三峡库区特大滑坡灾害防治工程评价方法初探

以三峡库区特大滑坡灾害为研究对象,汇总、分析了库区72处特大滑坡灾害的防治工程措施,总结了三峡库区特大滑坡灾害防治技术的特点。通过对三峡库区特大滑坡灾害防治工程的基本类型与防灾特点的分析,建立了特大滑坡灾害防治措施的评价指标体系,并依照评价指标和标准对滑坡灾害防治工程效果进行分级。     

长江下游感潮河段大洪水和特大洪水的形成及趋势

分析了长江下游感潮河段大洪水和特大洪水高水位形成的水文因素,揭示了年最高水位今后一段时期内可能的变化趋势。主要结论是:该河段大洪水和特大洪水高水位的形成原因十分复杂,本世纪以来每次大洪水和特大洪水高水位的形成几乎都有其主要原因;该河段大洪水特大洪水高水位出现的频次有增加趋势;自1975年以来,年最高水位的均值呈明显的升高趋势,其主要原因是人类活动对防洪产生的负面影响,海平面上升也有一定的影响。     

Evolution of an Ancient Large Lake in the Southeast of the Northern Tibetan Plateau

Nam Co is the largest (1920 km2 in area) and highest (4718 m above sea level) lake in Tibet. According to the discovery of lake terraces and highstand lacustrine deposits at several places in Nam Co and its adjacent areas, the authors confirm the existence of an ancient large lake in the southeastern part of the northern Tibetan Plateau. On the basis of the U-series, 14C and ESR dating, coupled with the levelling survey of lake deposits and geomorphology, the evolutionary process of the ancient large lake in the southeastern part of the northern Tibetan Plateau may fall into three stages: (1) the ancient large lake stage at 115-40 ka BP, when the ancient lake level was 140-26 m above the level of present Nam Co; (2) the outflow lake stage at 40-30 ka BP, when the ancient level was 26-19 m above the present lake level; and (3) the Nam Co stage since 30 ka BP, when the ancient lake level was < 19 m above the present lake level. During the ancient large lake stage, a large number of modern large, medium-siz     

燕山地区中元古代常州沟组潜穴化石

在燕山地区中元古代常州沟组中发育有大量的潜穴化石，潜穴产于常州沟组中部的泥质粉砂岩中。潜穴呈个体较大的直管状，垂直层面保存。这是我国迄今为止发现的最古老的遗迹化石，表明在距今近1800Ma前就已出现古老的后生动物，这对于研究后生动物的起源及演化具有重要意义。     

Numerical studies on the influence of the variations of the Kuroshio Path on the transport of fish eggs and larvae

Main spawning and nursery grounds of the Pacific Sardine are formed in the coastal boundary regions of the Kuroshio S of Kyushu and S of Honshu, respectively. Numerical experiments on the transport and dispersion of particles in and neighbouring areas of the Kuroshio were done to investigate the transport process of the fish eggs and larvae from the spawning ground to the downstream nursery ground. Surface currents measured with GEK in the past were averaged for both paths with and without large meanders of the Kuroshio in the S of Honshu and used as the data basis. Particles were released in the Kuroshio SE of Kyushu. The results show that the transport rate of them into the S coastal waters of Honshu during large meandered path is larger than the rate during the straight path period. However, recruitment rates of the Pacific Sardine in the S coastal waters of Honshu decreases during the large meander periods of the Kuroshio path. This inverse correlation is considered to be caused by the poorer food environment strongly influenced by the intrusion of the Kuroshio water.     

Major element composition of the pelites of the Scottish Dalradian

Major element composition of the available analysed pelitic rocks of the Dalradian of Scotland is examined in relation to geographical position, mineralogy, metamorphic grade and stratigraphy. Some of the large variations found are due to geographical position, possibly reflecting different provenance. A major compositional difference exists between the two lower Barrovian metamorphic zones and the four higher zones. This is considered to be a reflection of the original sedimentary composition and large scale metasomatism is not considered likely.     

Predicted new large oil pools in the main petroliferous belt of the Lena-Tunguska province

Almost all the gas-oil and oil-gas fields in the Lena-Tunguska province (Siberian Platform) were discovered in the Baikit, Katanga, and Nepa-Botuobiya petroliferous regions, which form an E-W-striking band. The latter, named “the main petroliferous belt,” includes one giant and 11 large fields (by recoverable oil reserves).New large oil pools are predicted within the main belt. The prediction is based on the analysis of geological data and the quantitative estimation of hydrocarbon resources. Promising areas with large fields in the Baikit, Katanga, and Nepa-Botuobiya petroleum regions are substantiated.     

Long-period ground motion in the epicentral area of major earthquakes

In view of the potential importance of long-period ground motion in the design of large structures, near-field ground displacement is computed by the elastic dislocation theory for several earthquake fault models. The validity of such computations is confirmed by comparing the computed seismogram with the observed long-period seismogram of the 1923 Kanto earthquake. The ground motions are computed for three hypothetical earthquakes, a hypothetical Kanto earthquake, Tokai earthquake and Nemuro-Oki earthquake. The location and the nature of the faulting of these earthquakes are predicted by plate tectonics and precise earthquake mechanism studies. Major conclusions are: Tokyo may suffer, in the hypothetical Kanto earthquake, ground motions about half as large as those experienced in the 1923 Kanto earthquake; Hamamatsu, a large city on the Tokai coast, may experience in the hypothetical Tokai earthquake ground motions which are as large as, or even larger than, those experienced in the epicentral area of the 1923 Kanto earthquake; the hypothetical Nemuro-Oki earthquake may cause ground motions as large as those experienced in the 1968 Tokachi-Oki earthquake on the coastal cities in Hokkaido.     

近30 a来雅鲁藏布江流域冰川系统特征遥感研究及典型冰川变化分析

综合运用RS和GIS手段, 利用卫星遥感影像, 结合中国第一次冰川编目数据及数字高程模型(DEM), 获取了雅鲁藏布江流域不同朝向上冰川面积分布、 冰川面积随高度带分布状况统计结果, 及3个冰川聚集区21条大型海洋性冰川在1976、 1988、 2005年的冰川面积、 厚度、 冰储量及物质平衡线等基本参数, 丰富了该研究区相关冰川信息, 并统计分析了21条大型冰川面积变化状况及与气候变化的响应关系. 研究表明: 3个区域冰川在1976-1988年和1988-2005年时间段内随着气温、 降水的变化出现了相应的波动, 但总的来说在1976-2005年间, 这21条大型海洋性冰川并没有出现明显的前进或退缩现象, 这可能是由于降水的增加抵消了气温升高给冰川积累带来的不利影响, 也可能是由于大型冰川在高海拔地区有较大的积累区补给造成的, 进一步的研究亦在进展中.     

乌石凹陷南部陡坡带流二段大型储集体发育条件及特征

综合钻井、古生物、地震、薄片等资料,分析了乌石凹陷南部陡坡带大型储集体的发育条件、类型、特征及有利勘探方向。研究结果认为:提出湖平面、物源、断裂及古地貌等耦合控制了断陷湖盆陡坡带大型储集体的发育,其中强烈的湖退事件是发育大型储集体的古湖盆演化基础;充足的物源供给是形成大型储集体的物质保证;显著的断裂聚砂效应和适宜的地貌条件是构建大型储集体的重要汇水机制。大型储集体的主要类型为扇三角洲和辫状河三角洲,其中扇三角洲主要受断面缓坡带及沟谷地貌的控制,沉积上岩性较粗,微相以水下分流河道和水下分流间湾为主;辫状河三角洲主要受转换断阶带、帚状断阶带及相对宽缓地貌的控制,沉积上岩性较细,微相除水下分流河道、水下分流间湾以外,河口坝及远砂坝也较为发育。在此基础上,结合大型储集体的发育特征,明确了乌石凹陷南部陡坡带东段的有利勘探层系为流二段下层序高位域,西段的有利勘探层系为流二段上层序低位及湖侵域;而各大型储集体的前端,由于岩性圈闭、岩性-构造圈闭及构造圈闭等发育,且埋藏浅、靠近生烃中心,还位于油气运聚的优势方向,为有利的勘探区域。     

气藏盖层封气能力评价方法的改进及应用——以我国46个大中型气田为例

通过统计我国46个大中型气田得到盖层厚度、排替压力、断裂对盖层破坏程度、气藏压力和天然气粘度是影响我国大中型气田盖层封气能力的主要因素。根据这5个主要因素与盖层封气能力作用关系,改进了气藏盖层封气能力评价方法,利用此方法对我国46个大中型气田盖层封气能力进行了评价,结果得到我国46个大中型气田盖层封气能力等级以差为主,其次是中等封盖保存能力的大中型气田,再次是好封盖保存能力的大中型气田,最少为较好封盖保存能力的大中型气田。通过我国46个大中型气田盖层封气能力与其储量丰度之间关系研究得到,二者之间为正相关关系。中等盖层封气能力的大中型气田平均储量丰度最高;其次是较好盖层封盖保存能力的大中型气田;最低的是好和差盖层封盖保存能力的大中型气田。这表明盖层封气能力并不是我国高储量丰度大中型气田形成的唯一主控因素,其储量丰度高低还要受到其它成藏条件的制约。     

淮河流域大型水库联合优化调度的动态规划模型解

淮河流域暴雨洪水频繁,常常遭遇恶劣雨型的组合。为使大型水库群在大范围暴雨洪水期间综合效益达到最优,采用动态规划模型求解淮河流域大型水库群的联合优化调度问题,利用国产曙光１０００巨型计算机的高速度和大容量的优势,解决了优化中的“维数灾”和“网格灾”问题,给出了淮河流域９个大型水库联合优化调度模型极效地提高了防洪水库的利用率。     

H型钢组合支撑在地铁基坑中的应用研究

H型钢组合支撑具有可回收、高强连接、可施加预应力、可靠性高等优点,在国内的应用不断增多.房建基坑中应用的H型钢组合内支撑体系,竖向支撑结构较多,不能很好地适应地铁基坑的土方开挖要求.以地铁工程中常见的标准车站基坑(宽度约20 m)为例,通过计算对比分析,设计出大跨度、大间距的H型钢组合内支撑截面型式,相较于传统钢管支撑...     

浅层不均匀体对大定源瞬变电磁响应的影响

根据瞬变电磁法基本原理,当大定源发射回线下方存在局部不均匀体时,由于不均匀体在接收线圈中产生的二次场方向不同,导致衰减曲线与均匀大地响应曲线偏离。为了分析浅层不均匀体对衰减曲线的影响,采用大定源回线装置发射电流为梯形波,回线面积为150 m×150 m,电流波形为梯形波,幅值为10 A,关断时间为176 μs;对于时间常数分别为1、3、5 ms的浅层不均匀体,利用多匝密绕的闭合线圈（即异常线圈模型）的电磁信号衰减规律,来模拟其响应衰减曲线。研究表明,当异常线圈位于发射回线下方或者是框边下方时,随着发射、异常、接收之间的相对位置的变化,三者之间的互感发生变化,引起异常线圈的响应可能为负值,致使接收到的综合响应衰减曲线出现过0情况。因此,大定源回线结构下存在不均匀体时,产生的负响应值在后续处理时需要引起注意。     

An Exploration into the West Henan Large Sliding Structure in the South of the North China Plate

The West Henan large sliding structure is located in the southern part of the North China plate. It is a planar structural feature of a relatively large scale. To its northwest lie the Taihang Mountains, and to the southwest the Funiu Mountain. In the east it extends between the broad plain and hilly land. Formed in the early Indosinian Period, its main sliding surface is the coal seam II 1 with the sliding direction from NW to SE, and a sliding area of about 23,000 km2. Affected by the big sliding, the coal seam II1 in West Henan occurs in the state of powder, and thickens to the SE. Some small penetrating sliding structures were developed over II 1 in the early Yanshanian Period, causing a disorder on the south border of the North China coal-accumulating basin in the late Palaeozoic Era. An exploration into the West Henan large sliding structure is of great importance in the geological study.     

Petrology of the mafic rocks of the Xigaze ophiolite,Tibet

The Xigaze ophiolite (Yarlung-Zangbo suture zone, Southern Tibet, China) shows an unusual crustal sequence characterized by a lack of large masses of cumulate gabbros, by dolerites intrusive throughout the whole ophiolite sequence, and by the injection of dolerites in already serpentinized peridotites. The abyssal tholeiitic nature of all the mafic rocks indicates that they have been generated at an oceanic ridge. All the geological arguments and petrological and textural data on the mafic rocks point to very low heat production and large heat losses through widespread intensive sea-water circulation, for the spreading centre in which they have been formed, in good agreement with a slow-spreading ridge origin.     

Occurrence patterns of large earthquakes in the seismic zones along the Hellenic Arc

Occurrence patterns of large shallow and intermediate depth earthquakes in the seismic zones along the Hellenic Arc have been investigated. It is shown that throughout this active region the earthquakes tend to occur in a rather systematic manner. At each time-period earthquakes occur within a discrete activated segment of the arc. These occurrence patterns are considered to offer an insight into identifying where large earthquakes are expected to occur in the future.     

Development of the distinct lattice spring model for large deformation analyses

This study develops the distinct lattice spring model (DLSM) for geometrically nonlinear large deformation problems. The formulation of a spring bond deformation under a large deformation is derived under the Lagrange framework using polar decomposition. The results reveal that the DLSM's stiffness matrix under small deformations is the tangent stiffness matrix of the DLSM under large deformations. The formulation of the spring bond internal force under a given configuration is also presented and can be used to calculate the unbalanced force. Using these formulations, three nonlinear solving methods (the Euler method, modified Euler method, and Newton method) are developed for the DLSM with which to tackle large deformation problems. To investigate the performance of the developed model, three numerical examples involving large deformations are presented, the results of which are also in good agreement with the analytical and finite element method solutions. Copyright © 2013 John Wiley & Sons, Ltd.     

Perspectives of the discovery of large and unique noble metal deposits in the northeastern Siberian Platform

Geological prospecting indicators of a potential presence of the Witwatersrand-type large and superlarge noble metal deposits containing optional Pt, Ir, Os, Rh, U, and diamond are presented. Perspective areas of native gold concentration in the northeastern Siberian Platform are indicated. Gold metallogeny of this region was basically developed in Early Precambrian in association with greenstone belts and granulitegneiss complexes. Promising zones with noble metal mineralization encompass large areas at the junction of tectonic provinces.