地球化学的理论体系与方法论

本文根据地球化学作用与时-空结构辩证统一的观点提出地球化学的理论体系与方法论,认为地球化学体系应由地球化学系统的物质、地球化学作用、地球化学过程和地球化学场等四大部分所构成,其中以地球化学系统的物质为基础,而地球化学作用居于核心地位。地球化学作用与时-空结构的统一性应该作为一切地学研究的指导思想。作者指出,必须用系统思想和系统科学研究地球化学系统,应用不可逆过程热力学中的“耗散结构”（dissipativestructures）理论研究地球化学作用与时-空结构的内在联系。     

Delineation of long-wavelength magnetic anomalies over central India by rectangular harmonic analysis

The method of rectangular harmonic analysis is applied to the geomagnetic field data from central India to isolate long wavelength magnetic anomalies associated with largescale crustal structures. The long-wavelength anomalies have accounted for approximately 20 % of the spatial variability of the residual magnetic field over the International Geomagnetic Reference Field. On the magnetic anomaly map, reflecting the surface expression of longwavelength anomalies, the Tapi-Narmada-Son zone is characterized by a feeble positive anomaly bounded by a strong negative anomaly. The anomaly pattern is believed to be caused by the large-scale undulation in Moho and related variations in the thickness of the lower (basaltic) crust. The other two prominent anomalies, the magnetic low striking northwest and the magnetic high trending east-northeast, appear to be related to the deep structural feature of the Godavari graben and the eastern Rajasthan lineament respectively.     

基于位移的底部框架-抗震墙房屋抗震能力分析

在基于性能/位移抗震设计思想下,通过动力时程分析,研究了底部两层框剪砖房结构在不同地震强度作用下的弹塑性反应和变形特征;针对《规范》中对底部两层框剪砖房结构侧向刚度比的限定条件,研究了不同侧向刚度比条件下结构的抗震能力,得到了相关结论。     

921台湾集集地震灾害最严重地区的烈度评定

根据9.21台湾集集大地震过后南投县、台中县、台北县和苗栗县这四个主要受害地区的建筑物震害,参考不同的评定烈度标准综合确定出这四个地区的地震烈度,然后又计算出四地区的地震动峰值加速度、峰值速度、峰值谱加速度、峰值谱速度以及峰值谱位移的平均值。将这些均值分别与地震烈度进行基于最小二乘法的线性回归,发现这些地震动参数均值除峰值谱位移外都和烈度有很好的相关性,相关系数均在0.95以上,这说明研究评定的这四个地区的地震烈度是正确合理的,可以加以推广并应用于其它地震研究工作中。同时由于地震烈度是描述地震破坏后果的物理概念,地震动参数和烈度间的良好相关性也说明地震动参数和建筑物震害有很大的关联性,能够体现对结构的潜在破坏势。     

Mitigation of seismic and meteorological hazards to marine oil terminals and other pier and wharf structures in California

For the past 12 years, the California State Lands Commission has been involved in the operational monitoring, structural inspection and requalification of 45 marine oil terminals along California’s coast, which have an average age of about 50 years and plans to keep these structures in service for another 20–40 years. Having seen the port and harbor damage from the 1995 Kobe and 1999 Izmit earthquakes, the potential for a major disruption in petroleum product production is real. Losing the daily gasoline production for a period of weeks or months as a result of a moderate earthquake or tsunami could significantly affect the economic well being of California and much of the western United States. In addition, a major oil spill resulting from such an event could cause the closure of a major port for days or even weeks. Such a closure would further affect the economy of California and the United States. Most of these facilities were designed to primitive seismic standards and for vessels much smaller than those currently moored. Many of these structures have never had a comprehensive underwater inspection. Wind and current forces on large tank ships can cause mooring lines to break or cause serious structural damage to supporting structures. In California, non-regulatory progress has been made in the following areas: (i) underwater and above water inspections or audits; (ii) mooring analyses and structural/environmental monitoring in high velocity current areas; (iii) seismic analyses and structural rehabilitation with updated seismic hazard data; and (iv) accelerometers on marine structures. In addition, standards have been developed and are proposed to be regulatory by early 2004. The new standards include most of the items listed above, but also extend into many other areas. Along with the proposed regulations come many issues that raise economic and political questions. These issues are not unique to marine oil terminals and are applicable to other pier and wharf structures in harbors.     

Semivariogram Models Based on Geometric Offsets

Kriging-based geostatistical models require a semivariogram model. Next to the initial decision of stationarity, the choice of an appropriate semivariogram model is the most important decision in a geostatistical study. Common practice consists of fitting experimental semivariograms with a nested combination of proven models such as the spherical, exponential, and Gaussian models. These models work well in most cases; however, there are some shapes found in practice that are difficult to fit. We introduce a family of semivariogram models that are based on geometric shapes, analogous to the spherical semivariogram, that are known to be conditional negative definite and provide additional flexibility to fit semivariograms encountered in practice. A methodology to calculate the associated geometric shapes to match semivariograms defined in any number of directions is presented. Greater flexibility is available through the application of these geometric semivariogram models.     

A field experiment on streambed stabilization by gravel structures

We report an experiment to study particle restraint imposed by bed surface aggregate structures in a small headwater stream. Extant structures (clusters, stone lines, and partial stone cells) were manually destroyed in one reach of the channel (treated reach) whilst leaving them intact in an adjacent reach (reference reach), establishing two reaches of similar sediment texture and gradient that differed primarily in degree of structure development. After the first flood, the sediment yield from the treated reach was 32% greater than from the reference reach. For material > D₈₄, the treated reach yielded 24× that from the reference reach. The critical Shields number was reduced by more than 18% in the treated reach to the value generally accepted for loose, heterogeneous sediment. The effect of structural development on particle mobility was subsequently studied in the treated reach over the course of three flow events that did not significantly exceed the Shields threshold, so that bed material transport remained low. After these events, mobility of the larger clasts was substantially reduced, permitting the inference that particle restraint in the treated reach approached that of the reference reach. This corresponds with direct evidence of structure development in the treated reach as indicated by the movement and emplacement of marked grains. A major flood, however, caused a reversion toward unstructured conditions in the treated reach, indicating that structures had not developed the resilience exhibited in the reference reach.     

Caractérisation géométrique et cinématique des structures liées aux phases compressives de l'Éocène au Quaternaire inférieur en Tunisie : exemple de la Tunisie nord-orientale

During Eocene to Early Quaternary period, three compressive tectonic phases are recognized in Northeast Tunisia: a NW–SE to north–south phase during the Late Eocene, a N120-to-N140 phase in the Late Miocene, and a NW–SE to north–south phase in the Plio-Early Quaternary. The first Eocene phase has built NE–SW folds and remobilised east–west-to-N120 and NE–SW faults with a reverse component. The second Miocene phase is characterized by east–west-to-N120 faults with a normal component and NE–SW folds. The third phase occurred during the Plio-Early Quaternary has edified NE–SW folds associated with east–west-to-N120 dextral reverse strike-slip faults and NE–SW faults with a reverse component. To cite this article: H. Mzali, H. Zouari, C. R. Geoscience 338 (2006).     

流域湿地水质净化功能研究进展

湿地具有去除水中营养物质或污染物质的特殊结构和功能属性,在维护流域生态平衡和水环境稳定方面发挥巨大作用。提出了流域湿地是将流域中湿地看作一个整体,研究其水质净化功能。对国内外湿地净水功能的特殊属性、湿地系统各组分对污染物质的去除作用及湿地对污染物质的去除过程研究作了不同程度的探讨。在流域的尺度上,进行了流域湿地水质净化功能的环境因子、影响流域湿地水质净化功能的重要湿地类型和流域湿地整体水质净化功能的研究,总结了流域湿地水质净化功能。对流域湿地水质净化功能未来的研究进行了讨论与展望。     

工程结构性态抗震设计和控制研究"项目成果介绍

本文介绍了“工程结构性态抗震设计和控制研究”项目的立项背景、目标、所开展的主要工作、取得的成果及研究成果的社会效益,并展望了该领域研究的未来工作。