季节性冻结-冻融期地中蒸渗计资料处理探讨

本文针对地中蒸渗计在冻结-冻融期存在的问题,利用实验站冻土及土壤水分势能资料,探索了冻土层的发育及其水分运移规律,通过对亚砂土不同埋深及不同年度的地中蒸渗计资料处理,得出冻结期和冻融期地中蒸渗计资料的处理方法及其埋深临界值。这对准确利用冻结-冻融期地中蒸渗计资料具有重要的指导意义。     

Seismic response of self‐centring hysteretic SDOF systems

The seismic response of single‐degree‐of‐freedom (SDOF) systems incorporating flag‐shaped hysteretic structural behaviour, with self‐centring capability, is investigated numerically. For a SDOF system with a given initial period and strength level, the flag‐shaped hysteretic behaviour is fully defined by a post‐yielding stiffness parameter and an energy‐dissipation parameter. A comprehensive parametric study was conducted to determine the influence of these parameters on SDOF structural response, in terms of displacement ductility, absolute acceleration and absorbed energy. This parametric study was conducted using an ensemble of 20 historical earthquake records corresponding to ordinary ground motions having a probability of exceedence of 10% in 50 years, in California. The responses of the flag‐shaped hysteretic SDOF systems are compared against the responses of similar bilinear elasto‐plastic hysteretic SDOF systems. In this study the elasto‐plastic hysteretic SDOF systems are assigned parameters representative of steel moment resisting frames (MRFs) with post‐Northridge welded beam‐to‐column connections. In turn, the flag‐shaped hysteretic SDOF systems are representative of steel MRFs with newly proposed post‐tensioned energy‐dissipating connections. Building structures with initial periods ranging from 0.1 to 2.0s and having various strength levels are considered. It is shown that a flag‐shaped hysteretic SDOF system of equal or lesser strength can always be found to match or better the response of an elasto‐plastic hysteretic SDOF system in terms of displacement ductility and without incurring any residual drift from the seismic event. Copyright © 2002 John Wiley & Sons, Ltd.     

ENSO动力学与预测

发生在热带太平洋地区的ENSO现象是海气相互作用的集中表现,是年际气候变化中的最强信号.由于它的发生会在全球许多地区引起严重的气候异常,极大地影响着这些地区的工农业生产和人民生活,因此,对ENSO的机理及其预测的研究一直是大气海洋界的一个热点研究课题.中国科学院大气物理研究所在ENSO的机理及其预测等方面进行了大量的研究,取得了许多研究成果.作者将对中国科学院大气物理研究所在这方面的一些研究成果进行回顾和介绍.     

Magnitude of lateral displacement on the Crevillente Fault Zone (Betic Cordillera,SE Spain): stratigraphical and sedimentological considerations

The Crevillente Fault Zone (CFZ) comprises a system of northeast to southwest oriented dextral faults that extend for some 600 km in the External Zones of the Betic Cordillera (SE Spain). The magnitude of lateral displacement related to this fault zone is not well constrained, and it is considered to be between 20 and 400 km. The stratigraphical and sedimentological criteria used in this work have proven effective in quantifying the magnitude of the displacement along this structure. We have analysed an oolitic turbidite facies in the Middle Jurassic of the Sierra de Ricote (Median Subbetic of Murcia Province). A detailed revision of ooidal limestone outcrops has revealed that the source area of these deposits was to the Internal Subbetic zone, north of Vélez Rubio (Almería Province). These two tectonic units, the Median and Internal Subbetic, are currently 75 km from each other and separated by the CFZ. The conclusions arising from our stratigraphical, petrological and sedimentological studies favour interpretation of a 75–100 km lateral displacement. After restoring the Late Jurassic–Cretaceous anticlockwise rotation of Iberia, the CFZ appears to belong to the E–W palaeofault system that is related to the extension of the South Iberian Continental Margin (SICM). Copyright © 2004 John Wiley & Sons, Ltd.     

From Predictive Mapping of Mineral Prospectivity to Quantitative Estimation of Number of Undiscovered Prospects

This paper proposes that the spatial pattern of known prospects of the deposit‐type sought is the key to link predictive mapping of mineral prospectivity (PMMP) and quantitative mineral resource assessment (QMRA). This proposition is demonstrated by PMMP for hydrothermal Au‐Cu deposits (HACD) and by estimating the number of undiscovered prospects for HACD in Catanduanes Island (Philippines). The results of analyses of the spatial pattern of known prospects of HACD and their spatial associations with geological features are consistent with existing knowledge of geological controls on hydrothermal Au‐Cu mineralization in the island and elsewhere, and are used to define spatial recognition criteria of regional‐scale prospectivity for HACD. Integration of layers of evidence representing the spatial recognition criteria of prospectivity via application of data‐driven evidential belief functions results in a map of prospective areas occupying 20% of the island with fitting‐ and prediction‐rates of 76% and 70%, respectively. The predictive map of prospective areas and a proxy measure for degrees of exploration based on the spatial pattern of known prospects of HACD were used in one‐level prediction of undiscovered mineral endowment, which yielded estimates of 79 to 112 undiscovered prospects of HACD. Application of radial‐density fractal analysis of the spatial pattern of known prospects of HACD results in an estimate of 113 undiscovered prospects of HACD. Thus, the results of the study support the proposition that PMMP can be a part of QMRA if the spatial pattern of discovered prospects of the deposit‐type sought is considered in both PMMP and QMRA.     

若尔盖沼泽湿地的萎缩机制

1960年以来,若尔盖沼泽湿地的快速萎缩严重影响黄河上游水量补给和当地湿地生态系统,但其机制尚不清晰。基于2010—2013年野外调查、气象水文资料和遥感影像,分析若尔盖沼泽退化的主要原因与机制。尽管气温的缓慢升高,但降水量并未减少,考虑到沼泽的季节性特征,气候变暖对沼泽萎缩影响相当有限,但不是主要原因。经遥感判读和统计,共识别现有920 km的人工渠道,其疏干的沼泽面积约648.3 km2,占总萎缩面积的27%。人工开渠作为强烈的人类活动干扰,是若尔盖沼泽快速萎缩的重要原因。自然水系的溯源侵蚀长期疏干沼泽、降低地下水水位和放射状地向沼泽内部切穿是沼泽萎缩的重要机制。人工开渠连通自然水系强化沼泽内河床下切和排水作用。     

多年冻土区输油管道-管周冻土热力相互作用研究进展

冻土区管道工程建设面临冻土工程特性及相关地质问题的严重挑战,开展管道-冻土相互作用研究对于解决管道稳定性问题具有重要的实际指导意义。综述国内外输油管道-冻土热力相互作用研究进展发现,目前研究集中在特定（定值或周期变化）油温下管周土温度场的定量描述以及差异冻胀/融沉下交界面处管道力学响应规律的解耦分析,缺乏完整时空序列的现场综合观测与管土界面特性及其动态演化研究。对管道防融沉措施进行归纳总结发现,各措施应用效果缺乏管道应力与变形数据的有效支持。应加强管道本身与管道沿线次生冻融灾害监测及相关数据获取,以此为校验开展管土界面特性及演化规律的系统研究,以便构建更为合理的管土接触面单元模型,将其和具有普适性的冻土模型相结合,植入有限元软件提高管土相互作用模型计算可靠性,并建议立足管道变形角度对防融沉措施的工程应用效果予以综合评价。     

天山北坡城市群空间组织形态的识别研究

 正确认识天山北坡城市群的空间组织结构以及空间发展形态,对于完善绿洲城市群的发展理论和规划具有重要意义。以天山北坡城市群为研究对象,通过资源环境承载力的分析,总结出未来城市群发展面临的客观制约因素;通过中心性分析、断裂点理论修正的Voronoi多边形等方法识别出城市群的中心城市及各自的辐射范围城市;通过引力模型识别出城市之间的社会经济联系强度。据此,利用多维尺度分析的方法,可视化地展现了天山北坡城市群发展的空间组织形态。经调查了解：（1）乌鲁木齐市与克拉玛依市是未来城市群发展的两个中心城市,五家渠市、阜康市、昌吉市、石河子市周边目前属于乌鲁木齐市的辐射范围城市,奎屯市,乌苏市属于克拉玛依市的辐射范围城市;（2）城市群内部的城市之间的联系比较松散,特别是两个中心城市之间联系较弱;（3）城市群的空间发展形态为串珠式,是一种特殊的走廊式空间形态。     

南海季风爆发的统计动力分析

作者对南海季风爆发作了统计动力分析,即将南海季风爆发前后的高低层风场看成一个整体,并以南海季风爆发日为基准,对风场作了经验正交函数(EOF)分析,得到了以下结论:偏差风场的第一模态反映了高低层东亚夏季风环流在南海季风爆发日前后有剧烈变化,这直接体现了南海季风的爆发,并表明此时大气环流有突变发生;第二、三模态则分别反映了具有5～7天振荡周期的中高纬大气长波活动和亚洲季风区中准双周低频振荡的主要活动区,以及中低纬度大气环流的相互作用;第二模态体现了偏差风场的幅散风部分而第三模态则体现了旋转风部分.     

中国南海夏季风强、弱年多尺度相互作用能量学特征

中国南海夏季风为东亚季风的主要系统之一,其具有多重尺度特征,除季节平均环流场外,低频（季节内振荡）和高频（天气尺度）扰动也十分活跃,各尺度系统存在明显的年际变化。该研究使用ERA-Interim和NCEP/NCAR两套再分析资料,从季风平均动能（MKE）诊断的角度出发,探讨了1979-2010年中国南海夏季风环流年际变化的能量来源及其和扰动场的相互作用过程。结果表明:中国南海夏季风对流活跃年份,中国南海南部（12°N以南）及中南半岛一带为季风平均动能显著增强区,此与南亚季风区西风急流的增强并向东延伸有关;中国南海北部（12°N以北）及西太平洋为气旋性环流盘踞,季风槽加深。中国南海南部季风平均动能增强的能量源自于扰动动量通量与平均环流的相互作用,强季风年,平均环流失去较少的动能给扰动场（亦即平均环流保留较多的动能）。通过进一步探讨高频（<10 d）及低频（10-90 d）扰动场与平均环流不同分量的（散度、涡度、风垂直切变）相互作用过程,发现季风平均动能的增长主要来自于<10 d扰动与季风平均散度和涡度的相互作用。中国南海北部季风槽区季风平均动能的维持来自于大气热源和平均上升运动的相互作用,但同时有较多的季风平均动能向扰动动能转换,有利于扰动的成长。因此,强季风年,中国南海北部热带气旋生成数目增多,夏季北传的季节内振荡也增强,导致中国南部沿海及华南地区出现较多的灾害天气。