On the number and spacing of faults

Orogens and rift zones have a finite number of regional faults. The accretionary prisms analysed here have a number of thrusts < 50, whereas extensional areas have a number of normal faults ranging between six and 44. The average spacing of thrusts is between 5 and 25 km; spacing of normal faults is more restricted into two peaks, at 25–29 km and 4–6 km, in which the latter is the most common. The number and spacing of faults appear to be mainly controlled by the depth of the decollement plane, which seems to be more variable in compressive settings with respect to rift zones. Basement‐involved orogens present fewer and more spaced thrusts; by contrast, a greater number of thrusts with shorter spacing characterize thin‐skinned thrust belts. The shallower the decollement is, the stronger it appears to control the palaeogeography, in the sense of rheological lateral variations in the sedimentary cover.     

Rehabilitation of asbestos mining waste: a Rehabilitation Prioritisation Index (RPI) for South Africa

The much publicised problem with major asbestos pollution and related health issues in South Africa, has called for action to be taken to negate the situation. The aim of this project was to establish a prioritisation index that would provide a scientifically based sequence in which polluted asbestos mines in Southern Africa ought to be rehabilitated. It was reasoned that a computerised database capable of calculating such a Rehabilitation Prioritisation Index (RPI) would be a fruitful departure from the previously used subjective selection prone to human bias. The database was developed in Microsoft Access and both quantitative and qualitative data were used for the calculation of the RPI value. The logical database structure consists of a number of mines, each consisting of a number of dumps, for which a number of samples have been analysed to determine asbestos fibre contents. For this system to be accurate as well as relevant, the data in the database should be revalidated and updated on a regular basis.     

Construction and systematic assessment of relative deformation histories

The systematics of deformation histories have been investigated using basic combinatorial mathematics. Using this approach, the number of deformation histories and the number of relationships associated with a given number of structures can be calculated. The range of possible deformation histories can also be determined. Using this information, the ambiguous nature of all deformation histories is examined together with the impact of unobserved relationships. The number of possible deformation histories that are compatible with a collection of age relationships is used as a crude measure of confidence in those histories. A procedure is described for the construction of deformation histories that is systematic, repeatable and rapid and within which ambiguities can be easily recognised.     

检波器数量对组合压噪能力的影响

根据组合压噪的有关理论,在其他因素不变的情况下,采用数量越多的检波器,组合压制干扰波的效果越好。这使得人们认为在施工中应该采用尽量多的检波器以提高资料的信噪比。但是通过分析组合中检波器数量对规则干扰波,随机干扰波以及耦合高频微震衰减的影响证明:在其他因素不变的情况下,线性等灵敏度组合增加到"γ_max+3"个检波器以后(其中γ_max=组合基距/最小干扰波视波长), 组合对于规则干扰波的衰减能力不再随着检波器数量的增加而显著提高。在组合基距确定的情况下,检波器数量越多,对随机干扰的衰减越明显(包括在组内距小于随机干扰相关半径的情况下);但是增加到一定数量后,衰减效果不再出现明显变化。检波器数量的多少对衰减耦合高频微震没有明显作用。同时指出,确定组合中合理的检波器数量要与组合的摆放形式相结合;组合图形不合理的情况下,增加检波器数量不会显著提高组合的压噪能力;灵敏度分布不合理,是导致组合压噪能力降低的重要原因。在线性等灵敏度组合的基础上,利用玫瑰图进行分析,可以确定工区面积组合(包括道间混波后)中使用的合理的检波器数量。     

ERRATA

The following corrections should be made to Figs. 9, 13 and18. (1) Fig. 9. The time value in the uppermost left domain plotshould read 50 000 years. (2) Fig. 13. The number labels (1, 2) on the curves in the uppermostleft plot should be reversed. (3) Fig. 18. The number labels (1, 2) on the curves in the lowermostright plot should be reversed.     

一个值得重视的水文地质问题：地下水位持续上升

地下水位持续上升问题已成为当前一个国际性问题，上升的原因是多方面的，主要是水质恶化和开采量减少。地下水位持续上升带来一系列水文地毯，环境和建筑工程问题，可采取一定措施加以预防和治理，其方法是以数值法为手段，进行水质水量模拟预报，预防，处理相应的水危害和规划城市建设。     

长江流域夏季日面雨量精度与不同站数间关系研究

为探讨不同测量站配置数对统计长江流域夏季日面雨量精度的影响,选取金沙江下游、鄂东北、青弋水阳江3个流域作为研究对象,并挑选出不同站网分布,统计各站网分布计算的2016—2018年夏季日面雨量,运用平均绝对误差（MAE）、均方差（MSE）和相关系数（r）三个技术指标来评价各流域夏季日面雨量精度与站数之间的关系。结果表明：各流域夏季日面雨量精度均受站数变化的影响,MAE、MSE均随站数的增加而减小,但当站数增加到一定数量之后趋于稳定,r也有相同的变化规律,只是随站数增加而增大。同时,通过计算三个技术指标随站数平均变化值,定量揭示了以上变化规律并得到金下、鄂东北、青弋水阳江流域代表性站数分别为405站、293站、126站,与现有站数相比,分别减少25.1%、55.8%、56.6%,可为计算长江流域夏季日面雨量选用站数和站网布局提供参考。     

Environmental implication on chamber accretion of <Emphasis Type="Italic">Neogloboquadrina pachyderma</Emphasis> (Ehrenberg) in southern Indian Ocean

Morphological variations with respect to the number of chambers in Neogloboquadrina pachyderma (Ehrenberg) were investigated in 25 surficial sediments of Indian Ocean taken along the N-S transect between 9.69° N and 55.01° S latitude and 80° E and 40° E longitude. The number of chamber was counted for at least 40 specimens picked for each sample. The average number of chamber was correlated with the average temperature and salinity along the changing latitude. The results showed a high correlation between the number of chambers and temperature and salinity. It was noted that number of chambers decreases from equatorial to polar region. The carbonate saturation and nutrient availability could possibly be other causes for the change in number of chambers. The results of this study, if applied on the subsurface marine sediments, will bear implications on paleoclimatic condition in the Indian Ocean region.     

Radio spectra of objects in the RATAN-600 RZF catalog and a population analysis of faint radio sources

Results of centimeter-wavelength RATAN-600 observations of several hundred NVSS objects with a wide range of flux densities are presented. Changes in spectral-index distributions from strong-to faint-object populations are estimated. In the transition from strong to faint radio sources, the number of steep-and ultrasteep-spectrum objects decreases and the minimum between steep-and flat-spectrum objects, which was first discovered in the 1970s, becomes less distinct. A less certain increase in the fraction of inverted-spectrum objects is also found. Comparison with theoretical models of radio-source evolution suggests that the decrease in the number of steep-and ultrasteep-spectrum objects can be naturally explained by a sharp decrease in the fraction of classical FRII radio galaxies. The decrease in the sharpness of the minimum may be due to the growing contribution from the population with spectral indices 0.7–0.5, which is usually identified with starbust galaxies. The small increase in the fraction of inverted-spectrum radio sources can be attributed to the growing number of objects with active nuclei. Our spectrum-based conclusions are confirmed by the morphology of the FIRST Catalog images. The number of radio sources associated with supermassive black holes in the Early Universe is estimated using data from the SDSS Catalog.     

Efficient reservoir history matching using subspace vectors

In this paper, we describe a method of history matching in which changes to the reservoir model are constructed from a limited set of basis vectors. The purpose of this reparameterization is to reduce the cost of a Newton iteration, without altering the final estimate of model parameters and without substantially slowing the rate of convergence. The utility of a subspace method depends on several factors, including the choice and number of the subspace vectors to be used. Computational gains in efficiency result partly from a reduction in the size of the matrix system that must be solved in a Newton iteration. More important contributions, however, result from a reduction in the number of sensitivity coefficients that must be computed, reduction in the dimensions of the matrices that must be multiplied, and elimination of matrix products involving the inverse of the prior model covariance matrix. These factors affect the efficiency of each Newton iteration. Although computation of the optimal set of subspace vectors may be expensive, we show that the rate of convergence and the final results are somewhat insensitive to the choice of subspace vectors. We also show that it is desirable to start with a small number of subspace vectors and gradually increase the number at each Newton iteration until an acceptable level of data mismatch is obtained.     

2018年度工程地质学自然科学基金项目受理与资助分析

对2018年工程地质学的基金申请情况、资助情况、研究队伍等进行了详细分析。工程地质学的基金项目申请数量有所下降,主要是青年科学基金和重大项目申请数量下降,重点项目和面上项目申请数量保持稳定,优秀青年科学基金项目申请量增加。近10年的统计数据表明,同行评议专家对申请书的评议尺度保持稳定。面上项目申请者的年龄结构趋于年轻化,青年科学基金申请者的年龄结构比较合理。重点项目的申请人仍以60年代出生的科学家为主,但70年代出生的申请人正在增加并逐渐获得资助。工程地质学在多个不同的项目类型中都获得了资助,呈现出越来越强的竞争力。     

江苏金湖凹陷古近系奇碳优势和偶碳优势共存的正构烷烃

苏北盆地金湖凹陷古近纪阜宁组二段暗色泥岩及其生成的原油中,正构烷烃系列存在着偶碳优势、奇碳优势以及二者共存的3种分布型式。本文重点探讨正构烷烃奇碳优势和偶碳优势共存的形成原因。在这类暗色泥岩与原油中,正构烷烃通常低碳数部分呈nC15、nC17优势,中碳数具有nC20、nC22优势,高碳数为nC25、nC27、nC29、nC31优势;并且具有强烈的植烷优势、较高的伽玛蜡烷指数、含有一定量β胡萝卜烷和C24四环萜烷。分析认为沉积水体环境和有机质来源的变化决定了正构烷烃的分布形式,该类正构烷烃形成于湖盆水体盐度分层的沉积环境,主要来源于湖盆内藻类和湖盆外高等植物蜡。      

2014年度工程地质学自然科学基金项目受理与资助分析

对2014年工程地质学的基金申请情况、资助情况、研究队伍等进行了详细分析。工程地质学的基金项目申请数量有所下降,而且面上项目申请量持续明显下降。同行评议专家比较准确地把握了对申请书特别是青年科学基金的评议尺度。基金申请者的年龄结构正趋于合理,各年龄段的申请人获得资助的比率出现了合理的差异。工程地质学科国家杰出青年基金和优秀青年科学基金申请不够积极。重点项目申请人年龄偏大,获资助人的年龄严重偏大,这一现象需要引起重视。     

2015年度工程地质学自然科学基金项目受理与资助分析

对2015年工程地质学的基金申请情况、资助情况、研究队伍等进行了详细分析。工程地质学的基金项目申请数量呈上升趋势,特别是面上项目申请量增加明显。同行评议专家比较准确地把握了对申请书,特别是青年科学基金的评议尺度。无论是青年科学基金还是面上项目,申请者的年龄结构正趋于合理,各年龄段的申请人获得资助的比率呈现出合理的差异。工程地质学科国家杰出青年基金申请仍不够积极。申请重点项目的科学家年龄整体偏大,获资助人的年龄严重偏大。     

矿床分割法在以GIS为平台的铀资源定量估算中的应用——以双桥-新路地区为例

数量化理论Ⅰ模型规定:参与定量估算的预测要素数目小于等于研究区内已确定的典型矿床模型数目。事实上,多数研究区内可作为模型的典型铀矿床数目较少,因而限制了预测要素的选取,降低了预测精度,为解决此局限性,提出了一种新方法——矿床分割法。该方法是将某一典型铀矿床模型按其具有相似预测要素的矿带进行逆向分割,即拆分成一定数目的铀矿模型,扩充了模型数目,并保持分割后各模型区资源量不变。双桥-新路地区试验结果证明:运用"矿床分割法"后,预测要素的选取数目有了明显增加,提高了方向系数值,资源量估算值更接近模型区的实际资源量。     

Shape detection of multiple subsurface cavities by particle filtering with elastic wave propagation

A numerical technique for detecting the number and shape of subsurface cavities is presented, applying the particle filter and the parametric level set method to elastic wave propagation under the ground. When subsurface cavities exist, the elastic wave propagating in the ground is reflected at the boundary faces of the cavities. Observing the velocity of the reflection wave at the surface of a ground that includes multiple cavities and parameterizing the shape of the cavities by the parametric level function, both the number and the shape of the cavities can be identified by the particle filter. Numerical experimentation for detecting multiple cavities is conducted with synthetic observation data. The results show that the proposed technique enables the number of cavities to be identified by the number of peaks in the posterior probabilistic distribution function and solves geometric inverse problems by estimating the shape of the cavities through the parameter identification of the level set function.     

Planning Geotechnical Investigation Using ANFIS

Engineering experience may be written in mathematical form by using adaptive network-based fuzzy inference system (ANFIS). In this article we propose a method to use engineering experience and build a model, which can be used as a systematic decision support tool for engineers dealing with new problems. Planning geotechnical investigations is based on experience, which are used to obtain optimal number of investigation points, field and laboratory tests. To achieve this objective we define minimum number of investigation points and several input parameters which could increase or decrease the number of investigation points. The expert’s evaluations were put in a table, from which we generate the basis of the system. The paper presents a concept for planning geotechnical investigation for buildings using ANFIS and practical examples show its usefulness.     

Principal component analysis of lithologic variables in Early Permian Barakar coal-measures,western Singrauli Gondwana sub-basin of central India

The quantitative relationships between lithological variables of Early Permian Barakar coal measures of western Singrauli Gondwana sub-basin are investigated using principal component analysis in an attempt to reveal simple relationships undetected by conventional quantitative methods. The results not only confirm and amplify those of the simple regression analysis described in Casshyap et.al. (1988), but are also interpreted in terms of evolution of coal swamps. If the total thickness of strata, total thickness of clastic sediments, total thickness of coal seams, number of sandstone beds, number of shale beds, number of coal seams and clastic ratio are considered, the first three components accounts for 80% of the total variance and the lithological variables generally fall into two groups. One group contains the first four variables, namely, total thickness of strata, total thickness of sandstone, total thickness of shale and total thickness of coal seams, all of which have basin-like regional patterns of sedimentation linked to net subsidence. The other group of variables, which are somewhat less closely related to net subsidence such as number of sandstone beds, number of shale beds and number of coal seam. The sand/shale ratio and clastic ratio are dependent on the other variables and seem to be unrelated to net subsidence. The principal component results, at best in geological term, may be explained by the to and fro lateral migration of a river channel across its flood plain coupled with a gradual isostatic adjustment of the basin floor in response to the weight of the sediments and differential subsidence through space and time.     

含水率影响下尾矿砂内摩擦角随标贯击数变化研究

尾矿砂样品在运输和存放过程中均存在易扰动的特点,但考虑到工程造价以及人力资源等因素,目前在大部分上游式尾矿坝的工程地质勘察中难以建立现场试验室,所得抗剪强度指标与实际情况存在一定误差。针对这种现状,结合某铅锌矿尾矿坝现场试验结果,从现场简易试验获得的含水率和标准贯入击数进行分析,并对基于含水率影响下尾矿砂内摩擦角随标准贯入击数变化规律进行了研究,提出了考虑上覆压力作用下标准贯入击数的修正公式,并推出了用标准贯入击数估算尾矿砂内摩擦角的方法。通过几个实例验证：除当修正后的标准贯入击数N1>8（5%< <20%）情况下以外,该方法均能够有效地估算尾矿砂内摩擦角。研究结果表明,该方法在以后的上游式尾矿堆积坝的工程地质勘察工作中具有较强的应用价值。