国产海底地震仪研制现状及其在海底结构探测中的应用

海底地震仪(Ocean Bottom Seismographs,OBS)及由其组成的海底流动地震观测台阵是近年来发展起来的高新技术,在油气探测、科学研究、防灾减灾等方面有广泛的用途,是地球物理仪器与探测技术发展中的一个新增长点.本文介绍了由中国科学院地质与地球物理研究所研制成功的宽频带、7通道海底地震仪((I-7C) ...     

西安清真寺木牌楼结构特性与抗震性能分析

研究木结构古建筑的结构特性对保护和维修古建筑遗产具有重大意义.文中以西安清真寺木牌楼为研究对象,用弹簧单元模拟榫卯连接的半刚接特性,对其进行有限元数值分析.通过对榫卯连接的非线性接触分析得到了其各方向刚度值;在竖向荷载作用下结构的实际内力远小于其强度设计值,其安全裕度在60％以上;给出了结构的运动微分方程,结构模态分析...     

聚丙烯纤维增强异形柱边节点的抗震性能研究

通过3个聚丙烯纤维增强混凝土异形柱边节点和1个普通混凝土异形柱边节点的低周反复荷载试验,对比研究了聚丙烯纤维增强对混凝土异形柱节点抗震性能的影响。结果表明:采用聚丙烯纤维增强可以提高节点的开裂荷载和变形能力,减小核心区内裂缝的数量和宽度,延缓构件的刚度退化,减轻节点的累积损伤程度,有效改善节点的破坏形态,有利于节点抗震。     

Shaking‐table tests of a full‐scale single‐story masonry veneer wood‐frame structure

This paper presents the findings of shaking‐table experiments conducted to examine the seismic performance of a full‐scale, one‐story, wood‐framed structure with masonry veneer. The structure was designed and constructed in accordance with current U.S. code provisions. The veneer was attached to the wood backing with two kinds of metal anchors, corrugated ties fastened with 8d nails and rigid ties fastened with #8 screws. The tests have shown that the use of nails to fasten veneer anchors to the wood studs is highly unreliable due to the high variation of the nail extraction capacity, which can be influenced by the moisture content of the wood. Other than this, both the wood frame and the masonry veneer performed well under severe ground motions far exceeding a design level earthquake for Seismic Design Category D. Good performance was observed for the rigid veneer ties, which were attached to the wood studs with screws. The results have shown that the veneer walls parallel to the direction of shaking helped to restrain the motion of the wood structure and therefore should not be simply treated as added mass. The detailing of wood roof diaphragms requires special attention in consideration of the out‐of‐plane inertia force of the veneer that can be transmitted through the top plate of the wood‐stud wall to the rim joist. Copyright © 2010 John Wiley & Sons, Ltd.     

Compositional changes in sigmoidal carbonate clinoforms (Late Tithonian,eastern Sardinia,Italy): insights from quantitative microfacies analyses

Quantitative analysis of sediment composition was performed on a kilometre wide section of Upper Tithonian low relief (up to 70 m), gently inclined (3° to 15°), sigmoidal carbonate clinoforms (eastern Sardinia) to identify changes in sediment composition along the slope and across the studied succession. These changes may reflect modifications of the carbonate factory and of processes responsible for sediment transport. Point‐count analysis of carbonate microfacies, Q‐mode/R‐mode cluster analysis and Spearman’s rank provided a composition‐based classification of microfacies and highlighted relationships among sediment components. The studied clinoforms are mainly composed of non‐skeletal grains (70%), such as peloids and lithoclasts, together with micrite and cements and only a limited contribution from coated grains (2%). Among skeletal grains (28%), the greatest contribution derives from a coral–stromatoporoid–encruster reef that provided 15% of the components. Crinoids, brachiopods and other along‐slope thriving biota provided nearly 5% of the allochems, whilst fragments of molluscs (gastropods, bivalves and diceratids) from the backreef sourced another 2%. The contribution of platform interior biota is negligible (1%). The association of composition‐based facies varies along the slope. The upper slope beds consist of coral‐stromatoporoid grainstone to rudstone; the middle slope deposits are dominated by encruster‐lithoclast grainstone and packstone. At the lower slope, peloidal lithoclastic packstone as well as brachiopod–crinoidal wackestone prevail. Also the association of skeletal grains changes along the slope. The encruster–frame builder association typifies the upper slope whilst encrusters characterize the middle slope sediments. In the lower slope encrusters are equally represented as the brachiopod–crinoid association. Along‐slope compositional changes evidence a scarce downslope transport of frame builders and a progressive enrichment in along‐slope thriving biota. Quantitative analysis of microfacies allowed the sigmoidal clinoforms to be grouped into six sets. Each set gathers sigmoids with a similar sediment composition. Coated grains are dominant in the first set whilst they are lacking in the overlying sets reflecting a change in the carbonate factory. Other major compositional changes among the sets concern the relative amounts of peloids, micrite, frame builders (corals and stromatoporoids) and encrusters. The contribution of peloids varies inversely to that of cements and micrite as evidenced in the third and fifth sets which, respectively, record the highest occurrence of peloids or cement and micrite. Variations in the amount of frame builders and encrusters are instead non‐linear. High percentages of both frame builders and encrusters, as recorded in the second and fifth sets, are related to low amounts of peloids and lithoclasts that probably reflect episodes of reduced background sedimentation. This study demonstrates that quantitative analysis of carbonate microfacies represents a powerful tool that can improve the reconstruction of the stacking pattern in carbonate slope successions both in outcrop and in subsurface settings.     

地下连续墙施工中几种接头形式的对比分析及应用

随着地下连续墙的应用越来越多,地下连续墙的接头形式也在不断地发生变化。结合工程实践,对常用的几种地下连续墙接头形式进行对比分析,阐述了不同形式接头的优缺点及适用范围,为工程设计施工提供借鉴。     

PP-PS联合反演含气性预测方法及应用

讨论了利用PP波和PS转换横波进行叠前联合反演的理论和实现方法,结合某油田实际多波地震资料,在叠前联合反演的基础上,对深层火成岩气藏进行了含气性预测。经钻井资料验证,根据联合反演资料预测的气藏结果与井资料吻合较好。实践证明,纵横波叠前联合反演可以避免单纯使用纵波信息进行弹性反演而造成的岩石弹性参数的多解性,提高气藏预测的准确性。     

Joint toxic effects of heavy metals and atrazine on invasive plant species <Emphasis Type="Italic">Solidago Canadensis L</Emphasis>.

In this study, the joint effects of Cd(Ⅱ), Pb(Ⅱ) and atrazine (ATR) on Solidago Canadensis L. were investigated. The results showed that soil containing Cd, Pb and ATR could inhibit root elongation of Solidago Canadensis L., and that there was a positive linear relationship between the inhibitory rate of root elongation and the concentrations of Pb(Ⅱ). The mixture of Cd(Ⅱ) and Pb(Ⅱ)-ATR in soil showed a significant adverse effect on root and shoot biomass of Solidago Canadensis L. Acetylsalicylic acid (ASA) contents increased slightly at the lower concentrations of Cd(Ⅱ)-ATR, then decreased when Cd(Ⅱ)-ATR concentrations were higher than those of 1.0 TUmix(Cd+ATR). The toxic effect of Pb(Ⅱ)-ATR on the ASA contents of Solidago Canadensis L. was greater than that of Cd(Ⅱ)-ATR. Soluble sugar contents firstly decreased and then increased with increasing concentrations of Cd(Ⅱ)-ATR and displayed fluctuation with increasing concentrations of Pb(Ⅱ)-ATR. Total protein contents in-creased with increasing concentrations of Cd(Ⅱ) and Pb(Ⅱ)-ATR , relative to the control sample. The NP-SH con-tents showed a significant increase up to 12.2 mg/gfw of Cd(Ⅱ)-ATR, followed by a significant decline to 4.5 mg/gfw after 14 days of exposure. The effect of Pb(Ⅱ)-ATR was similar to that of Cd(Ⅱ)-ATR but the amount of NP-SH was not higher than that of Cd(Ⅱ)-ATR.     

吉林海沟金矿的构造应力场分析与变形期次

对海沟金矿的断层、节理进行野外和井下研究,应用赤平投影方法对节理产状进行统计与分析,确定研究区节理有6 个较为明显的优势产状,构成3 个节理系,并进一步确定了3 期变形作用的构造应力场。海沟金矿早期受到NW--SE 向伸展作用影响,使先存的近EW 向海沟断层发生左行走向滑移,在海沟断层上盘形成NE 向正断层组合,同时伴有含金石英脉的贯入; 中期受到NEE--SWW 向挤压作用,NE 向正断层组合和发育于断层之中的含金石英脉受到压扭性变形作用的改造; 晚期受到 NW--SE 向挤压作用,海沟断层表现为右行走滑的特征,NE 向断层组合再次受到挤压作用改造,同时形成NWW 向和NNW 向走滑断层,使早期形成的断层和含金石英脉受到变形改造而发生空间上的错位。3 期变形作用很可能是自白垩纪以来发生的,与太平洋板块向欧亚大陆的俯冲作用有关。     

合肥地区上更新统黏土中节理的几何学特征与构造意义

城市大规模工程建设揭露了蕴含在土层中的丰富变形信息,调查发现合肥地区上更新统黏土中发育有数量众多的节理,节理成组产出,呈现不同交切、配套关系。通过对大量的调查数据进行统计分析,并绘制各调查点的节理玫瑰花图,将研究区内节理发育与断层分布逐一对比分析,结果显示合肥地区上更新统黏土中广泛发育的节理产状与场地附近的主要断层产状有关。走向玫瑰花图显示节理优势分布方位与场地附近主要断层走向近似一致;如果场地附近有多条断层交汇,土层中节理有以北西向较为优势的特征。