏季湖北电网气象敏感负荷与面均气象敏感负荷条件指数的多项式预测关系模型.经2010年9月模型应用检验表明,预测平均误差低于6％.该模型可用于夏季湖北省电力专业气象服务工作.