Basin modeling meets rift analysis – A numerical modeling study from the Jeanne d'Arc basin,offshore Newfoundland,Canada     

Friedemann Baur  Ralf Littke  Hans Wielens  Carolyn Lampe  Thomas Fuchs 《Marine and Petroleum Geology》2010

The Jeanne d'Arc basin, on the Grand Banks offshore Newfoundland, is a confined, failed-rift basin. Its initial development and burial history were controlled by crustal stretching and thinning. This study provides a detailed analysis of the heat flow-, tectonic subsidence-, stretching factor-, maturation- and temperature history, based on 44 1D models- and one full 4D (space and time) model.  相似文献   

EH-4电磁测量在化马湾地区金矿找矿中的应用          下载免费PDF全文

王海芹  王虹  王玉和  霍光辉 《山东国土资源》2008,24(7)

在山东省泰安市化马湾地区金矿找矿中首次进行EH-4电磁测量，获得了分辨率较高的电性剖面和较可靠的地质解释资料，经钻探验证发现了隐伏金矿体。测量结果表明，岩层深部高阻背景下的低阻带是寻找金矿化带的有利部位，低阻带的展布范围反映了金矿化带的延伸趋势。  相似文献   

Water level changes in Lake Constance and their relationship to changes in macrophyte settlement in the outflows of Lake Constance Upper and Lower Lake     

《Limnologica》2021

Since 2008, water level differences between Upper and Lower Lake Constance have increased after they decreased significantly in the 20th century. Questioning the causes leads to the hypothesis that the significant changes in the submerged macrophyte vegetation due to eutrophication and subsequent oligotrophication have played an essential role over the past decades. To clarify whether macrophyte vegetation is the cause of the changed water levels, the spatial distribution of Swiss pondweed Potamogeton helveticus (syn. Stuckenia helvetica) and the other submerged macrophytes was mapped in 2017. Swiss pondweed, in particular plays a key role as a perennial plant type in flow channels. Shoot densities and lengths of this species were recorded by diving. The investigations were supplemented by hydrodynamic modeling of the effects of macrophyte flow resistance on lake water level relationships.The results show that P. helveticus has indeed increased significantly over the past decade. The species colonizes the bottom of flow channels in the Seerhein up to 6 m deep with up to 1000 shoots per square meter and a length of up to 5 m, whereas in the previous decades it only occurred at the edges of flow channels as small stands with shoot lengths of less than 1 m. In the shallow water zones outside the flow channels, stoneworts in particular have spread in the Seerhein over the past decade. The hydrodynamic modeling supports the hypothesis that aquatic plants are the cause of the changed lake water level conditions and illustrate the related changes in the flow velocity field.  相似文献   

梳状防波堤上波浪反射     

傅朝方  朱大同 《海洋工程》2013,31(4):37-41

对梳状沉箱防波堤的波浪反射特征进行研究。在对梳状沉箱防波堤非线性消耗波能机理分析基础上,采用阻抗分析方法,导出一组所有参数都是事先知道的、完全封闭的波反射系数公式。  相似文献   

Evaluation of State Parameter of Crushable Jeju Sand Using Cone Resistance     

Moon-Joo Lee  Raehyun Kim  Sung-Jin Hong 《Marine Georesources & Geotechnology》2013,31(1):30-48

This study was performed to evaluate the critical state parameter of crushable Jeju sand and to suggest the relationship between the state parameter and cone resistance of Jeju sand. It is observed from a drained triaxial test that Jeju sand mainly shows contractive behavior due to high void ratio and large compressibility. Although strain localization is not evident, the particle crushing results in a lower void ratio than the critical state void ratio of some Jeju specimens. Critical state parameters of Jeju sand are similar to those of calcareous sands, but significantly larger than those of common sands. The relationship between the normalized cone resistance and state parameter of Jeju sand significantly differs from that of other materials, and this relation appears to be affected by the stress level. This is because the variation of stress level affects the state parameter of Jeju sand more significantly than that of common sand due to the high compressibility of Jeju sand.  相似文献   

Aeromonas veronii, a tributyltin (TBT)-degrading bacterium isolated from an estuarine environment, Ria de Aveiro in Portugal   总被引：1，自引：0，他引：1  

Cruz A  Caetano T  Suzuki S  Mendo S 《Marine environmental research》2007,64(5):639-650

Organotin compounds are used in a variety of industrial processes therefore their subsequent discharge into the environment is widespread. Bacteria play an important role in biogeochemical transformations acting as natural decontamination agents. Therefore, screening for tributyltin (TBT)-resistant and -degrading bacteria is relevant for the selection of isolates with decontamination ability of these polluted areas. With this purpose, 50 strains were isolated from sediment and water from Ria de Aveiro and their tolerance to TBT, up to 3mM, was evaluated. Generally, occurrence of highly TBT-resistant bacteria was observed, and Gram negative bacteria exhibited more tolerance to TBT than Gram positive bacteria. A memory response was observed when bacteria were progressively exposed to increasingly higher TBT concentrations. One isolate, Aeromonas veronii Av27, highly resistant to TBT (3mM) uses this compound as carbon source and degrades it to less toxic compounds.  相似文献   

压力分散型锚索在地质灾害应急抢险工程中的应用          下载免费PDF全文

张成杰 《探矿工程》2009,36(7):69-72

压力分散型锚索有效地避免了锚固段应力集中、钢绞线受力不均而导致某些锚固段上的钢绞线过早拉断的现象,受力性能更加合理,工程适用性广。近年来,压力分散型锚索在高边坡,特别是破碎岩体边坡加固方面得到了越来越多的应用,并取得了良好的加固效果。以广州南沙某地质灾害应急抢险工程为例,通过现场分散型锚索极限抗拉拔试验提出设计原则和设计值,并详细介绍了压力分散型锚索的施工工艺。  相似文献   

氧化铁涂层石英砂滤料表面特征研究     

张建锋  张慧琴  张苑茹 《岩石矿物学杂志》2009,28(4):395-399

采用高温加热法制备氧化铁涂层石英砂(IOCS),研究固化温度、改性剂浓度等因素对滤料表面性能的影响,通过磨损实验分析氧化铁涂层的耐磨稳定性.研究结果表明,IOCS表面氧化铁涂层的厚度大约为30～60 μm,固化温度影响涂层的形态和成分,进而影响IOCS表面电位,涂层处理过程要求改性剂浓度大于1.0 mol/L.在实际滤池反冲洗产生的磨损强度范围内,涂层磨损剥离量随磨损次数增加逐渐减小,涂层质量最终趋于稳定.  相似文献   

DEFORMATION OF MOISTURE FLUX CIRCULATION SURROUNDING THE LANDFALL TYPHOON “BILIS”   总被引：2，自引：0，他引：2  

冉令坤  杨文霞  洪延超 《热带气象学报(英文版)》2009,15(2):167-180

The deformation parameter (DP), which is defined as the product of shear deformation and stretching deformation of moisture flux circulation, is introduced. The tendency equation of DP is derived in pressure coordinates. Furthermore, DP is used to diagnose the deformation character of moisture flux circulation in the periphery of Bilis. The analysis showed that before Bilis landed, DP presented eight abnormal areas, which distributed alternately and closely encircled the low-pressure center. This indicated that the moisture flux circulation in the periphery of Bilis rotated counterclockwise and stretched longitudinally and latitudinally to deform. After Bilis landed, DP weakened gradually and its regular pattern of horizontal distribution loosened. The shear and stretching deformations of moisture flux circulation surrounding Bilis weakened after the typhoon landed. The deformation of moisture flux circulation in the periphery of Bilis mainly appeared in the middle-lower troposphere. There existed 1/2 phase difference between the shear and stretching deformations in the vertical-latitudinal cross section and aπ/4 phase difference between them on the horizontal plane. As Bilis landed and further moved inland of China, the intensities of DP, shear and stretching deformations decreased, meanwhile their vertical and horizontal structures became irregular. The chief dynamic factors responsible for the deformation of moisture flux circulation in the periphery of Bilis were the three terms associated with the three-dimensional advection transportation of DP, square difference between shear and stretching deformations coupling with Coriolis parameter, and horizontal gradient of geopotential height before Bilis landed. The last two dynamic factors impacted jointly on the deformation of moisture flux circulation after Bilis landed.  相似文献   

Load transfer analysis of rock-socketed drilled shafts by coupled soil resistance     

Hoonil Seol  Sangseom Jeong  Yongmin Kim 《Computers and Geotechnics》2009

The load distribution and deformation of rock-socketed drilled shafts subjected to axial loads are evaluated by a load transfer method. The emphasis is on quantifying the effect of coupled soil resistance in rock-socketed drilled shafts using 2D elasto-plastic finite element analysis. Slippage and shear-load transfer behavior at the pile–soil interface are investigated by using a user-subroutine interface model (FRIC). It is shown that the coupled soil resistance acts as pile-toe settlement as the shaft resistance is increased to its ultimate limit state. Based on the results obtained, the coupling effect is closely related to the ratio of the pile diameter to soil modulus (D/E_s) and the ratio of total shaft resistance against total applied load (R_s/Q). Through comparison with field case studies, the 2D numerical analysis reasonably estimated load transfer of pile and coupling effect, and thus represents a significant improvement in the prediction of load deflections of drilled shafts.  相似文献