我国台风路径业务预报误差及成因分析   总被引：4，自引：1，他引：3  

余锦华  唐家翔  戴雨菡  虞本颖 《气象》2012,38(6):695-700

利用2005 2009年中国气象局(CMA)提供的西北太平洋(包括南海)台风路径业务预报资料,比较了各类型台风路径、台风登陆位置及登陆时间的预报误差,登陆台风不同阶段以及华东登陆和华南登陆台风的路径预报误差。结果表明:CMA在2005 2009年的路径预报水平与1999 2003年的相比有了显著提高。平均南海台风预报误差大于西北太平洋。异常路径台风主要出现于南海,三个预报时效(24、48和72 h)异常路径的预报误差平均都小于正常路径。将登陆台风分为远海、登陆期间和登陆后三个阶段,显示登陆期间台风预报误差最大,同一阶段华南登陆台风的预报误差大于华东登陆台风。台风登陆位置在24、48和72 h预报时效的平均预报误差分别为71.1、122.6和210.6 km,48和72 h台风实际登陆时间有70%早于预报时间,平均分别提早8和12 h。比较大尺度引导气流与台风移动的偏差及24 h路径预报误差,得到南海三种典型登陆台风路径的大尺度引导气流与台风移动的偏差及其与路径预报误差的关系不一样,即误差成因不同。南海倒抛物线型的大尺度引导气流与台风移动的偏差最大,其预报误差最小;西一西北型的大尺度引导气流与台风移动的偏差最小,其预报误差最大,可能与大尺度环流预报准确性差有关。登陆华东的预报误差小于登陆华南台风的预报误差,这与台风登陆华南时其大尺度引导气流和台风移动的偏差大于登陆华东的台风有关。  相似文献   

水与大火成岩省的形成     

陈欢  顾笑龑  夏群科 《矿物岩石地球化学通报》2019,(2):248-259,445

大火成岩省(LIPs)是发生在板块内部的超大规模岩浆活动的产物,其成因一直是地学界研究的前沿和热点。影响LIPs形成的主要因素包括温度、压力、源岩性质和源区水含量,虽然已积累较多的成果,但对于地幔源区中的水是否影响及如何影响LIPs的形成,目前还知之甚少。本文回顾了已有的实测LIPS水含量研究工作,并介绍了一种新的分析手段,即利用傅里叶变换红外光谱(FTIR)测定早期结晶的单斜辉石斑晶水含量,然后结合水在单斜辉石斑晶和熔体间的分配系数来反演得到LIPs的"原始"水含量。通过塔里木和峨眉山两个大火成岩省的研究实例,综合评价了温度、压力、源岩性质和水含量这4个因素的影响,指出很可能只有当这些因素同时具备了才能产生LIPs。  相似文献   

Numerical modelling of staged stope extraction in a tabular steeply dipping deposit     

Wael R. Abdellah  Haitham M. Ahmed  Mohammed A. Hefni 《Geomechanics and Geoengineering》2019,14(1):41-51

Stope stability is a key factor for the success of a mining operation. To optimise ore productivity while maintaining stope stability, the mining block/stope must be extracted in stages. Ore dilution will occur if the stope is not properly excavated/blasted. This study examines stope stability during mining in three stages, where the height of each stage stope is 10 m. The paper also presents simulation analysis of a typical steeply dipping tabular orebody at 1200 m depth below the surface, which is common in many Canadian underground hard rock mines. Numerical modelling analysis was conducted using the finite element program, RS^2D, where the non-linear elasto-plastic Mohr-Coulomb failure criterion was adopted. The rock reinforcement system (i.e. cable bolts) was modelled/installed in the stope footwall after each mining stage to strengthen access drifts and stabilise the rock mass around the stope that was disturbed by mining activity. Results are discussed in terms of depth of failure zones, total deformation and axial forces in cable bolts with respect to mining stage.  相似文献   

用沉积记录来估计峨眉山玄武岩喷发前的地壳抬升幅度   总被引：15，自引：4，他引：11  

何斌  徐义刚  王雅玫  罗震宇  王康明 《大地构造与成矿学》2005,29(3):316-320

玄武岩喷发前公里规模的地壳抬升是大火成岩省地幔柱成因的一个重要标志,此类地质证据的缺乏反过来被一些学者用来否定地幔柱学说。本文在厘定峨眉山大火成岩省中冲积扇沉积记录的基础上,根据茅口组顶部的剥蚀特征,估算峨眉山地幔柱上升造成的地壳抬升幅度大于1000m,这与CampbellandGriffiths的地幔柱理论模型基本吻合,从而为峨眉山大火成岩省的地幔柱形成机制,乃至激烈争议中的地幔柱学说提供了有力的佐证。  相似文献   

高层钢结构地震反应形状记忆合金拉索控制研究   总被引：3，自引：0，他引：3  

丁阳  张笈玮 《地震工程与工程振动》2005,25(3):152-157

本文通过形状记忆合金(SMA)材料的超弹性性能试验确定了SMA材料的各项参数和常温状态下的本构模型。对采用SMA拉索实施振动控制的20层钢结构的Benchmark模型的地震响应进行了时程分析。计算结果表明,实施SMA拉索控制后,层间相对位移可降低70％左右,且SMA材料很好的耗能作用有效地减少了地震能量向上部楼层的传递,对上部结构具有一定的隔振作用;顶层相对位移的控制效果达到51％;顶层加速度可降低43％;地震波强度和拉索初应变对拉索的被动控制效果影响较大。最后给出了拉索的安装位置与拉索的应变之间的关系曲线,建议了合理的布置方案。  相似文献   

福建某高速公路段路堑边坡滑坡整治     

张家金  陈文通  邱宗新  张永荣 《福建地质》2005,24(1):51-56

福建某高速公路K286 290～K286 345段右侧路堑边坡设计为一至四分级坡,最大坡高近30m,坡体岩石差异风化．且局部发育不良软弱结构面。2002年8月该段四级坡段发生滑坡,阻断了交通,造成了重大经济损失。从坡体岩土结构出发,详细分析了该段边坡失稳的原因及发展趋势,并提出了科学合理的治理加固建议。  相似文献   

复杂岩层大直径嵌岩桩钻进技术   总被引：2，自引：0，他引：2  

刘睦峰 《地质与勘探》2009,45(5):621-626

在软硬互叠产状变化大且岩层坡面偏陡的地层中进行大直径嵌岩桩基础施工是当今岩土钻掘工程界面临的主要技术难题之一。结合某桥址的工程地质特征,分析了滚刀的碎岩机理和滚刀的分布规律,采用大扭矩动力头液压钻机配组合式滚刀钻头钻进的施工工艺,改进了常规的气举反循环排渣方式,总结出回次钻进技术方法,探索出一套适应该地层的泥浆性能指标、钻压、转速和小时进尺等工艺技术参数值;研究发现泥浆对钻具的浮力影响是不能忽略的,提出了一种行之有效简易确定钻压的方法,这些技术参数和工艺方法对类似工程的施工具有一定的指导意义。  相似文献   

Mafic-ultramafic magmatism of the Early Precambrian (from the Archean to Paleoproterozoic)     

E. V. Sharkov  M. M. Bogina 《Stratigraphy and Geological Correlation》2009,17(2):117-136

Compositional evolution of the Archean mafic-ultramafic volcanics is considered in comparison with evolution of the Paleoproterozoic volcanism using available data on the Baltic shield, Pilbara (Australia) and Superior (Canada) cratons, and the Isua greenstone belt (Greenland). The Archean volcanics of mantle origin are of two major types, represented (a) by komatiite-basaltic complexes (komatiites, komatiitic and tholeiitic basalts) and (b) by geochemical analogs of boninites (GAB) and siliceous high-Mg series (SHMS) of volcanic rocks. As is established, the komatiitic and GAB volcanism ceased in the terminal Archean, whereas the SHMS rocks prevailed in the Paleoproterozoic to become extinct about 2 Ga ago in connection with transition to the Phanerozoic type of tectonomagmatic activity. Geochemical trends of mafic-ultramafic associations occurring in the considered cratons are not uniform, being of particular character to certain extent. With transition from the Paleo- to Neoarchean, rock associations of both types reveal a minor increase in Ti and Fe contents. Comparatively high Fe₂O_3tot TiO₂, and P₂O₅ concentrations (maximal ones in the Archean), which are characteristic of the Neoarchean (2.75–2.70 Ga) basalts from the Superior and Pilbara cratons or the Baltic shield, represent a result of relatively high-Ti intracratonic magmatic activity that commenced in that period practically for the first time in the Earth history. This magmatic activity of the Neoarchean was not as intense as the high-Mg basaltic volcanism, and the absolute maximum in concentrations of the above components was attained only 2.2–1.9 Ga ago, at the time of appearance in abundance of Fe-Ti picrites and basalts typical of the Phanerozoic intraplate magmatism. The Archean volcanic complexes demonstrate gradual secular increase in concentrations of incompatible elements (LREE inclusive) and growth of Nb/Th ratio that apparently reflected the progressing influence of mantle plumes. In the early Paleoproterozoic (2.5–2.35 Ga), values of that ratio considerably declined in the SHMS rocks and then quickly grew in the Middle Paleoproterozoic volcanics (2.2–1.9 Ga) to attain finally the values typical of the Phanerozoic magmas associated in origin with mantle plumes. The ?_Nd(T) parameter was decreasing with time from positive values in the Paleoarchean to negative ones in the SHMS rocks of the Paleoproterozoic most likely in response to grown proportion of ancient crustal material in magmatic melts. Since the mid-Paleoproterozoic, the ?_Nd(T) values turn in general into positive again reflecting change in the character of magmatic activity: the SHMS melts gave place at that time to the Fe-Ti picrite-basaltic magmas. The primary crust of the Earth was presumably of sialic composition and originated during solidification from the bottom upward of the global magma ocean a few hundreds kilometers deep, when most fusible components migrated up to the surface to form there the granitic crust. Geological history of the Earth commenced at the appearance time of granite-greenstone terranes and granulite belts separating them, the first large tectonic structures formed under influence of raising mantle superplumes.  相似文献   

城市基础空间数据质量检查技术研究   总被引：6，自引：0，他引：6  

沈涛  李成名  赵园春 《测绘科学》2005,30(5):48-49,64

本文在现有城市空间数据质量检查与控制的理论上,结合大比例尺数据生产的实际情况,提出对空间数据进行几何误差、属性误差及逻辑误差进行整体检查的方法,同时对实际接边误差进行研究,提出了检查和处理的方法。  相似文献   

大直径岩溶水井施工技术          下载免费PDF全文

谢常茂 《探矿工程》2009,36(7):21-24

通过广西河池市九圩镇水厂大直径供水井的施工实例,详细介绍了岩溶复杂地层大直径、大涌水钻孔的空气潜孔锤钻进技术、扩孔技术、钻孔护壁技术及施工工艺。  相似文献