柴达木盆地北缘中、新生代构造演化探讨

本文通过近年来的地震反射信息研究,对柴达木盆地北缘中、新生代地质构造演化进行了分析,透过红山地区这个窗口,揭示柴达木盆地内中、新生代两个世代的构造成因类型,展示二者叠置关系和构造样式,认为该区存在先张后压的演化历史,且后期挤压作用破坏和改造早期拉张构造样式,从而更有效地指导盆地中生代油气藏的勘探。     

Plio-Quaternary paleostresses in the Atlantic passive margin of the Moroccan Meseta: Influence of the Central Rif escape tectonics related to Eurasian-African plate convergence

The Atlantic Moroccan Meseta margin is affected by far field recent tectonic stresses. The basement belongs to the variscan orogen and was deformed by hercynian folding and metamorphism followed by a post-Permian erosional stage, producing the flat paleorelief of the region. Tabular Mesozoic and Mio-Plio-Quaternary deposits locally cover the Meseta, which has undergone recent uplift, while north of Rabat the subsidence continues in the Gharb basin, constituting the foreland basin of the Rif Cordillera.The Plio-Quaternary sedimentary cover of the Moroccan Meseta, mainly formed by aeolian and marine terraces deposits, is affected by brittle deformations (joints and small-scale faults) that evidence that this region – considered up to date as stable – is affected by the far field stresses. Striated faults are recognized in the oldest Plio-Quaternary deposits and show strike-slip and normal kinematics, while joints affect up to the most recent sediments.Paleostress may be sorted into extensional, only affecting Rabat sector, and three main compressive groups deforming whole the region: (1) ENE–WSW to ESE–WNW compression; (2) NNW–SSE to NE–SW compression and (3) NNE–SSW compression. These stresses can be attributed mainly to the NW–SE oriented Eurasian-African plate convergence in the western Mediterranean and the escape toward the SW of the Rif Cordillera. Local paleostress deviations may be related to basement fault reactivation. These new results reveal the tectonic instability during Plio-Quaternary of the Moroccan Meseta margin in contrast to the standard passive margins, generally considered stable.     

Inelastic displacement demands in steel structures and their relationship with earthquake frequency content parameters

This paper deals with the estimation of peak inelastic displacements of SDOF systems, representative of typical steel structures, under constant relative strength scenarios. Mean inelastic deformation demands on bilinear systems (simulating moment resisting frames) are considered as the basis for comparative purposes. Additional SDOF models representing partially‐restrained and concentrically‐braced (CB) frames are introduced and employed to assess the influence of different force‐displacement relationships on peak inelastic displacement ratios. The studies presented in this paper illustrate that the ratio between the overall yield strength and the strength during pinching intervals is the main factor governing the inelastic deformations of partially‐restrained models and leading to significant differences when compared with predictions based on bilinear structures, especially in the short‐period range. It is also shown that the response of CB systems can differ significantly from other pinching models when subjected to low or moderate levels of seismic demand, highlighting the necessity of employing dedicated models for studying the response of CB structures. Particular attention is also given to the influence of a number of scalar parameters that characterise the frequency content of the ground motion on the estimated peak displacement ratios. The relative merits of using the average spectral period T_aver, mean period T_m, predominant period T_g, characteristic period T_c and smoothed spectral predominant period T_o of the earthquake ground motion, are assessed. This paper demonstrates that the predominant period, defined as the period at which the input energy is maximum throughout the period range, is the most suitable frequency content scalar parameter for reducing the variability in displacement estimations. Finally, noniterative equivalent linearisation expressions based on the secant period and equivalent damping ratios are presented and verified for the prediction of peak deformation demands in steel structures. Copyright © 2011 John Wiley & Sons, Ltd.     

邢台地震区大地电磁观测与研究

在邢台地震区进行了大地电磁观测,并对该地区电性结构与地震的关系进行了研究.该地区地下电性结构较复杂,电性在纵向及横向都存在着显著的变化.一维结果表明,该地区电性纵向分布可分五层,第三层为高导层,埋深约10—20 km.在地震震源集中区,高导层深度有较大变化.电性横向分布也有明显变化.总体上看,地震区内电阻较高,可是地震并不发生在电阻率最高的地点,而多发生在电性变化较大地段.     

Harmonic generation past a submerged porous step

Experiments were conducted in a wave flume to study the differences between harmonic evolution of monochromatic waves as they propagate over a submerged impermeable or porous step under non-breaking conditions. Results are used as a preliminary analysis to establish some engineering design criteria on harmonic generation on submerged porous structures. The root-mean-squared wave height evolution is also studied and compared to linear models as a first approximation. It is shown that porous structure increases the effective relative depth and decreases the relative wave height, resulting in a lower Ursell number and a lower chance to generate harmonics. The effective water depth over a step as defined in the paper, provides information to evaluate the potential harmonic generation.     

The Optimal Design of TMD for Offshore Structures

This paper presents the optimal design procedure of Tuned Mass Damper(TMD)for re-ducing vibration of an actual steel jacket offshore platform excited by random wave loading.In this study,a frequency domain is taken.The force on the structure is determined by use of the linearized Morisonequation for an input Power Spectral Density(PSD)of wave elevation.The sensitivity of optimum valuesof TMD to characteristic parameters of random wave spectrum is analyzed.An optimized TMD designfor the modeled platform is given based on design conditions and the findings of the study.     

反射系数（K）法在激电测深找矿中的应用

反射系数（Ｋ）法是一种电测深ρｓ资料的解释手段和处理方法。从湖南某砂岩铜矿利用激电测深确定红层中的含矿层,某铅锌矿利用激电测深探测两条含矿破碎带的实例,说明反射系数（Ｋ）法在对激电测深ρｓ资料解释的基础上,结合激电异常的特点,能有效地确定不同的地质构造,达到间接找矿的目的。     

城市中小河道水工建（构）筑物调查测绘技术方法的探讨

结合具体工程实例介绍了当前城市中小河道测量工程中常见水工建（构）筑物的类型、调查量测内容及对应精度指标、外业测绘取舍及内业成图表示方法等,特别是根据实地水工建（构）筑物的规模大小、复杂程度,探讨了对其进行调查测绘的技术方法,并结合CAD绘图系统提出了相应的解决办法.     

Some statistical characteristics of large deepwater waves around the Korean Peninsula

The relationship between significant wave height and period, the variability of significant wave period, the spectral peak enhancement factor, and the directional spreading parameter of large deepwater waves around the Korean Peninsula have been investigated using various sources of wave measurement and hindcasting data. For very large waves comparable to design waves, it is recommended to use the average value of the empirical formulas proposed by Shore Protection Manual in 1977 and by Goda in 2003 for the relationship between significant wave height and period. The standard deviation of significant wave periods non-dimensionalized with respect to the mean value for a certain significant wave height varies between 0.04 and 0.21 with a typical value of 0.1 depending upon different regions and different ranges of significant wave heights. The probability density function of the peak enhancement factor is expressed as a lognormal distribution, with its mean value of 2.14, which is somewhat smaller than the value in the North Sea. For relatively large waves, the probability density function of the directional spreading parameter at peak frequency is also expressed as a lognormal distribution.     

村镇滑移隔震建筑瞬时摩擦耗能的参数敏感性分析

给出了村镇滑移隔震建筑瞬时摩擦耗能的概念,并以此概念为响应指标。通过极差大小的对比,分析了该响应指标对刚度比、第二阶段刚度系数、隔震层屈服位移、隔震层摩擦系数、系统质量比和上部结构自振周期六个参数变化的敏感程度,阐述了上述系统参数对瞬时摩擦耗能这一响应指标的影响规律。研究表明:场地条件和地震动幅值大小对瞬时摩擦耗能均有显著影响;在所考虑的参数范围内,上部结构自振周期总是对瞬时摩擦耗能有较为显著的影响,摩擦系数对瞬时摩擦耗能的影响跟场地条件有关,Ⅰ类场地条件中摩擦系数对瞬时摩擦耗能影响不显著,而Ⅱ、Ⅲ和Ⅳ类场地条件中,摩擦系数对瞬时摩擦耗能的影响则非常显著;隔震层屈服位移、刚度比和第二阶段刚度系数总得来讲对瞬时摩擦耗能影响不显著,质量比对瞬时摩擦耗能影响居中。