The stratigraphy and structure of the Galley Head culmination zone: An area of enhanced shortening related to basin geometry within the Irish Variscides

In southwest Ireland an Upper Devonian to Lower Carboniferous clastic succession was deposited in an ENE–WSW trending half-graben, known as the South Munster Basin. Across the Galley Head peninsula on the south coast, this stratigraphical succession is attenuated due to the presence of a palaeogeographical feature called the Glandore High. Evidence suggests that the Glandore High was an east–west feature, faulted to the north and east, which was part of the southern flank (hangingwall rollover) of the South Munster Basin. During post-Carboniferous Variscan deformation the relatively thin stratigraphy of Galley Head underwent prolonged folding, causing a local periclinal fold pair to develop within the hinge zone of a regional syncline. The main cleavage then developed parallel to bedding on the overturned south limb of the anticline of this fold pair. The local enhanced shortening caused the development of a structural culmination, and south facing, tight to isoclinal folds. The culmination was enhanced and tightened by a fault system of contractional, strike-parallel faults linked by cross faults. Secondary folds occur across the hinges of regional anticlines and also on major fold limbs as isolated fold pairs and in monoclinal fold zones, some of which may have nucleated on irregular sandstone bodies. Local crenulation cleavages are related to late fault movements. Syn-cleavage, conjugate, wrench faults record 10 per cent to 15 per cent strike-parallel extension in the culmination. The deformation chronology of the Galley Head area is somewhat anomalous for the Irish Variscides in that the folds were well established before the onset of the main cleavage development. The enhanced shortening across the area was compartmentalized by major cross faults and a minor component of north–south sinistral shear was also active across the area causing a swing in strike and a late set of minor cross faults. Structural facing directions in southwest Ireland appear to be directly linked with the geometry of the deformed basins. Hence the southward facing along the south coast is due to the proximity of the southern margin of the South Munster Basin. Structural facing directions fan northwards across the basin and major folds are overturned to the north at the northern margin of the basin.     

水文地质研究新动向

由于日益增长的社会发展的需要，水文地质研究正在产生巨大变化。人们对各种工农业活动所产生的诸多环境污染问题的关注，以及对“高放”放射性废物和毒性液体的地下深层埋设的安全评价需求，致使水文地质研究产生许多新的生长点。无论是在水文地质研究的学科发展领域，还是在解决重大社会问题方向，水文地质学家均面临着巨大的挑战和机遇。     

中国油气储层地质研究面临的挑战和发展方向

论述了我国采取“稳定东部 ,发展西部”的油气战略后 ,油气地质所面临的形势 ,以及油气工业的发展对储层地质提出四个领域的挑战 :深部储层、挤压盆地储层、低渗透储层和碳酸盐岩储层 ;这些都是石油勘探开发中久攻不克的难题。根据我国陆上东西部油气区的勘探开发实际和近年的储层研究实践 ,文章系统多视角地分析了这四个难题 ,并提出了相应客观的研究思路和研究方向。     

矢量地理数据安全保护关键技术和方法

近年来,矢量地理数据在政府、国防、国土、交通、海洋等多个领域广泛应用.矢量地理数据在存储、传输、共享过程中正面临日趋严重的安全威胁.矢量地理数据的安全保护与数据共享矛盾已成为制约地理信息产业发展的关键问题之一.针对上述问题,分析了现有矢量地理数据安全保护中数据加密、数据水印、数据置乱和信息伪装等若干关键技术及其进展,分析了矢量地理数据安全保护所面临的方法及新技术融合带来的技术挑战.结合当前矢量地理数据和网络空间安全领域的新进展,提出了敏感信息度量和局部动态处理等一些未来研究和发展的重要方向,为矢量地理数据安全保护与数据共享技术的研究和应用作出一些有益的探索.      

Statistical calibration of federal highway administration simplified models for facing tensile forces of soil nail walls

This study first develops a database containing 56 measured facing tensile forces from instrumented soil nail walls during or at completion of construction. Based on the compiled database, the accuracies of both default and modified federal highway administration (FHWA) simplified models for estimation of short-term facing tensile forces are evaluated. Here, accuracy is defined by the model bias computed as the ratio of measured to predicted facing tensile force. The analysis results show that predictions are highly conservative and highly dispersive using the default model, and moderately conservative and medium dispersive using the modified model. Moreover, the prediction accuracy is statistically correlated with magnitudes of the computed facing tensile forces and several model input parameters. An out-of-sample approach is used to develop and validate a recalibrated FHWA model which is then demonstrated to have least empirical constants but best accuracy compared to the default and modified models. The biases for the three models are characterized as lognormal random variables. An example of reliability-based analysis for facing flexure limit state is illustrated to both elaborate the application and highlight the benefit of using the recalibrated model for design practice from the perspective of cost-effectiveness.

     

The determination of joint directions by seismic refraction measurements at the Avedat plateau (Israel)

A seismic refraction experiment was conducted in an area at a site where joints had been mapped in detail in order to determine whether velocity anisotropy could be correlated with joint directions. The purpose was to assess the possibility of using seismic refraction techniques for mapping joint directions in alluvium-covered areas.The results of the experiment show that a velocity anisotropy can be detected by simple seismic refraction measurements, and that the anisotropy can be correlated with the dominant joints. It is believed that the technique is applicable to the determination of joint directions in alluvium-covered areas.     

Palaeomagnetism and tectonic rotation of the Hastings Terrane,eastern Australia

The Hastings Terrane comprises two or three major fragments of the arc‐related Tamworth Belt of the southern New England Orogen, eastern Australia, and is now located in an apparently allochthonous position outboard of the subduction complex. A palaeomagnetic investigation of many rock units has been undertaken to shed light on this anomalous location and orientation of this terrane. Although many of the units have been overprinted, pre‐deformational magnetizations have been isolated in red beds of the Late Carboniferous Kullatine Formation from the northern part of the terrane. After restoring these directions to their palaeohorizontal (pre‐plunging and pre‐folding) orientations they appear to have been rotated 130° clockwise (or 230° anti‐clockwise) when compared with coeval magnetizations from regions to the west of the Hastings Terrane. Although these data are insensitive to translational displacements, a clockwise rotation is incompatible with models previously proposed on geological grounds. While an anti‐clockwise rotation is in the same sense as these models the magnitude appears to be too great by about 100°. Nevertheless, the palaeomagnetically determined rotation brings the palaeoslopes of the Tamworth Belt, facing east, and the Northern Hastings Terrane, facing west before rotation and facing southeast after rotation, into better agreement. A pole position of 14.4°N, 155.6°E (A₉₅ = 6.9°) has been determined for the Kullatine Formation (after plunge and bedding correction but not corrected for the hypothetical rotation). Reversed magnetizations interpreted to have formed during original cooling are present in the Werrikimbe Volcanics. The pole position from the Werrikimbe Volcanics is at 31.6° S, 185.3° E (A₉₅ = 26.6°). These rocks are the volcanic expression of widespread igneous activity during the Late Triassic (～ 226 Ma). While this activity is an obvious potential cause of the magnetic overprinting found in the older units, the magnetic directions from the volcanics and the overprints are not coincident. However, because only a few units could be sampled, the error in the mean direction from the volcanics makes it difficult to make a fair comparison with the directions of overprinted units. The overprint poles determined from normal polarity magnetizations of the Kullatine Formation is at 61.0°S, 155.6°E (A₉₅ = 6.9°) and a basalt from Ellenborough is at 50.7° S, 148.8° E (A₉₅ = 15.4°), and from reversed polarity magnetizations, also from the basalt at Ellenborough is at 49.4° S, 146.2° E (A₉₅ = 20.4°). These are closer to either an Early Permian or a mid‐Cretaceous position, rather than a Late Triassic position, on the Australian apparent polar wandering path. Therefore, despite their mixed polarity, and global observations that the Permian and mid‐Cretaceous geomagnetic fields were of constant polarities, the age of these overprint magnetizations appears to be either Early Permian or mid‐Cretaceous.     

面板对路堤式加筋土挡墙力学特性的影响

加筋土挡墙作为一种新型的轻型支挡结构,广泛应用于公路、铁路、港口等工程中。随着加筋土挡墙技术的发展,面板的类型也越来越丰富。利用Plaxis有限元软件,对路堤式加筋土挡墙进行了二维有限元计算分析。针对墙背水平土压力、垂直土压力、挡墙侧向位移、筋材应变和挡墙稳定系数等计算结果的分析,探讨了3种类型面板（返包式面板、整体式面板和拼装式面板）对路堤式加筋土挡墙力学性能的影响。研究结果表明,垂直和水平土压力的数值计算结果均小于理论值;相比较与其他两种面板的加筋土挡墙,返包式面板加筋土挡墙筋材的应变最大;面板类型对于加筋土挡墙的整体稳定性几乎没有影响。研究成果为实际工程的应用提供了理论指导。     

环境沉积学的兴起

面对生态、环境、灾害、全球变化等重大问题和环境科学、沉积学的发展,环境沉积学应运而生。环境沉积学的发展经历了萌芽和兴起2个阶段,直至20世纪90年代中后期,其研究始得以广泛关注。在前人研究的基础上,初步厘定了环境沉积学的概念和研究目的,指出其研究内容既包括沉积学中的环境问题,又包括环境科学中的沉积问题,4个研究方向分别为原生环境沉积学、污染物环境沉积学、生态环境沉积学和全球变化环境沉积学。环境沉积学以环境和灾害研究为己任,将在解决人类面临的环境污染、生态破坏、地质灾害、全球气候变化等重大问题的研究中发挥越来越重要的作用,是未来沉积学发展的重要方向之一。     

兰州Q4黄土各向异性的初步研究

水敏感性和结构性是黄土区别于其他类型土的主要特点,得到了广泛的研究,但大多数试验研究都采用垂直方向制备的试样,仅考虑了黄土垂直方向的力学特性,这对于以承受上部垂直荷载为主的黄土地基基础等工程类型来说是合理和准确的,而对于受力状态较为复杂的边坡和隧道及地下结构等工程类型,黄土力学性质的各向异性可能更为重要。分别从垂直向和水平向制取兰州Q4黄土的原状土试样,通过三轴剪切试验研究了其抗剪强度和变形参数在不同围压下和不同方向上的差异性,并与直剪试验获得的强度参数进行对比。结果表明：兰州Q4黄土力学性质的各向异性是较为显著的,强度方面的差异主要体现在黏聚力,而内摩擦角的差异性较小;变形特征具有随围压增加而从脆性向塑性转化的特点,垂直方向的变形模量比水平方向的变形模量平均要大2倍左右。用黄土的结构性强度及其形成机制解释了试验结果,认为黄土力学性质的各向异性特点是其结构性的另一种表现方式,应重视黄土在不同方向上强度和变形特征的差异性,以获得更安全合理的参数。     

利用地质统计学方法模拟岩石裂隙网络的三维空间分布——以云南个旧高松矿田为例

裂隙在地学的诸多领域中均具有重要意义,其空间分布可以使用地质统计学方法进行模拟,同时考虑裂隙的方向(走向和倾角)。利用序贯高斯模拟方法可以估计裂隙密度的空间分布,并根据裂隙密度数值随机产生裂隙位置的空间分布。裂隙方向被划分成若干(非)均等的方向组,将裂隙方向归属到其所属方向组,表示为由若干二值变量组成的指示形式,0和1分别代表该裂隙方向不属于和属于该组。为了便于计算,减少方向指示变量的成分数目,使用主成分分析法求出方向指示变量的主成分,用普通克里格法估计各主成分的空间分布。把估计结果反演为原始的指示形式,并找出其中数值最大的方向组且将其赋值为1。按照对应方向组内裂隙方向的累积密度函数,随机产生裂隙的方向。根据估计结果,将符合一定距离和角度标准的裂隙元连接为一个裂隙面,从而形成裂隙网络。根据在云南个旧锡矿高松矿田白云岩中进行裂隙网络模拟的应用,可见该方法由于组合了序贯高斯模拟法、普通克里格法和主成分分析法,可以较好地对岩石裂隙位置和方向进行合理的模拟。     

Applicability of artificial neural networks for obtaining velocity models from synthetic seismic data

Seismic velocity analysis is a crucial part of seismic data processing and interpretation which has been practiced using different methods. In contrast to time consuming and complicated numerical methods, artificial neural networks (ANNs) are found to be of potential applicability. ANN ability to establish a relationship between an input and output space is considered to be appropriate for mapping seismic velocity corresponding to travel times picked from seismograms. Accordingly a preliminary attempt is made to evaluate the applicability of ANNs to determine velocity and dips of dipping layered earth models corresponding to travel time data. The study is based on synthetic data generated using inverse modeling approach for three earth models. The models include a three-layer structure with same dips and same directions, a three-layer model with different dips and same directions, as well as a two-layer model with different dips and directions. An ANN structure is designed in three layers, namely, input, output, and hidden ones. The training and testing process of the ANN is successfully accomplished using the synthetic data. The evaluation of the applicability of the trained ANN to unknown data sets indicates that the ANN can satisfactorily compute velocity and dips corresponding to travel times. The error intervals between the desired and calculated velocity and dips are shown to be acceptably small in all cases. The applicability of the trained ANN in extrapolating is also evaluated using a number of data outside of the range already known to ANN. The results indicate that the trained ANN acceptably approximates the velocity and dips. Furthermore, the trained ANN is also evaluated in terms of capability of handling deficiency in input data where acceptable results were also achieved in velocity and dip calculations. Generally, this study shows that velocity analysis using ANNs can promisingly tackle the challenge of retrieving an initial velocity model from the travel time hyperbolas of seismic data.     

土钉墙面层土压力的计算分析

在目前的土钉墙设计中,面层通常被当作构造处理而不参与计算,墙后的主动土压力全部由土钉承担。实际上,土钉墙面层承受一部分土（水）压力。文中把土钉墙面层看作是弹性地基上的有限长梁,基于试验,推导了成层地基上土钉墙面层在土钉拉力作用下的挠曲线、转角、弯矩和剪力方程,并与实测数据进行了比较分析,验证了模型的合理性,得到的解析解基本上可以反映土钉墙面层土压力的分布。在此基础上,探讨了不同土性土层中土钉墙面层土压力的分布。面层土压力在土层的分界面上,位移连续,土压力发生突变;软弱土层分布的面层土压力较硬土层为大;上软下硬型较上硬下软的土层分布更能使面层土压力得到充分发挥,同时计算了面层土压力换算成荷载与土钉拉力的比值,其值随着开挖深度的增加越来越大,面层对于土压力的作用随着深度的增加表现得愈加明显,并提出针对不同地区、不同深度和不同土性条件下应给出比值的建议值,以使土钉墙的设计更符合其真实的作用机制,得到的结论和上述比值的计算方法对于进一步研究土钉墙的作用机制及设计中如何充分发挥面层的作用等具有重要的理论意义和实际应用价值。     

面板对加筋土挡墙影响的离心模型试验研究

加筋土挡墙因其特有的景观性能、协调变形性能而日益受到设计者青睐。面板作为加筋土挡墙的组成部分,对墙体的承载能力影响显著。针对现有设计规范无法考虑面板形式对结构自身力学变形特性的影响,设计并开展了整体式与分块式面板的离心模型试验。数据测试分析显示：整体式面板加载期的位移小于分块式面板位移;由于分块式面板位移较大,所以其水平土压力小于整体式面板土压力;加筋土挡墙面板底部存在应力集中现象;分块式面板筋-土界面的摩擦系数发挥值大于整体式面板数值,但两者均小于设计规范建议值;由于模型筋材长度较长并且连接件的存在,导致原型设计较为保守。     

方向性岩石渗透率的矢量特性与计算模型

岩石渗透率的大小往往具有明显的方向性,因而方向渗透率是矢量。介绍了方向渗透率的地质成因;分析了在理解和应用岩石渗透率矢量特性时容易混淆的一些认识,并指出：不能把两个不同方向上的渗透率矢量合成在一起而作为该合矢量所对应方向上的岩石渗透率,也不能把渗透率矢量在某个方向上的投影作为该投影方向上的渗透率值。此外,还推导建立了一种各向异性渗透率的定量计算模型,据此,可以计算出平面内任意方向上的岩石渗透率值。该渗透率计算模型可用于油藏数值模拟中不同方向上的传导率计算以及各向异性油藏中不同方位上的井距设计。     

Incorporation of fracture directions into 3D geostatistical methods for a rock fracture system

Simulating a rock fracture distribution is an important problem common to various fields in geosciences. This paper presents GEOFRAC, a geostatistical method to simulate a fracture distribution by incorporating the directions (strikes and dips) of the sampled fracture data into the simulation. Fracture locations are generated randomly following fracture densities assigned by a sequential Gaussian simulation. Fracture directions are transformed into an indicator set consisting of several binary (0 and 1) variables and the variables are compressed using the principal component analysis. Ordinary kriging is then employed to estimate the distributions of these principal values and the results are back-transformed into the coordinate system of the original indicator set. Fracture directions are generated randomly using their histograms within the defined directional interval. Finally, facets (fracture elements) are determined from the simulated locations and directions, and the fractures within the angle and distance tolerances are connected to form a fracture plane. From a case study of applying GEOFRAC to the fracture data in Kikuma granite, southwest Japan, GEOFRAC was shown to be able to depict a plausible fracture system because the simulated directions corresponded well to those measured. Furthermore, the simulated fracture system was available to estimate the hydraulic conductivity of the study site, which was roughly in agreement with the average of hydraulic test results.     

水文相似概念与理论发展探析

目前,工程水文领域面临诸多问题有待解决,例如怎样合理地将现有水文观测成果外推至无资料流域,这也成为国际水文科学协会“无测站流域水文预测计划（PUB）”所遭遇的理论瓶颈。一个可行的方法就是依据流域结构特征构建水文相似因子,并对流域进行分类,在相似框架下完成观测成果向无（缺）测站流域的转化。分析发现,水文学缺乏类似于水力学、化学和生物学的分类与相似理论体系。通过对不同学科相似理论的回顾,定义了水文相似的概念,给出了构成流域水文相似的三要素,即驱动力、结构和水动力要素。最后,讨论了可用于水文相似研究的两类方法:数理解析法和量纲分析法,并给出了其用于实际流域水文相似研究时存在的问题及解决途径。     

论地质安全研究的框架体系

我国地处欧亚板块东缘,地貌类型多样,地质条件复杂,国家重大战略的顺利实施与生态文明建设的有效推进面临着严峻的地质安全风险,因此亟需解决各种地质作用对人居环境与工程活动带来的地质安全问题。本文以地球系统科学为指导,以圈层相互作用、内外动力耦合、人地协调互馈为理论核心,聚焦国土空间地质安全、重大工程地质安全、城市建设地质安全、生态环境地质安全及资源开发地质安全等方面,分析国家战略发展面临的重大地质安全挑战,剖析地质安全牵引出的系列前沿科学问题,勾画出地质安全主要研究方向。地质安全是保障人民高质量生活、推动社会经济绿色发展、构建宜居地球的重要前提,对于解决当前和今后发展面临的重大工程建设、重大灾害防控、生态环境保护和人地和谐安居等相关地质安全问题,推进科技进步与社会可持续发展具有重要科学意义。     

鄂尔多斯盆地中部奥陶系方解石脉中包裹体流体势研究

结合前人研究成果，归纳出了一种利用盐水包裹体均一温度与盐度确定流体势的方法，并对鄂尔多斯盆地中部气田奥陶系方解石脉中包裹体进行了流体势计算，推算出了古流体运移方向。     

Effect of bedding structural diversity of coal on permeability evolution and gas disasters control with coal mining

Bedding structure has affected gas flow in coal seam greatly, which also controls gas permeation direction and gas extraction results, and finally it has tremendous influence on prevention and control of gas disaster accidents. Combined with engineering practice of gas disaster prevention and control in China, in this paper, permeability evolution of nature coal in different bedding directions in the condition of loading is studied, and the results showed that in three directions of bedding fractures, permeability of coal which is parallel to bedding planes is the highest; it would be much easier for gas percolation along the bedding planes than other directions. In the unloading process, tension–shear destruction appears in coal sample which is oblique to bedding along the bedding planes, with a sudden increase in permeability. It is difficult for the crack damage from loading process to recover in unloading process, that is, permeability of unloading isn’t just a simple reverse process of loading. Combined with the permeability evolution of the three coal samples in the whole process, three permeability evolution models which include elasticity, plasticity and fracture are proposed. Based on the experimental results, gas extraction using boreholes along coal seam and through coal seam is compared during depressurized mining. Due to the bedding structure of coal seam, a large area of fracture network of “boreholes–bedding fractures” is formed among boreholes through coal seam and bedding structure, which makes the good effect of gas extraction using boreholes through coal seam. Research results will be of important guiding significance for choosing the best gas extraction scheme, layout of setting parameters of drilling boreholes and gas disaster prevention in the underground coal mine.