东营凹陷陡坡带油井前兆异常及其动力学成因讨论

分析了东营凹陷陡坡带断裂体系 ,研究了东营凹陷陡坡带油井前兆异常与地震活动的关系 ,探讨了油井前兆异常的动力学成因。孕震过程是应力场变化和调整的过程 ,应力场变化导致孔隙压力变化 ,使得油井产生前兆异常。特定的地质环境是油井前兆异常的基础 ,应力转化为孔隙压力是油井前兆异常的前提。油井前兆异常是正异常还是负异常 ,取决于油井所处的地质环境在孕震过程中地应力是增加还是减小 ,前兆异常幅度取决于孔隙压力的变化幅度     

带TMD的结构基于动力可靠性约束的优化设计

本文在运用复模态法求得多自由度带TMD结构随机地震响应解析解的基础上．采用基于动力可靠性约束的优化设计方法对TMD装置参数的优化取值进行了系统研究,以结构最大位移响应的期望值为目标函数,以TMD装置响应的动力可靠性为约束条件,运用罚函数法获得到TMD装置的优化设计参数．并给出了算例,从而建立了带TMD结构基于动力可靠性约束的抗震优化设计的一整套方法,本文方法也可用于基础隔震结构、带TLD减震结构以及带TMD和TLD抗风结构的优化设计。     

考虑各向异性的层土-盾构隧道地震反应数值模拟

在层状各向异性土体-盾构隧道地震反应分析中,引入了横观各向同性弹塑性模型理论,建立了适合于横观各向同性介质的双渐近-多向透射边界条件。针对地铁区间盾构隧道抗震设计的特点,基于横观各向同性弹塑性模型,研制了考虑层状土体各向异性和施工开挖效应,适合于盾构隧道动力计算的各向异性弹塑性动力有限元程序。在程序中对于不同的材料采用了不同的本构关系和不同的单元形式,并采用了关联流动法则和多种屈服准则,可同时进行各向异性土体与地下结构的二维平面应力、平面应变和轴对称问题的静力和动力数值分析。最后利用所研制的程序进行了上海地铁二号线石门一路站附近区间隧道在不同超越概率地震动输入下的隧道反应计算。结果表明,在层状土体-地铁区间隧道的抗震分析中考虑土体各向异性的影响是必要的,所提出的计算模型是可行的。     

柔性承台板与群桩的竖向动力作用

采用动力文克尔地基模型模拟均质粘弹性土层,推导出了均质土中单桩动阻抗;引用桩-桩动力相互作用因子,得到了刚性承台下群桩的动阻抗;而且建立了柔性承台与桩基础的竖向振动模型,该模型考虑了筏板自身的变形,并导出了其共同作用的运动方程。最后对柔性承台与刚性承台的计算结果作了对比分析。     

强夯法施工振动效应分析

对强夯法施工引起的振动效应进行了详细分析,得出对邻近建筑物影响因素的估计,为强夯施工方案设计提供设计借鉴。     

Liquefaction mitigation in silty soils using composite stone columns and dynamic compaction

The objective of this study is to develop an analytical methodology to evaluate the effectiveness ofvibro stone column (S. C.) and dynamic compaction (D.C.) techniques supplemented with wick drains to densify and mitigate liquethctionin saturated sands and non-plastic silty soils. It includes the following: (i) develop numerical models to simulate and analyze soil densification during S.C. installation and D.C. process, and (ii) identify parameters controlling post-improvement soil density in both cases, and (iii) develop design guidelines for densification of silty soils using the above techniques. An analytical procedure was developed and used to simulate soil response during S.C. and D.C. installations, and the results were compared with available case history data. Important construction design parameters and soil properties that affect the effectiveness of these techniques, and construction design choices suitable for sands and non-plastic silty soils were identified. The methodology is expected to advance the use of S.C. and DC. in silty soils reducing the reliance on expensive field trials as a design tool. The ultimate outcome of this research will be design charts and design guidelines for using composite stone columns and composite dynamic compaction techniques in liquefaction mitigation of saturated silty soils.     

A simplified methd of evaluating the seismic performance of buildings

This paper presents a simplified method of evaluating the seismic performance of buildings. The proposed method is based on the transformation of a multiple degree of freedom (MDOF) system to an equivalent single degree of freedom (SDOF) system using a simple and intuitive process. The proposed method is intended for evaluating the seismic performance of the buildings at the intermediate stages in design, while a rigorous method would be applied to the final design. The performance of the method is evaluated using a series of buildings which are assumed to be located in Victoria in western Canada, and designed based on the upcoming version of the National Building Code of Canada which is due to be published in 2005. To resist lateral loads, some of these buildings contain reinforced concrete moment resisting frames,while others contain reinforced concrete shear walls. Each building model has been subjected to a set of site-specific seismic spectrum compatible ground motion records, and the response has been determined using the proposed method and the general method for MDOF systems. The results from the study indicate that the proposed method can serve as a useful tool for evaluation of seismic performance of buildings, and carrying out performance based design.     

基于微地貌特征的西太平洋菲律宾海海底稳定性评价

随着海洋战略地位的逐步提高,深远海海底资源开发和海洋工程建设将面临巨大挑战,主要是受限于技术手段,高精度调查资料难以获取,无法全面准确地进行海底稳定性评价.针对这一问题,本文提出了基于微地貌特征的深远海海底稳定性评价方法.基于已有的研究工作,本文选取西太平洋菲律宾海中南部某区域为研究区,利用ArcGIS平台建立研究区D...     

Impact of Ocean Mean Dynamic Topography on Satellite Data Assimilation

The response of an eddy-permitting ocean model to changes imposed by the use of different mean dynamic topographies (MDT) is analyzed in a multivariate assimilation context, allowing the evaluation of this impact, not only on the surface circulation, but also on the interior ocean representation. The assimilation scheme is a reduced-order sequential Kalman filter (SEEK). In a first set of experiments, high resolution sea surface temperature, along-track sea surface height and sea surface salinity from climatology are assimilated into a 1/3° resolution North and Tropical Atlantic version of the HYCOM model. In a second experiment, in situ profile data are assimilated in addition to the surface measurements.

The first set of experiments illustrates that important differences in the representation of the horizontal model circulation pattern are related to differences in the MDT used. The objective of assimilation is to improve the representation of the 3D ocean state. However, the imperfect representation of the mean dynamic topography appears to be an important limiting factor with regard to the degree of realism obtained in the simulated flow.

Vertical temperature and salinity profiles are key observations to drive a general circulation ocean model toward a more realistic state. The second set of experiments shows that assimilating them in addition to sea surface measurements is a far from trivial exercise. A specific difficulty is due to inconsistencies between the dynamic topography diagnosed from in situ observations and that diagnosed from sea surface height. These two fields obtained from different data sources do not contain exactly the same information. In order to overcome this difficulty, a strategy is proposed and validated.     

Improving the Coastal Mean Dynamic Topography by Geodetic Combination of Tide Gauge and Satellite Altimetry

Abstract

The ocean mean dynamic topography (MDT) is the surface representation of the ocean circulation. The MDT may be determined by the ocean approach, which involves temporal averaging of numerical ocean circulation model information, or by the geodetic approach, wherein the MDT is derived using the ellipsoidal height of the mean sea surface (MSS), or mean sea level (MSL) minus the geoid as the geoid. The ellipsoidal height of the MSS might be estimated either by satellite or coastal tide gauges by connecting the tide gauge datum to the Earth-centred reference frame. In this article we present a novel approach to improve the coastal MDT, where the solution is based on both satellite altimetry and tide gauge data using new set of 302 tide gauges with ellipsoidal heights through the SONEL network. The approach was evaluated for the Northeast Atlantic coast where a dense network of GNSS-surveyed tide gauges is available. The typical misfit between tide gauge and satellite or oceanographic MDT was found to be around 9?cm. This misfit was found to be mainly due to small scale geoid errors. Similarly, we found, that a single tide gauge places only weak constraints on the coastal dynamic topography.