广清高速公路改扩建工程岩溶塌陷主要影响因素分析

岩溶塌陷对工程建设的影响不容小视。为了研究广清高速公路改扩建工程中影响岩溶塌陷的两个主要因素冲击荷载作用和地下水下降对塌陷的影响程度,在资料收集和现场调研的基础上,统计工程区12处岩溶塌陷的基本情况,总结塌陷特征并分析影响塌陷的主要因素,建立与实际覆盖层结构相符的塌陷地质模型-砂土+粉质黏土+灰岩地质模型。根据极限平衡理论,分别在冲击荷载和水位下降两种力学作用下对塌陷地质模型进行稳定性计算。通过计算得出,最大冲击荷载的作用在一定程度上会影响覆盖层的稳定性,但不是导致地面塌陷的主要因素,而地下水位下降对工程区岩溶塌陷起到了决定性的作用。通过进一步分析水位下降对塌陷的影响程度,确定水位降幅4m为警戒值, 6m为危险值,为保证施工的安全性提供一定的理论依据。     

Spatial and temporal variation of organic carbon in the northern South China Sea revealed by sedimentary records

Three sediment cores were taken from the Pearl River estuary and adjacent northern South China Sea (SCS). These sediment cores span the time interval 1900–2000 AD. The stratigraphy of the concentration, the ratio of total organic carbon (TOC) to total nitrogen (TN) and stable isotope (δ¹³C_org) of organic carbon (OC) from three high-resolution sediment cores were analyzed. The stratigraphic profiles of OC concentration, TOC/TN ratios and δ¹³C_org for the near past 100 yrs indicate that terrestrial organic matter decreases from 68.3% to 27.4% of the TOC in the Pearl River estuary, while Dapeng Bay (offshore east of Hong Kong) apparently had throughout little terrestrial organic matter input. The highest deposited OC occurs at the Humen River mouth and the OC concentrations are higher in the outer estuary than in the inner shelf of the northern SCS. The deposited OC at the River mouth increased with time, which could be caused by the high precipitation of land-derived organic matter and the high input of terrestrial organic matter, which is likely related to the rapid urbanization and industrial development in the Pearl River Delta since the 1970s. The OC concentrations did not exhibit an obvious increase with time in most areas of the Pear River estuary and adjacent inner shelf of the SCS, but the algal-derived OC concentration inferred from the δ¹³C_org values increased with time especially from 1980 to 2000 in the outer Pearl River estuary and Dapeng Bay. This increase is presumably caused by enhanced primary marine productivity supported by higher anthropogenic nutrient inputs.     

2005年6月桂南沿海降水异常偏多成因分析

2005年6月桂南沿海降水异常偏多,通过分析气候背景,环流形势特征,并将其与历史多雨年和少雨年做对比分析得出:2005年6月桂南沿海降水偏多是在多雨的大气候变化周期中发生的;西太平洋副热带高压强度偏强、西伸脊点位置偏西、脊线位置偏南是2005年6月桂南沿海降水异常偏多的主要原因.     

基于GIS的雷电数据可视化地图组件设计与实现

雷电发生发展于地理空间,具有明显的时空特性,因此在地理信息平台的支持下进行各种雷电数据空间及其属性特征分析具有重要的意义。在ArcEngine的基础上,设计研发了雷电数据可视化地图组件（Thunder Map）,按照数据定义层、数据功能层以及地图UI层的3层逻辑结构,实现了各种雷电相关数据基于地理信息平台的可视化表达,并提供了相关数据管理与功能分析的操作接口,为基于地理空间信息的雷电数据处理提供可视化的功能组件支持。     

南海海岛自动气象站防护应用技术探索

立足海南及南海的自然条件,结合海岛自动气象站在南海高温、高湿、高盐雾、强辐射、强风等恶劣气候环境下使用情况,通过对历年来海岛自动气象站故障及失效模式的统计和分析,总结分析故障原因。根据设备维护人员多年气象设备保障工作积累总结的经验,从海岛自动气象站结构和防护要求出发,集成应用市场上优质材料、先进工艺和多种成熟、关键设备防护技术,形成一些气象设备防护的有效方法措施,以提高海岛自动气象站对海洋环境的适应性和性能,延长设备使用寿命。     

龙卷风的风强分析与极值推断

本文采用1955－1997年影响盐城市的龙卷风资料,按富士达F等级定义龙卷风风强分类级别,对盐城市受袭击点的破坏程度进行风强分级,并分析各个时段龙卷风风强等级的频数。应用耿贝尔极值分布理论,对影响盐城市的龙卷风风速极值进行统计推断,获得1％风险度龙卷风风速极值,以及各种特定重视期间的极值。     

Electro-osmotic permeability model based on ions migration

Acta Geotechnica - Electro-osmotic permeability is a very important parameter in soil drainage and electrochemical remediation. The present widely used equation for calculating the electro-osmotic...     

大洋岩石圈拆沉与大陆下地壳拆沉：不同的机制及意义——兼评“下地壳＋岩石圈地幔拆沉模式”

拆沉作用（delamination）是地球科学中一个重要的科学问题。本文认为,大洋岩石圈拆沉和大陆下地壳拆沉是不一样的：（1）拆沉的物质不同。大洋岩石圈拆沉的物质包括大洋地壳、岩石圈地幔甚至一部分软流圈地幔,它们共同进入地幔深部;而大陆下地壳拆沉仅仅限制在下地壳,不包括岩石圈地幔。（2）拆沉的动力不同。大洋岩石圈拆沉是由板块俯冲引起的,是地幔对流的产物,因此是一种快速的主动的拆沉;而下地壳拆沉是由于下地壳加厚使下地壳密度增加引起的,还要求其下刚性的岩石圈地幔转变成塑性的软流圈地幔才有可能发生。因此下地壳拆沉要克服许多阻力才能实现,使拆沉成为一个漫长的过程,是慢速的和被动的拆沉。（3）拆沉的过程不同,大洋岩石圈拆沉是由板块俯冲触发的,俯冲导致碰撞,大洋岩石圈从根部断裂,拆沉进入地幔。大陆下地壳拆沉由地壳加厚开始,使下地壳转变为榴辉岩相;随后,岩石圈地幔减薄,直至全部转化为软流圈地幔;下地壳发生部分熔融,形成大规模的（埃达克质）岩浆,使下地壳榴辉岩的密度大于下伏的地幔,从而引发拆沉。大陆下地壳拆沉不大可能是整体进行的,可能是一块一块地被蚕食,被拆沉的。（4）拆沉后的效液压不同,大洋岩石圈地幔拆沉,使热的软流罪状地幔上涌,从而引发了一系列地质效应;如岩浆活动,地壳抬升,构造松弛以及随后的造山带垮塌等。而下地壳拆沉只引起地壳减薄,高原和山脉垮塌,并不伴有大规模的岩浆活动和地壳抬升等过程。（5）拆沉与岩浆活动的关系不同,主动拆沉导致大规模岩浆活动,而被拆沉是在大规模岩浆活动的基础上开始的。此外,文中还对“下地壳＋岩石圈地幔拆沉”模式提出了质疑,认为该模式有许多难以理解的问题和太多推测的成分,而且与现在保存的地质事实不符。     

Contemporary crustal deformation of the Chinese continent and tectonic block model

We obtain the preliminary result of crustal deformation velocity field for the Chinese continent by analyzing GPS data from the Crustal Motion Observation Network of China (CMONOC), particularly the data from the regional networks of CMONOC observed in 1999 and 2001. We delineate 9 technically active blocks and 2 broadly distributed deformation zones out of a dense GPS velocity field, and derive block motion Euler poles for the blocks and their relative motion rates. Our result reveals that there are 3 categories of deformation patterns in the Chinese continent. The first category, associated with the interior of the Tibetan Plateau and the Tianshan orogenic belt, shows broadly distributed deformation within the regions. The third category, associated with the Tarim Basin and the region east of the north-south seismic belt of China, shows block-like motion, with deformation accommodated along the block boundaries only. The second category, mainly associated with the borderland of the Tibetan Plateau, such as the Qaidam, Qilian, Xining (in eastern Qinghai), and the Diamond-shaped (in western Sichuan and Yunnan) blocks, has the deformation pattern between the first and the third, i.e. these regions appear to deform block-like, but with smaller sizes and less strength for the blocks. Based on the analysis of the lithospheric structures and the deformation patterns of the regions above, we come to the inference that the deformation modes of the Chinese continental crust are mainly controlled by the crustal structure. The crust of the eastern China and the Tarim Basin is mechanically strong, and its deformation takes the form of relative motion between rigid blocks. On the other hand, the northward indentation of the Indian plate into the Asia continent has created the uplift of the Tibetan Plateau and the Tianshan Mountains, thickened their crust, and raised the temperature in the crust. The lower crust thus has become ductile, evidenced in low seismic velocity and high electric conductivity observed. The brittle part of the crust, driven by the visco-plastic flow of the lower crust, deforms extensively at all scales. The regions of the second category located at the borderland of the Tibetan Plateau are at the transition zone between the regions of the first and the third categories in terms of the crustal structure. Driven by the lateral boundary forces, their deformation style is also between the two, in the form of block motion and deformation with smaller blocks and less internal strength.     

金沙江支流黑水河松新电站短须裂腹鱼（Schizothorax wangchiachii）过坝后上溯行为

鱼类过坝后的上溯行为对鱼类寻找适宜的产卵、索饵等功能性栖息地至关重要。现阶段我国大多数研究聚焦于鱼类上溯通过鱼道的游泳行为量化,而过坝后的上溯行为分析鲜有报道。本研究在金沙江下游支流黑水河松新坝址处利用PIT(passive integrated transponder)遥测技术对松新电站过鱼对象短须裂腹鱼(Schizothorax wangchiachii)过坝后的上溯行为开展监测,考虑监测过程中水文情势变化对过坝后上溯行为的影响,采用生存分析方法,构建了耦合多因素(流量、水温、河道涨落水率、昼夜节律、肥满度等)的Cox风险比例回归模型,利用AIC模型准则筛选出最优模型参数,识别了影响鱼类过坝后上溯成功率的关键因素。结果表明:(1)短须裂腹鱼在松新鱼道的上溯效果显著优于河道;(2)水温及河道涨落率是影响短须裂腹鱼过坝后上溯效果的关键因素;(3)水温与短须裂腹鱼过坝后河道上溯成功率呈负相关,当水温超过短须裂腹鱼最适温度后,河道上溯成功率随着温度的上升呈递减趋势;河道涨落水率与短须裂腹鱼过坝后河道上溯成功率呈正相关,其中涨水情势下短须裂腹鱼河道成功上溯的概率高于落水,河道上溯成功率随着涨...