淮河洪峰与致洪暴雨   总被引：1，自引：0，他引：1       下载免费PDF全文

李国杰  张业雯  徐东明  马红  周晓林 《大气科学》1997,21(1):111-117

本文从气象与水文角度， 首先研究淮河关键地段（王家坝）水位变化规律和洪峰出现的特征， 并从数理统计理论上对超定量出现次数和洪峰数值进行了随机变量的独立性检验， 然后求出淮河洪峰遵从的概率分布， 并定性和定量地给出超定量大小与超定量历时关系。最后， 结合多年气象资料分析， 指出洪峰出现与淮河致洪暴雨有密切关系。  相似文献   

MODELING STUDY ON SEDIMENTATION CONFIGURATION IN FRONT OF THE DAM AND IN THE PRESSURE CONDUIT OF BOTTOM OUTLETS BY FLUME EXPERIMENT     

XU Guobin Senior Research Engineer  Tianjin Institute of Hydroelectric Investigation  Design  Research  Ministry of Water Resources. Dongting Road  Hexi District  Tianjin  P R. China. BAI Shilu Senior Research Engineer  Tianjin Institute o 《国际泥沙研究》1997,(3)

I.INTRODUCTIONReseri,oirsonoverloadedriverswillreachthestateofrelativeequilibriumwithcontinuousdevelopmentofsedimentation.Insuchcase,thereisdePOsitinfrontofthedam.Thereforethesiltpressureonthedambodyisconsiderablylarge.Sedimentationelevationinfrontofthedamisoneofthefactorsofcalculatingthesiltpressure.Inaddition,tokeeplong-termworkingstorageinreservoif,itisnecessarytoinstallbottomoutlets.Asthereisapressureconduitinfrontoftheoperatinggateofthebottomoutlet,thesedimelltenteredtheconduitwill…  相似文献   

东北输油管道锦县,盖县,海城段地基土抗液化强度研究     

廖旭  高常波 《东北地震研究》1997,13(4):76-80

对东北输油管道锦县，盖县，海城段的粉土细砂，中砂，粉砂进行了振动液化试验，取得了和类土的τｄ－ｌｏｇＮｆ曲线，τｄ／σ′－ｌｏｇＮｆ曲线，为在以上地区进行液化判别提供了重要的基础资料，同时也为研究其它的地区相同土质的振动性能提供借鉴。  相似文献   

Analysis of DNAPL infiltration in a medium with a low-permeable lens     

M.J. de Neef  J. Molenaar 《Computational Geosciences》1997,1(2):191-214

In this paper we study the infiltration of DNAPL in a porous medium containing a single low-permeable lens. Our aim is to determine whether or not DNAPL infiltrates into the lens. A key role is played by the capillary pressure: DNAPL cannot infiltrate into the lens unless the capillary pressure exceeds the entry pressure of the lens. In the model this is reflected by an interface condition, the extended capillary pressure condition. To derive analytical approximations we first consider a steady-state DNAPL plume in a homogeneous medium. This results in an estimate of the DNAPL plume width as a function of depth, and an asymptotic solution for small saturations. Assuming that the extent of the lens is much larger than the width of the unperturbed DNAPL plume in the homogeneous medium, we derive an explicit criterion for DNAPL infiltration into the lens in terms of a critical inflow rate. A numerical algorithm is presented in which the extended capillary pressure condition is incorporated. The numerical and analytical results show good qualitative agreement. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

辽东早元古代裂谷多金属硫铁矿地质及其成矿规律     

夏学惠 《化工矿产地质》1997,19(2):85-92

辽东早元古代地层内赋存着一系列多金属硫铁矿床。矿床的形成与分布主要受裂谷盆地演化及含矿建造控制。在不同的演化阶段分别形成了含钴黄铁矿 含铜黄铁矿 含硬石膏黄铁矿矿床系列和含硼（镁电气石）磁黄铁矿 含铅锌黄铁矿 重晶石闪锌黄铁矿矿床系列。依据成矿特征可分为海底火山喷气沉积与海底喷气沉积两种成因类型。成矿作用受裂谷、次级盆地、一定含矿层位和特殊容矿岩石相互联系与配套的控矿因素制约。在对成矿规律研究的基础上将该区多金属硫铁矿划分为６个成矿远景区。  相似文献   

Shear-wave anisotropy: spatial and temporal variations in time delays at Parkfield, Central California   总被引：4，自引：0，他引：4  

Yun Liu  Stuart Crampin  Ian Main 《Geophysical Journal International》1997,130(3):771-785

Shear-wave splitting is analysed on data recorded by the High Resolution Seismic Network (HRSN) at Parkfield on the San Andreas fault, Central California, during the three-year period 1988-1990. Shear-wave polarizations either side of the fault are generally aligned in directions consistent with the regional horizontal maximum compressive stress, at some 70° to the fault strike, whereas at station MM in the immediate fault zone, shear-wave polarizations are aligned approximately parallel to the fault. Normalized time delays at this station are found to be about twice as large as those in the rock mass either side. This suggests that fluid-filled cracks and fractures within the fault zone are elastically or seismically different from those in the surrounding rocks, and that the alignment of fault-parallel shear-wave polarizations are associated with some fault-specific phenomenon.
Temporal variations in time delays between the two split shear-waves before and after a M_L = 4 earthquake can be identified at two stations with sufficient data: MM within the fault zone and VC outside the immediate fault zone. Time delays between faster and slower split shear waves increase before the M_L = 4 earthquake and decrease near the time of the event. The temporal variations are statistically significant at 68 per cent confidence levels. Earthquake doublets and multiplets also show similar temporal variations, consistent with those predicted by anisotropic poroelasticity theory for stress modifications to the microcrack geometry pervading the rock mass. This study is broadly consistent with the behaviour observed before three other earthquakes, suggesting that the build-up of stress before earthquakes may be monitored and interpreted by the analysis of shear-wave splitting.  相似文献   

中国西北部“4.5”沙尘暴过程中尺度低压的数值模拟   总被引：3，自引：9，他引：3  

陈伟民  王强  牛志敏  徐建芬  高风荣 《中国沙漠》1996,16(2):140-144

利用改进型ＰＳＵ／ＮＣＡＲ中尺度数值模式（ＭＭ４标准版），取模式水平格距４０ｋｍ，４６×６１网格，垂直方向ａ取１５层，即从地面到模式顶（１００ｈＰａ），σ＝０．０、０．１、０．２、０．３、０．４、０．５、０．６、０．７、０．７８、０．８４、０．８９、０．９３、０．９６、０．９８、０．９９、１．００，采用ＮＣＡＲ的３０＇×３０＇地形资料，以常规观测资料作为初始场，较好地模拟了此次沙尘暴过程的海平面气压的演变和分布，特别是张掖、柴达本盆地以及敦煌附近的三个中低压。同时，模拟了张掖中低压与蒙古冷高压之间的甘肃河西沙尘暴东大风。敏感性试验表明，沙尘暴中低压的形成发展主要是受于物理过程制约；沙尘暴中尺度系统的研究与暴雨中尺度系统的研究是有区别的，积云对流参数化并不是特别重要，在设计研究沙尘暴的数值模式中，应当合理地处理其他的热力、动力过程及大气外强迫源的作用。模式水平格距、地形真实程度对模拟中低压的位置、中心强度有重要贡献；下垫面变化中低压强度有一定影响。张掖热低压的形成发展主要是在有利的环境形势下，特殊地势起了重要作用，表现为直接动力强迫和间接热力强迫。  相似文献   

高围压下冻结砂土的强度特性   总被引：2，自引：6，他引：2  

马巍  吴紫汪 《冰川冻土》1996,18(3):268-272

在高围压条件下，对冻结兰州砂土在不同温度和不同应变速度下进行三轴压缩试验，试验结果表明，围压的增大和应变速度的减小明显增强了冻土的塑性性能；同时，随围压的增大，冻土的抗剪强度增加，但随围压的进一步增加，它出现降低的趋势，存在一个临界 围压，此临界围压值随温度的变化而变化，但不随应变速率而变化。  相似文献   

欠压实地层古地层压力恢复的统计模拟法及其在松辽盆地中的应用   总被引：1，自引：0，他引：1  

付广  庞雄奇  姜振学  张树林 《沉积学报》1996,(1)

恢复烃源岩古地层压力和对于研究其生留排烃过程具有重要意义。Ｎａｋａｙａｍａ［１］等在开展盆地模拟研究时应用Ｒｕｂｅｙ（１９５９）和Ｃｈａｐｍａｎ（１９７）等人提出的数学地质模型对欠压实地层的古地层压力进行恢复。本文通过对松辽盆地欠压实地层的研究发现欠压实因子随地层厚度、埋深、围岩渗透性等地质条件的不同而改变，在此基础上提出了欠压实地层压力恢复的统计模拟法，克服了目前Ｎａｋａｙａｍａ［１］等将地层埋藏过程中的欠压实因子视为常数的不足，从而使计算结果更接近实际。统计模拟法在松辽盆地的应用结果表明了这一方法在实用中的可行性和有效性。  相似文献   

运用X射线衍射和多重峰分离程序解析高岭石的结构缺陷   总被引：4，自引：0，他引：4  

姚林波  高振敏 《矿物学报》1996,16(2):132-140

本文尝试运用Ｘ射线衍射与多重峰分离方法研究高岭石的结构缺陷，重新评价了Ｈｉｎｃｋｌｅｙ（１９６３）结晶指数（ＨＩ），运用０２，１１区域对（１１１）和（１１１）峰的分峰结果，定义了新的结晶度指数：ＣＩ＝（Ｉ１１１＋Ｉ１１１）／Ｉ１１０，它完全以衍射峰的强度进行计算，较灵敏地反映出高岭石真实的结构信息，探讨了高岭石结晶度与高峰石对称性，有序度以及与高岭石Ｐｂ／３滑移缺陷的关系，结果证明高岭石结晶度越高  相似文献