层间错动带的强度参数取值探讨

为获得高应力下具有剪切错动历史、延展规模大、组合结构和矿物构成多元化等特点的白鹤滩层间错动带强度值（黏聚力和内摩擦角）,首先介绍了6种错动带试验研究,包括针对错动带泥化软层的环剪试验、高压直剪试验和三轴压缩试验,以及针对错动带复合体的直剪试验、三轴压缩试验和现场试验。综合分析不同试验对象和不同试验条件下获得的错动带强度值,归纳出了错动带黏聚力和内摩擦角与试验方式、加载的法向应力大小、试样特点及含水率之间的关系,并发现白鹤滩错动带强度特性具有典型的组合体结构效应、弱胶结效应、围压效应、水软化效应。在此基础上,提出“原状错动带强度”和“扰动错动带强度”两个概念,并进一步讨论了白鹤滩厂址区原状的和扰动的层间错动带强度参数取值问题。其研究结果可为白鹤滩地下洞室群的安全设计和深部地下工程中同类泥化夹层的力学参数取值提供参考     

华北克拉通北缘及邻区印支期岩浆活动与钼和金成矿作用

对华北克拉通北缘及邻区19处钼矿床和5处金矿床的产出环境、形成时代和成矿机理及其与印支期侵入岩的关系进行了讨论。尽管各个矿床所处的地理位置不同,但是它们大都在前寒武纪或早古生代地层中产出,并且与印支期侵入岩具有密切的时空分布关系。印支期钼矿床的形成作用可以从早三叠世一直持续到晚三叠世,大规模成矿作用高峰期为230~220 Ma。相比之下,金矿床的形成时间明显早于钼矿床,同位素年龄数据集中分布在245~239 Ma。研究结果表明,自早三叠世开始,华北克拉通北缘及邻区曾发生过多期大规模伸展构造作用,并且形成若干条近东西向展布的裂陷带。张裂构造作用所诱发的富碱性岩浆作用及相关流体活动为钼或金矿床的形成提供了动力和物质来源,因此,印支期侵入岩发育区是寻找隐伏钼或金矿床的有利地区。     

拓扑模型下的导航地图道路曲率引入

随着道路曲率的作用逐渐被认识,道路曲率引入导航地图,成为实现先进驾驶辅助系统(ADAS)的重要途径,也是未来导航地图的发展趋势之一。曲率依附于曲线存在,难以直接引入基于拓扑模型的导航地图。为了避免模型转换带来的巨大工作量和不确定性,本文尝试了拓扑模型下道路曲率引入的研究。首先在现有导航地图道路数据基础上,使用了完全曲线拟合与组合线型拟合两种方法计算曲率;然后结合两种计算方法对应的曲率存在形式,探索了在拓扑模型下的道路曲率引入方式,分别是引入点、引入线和引入多线;最后使用导航地图道路数据进行曲率计算和曲率引入的试验。结果表明,本文的方法具有可行性,为今后大数据量的导航地图道路曲率引入打下了铺垫。     

天津地区台基背景噪声特征分析

利用Welch算法,选取天津数字地震台网31个台站记录资料中不同时段的无震记录,对无震观测资料进行功率谱计算,然后进行统计分析,得出了天津地区的背景噪声特征:就季节而言,背景噪声值的高值出现在夏天和秋天,低值出现在春天和冬天;就时间而言,高值出现在白天的14时,低值出现在夜间的2时。对比噪声功率谱曲线发现,在0.125~1 Hz频段内有一个明显的峰值,这主要是受海洋的影响。在1~20 Hz频段内,天津地区的背景噪声值高值区出现在中心城区、静海、滨海新区,低值区出现在蓟县、宝坻、宁河、武清,且中心城区、静海、滨海新区白天时段的背景噪声值明显高于夜间时段,这主要是受人为噪声的影响,而在0.125~1 Hz频段内,天津所有地区差异不大。     

利用地震P波方位/角度信息预测煤层裂隙发育——以阳泉矿区为例

查明煤层瓦斯富集区域,对可能的瓦斯突出点进行预报,是当前煤矿生产中亟待解决的重要课题.利用地震P波对裂缝性地层所表现出的方位各向异性特征和AV0特征,应用地震P波方位/角度信息评价煤层裂隙发育带.通过对阳泉新景煤矿三维地震资料的处理,获得4个方位的偏移数据体和8个方位/角度的偏移数据体,从中提取了3种对煤层裂隙响应灵敏的地震属性,综合利用3种地震属性计算出裂隙的发育密度.预测结果表明,利用P波方位/角度信息比仅利用P波方位信息评价煤层裂隙发育带更具有优势,它能同时利用煤层反射波的各向异性特征和AVO特征,更有利于进行煤层的岩性解释.     

Petrogenesis of diabase from accretionary prism in the southern Qiangtang terrane,central Tibet: Evidence from U–Pb geochronology,petrochemistry and Sr–Nd–Hf–O isotope characteristics

The Bangong–Nujiang suture (BNS) between the Lhasa and Qiangtang terranes is an important boundary and its petrogenesis is controversial. Diabase from the accretionary prism in the southern Qiangtang terrane yields a zircon U–Pb age of 181.3 ± 1.4 Ma. All the diabases show tholeiitic basalt compositions, gentle enrichment patters of light rare earth elements (REE), variable enrichment in incompatible element concentrations (e.g. Th and Rb), and no anomaly in high field strength elements (e.g. Nb and Ta), similar to that of enriched mid‐ocean ridge basalt (E‐MORB). They have relatively homogeneous whole rock Nd (εNd(t) = 7.3–9.1) and zircon Hf–O isotopic compositions (εHf(t) = 14.8–16.1, and δ¹⁸O = 4.57–6.12‰), possibly indicating melting of the depleted mantle and no significant crustal contamination during the petrogenesis. The element variations suggest that the diabases were formed by plume–ridge interaction at a mid‐ocean ridge within the Bangong–Nujiang ocean.     

Time-domain solution for transient dynamic response of a large-diameter thin-walled pipe pile

The propagation of stress waves in a large-diameter pipe pile for low strain dynamic testing cannot be explained properly by traditional 1D wave theories. A new computational model is established to obtain a wave equation that can describe the dynamic response of a large-diameter thin-walled pipe pile to a transient point load during a low strain integrity test. An analytical solution in the time domain is deduced using the separation of variables and variation of constant methods. The validity of this new solution is verifi ed by an existing analytical solution under free boundary conditions. The results of this time domain solution are also compared with the results of a frequency domain solution and fi eld test data. The comparisons indicate that the new solution agrees well with the results of previous solutions. Parametric studies using the new solution with reference to a case study are also carried out. The results show that the mode number affects the accuracy of the dynamic response. A mode number greater than 10 is required to enable the calculated dynamic responses to be independent of the mode number. The dynamic response is also greatly affected by soil properties. The larger the side resistance, the smaller the displacement response and the smaller the refl ected velocity wave crest. The displacement increases as the stress waves propagate along the pile when the pile shaft is free. The incident waves of displacement and velocity responses of the pile are not the same among different points in the circumferential direction on the pile top. However, the arrival time and peak value of the pile tip refl ected waves are almost the same among different points on the pile top.     

科尔沁沙地沙丘-草甸相间地区1986-2013年湖泊演变

湖泊变化敏感地记录着气候变化的信息。以科尔沁沙地沙丘-草甸相间地区为研究区,利用多时相TM/ETM+遥感影像,基于遥感和GIS技术提取研究区1986-2013年湖泊个数与面积信息,分析其变化规律及空间分异特征。在此基础上,联系降水量、蒸发量等气候要素和以人类活动影响为主的时间因子t,采用多元统计分析方法对研究区湖泊面积进行了模拟分析。结果表明:(1)研究区小型湖泊近30年间面积和个数均发生了不同程度的变化,其变化趋势与降水量呈现很强的正相关,与蒸发量呈较强的负相关,人类活动对小型湖泊面积的影响不太显著,随着时间的推移,研究区湖泊面积趋于萎缩,这种萎缩主要归因于气候的干化;(2)研究区t年湖泊面积A_t与前一年湖泊面积A_t-1、t年降水量P_t和蒸发量E_t存在较强的相关关系;(3)1986-2013年研究区典型湖泊--王巴哈嘎湖泊总体上呈萎缩状态,但不同方向上既有萎缩也有扩张,Ⅰ、Ⅱ、Ⅴ、Ⅵ区域(以北向为0°,顺时针每45°一个区域,并顺序标记为Ⅰ~Ⅷ区域)萎缩,其他区域扩张,其中以Ⅱ、Ⅲ、Ⅷ、Ⅳ区域为主导变异方向,Ⅵ方向次之,其他方向变化缓滞。研究成果不仅为科尔沁沙地生态系统的健康维持提供技术支撑,对其他同类地区湖泊环境的研究也具有指导作用。     

The Net Flow of Carbon Emissions Embodied in Trade of China

Based on the most current GTAP8 database, we analyzed flow, structure and change in tradeembodied carbon emissions between China and the developed world and the developing world from 2004 to 2007 using input-output model. We found that China was always a net embodied emissions exporting country over this period. Based on the LMDI decomposition method, we found that factors influencing net embodied emissions exported from China to developed countries and developing countries differ. Trade surpluses and differences in emissions factors were vital in determining net embodied emissions exported from China to the developed world. Differences in export structures and emissions factors were key factors influencing net emissions between China and developing countries. These were closely related to respective divisions amongst developed countries, China and other developing countries in the global industrial chain. From 2004 to 2007, the export structure of China was transformed to high-end manufacturing with domestic producing technology gradually approaching the level of developed countries. With further technological improvement, industrial upgrades and export structure optimization in China, the net export of embodied carbon emissions will decrease and the driving forces of trade for China's domestic carbon emissions will decline.