Monitoring of Three-dimensional Additional Stress and Strain in Shield Segments of Former Tunnels in the Construction of Closely-Spaced Twin Tunnels

In recent years, with the development of urbanization, the construction of closely-spaced twin tunnels is becoming more and more common. How to ensure the safety of the former tunnel during the construction of the later tunnel has become the focus of the construction of closely-spaced twin tunnels. To study the safety of the former tunnel segment structure, this paper analyzed the field monitoring data of practical engineering (the section with the minimum separation (4.5 m) between the twin tunnels from Anyuanxi station to Chunshenhu station on the Suzhou Metro Line 4 in Jiangsu, China) and obtained the dynamic change law of additional stress and strain of the former tunnel segment under the influence of the construction of later tunnel. Based on this research, the following conclusions were drawn: (1) The maximum circumferential tensile stress on the segmental structures was shown to be 2.62 MPa at the horizontal position on Section S2 in the side adjacent to the later tunnel, which should be main monitored. (2) The maximum values of the vertical deformation and peripheral convergence of the segments were 16.21 and 17.39 mm, separately, both of which were less than two-thirds of the allowable deformation. Therefore, the shield tunnel deformations were within allowable limits. This research results can provide guidance for similar engineering.     

能见度目标物图自动化制作系统设计与实现

针对目前国家气象观测站能见度目标物图是手工绘制的现状,开发了能见度目标物图自动化制作系统,实现了任意距离的能见度目标物图的自动化制作。具有观测站信息管理、目标物管理、绘图面板管理和图片输出等功能,图片大小、圆圈系数及生成半径可自行设置,还可以在一张图片上将1000和50000 m目标物图合成,满足现行最小能见度观测业务需要。该系统自动化程度高,操作简单,具有较强的可操作性和实用性。     

Study on visualization of virtual city model based on internet

With the rapid development of computer graphics, distributed-computing and Internet, it is possible to achieve Internet-based virtual city. This paper dwells on the method of the terrain and its feature modeling and complex entity modeling in the virtual city. Then, discusses the method for Internet-based virtual city 3D visualization and the design of the Browser/Server architecture of the system of virtual city in the network environment. Finally, Java and Java 3D are used to show an experiment example, and the related conclusion about Internet-based virtual city 3D displaying and the client-side interactive operation is given.     

Investigation of karst collapse based on 3-D seismic technique and DDA method at Xieqiao coal mine, China

Karst collapse is a serious geological problem in most of the coal mines in the north of China, but recently it has been found in the south as well. The present study is aimed at investigating subsidence mechanism and deformation field of a karst collapse column at Xieqiao, in the south of China. A method of three-dimensional (3-D) seismic technique has been successful in exploring the spatial morphology of the karst collapse at Xieqiao, and the discontinuous deformation analysis (DDA) method is used to calculate the deformation field and analyze the subsidence mechanism. The results indicated that DDA could approximately simulate and back analyze the subsidence process and strata deformation fields. The subsidence processes of the collapse column depend on the sizes of the karst caves. With the continuous expansion of the karst caves, a semi-elliptic stress field, local separation strata and fracture zone will be formed around the karst cave. Moreover, they will gradually expand upwards along the vertical direction. The paper also indicates that the subsidence failure stage may trigger a sudden collapse of the karst column because of the sudden energy release. Also, it will make a great impact on the vicinity working face so as to cause a rock burst. The effects of the friction angle of rock strata on the subsidence mechanism were reported firstly based on DDA.     

Spatial patterns of irrigation water withdrawals in China and implications for water saving

By considering numerical features, spatial variation, and spatial association, the spatial patterns of China's irrigation water withdrawals in 2001 and 2010 were explored at the regional, provincial, and prefectural scales. In addition, an overlay analysis was used to develop specific water-saving guidance for areas under different levels of water stress and with different degrees of irrigation water withdrawals. It was found that at the regional scale, irrigation water withdrawals were highest in the Middle-Lower Yangtze River region in both years, while at the provincial scale, the largest irrigation water withdrawals occurred in Xinjiang. During 2001–2010, the total of irrigation water withdrawals decreased; however, in the Northeast region, especially in Heilongjiang Province, it experienced a dramatic increase. The spatial variation was largest at the prefectural scale, with an apparent effect. The spatial association was globally negative at the provincial scale, and Xinjiang was the only significant high-low outlier. In contrast, the association displayed a significant positive relationship at the prefectural scale, and several clusters and outliers were detected. Finally, it was found that the water stress in the northern part of China worsened and water-saving irrigation techniques urgently need to be applied in the Northeast region, the Huang-Huai-Hai Plain region, and Gansu-Xinjiang region. This study verified that a multi-scale and aspect analysis of the spatial patterns of irrigation water withdrawals were essential and provided water-saving advice for different areas.     

中南部非洲镍矿成矿规律及资源潜力分析

中南部非洲镍矿资源丰富,大体可分为岩浆型和风化壳型2种预测类型。本文在对中南部非洲243处镍矿床/点资料系统收集整理的基础上,将产出的镍矿初步划分为新太古代、古元古代、中元古代和新元古代4个成矿期,南非卡普瓦尔北缘古元古代Cr-Ni-Cu（PGE）成矿带、津巴布韦大岩墙新太古代Ni-Cr（PGE）成矿带、博茨瓦纳弗朗西斯敦—赛莱比—皮奎新太古代Ni-Cu-Au成矿带、赞比亚赞比西津巴—卢萨卡新元古代Au-Ni-Cu成矿带、坦桑尼亚乌本迪—乌萨嘎仁古元古代Ni-Cu成矿带和坦桑尼亚—布隆迪基巴拉中元古代Ni-Cu-Co成矿带共6个成矿带,从整体上构成了北东向的中南部非洲巨型镍矿带;并分别对研究区内典型的与大陆边缘裂解有关的Ni-Cu（PGE）矿床、与造山带伸展背景有关的Ni-Cu矿床、与地幔柱有关的Ni-Cu（PGE）矿床和风化壳型镍矿床的矿床地质特征和成矿模式进行了研究。综合研究表明,布什维尔德矿集区、津巴布韦大岩墙矿集区、博茨瓦纳弗朗西斯敦—赛莱比—皮奎矿集区、坦桑尼亚—布隆迪穆松加迪—卡邦加矿集区镍矿资源潜力巨大,找矿前景优越。     

2001年4月2日太阳耀斑及其太阳质子事件的观测结果研究

2001年4月2日, 太阳爆发了一个近年来X射线通量最大的一次耀斑并伴有质子事件, 利用“资源一号”卫星星内粒子探测器和神舟二号飞船X射线探测器的观测资料, 对这一事件的高能粒子响应进行了特例研究. “资源一号”卫星运行于太阳同步轨道, 高度约800km, 和宁静时期的统计结果对比, 这次耀斑后, 星内粒子探测器在地球极盖区（地球开磁场区）观测到耀斑粒子的出现, 这是宁静时期没有的; 神舟二号飞船轨道高度400km, 倾角为42°, X射线探测器在42°中高纬地区也观测到高能电子通量比宁静时明显的增加, 这表明, 太阳耀斑引起的近地空间辐射环境的变化遍及纬度约40°以上的区域, 甚至在40°N附近400 km左右的高度上仍然有响应. 但是, 中高纬度、极光带和极盖区的粒子来源, 加速机制和响应方式却不一定相同, 需要分别讨论. 资料分析和对比还表明, 质子事件的强度并不一定和耀斑的X射线通量成正比, 因此, 近地空间高能粒子对耀斑的响应也不是完全决定于X射线强度.     

Shadow–highlight feature matching automatic small crater recognition using high-resolution digital orthophoto map from Chang’E Missions

This paper introduces a new method of small lunar craters’ automatic identification, using digital orthophoto map (DOM) data. The core of the approach is the fact that the lunar exploration DOM data reveal contrasting highlight and shadow characteristics of small craters under sunlight irradiation. This research effort combines image processing and mathematical modeling. Overall it proposes a new planetary data processing approach, to segment and extract the highlight and shadow regions of small craters, using the image gray frequency (IGF) statistical method. IGF can also be applied to identify the coupling relationships between small craters’ shape and their relative features. This paper presents the highlight and shadow pair matching (HSPM) model which manages to perform high-precision automatic recognition of small lunar craters. Testing was performed using the DOM data of Chang’E-2 (CE-2). The results have shown that the proposed method has a high level of successful detection rate. The proposed methodology that uses DOM data can complement the drawbacks of the digital elevation model (DEM) that has a relatively high false detection rate. A hybrid fusion model (FUM) that combines both DOM and DEM data, was carried out to simultaneously identify small, medium, and large-sized craters. It has been proven that the FUM generally shows stronger recognition ability compared to previous approaches and it can be adapted for high precision identification of craters on the whole lunar surface. The results meet the requirements for a reliable and accurate exploration of the Moon and the planets.

     

太湖YLL1孔沉积特征揭示的全新世太湖演化史

本文通过对太湖西山岛衙甪里孔(YLL1)沉积物的粒度、总有机碳含量(TOC)、质量磁化率、元素含量及沉积年代等进行测试分析,探讨了全新世以来太湖湖盆的演化历史。根据沉积特征,可将4m深的YLL1孔分为上、中、下三段明显不同的沉积层。中段(153~231cm)沉积物平均粒径为7.65φ,粘土级颗粒含量高达48.78%,对比上段(0~153cm,6.29φ,21.77%)和下段(231~400cm,6.91φ,30.88%)为全孔最细;并且中段粒径随深度变化很小,平均粒径标准偏差为0.13,明显低于上段的0.70和下段的0.38;中段TOC和质量磁化率平均值分别为0.78%和19.41×10^-8m^3/kg,为全孔最高;XRF扫描数据显示元素含量在三段中变化显著:中段Al、K、Fe等元素含量相对上段和下段为最高,而Si含量最低。YYL1孔沉积特征参数显示,近80cm厚的中段泥质层与上下段截然不同,是一段标志性沉积层。该标志层广泛存在于太湖及其周边地区的地层中,并且该层位含有大量的富铁质小球粒结核和菱铁矿结核,AMS14C显示该层位年龄约为7kaB.P.。研究表明,太湖YLL1孔沉积记录了湖盆环境的3个不同阶段:下段对应末次冰期后期11kaB.P.左右的风成硬黄土层沉积,此时太湖尚未完全形成;中段泥质沉积标志层代表太湖第一次大水面形成,时代在7kaB.P.左右;上段对应5kaB.P.左右以来的湖相沉积。     

全新世中期郑州地区古代农业的时空演变及其影响因素

郑州地区地处中原腹地,是我国旱作农业起源和稻作农业早期传播的重要区域之一,在华夏文明形成与发展过程中具有非常重要的地位。然而,由于区域性系统植物考古研究较少,目前全新世中期郑州地区古代农业的时空演变过程及其影响因素仍不清晰。文章在郑州地区选择位于不同地貌部位、不同等级规模的13处裴李岗-仰韶文化遗址进行系统采样,通过植硅体分析和AMS 14C测年,揭示出郑州地区在裴李岗文化和仰韶文化中晚期均属于以黍为主的稻-旱混作的农业模式,其形成得益于全新世适宜期暖湿气候下的稻作北传。裴李岗时期,黍粟旱作分布在浅山丘陵区的黄土台塬沟谷地带,稻-旱混作仅存在于冲积平原,农业模式的选择主要受地形和水文因素影响;仰韶中晚期,粟和稻的比例显著提高,稻作不再局限于冲积平原和大型聚落,在台塬沟谷和中小聚落也有分布,标志着农耕技术的进步和作物结构的优化,这意味着农业生产开始打破自然条件限制,为郑州地区农业社会的建立和文明化进程奠定了基础。