层状大地频率域长导线源激发的电磁场

采用Fourier变换法从Maxwell方程组出发,导出了层状大地模型上接地长导线源激发的电磁场表达式。结果表明：接地长导线源实际上是2个接地电极和线电流源构成的一个组合源;其电磁场表达式表明平行于长导线方向的电场分量为2个接地电极激发的平行于长导线方向的电场分量和线电流激发的电场的叠加,垂直于长导线方向的电场分量和电场的垂直分量均是2个接地电极激发的;平行于长导线方向的磁场分量由2个接地电极所激发,而垂直于长导线方向的磁场分量为2个接地电极激发的垂直于长导线方向的磁场分量和线电流激发的磁场的叠加,磁场的垂直分量为线电流源所激发。进一步的结果分析表明,在均匀半空间上、大收发距时,2个接地电极激发的平行于长导线方向的电场分量和线电流激发的电场分量是相等的,2个接地电极激发的垂直于长导线方向的磁场分量和线电流激发的磁场分量是相等的,且它们的振幅与2个电极之间的距离成正比。     

Effects of iron black varnish on petrophysical properties of building sandstone

In zones washed by rain (façades, pinnacles, pilasters), fine siliceous sandstones are covered by a black varnish, which gives a dirty appearance to monuments. In composition, structure and areas covered by it, it differs from the usual black gypsum crust. Experiments carried out on blocks covered by black varnish show the modifications due to their growth. Results show that despite their low thickness and the coherence of the stone below, the accumulation of hydrophobic matters and the wetting-drying cycles modify the transfer properties of sandstones several centimeters below the surface. Thus, although sandstones seem to be protected by the black varnish, in the long run, a flake detachment process, in the areas covered by it, affects them. Therefore, damage to sandstones by black varnish can be explained by the fact that a wetting and drying cycle modifies the pore network.     

非饱和膨胀土边坡的稳定性分析

为了提高非饱和膨胀土边坡的稳定,采用了土工膜覆盖边坡表面的方法.基于非饱和渗流理论,采用有限元程序对用膜覆盖和不覆盖的边坡分别进行了降雨蒸发干湿循环条件下的数值分析.在计算结果基础上,采用极限平衡法分析了边坡的稳定性.结果表明,用膜覆盖后边坡能长期保持非饱和状态,土体吸力较高,其稳定安全系数明显高于无膜保护的边坡,用复合土工膜覆盖边坡有利于提高非饱和膨胀土边坡的稳定.     

大牛地气田水平井通井卡钻处理

卡钻的处理方法主要有：通过施加外力如上提、下放钻具转动转盘使钻具恢复自由状态;通过调整钻井液性能、打稠塞、注酸、注解卡剂、反循环等方法使被卡钻具与井壁之间的填充物转移或者破坏;通过反丝钻具打捞甚至套铣起出被卡钻具。大牛地气田DPT-305水平井通井过程中发生一起严重的卡钻事故。通过重浆+清扫液、注酸、注解卡剂、环空憋压等方法处理被卡钻具与井壁之间的填充物;通过固定转盘上下活动来对被卡钻具施加扭矩;倒扣等方式处理这起卡钻事故,最终解卡。总结了事故的成因,分析了处理过程的得失,为以后处理此类事故积累了经验。     

用解析延拓求取剩余磁异常来圈定浅部隐伏磁铁矿脉

剩余磁异常求取是一种对磁场强度进行化极,解析延拓后提取浅部磁性介质异常的高通滤波方法。对于处于强磁性围岩的磁铁矿脉来说,浅部磁铁矿脉的异常往往被大规模的磁性围岩所引起的异常所掩盖。磁场强度与场源到测点距离的平方(二度体)或者立方(三度体)成反比,进行向上延拓的时候,由浅部场源引起的高频异常衰减快,深部场源引起的低频异常衰减的慢,因此地面实测磁场去掉向上解析延拓后的磁场值,可突出反映近地表磁性体引起的高频异常。这里通过解析延拓求取剩余异常,实现浅部磁铁矿脉异常信息的提取,为寻找隐伏的磁铁矿脉提供依据。并且利用此方法在秘鲁共和国Morritos铁矿圈定隐伏磁铁矿脉,验证了剩余异常在大规模的高磁性围岩中寻找隐伏磁铁矿脉的应用效果。     

曲线翼型裂纹扩展路径理论分析及试验验证

采用数值和试验的方法对翼型裂纹的扩展路径进行分析,发现单轴下张开型裂纹的翼型裂纹的扩展路径逼近于过原主裂纹中心点、平行于最大主应力的一条直线。基于翼型裂纹路径这个特点,采用了双曲线参数方程近似表达真实翼型裂纹的扩展路径,通过翼型裂纹的起裂角、起裂点及翼型裂纹的渐近线方程求解了双曲线方程中的未知参数。采用双曲线翼型裂纹路径和试验中所得翼型裂纹路径进行了对比分析,二者吻合得很好,验证了采用双曲线近似表示真实存在的翼型裂纹模型的正确性。应用双曲线翼型裂纹模型对翼型裂纹的扩展和失稳进行分析,采用ABAQUS求解了双曲线翼型裂纹模型的应力强度因子,并与试验进行对比,发现双曲线翼型裂纹模型能很好地解释翼型裂纹的实际扩展规律,这表明了采用双曲线近似表示真实翼型裂纹路径的有效性。     

Investigation of the Structure of Geological Process through Multivariate Statistical Analysis—The Creation of a Coal

The purpose of this study was to capture the structure of a geological process within a multivariate statistical framework by using geological data generated by that process and, where applicable, by associated processes. It is important to the practitioners of statistical analysis in geology to determine the degree to which the geological process can be captured and explained by multivariate analysis by using sample data (for example, chemical analyses) taken from the geological entity created by that process. The process chosen for study here is the creation of a coal deposit. In this study, the data are chemical analyses expressed in weight percentage and parts per million, and therefore are subject to the affects of the constant sum phenomenon. The data array is the chemical composition of the whole coal. This restriction on the data imposed by the constant sum phenomenon was removed by using the centered logratio (clr) transformation. The use of scatter plots and principal component biplots applied to the raw and centered logratio (clr) transformed data arrays affects the interpretation and comprehension of the geological process of coalification.     

The Middle–Late Jurassic forced regression and disconformity in central Portugal: eustatic, tectonic and climatic effects on a carbonate ramp system

Abstract Successions across the Middle–Upper Jurassic disconformity in the Lusitanian Basin (west‐central Portugal) are highly varied, and were probably developed on a large westward‐inclined hangingwall of a half‐graben. The disconformity is preceded by a complex forced regression showing marked variations down the ramp, and provides an example of the effects of rapid, relative sea‐level falls on carbonate ramp systems. In the east, Middle Jurassic inner ramp carbonates (‘Candeeiros’ facies) are capped by a palaeokarstic surface veneered by ferruginous clays or thick calcretes. In the west, mid‐outer ramp marls and limestones (‘Brenha’ facies) are terminated by two contrasting successions: (1) a sharp‐based carbonate sandbody capped by a minor erosion surface, overlain by interbedded marine–lagoonal–deltaic deposits with further minor erosion/exposure surfaces; (2) a brachiopod‐rich limestone with a minor irregular surface, overlain by marls, lignitic marls with marine and reworked non‐marine fossils and charophytic limestones, with further minor irregular surfaces and capped by a higher relief ferruginous erosional surface. The age ranges from Late Bathonian in the east to Late Callovian in the west. This disconformity assemblage is succeeded by widespread lacustrine–lagoonal limestones with microbial laminites and evaporites (‘Cabaços’ facies), attributed to the Middle Oxfordian. Over the whole basin, increasingly marine facies were deposited afterwards. In Middle Jurassic inner‐ramp zones in the east, the overall regression is marked by a major exposure surface overlain by continental sediments. In Middle Jurassic outer‐ramp zones to the west, the regression is represented initially by open‐marine successions followed by either a sharp marine erosion surface overlain by a complex sandbody or minor discontinuities and marginal‐marine deposits, in both cases capped by the major lowstand surface. Reflooding led to a complex pattern of depositional conditions throughout the basin, from freshwater and brackish lagoonal to marginal‐ and shallow‐marine settings. Additional complications were produced by possible tilting of the hangingwall of the half‐graben, the input of siliciclastics from westerly sources and climate change from humid to more seasonally semi‐arid conditions. The Middle–Late Jurassic sea‐level fall in the Lusitanian Basin is also recorded elsewhere within the Iberian and other peri‐Atlantic regions and matches a transgressive to regressive change in eustatic sea‐level curves, indicating that it is related in part to a global event.     

考虑注浆压力的顶管施工引起土体变形计算方法

顶管施工引起周围地层变形的计算预测是顶管施工中必须加以重视的问题。地层的沉降变形与顶管施工的几个环节有密切的联系,如：①顶管姿态与开挖面土压;②顶进与换管;③注浆过程等。理论分析应考虑这几个施工中的关键因素。针对上述施工影响因素,提出了考虑注浆压力的顶管施工的地层移动的计算方法。用Mindlin的位移解分析模拟开挖面土压、顶进与换管过程中的侧面摩擦力的变化引起的位移;以Sagaseta的土体损失引起的土体位移模式分析姿态控制、土体损失等引起的变形;将圆孔扩张的Verruijt解拓展到三维,用于计算注浆压力引起的位移与变形。结果表明,考虑注浆压力的变化,可以得到更为合理的预测结果。     

混积岩的分类和成因

对在混合作用的特征者了系统的阐述和讨论,混积岩是陆源碎屑和碳酸盐颗粒及灰泥混合在一起的沉积岩,属曲型陆源碎屑岩和碳酸盐岩之间的过渡类型,据其成分可分为４类,陆源碎屑和碳酸盐颗粒,灰泥的混合作用从成因上分为５种类型,副件突变沉积混合,相缘渐变沉积混合,原地沉积混合,侵蚀再沉积混合,岩溶穿插再沉积混合。     

交通荷载作用下地基中Love波的传播特性

Love波的传播特性对动力响应和工程勘探都具有重要意义。运用解析法建立了交通荷载作用下双层地基中Love波的特征方程和位移表达式,并对方程进行了求解,得到了不同交通荷载情况下地基中Love波的弥散特性和位移分布情况。结果表明,交通荷载作用下Love表面波的传播速度不仅与土层的剪切波速度有关,而且与土层的压缩波速度有关。     

Microstructural evidence of rotation and non-rotation of mica porphyroblasts

Abstract Mica porphyroblasts in schists from several regions show nearly planar inclusion trails that are parallel over areas much larger than the wavelengths of later folds. This indicates that the porphyroblasts have not rotated, with respect to geographical co-ordinates, during deformation. Instead, the matrix has rotated, as suggested by Ramsay (1962). Even in zones of marked shortening in the matrix adjacent to large rigid porphyroblasts (e.g. of cordierite or staurolite), small biotite porphyroblasts have not rotated, but have become thinned by solution, as indicated by parallelism of inclusion trails in separate biotite grains and by evidence of truncation of inclusion trails by the matrix foliation. Less common are biotite porphyroblasts that have single asymmetrical microfolds in the matrix adjacent to the porphyroblasts and so appear to have rotated; these porphyroblasts are characterized by kinking.     

重建古气温的环境证据-方法差异性分析

重建过去气温是PAGES关注的焦点之一,由于环境证据类型与重建的方法不同,重建的古气温记录存在一定差异。环境证据类型中孢粉、植物硅酸体、综合证据、氧同位素、冰川-冰缘重建同一时段、同一地点的气温依次降低,孢粉与植物硅酸体指示的气温最为接近,综合证据与氧同位素较接近;这说明孢粉重建的气温数值偏高,冰川-冰缘证据偏低,它们分别主要指示了植物生长季节和冬半年或冷期的气温;而综合证据与氧同位素则可能比较接近实际气温。按照重建方法,转换函数法重建的全新世气温记录普遍高于自然地理因子指示法,而自然地理因子指示法重建的温度记录变化幅度更大(尤其是冷事件),说明因子指示法重建的气温记录对于百年尺度的极端事件记录更为灵敏。     

多排孔注浆引起土体变形与孔压规律试验研究

目前尚未见到软土地区多排孔注浆引起土体变形和超孔压发展规律的系统研究,限制了注浆变形主动控制策略的深化发展。开展了多排孔注浆现场试验,系统研究了单排孔逐孔注浆、多排孔逐排注浆引起土体水平位移和超孔压的变化与叠加规律。研究表明,注浆引起的超孔压随距离衰减迅速,变化规律可用幂函数表达,注浆距离取3 m左右时纠偏效果较好;天津地区超孔压消散较快,有利于注浆控制变形的快速稳定,超孔压随时间的消散规律可用指数函数表达,并提出了计算注浆引起超孔压的经验公式;多排孔逐排注浆时,先行注浆形成的注浆体墙对后续注浆一侧及另一侧土体变形分别具有反力效应和遮挡效应,控制既有建构筑物变形时应遵循“先远后近”逐排注浆的原则,以提高变形控制效果。     

压力分散型锚索作用效果的数值模拟分析

通过FLAC3D程序,用实体单元模拟了岩体和砂浆体,用结构单元来模拟锚索,在砂浆体和岩体间设置接触面,对锚索施加预应力时采用新的建模方法,即通过结构单元来模拟压力分散型锚索的承压板,代替在承压板的位置施加均布力的方法,建立预应力锚固数值仿真模型.通过模拟试验,分析了接触面单元、岩体单元以及砂浆体单元的应力云图等,更加清晰地显示了压力分散型预应力锚索作用下岩体沿锚索轴向的应力、砂浆体与孔壁之间的粘结应力分布等情况.     

基于6S模型的MODIS影像逐像元大气校正及其应用

以获取地物真实反射率为目的,介绍了逐像元大气校正的方法。应用6S模型逐像元综合考虑太阳天顶角、传感器天顶角、相对方位角、大气气溶胶厚度、观测波段以及地表海拔这6个参数,生成查找表,统计分析各参数关于反射率的敏感度;并与以往单一参数校正的方法比较了校正的效果。结果表明,逐像元大气校正算法更加接近地物的真实反射率。利用MODIS地表反射率产品对大气校正的结果进行验证,单一参数、逐像元大气校正的相对误差分别控制在26.9%和12.7%以内;在以植被指数(NDVI)为例的后续遥感定量化反演过程中,逐像元比单一参数大气校正方法计算的NDVI平均高出14.4%。     

注入水对地层伤害的评价

通过不同水样的岩心驱替实验，研究了注入水质对岩心渗透率的伤害率。结果表明：①现场注入水对岩心渗透率的伤害率大于50％；②注入处理不彻底的水后岩心渗透率的伤害变小，但伤害深度变大；③薄膜过滤后的水和处理后的水对岩心的伤害率基本相同；④注入水质应按处理后的水质指标控制。     

Migration of lignosulfonates in a karstic-fractured-porous aquifer: History and prognosis for a Zn-Pb mine,Pomorzany, southern Poland

Lignosulfonate lyes, which had been deposited by a paper factory for about 50 years into Quaternary sediments and accumulated in a quasistagnant depression, became mobile when a depression cone caused by mine activity in a deeper aquifer reached the erosion window close to the disposal site. Their transport parameters in the karstic-fractured-porous carbonate aquifer are shown to be mainly governed by diffusion between the mobile water in karstic channels and fractures and the stagnant water in matrix, although the hydraulic conductivity is shown to depend mainly on the karstic system. The main transport velocity is, with a sufficient accuracy, related to the hydraulic conductivity by a simple model in which matrix porosity is the governing rock parameter. The dispersivity, although also governed by matrix diffusion, depends strongly on several parameters that are difficult to determine.     

翡翠与相似玉石及仿制品的仪器鉴定

翡翠和相似玉石及仿制品肉眼下真假难辨,需借助仪器进行鉴定。常规仪器下的鉴定是根据其相关数据和结构特征判定;用红外光谱仪则是根据光谱图特征识别。通过常规仪器和红外光谱仪两种鉴定方式进行比较,得出红外光谱仪能更完全正确地对各类型玉石进行正确判断。     

The relationship between saline groundwater within the Arava Rift Valley in Israel and the present and ancient base levels as detected by deep geoelectromagnetic soundings

The time domain electromagnetic (TDEM) geophysical method was employed to detect saline groundwater bodies within and in the close margins of the Arava Rift Valley. The Arava Valley aquifers are known to occupy fresh to saline groundwater. The lateral subsurface inflow to the Arava from west and east is characterized by fresh to brackish waters. The results of the present study indicate that salination of groundwater is controlled by both present day and ancient base levels, namely by the Dead Sea in the north and by the Gulf of Elat in the south. The configuration obtained by the TDEM survey exhibits interfaces and palaeo-interfaces between fresh to brackish waters and underlying seawater or diluted seawater intruded inland from both base levels as well as brines intruded from the northern base level. The central Arava structural and hydrological divide seems to escape seawater or brine encroachment at least to the considerable depth of the TDEM measurements.