考虑地基土液化影响的桩基高层建筑体系地震反应分析   总被引：5，自引：2，他引：5  

陈国兴  谢君斐 《地震工程与工程振动》1995,15(4):93-103

本文建立了土体－结构体系地震反应分析的混合有限元法，并研究了地基土液化对地震反应的影响。本方法把土体－结构体系简化为一个完整的体系，该体系由梁（柱）单元、剪切杆单元、刚体单元、平面四边形等参单元与三角形单元、界面单元的任意组合来模拟。桩与上部结构材料视为线弹性体，土介质视为非线性材料。土的静应力－应变关系之间的非线性用邓肯一张模型来描述；土的动应力－应变关系之间的非线性和振动孔隙水压力对土的软化效  相似文献   

武汉市轨道交通二号线工程场地砂土液化分析   总被引：3，自引：0，他引：3  

卢芳 《东北地震研究》2005,21(3):65-72

本文详细介绍了武汉市轨道交通二号线工程场地地震地质灾害评价中对饱和砂土液化的分析方法及评价结果。  相似文献   

The geomorphological significance of airflow patterns in transverse dune interdunes   总被引：1，自引：0，他引：1  

M.C. Baddock  I. Livingstone  G.F.S. Wiggs   《Geomorphology》2007,87(4):322-336

  相似文献   

The role of sedimentation rate and permeability in the slope stability of the formerly glaciated Norwegian continental margin: the Storegga slide model   总被引：3，自引：0，他引：3  

Didier Leynaud  Nabil Sultan  Jürgen Mienert 《Landslides》2007,4(4):297-309

Despite the gently dipping slopes (ca 1°), large-scale submarine slope failures have occurred on the mid-Norwegian continental margin (Storegga, Sklinnadjupet, Traenadjupet), suggesting the presence of special conditions predisposing to failure in this formerly glaciated margin. With a volume estimated between 2,400 and 3,200 km³ and an affected area of approximately 95,000 km², the Storegga slide represents one of the largest and best-studied submarine slides of Holocene age known worldwide. Finite element modeling of slope failure indicates that a large (6.5 < Ms < 7.0) seismic triggering mechanism would not be sufficient to cause failure at more than 110 m below the seabed as observed for the slip planes at Storegga (northern sidewall). This implies that other factors (e.g., liquefaction, strain softening, gas charging, rapid burial) are needed to explain the occurrence of the Storegga slide with a deep surface of failure. In this paper, we discuss the importance of the compaction effect of rapidly accumulated sediments in the slide area. During compaction, sediment grains reorganize themselves, thereby, expelling pore water. Consequently, depending on sedimentation rate and permeability, excess pore pressures might result beneath less permeable sediments. Our modeling and cross-checking illustrate how excess pore pressure generation due to high sedimentation rate could explain the development of layers of weakness, and thus, how such a large slide might have been initiated in deep sediments. Using the highest sedimentation rate estimated in the area (36 and 27 m/kyr between 16.2 and 15 kyr BP), 1D modeling shows excess pore pressure values of around 200 kPa at a depth of 100 m below the seafloor 15 kyr BP and 60 kPa at a depth of 100 m at the time of the slide (8 kyr BP). Excess pore pressure apparently drastically reduced the resistance of the sediment (incomplete consolidation). In addition, 2D modeling shows that permeability anisotropies can significantly affect the lateral extent of excess pore pressure dissipation, affecting, that way, normally consolidated sediments far from the excess pore pressure initiation area.  相似文献   

Environmental isotopic and hydrochemical study of water in the karst aquifer and submarine springs of the Syrian coast   总被引：1，自引：0，他引：1  

Al Charideh  Abdul Rahman 《Hydrogeology Journal》2007,15(2):351-364

The groundwater of major karst systems and submarine springs in the coastal limestone aquifer of Syria has been investigated using chemical and isotopic techniques. The δ¹⁸O values of groundwater range from ?6.8 to ?5.05‰, while those for submarine springs vary from ?6.34 to +1.08‰ (eastern Mediterranean seawater samples have a mean of +1.7‰). Groundwater originates from the direct infiltration of atmospheric water. Stable isotopes show that the elevation of the recharge zones feeding the Banyas area (400–600 m a.s.l.) is higher than that feeding the Amrit area (100–300 m a.s.l.). The ¹⁸O_extracted (¹⁸O content of the seawater contribution) for the major submarine springs suggests a mean recharge area elevation of 600–700 m a.s.l., and lower than 400 m a.s.l. for the spring close to Amrit. Based on the measured velocity and the percentage of fresh water at the submarine springs outlet, the estimated discharge rate is 350 million m³/year. The tritium concentrations in groundwater (1.6–5.9 TU) are low and very close to the current rainfall values (2.9–5.6 TU). Adopting a model with exponential time distribution, the mean turnover time of groundwater in the Al-sen spring was evaluated to be 60 years. A value of about 3.7 billion m³ was obtained for the maximum groundwater reservoir size.  相似文献   

科尔沁沙地30种植物叶凋落物CO₂释放量及释放速率的研究     

孟庆涛  李玉霖  赵学勇  李玉强  赵玉萍 《中国沙漠》2007,27(6):960-967

 采用可以有效控制环境因子的室内土壤培养试验，初步研究了科尔沁沙地30种植物叶凋落物的CO₂释放量及释放速率。结果表明：①在28 d培养期内，不同植物叶凋落物释放的CO₂量差异很大，其中，多年生植物叶凋落物CO₂释放量平均值大于一年生植物，但二者之间的差异不显著；禾本科植物叶凋落物CO₂释放量平均值明显小于其他植物，二者之间呈显著差异。②在28 d培养期内，不同植物叶凋落物每四天CO₂释放速率差异很大。一年生与多年生植物叶凋落物28 d内每四天释放CO₂的速率无显著差异；禾本科与其他植物叶凋落物每四天释放CO₂的速率在培养的前16 d差异呈显著，而后差异消失。③植物叶凋落物的全碳含量，氮含量，C／N，灰分/N及灰分含量不同造成CO₂释放量及释放速率的差异。叶凋落物28 d释放CO₂的量与叶凋落物初始碳含量及灰分含量均无相关关系，与叶凋落物初始氮含量呈显著正相关，与叶凋落物C／N及灰分／N呈显著负相关。叶凋落物培养期内每四天释放CO₂的速率与叶凋落物初始碳含量无相关关系；叶凋落物0\_20天释放CO₂的速率与叶凋落物初始氮含量呈显著正相关，与叶凋落物C／N呈显著负相关；叶凋落物9\_28天CO₂释放速率与灰分／N呈显著负相关；培养后期（17\_28天）的CO₂释放速率与灰分含量呈显著负相关。  相似文献   

Determining magma flow in sills,dykes and laccoliths and their implications for sill emplacement mechanisms     

Ken Thomson 《Bulletin of Volcanology》2007,70(2):183-201

Three-dimensional seismic data from the Faeroe-Shetland Basin provides detailed information on the relationships between sills, dykes, laccoliths and contemporaneous volcanic activity. The data shows that sills are predominantly concave upwards, being complete or partial versions of radially or bilaterally symmetrical forms that possess flat inner saucers connected to a flat outer rim by a steeply inclined sheet. Such morphologies are only partially modified by pre-existing faults. Sills can be sourced from dykes or the steep climbing portions of deeper sills. Both sills and dykes can provide magma to overlying volcanic fissures and sills can be shown to feed shallow laccoliths. Magma flow patterns, as revealed by opacity rendering, suggest that sills propagate upwards and outwards away from the magma feeder. As an individual sill can consist of several leaves emplaced at different stratigraphic levels, and as a sill or dyke can provide magma to volcanic fissures, other sills and laccoliths, the data suggests that neutral buoyancy concepts may not provide a complete explanation for the mechanism and level of sill emplacement. Instead, the data suggests that the presence of lithological contrasts, particularly ductile horizons such as overpressured shales may permit sill formation at any level below the neutrally buoyant level. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Ken Thomson–deceased, April 2007  相似文献   

On the magnitude of upwelling fluxes in shelf-break canyons     

Jochen Kämpf 《Continental Shelf Research》2007

A hydrodynamic model is employed to derive the magnitude of on-shelf fluxes through a shelf-break canyon for a wide range of canyon sizes and ambient oceanic conditions. Predicted canyon-upwelling fluxes are of the order of 0.05–0.1 Sv (1 Sv=1 million m³/s), being several orders of magnitude greater than upslope fluxes in the bottom Ekman layer on the ambient continental slope. On the basis of ∼150 simulations conducted, a bulk formula of upwelling flux in a submarine canyon is derived. For typical conditions, the upwelling flux varies quadratically with forcing strength (speed of incident flow), linearly with canyon depth, and is inversely proportional to the buoyancy frequency of the density stratification inside the canyon. Other parameters such as density stratification above shelf-break depth and bottom friction are found to have minor influences on the resultant canyon-upwelling flux.  相似文献   

疏松砂岩稠油油藏出砂冷采机理及配套技术研究   总被引：3，自引：0，他引：3  

马超  李琳  鲁春宝  李少凡  刘铁立  赵淑范 《矿物岩石》2001,21(2):73-77

稠油出砂冷采技术对地层原油含有溶解气的各类疏松砂岩稠油油藏具有较广泛的适应性，它通过大量砂子的产出和泡沫油的形成，获得较高的原油产量，河南油田于1996年在国内率先开展稠油出砂冷采技术调研及可行性研究，出砂冷采机理及配套工艺技术研究，并于1997年6月进入现场先导试验，矿场试验已展示出明显出砂冷采特征的G4906井，日产油量20t-30t，是常规开采和蒸汽吞吐的10倍和4倍以上，开采成本比蒸汽吞吐降低47%，出砂冷采工业化应用配套技术的形成和应用，将使国内及河南油田稠油资源利用程度进一步提高。  相似文献   

Evaluation of density in layer compaction using SASW method   总被引：1，自引：0，他引：1  

Dong-Soo Kim  Min-Kyun Shin  Hyung-Choon Park   《Soil Dynamics and Earthquake Engineering》2001,21(1)

SASW test, which is non-intrusive and rapid in the field application, was used to evaluate the layer density in the roller compaction without performing the complicated inversion process. The concept of normalized shear wave velocity was introduced to minimize the effect of confinement in the density evaluation. SASW test was performed to determine the shear wave velocity of the layer, and the free–free resonant column (FF–RC) test was adopted to determine the correlation between the normalized shear wave velocity and density of the site, which is almost unique independent of confinement. Testing and data reduction procedures of both tests were briefly discussed and an evaluation procedure of the field density was proposed by effectively combining in-situ shear wave velocity determined by the SASW test with the correlation between the normalized shear wave velocity and the density determined by the FF–RC test. Finally, the feasibility of the proposed method was verified by performing a field case study at Hoengsung road construction site. Field densities determined by the proposed method matched well with those determined by sand cone tests, showing the potential of applying the proposed method in the field density evaluation.  相似文献