地下多洞室结构的中隔墙安全度区间计算方法

针对地下工程中相邻洞室和隧道群的中隔墙稳定性问题,提出一种基于虚拟应力系数原理的多洞结构中隔墙安全度定量计算方法。该方法通过迭代搜索一个虚拟应力系数K,使得在K倍初始地应力下洞群中隔墙正好出现贯通性的等效塑性应变带,并由此确定中隔墙安全度的下限值。同时,分析不同虚拟应力作用下中隔墙等效塑性应变带两侧特征点的相对变形特征曲线,以相对变形曲线出现突变拐点时对应的虚拟应力系数作为中隔墙安全度的上限值,从而获得中隔墙的安全度区间。通过对一物理模型试验结果的验证分析和西南一大型水电地下洞群中隔墙安全度的计算表明,该方法可以合理地给出中隔墙的安全区间,可为地下多洞室或隧道群中隔墙的安全性定量评价和支护设计提供科学依据。     

大型电气设备瓷套管地震易损性分析

通过对电气设备进行增量动力分析(IDA),得出在不同地震波作用下瓷套管根部的应力值,回归分析得出瓷套管应强比(RSS)与地震峰值加速度(PGA)的关系式.以瓷套管应强比作为整体性能指标,进行地震易损性分析,得出瓷套管在不同破坏状态下的应强比值区间,给出瓷套管地震失效概率与地震峰值加速度之间的计算公式,并绘制瓷套管在不同...     

基于渗流和管流耦合的管涌数值模拟

堤坝地基的渗透变形过程实际上是“土中水”转变为“水中土”的过程。在渗透变形发生的集中管涌通道区域,采用常规渗流分析理论,单纯增大管涌通道渗透系数的方法是不太合适的。在未发生渗透变形的区域,用常规渗流理论计算;在管涌通道区域,用管流理论,公共边界上两者之间水头相等、流量大小相等且方向相反,能够较好符合渗透变形的发展规律。为了适应计算过程中内部边界条件不断变化的特点,采用无网格法伽辽金法（element free Galerkin method,EFG）对渗流场进行计算。算例计算表明,这种渗流-管流耦合的方法能够模拟管涌通道绕过防渗墙等复杂的发展过程。     

北京首都机场的人工消雾及大气边界层特征的演变

在首都机场人工消雾作业过程中进行了大气边界层特征的观测,观测结果表明：用喷洒液氮进行人工消雾可以形成小面积降雪从而提高能见度,达到安全飞行的目的．人工消雾作业过程可影响小面积大气湍流特征,使湍流谱略偏离-5／3规律．人工消雾作业期间潜热通量明显大于作业期后．     

我国几种热带海藻的光合作用与光量子通量密度的关系

本文介绍用氧电极法测定海南岛潮下带产的凤尾菜Gracilaria eucheumoides等6种热带红藻和无肋马尾藻Sargassum enerve等3种热带褐藻的光合活性和光量子通量密度的关系。研究结果表明:1.红藻和褐藻的补偿点差别不大,9种热带海藻的光合作用补偿点都在24—28μE/(m~2·s)之间,而光合作用饱和点上的净光合作用速率为0.18—0.66mgO_2/(g鲜重·h),一般而言,红藻的较低,褐藻的较高;2.各种热带海藻的光合作用饱和点的差异,其规律也符合一般海藻的垂直分布规律;3.对人工栽培的凤尾菜、琼枝Eucheuma gelatinae卡帕藻Kappaphycus alvarezii等,可以扩大生长水层,在更深一些的水层中栽培,这对发展生产是非常有利的。     

匝道中线外一点高程CASIO编程解算

结合互通立交匝道和山区高速公路的特点及其现有路面横向设计的不足,推导出匝道中线外一点的高程算法并用CASIO进行编程。     

High-Resolution Mesoscale Analysis Data from the South China Heavy Rainfall Experiment (SCHeREX): Data Generation and Quality Evaluation

In this study,the observational data acquired in the South China Heavy Rainfall Experiment (SCHeREX)from May to July 2008 and 2009 were integrated and assimilated with the US National Oceanic and Atmospheric Administration's (NOAA) Local Analysis and Prediction System (LAPS; information available online at http://laps.fsl.noaa.gov).A high-resolution mesoscale analysis dataset was then generated at a spatial resolution of 5 km and a temporal resolution of 3 h in four observational areas:South China,Central China,Jianghuai area,and Yangtze River Delta area.The quality of this dataset was evaluated as follows.First,the dataset was qualitatively compared with radar reflectivity and TBB image for specific heavy rainfall events so as to examine its capability in reproduction of mesoscale systems.The results show that the SCHeREX analysis dataset has a strong capability in capturing severe mesoscale convective systems.Second,the mean deviation and root mean square error of the SCHeREX mesoscale analysis fields were analyzed and compared with radiosonde data.The results reveal that the errors of geopotential height,temperature,relative humidity,and wind of the SCHeREX analysis were within the acceptable range of observation errors.In particular,the average error was 45 m for geopotential height between 700 and 925 hPa,1.0-1.1℃ for temperature,less than 20％ for relative humidity,1.5-2.0 m s-1 for wind speed,and 20°-25° for wind direction.The above results clearly indicate that the SCHeREX mesoscale analysis dataset is of high quality and sufficient reliability,and it is applicable to refined mesoscale weather studies.     

High-Resolution Mesoscale Analysis Data from the South China Heavy Rainfall Experiment (SCHeREX): Data Generation and Quality Evaluation

In this study, the observational data acquired in the South China Heavy Rainfall Experiment (SCHeREX) from May to July 2008 and 2009 were integrated and assimilated with the US National Oceanic and Atmospheric Administration’s (NOAA) Local Analysis and Prediction System (LAPS; information available online at http://laps.fsl.noaa.gov). A high-resolution mesoscale analysis dataset was then generated at a spatial resolution of 5 km and a temporal resolution of 3 h in four observational areas: South China, Cent...     

引发雷州半岛地区干旱的典型生态环境

以气象、地质、水文、地貌及植被等调查和观测数据为基础,提出引发雷州半岛地区干旱的五个方面的生态环境因素,分析各种因素对引发干旱的作用,针对引发雷州半岛地区干旱的综合因素提出相应的对策,可为解决区内干旱问题提供科学依据和有效途径。