安丘地震台地震前兆数据跟踪分析

从安丘地震台数据跟踪分析工作实际出发,详述数据跟踪分析平台软件安装与使用,探讨日常数据分析常见问题及解决办法,分享数据跟踪分析工作经验,以期为地震前兆台站数据跟踪分析工作提供参考。     

有关钢结构地震作用的讨论

简要介绍了6本国内标准(TJ11-74、TJ11-78、GB J11-89、GB50011-2001、JG J99-98、CECS160:2004)有关钢结构地震作用的计算方法,包括荷载组合方法和底部剪力法。通过归一化后的结果比较,评价了各本标准地震作用的大小。分析表明,除JG J99-98和GB50011-2001 2本标准由于考虑钢结构的阻尼比为0.02或0.035后,其地震作用有显著增大外,其它4本标准的地震作用处于接近的水平。考虑到钢筋混凝土和砖石结构等的地震作用水平在新旧抗震规范中并无多大变化,过分提高抗震性能较优的钢结构的地震作用水平显然是不合理的。     

PERFORMANCE EVALUATION OF SUBMERGENCE RATIO OF A RECTANGULAR SUBMERGED VANE WITH A COLLAR

1 INTRODUCTION Odgaard and Kennedy (1983) suggested that for values of angle of attack, α greater than or equal to approximately 20o, a persistent scour hole is produced near the upstream end of a vane. As α was reduced the number of vanes producing obj…     

基于周期谱分析的线性合成概率预测方法在山东地区的应用

以基于周期谱分析基础上的线性合成概率预测方法,对山东内陆主体及其邻近的南黄海、冀鲁豫交界等地区中强以上和中等地震进行了试验性分析研究.结果表明,最初以新疆地区7级以上地震为例研究的强震预测方法,用于山东及其邻近区域的中强以上和中等地震也有较好的检验效果.对各分区的回顾性检验结果表明,方法的R值评分一般在0.6以上,最低为0.5.最后依据展望性预测结果对山东内陆主体区、冀鲁豫交界和南黄海地区未来几年的地震趋势做了初步估计.     

编码激励在岩石衰减(1/Q)检测中的应用

通过测量超声波衰减能够检测岩石强度,但超声信号的低信噪比特征一直是精确测量衰减的瓶颈.编码激励技术能够在不损失分辨率的情况下提高信噪比,因此成为超声检测岩石强度的关键.为了促进编码激励技术在实验室检测中的应用,我们系统研究了编码激励的原理和方法,通过数值和物理实验获得了该技术的使用条件.物理实验表明,编码激励技术能够抑...     

The Sensitive Properties of Hydrate Reservoirs Based on Seismic Stereoscopic Detection Technology

Higher-precision determinations of hydrate reservoirs, hydrate saturation levels and storage estimations are important for guaranteeing the ability to continuously research, develop and utilize natural gas hydrate resources in China. With seismic stereoscopic detection technology, which fully combines the advantages of different seismic detection models, hydrate formation layers can be observed with multiangle, wide-azimuth, wide-band data with a high precision. This technique provides more reliable data for analyzing the distribution characteristics of gas hydrate reservoirs, establishing velocity models, and studying the hydrate-sensitive properties of petrophysical parameters;these data are of great significance for the exploration and development of natural gas hydrate resources. Based on a velocity model obtained from the analysis of horizontal streamer velocity data in the hydrate-bearing area of the Shenhu Sea, this paper uses three VCs(longitudinal spacing of 25 m) and four OBSs(transverse spacing of 200 m) to jointly detect seismic datasets consisting of wave points based on an inversion of traveltime imaging sections. Accordingly, by comparing the differences between the seismic phases in the original data and the forward-modeled seismic phases, multiangle coverage constraint corrections are applied to the initial velocity model, and the initial model is further optimized, thereby improving the imaging quality of the streamer data. Petrophysical elastic parameters are the physical parameters that are most directly and closely related to rock formations and reservoir physical properties. Based on the optimized velocity model, the rock elastic hydrate-sensitive parameters of the hydrate reservoirs in the study area are inverted, and the sensitivities of the petrophysical parameters to natural gas hydrates are investigated. According to an analysis of the inversion results obtained from these sensitive parameters, λρ, Vp and λμ are simultaneously controlled by the bulk modulus and shear modulus, while Vs and μρ are controlled only by the shear modulus, and the latter two parameters are less sensitive to hydrate-bearing layers. The bulk modulus is speculated to be more sensitive than the shear modulus to hydrates. In other words, estimating the specific gravity of the shear modulus among the combined parameters can affect the results from the combined elastic parameters regarding hydrate reservoirs.     

尾砂胶结含盐冻结充填体力学特性研究

矿山充填开采正逐步向寒区甚至永久冻土区发展,这些区域含盐地下水分布非常广泛。同时,极端寒冷条件下往往需要向充填材料中加入一些防冻盐以防止料浆在输送过程中发生冻结。通过室内测试分析了?6 ℃环境下不同盐分（NaCl）膏体充填体力学特性（强度和初始弹性模型）随时间演化特征。利用单轴压力机测得了龄期为7、28、90 d膏体充填体的强度和初始弹性模量,结果表明NaCl的加入会降低冻结充填体的强度,其影响程度取决于胶结料类型。试样的强度随着养护时间的增加而增大。此外,不论盐分浓度、养护时间和胶结料类型,试样的强度与初始弹性模量之间存在显著的线性关系。该研究结果可以为寒区含盐膏体充填技术的开展提供一些依据。     

Free‐vibration analysis of a three‐dimensional soil–structure system

A procedure which involves a non‐linear eigenvalue problem and is based on the substructure method is proposed for the free‐vibration analysis of a soil–structure system. In this procedure, the structure is modelled by the standard finite element method, while the unbounded soil is modelled by the scaled boundary finite element method. The fundamental frequency, and the corresponding radiation damping ratio as well as the modal shape are obtained by using inverse iteration. The free vibration of a dam–foundation system, a hemispherical cavity and a hemispherical deposit are analysed in detail. The numerical results are compared with available results and are also verified by the Fourier transform of the impulsive response calculated in the time domain by the three‐dimensional soil–structure–wave interaction analysis procedure proposed in our previous paper. The fundamental frequency obtained by the present procedure is very close to that obtained by Touhei and Ohmachi, but the damping ratio and the imaginary part of modal shape are significantly different due to the different definition of damping ratio. This study shows that although the classical mode‐superposition method is not applicable to a soil–structure system due to the frequency dependence of the radiation damping, it is still of interest in earthquake engineering to evaluate the fundamental frequency and the corresponding radiation damping ratio of the soil–structure system. Copyright © 2001 John Wiley & Sons, Ltd.     

Lithospheric flexural modelling of the seaward and trenchward of the subducting oceanic plates

ABSTRACT

Based on a two-segment plate flexural modelling, we investigated the effective elastic thickness of global subducting oceanic lithosphere. Our results show that for the plate age of 0 to 50 Ma, the seaward effective elastic thickness T _e ^M values are located between 600 and 900°C isotherms, and do not track any isotherm, while the majority of the trenchward effective elastic thickness T _e ^m values are located between 300 and 600°C isotherms. For the plate age older than 50 Ma, T _e ^M values basically matches the 600°C isotherm with some fluctuations for the age older than 110 Ma, while T _e ^m values mainly fall between 200 and 400°C isotherms. The reduction in effective elastic thickness (T _e ^M-T _e ^m) varies from 2.6 to 30.1 km, or 11–68% of seaward T _e ^M. Thus, the absolute value of the decrease in the effective elastic thicknesses (T _e ^M-T _e ^m) increases with the plate age, while the percentage reduction in the effective elastic thickness (1-T _e ^m/T _e ^M) has no obvious relationship with the age, but more related to the curvature of bending plate. Almost all bending-related earthquakes occurred above the T _e ^M line, but many normal-faulting earthquakes are deeper than the T _e ^M-T _e ^m line, implying that the plate may still retain some thickness of an elastic property core in the areas (depth) where earthquakes occur.     

甘肃阳山金矿整装勘查区成矿与找矿关键科学问题

以阳山金矿为核心的甘肃阳山整装勘查区是中国107片整装勘查区之一。勘查区位于中央复合造山带中段西秦岭南缘,该区构造-岩浆演化复杂,成矿地质条件优越。区内以阳山、新关、关牛湾、塘坝等为主的金矿床,经过近20年的地质勘查和科研工作,取得了重要进展,目前勘查区正处于找矿勘查实现更大突破的关键时期。文章在系统梳理前期勘查和研究成果基础上,并经野外详细调查和分析,提出制约整装勘查区找矿突破的关键科学问题:基过于勘查区所处的大地构造环境和复杂造山过程,需从全新角度认识勘查区成矿地质环境和成矿作用的演化;基于野外勘查新发现的地质事实,进一步查明区内多期构造-岩浆活动与成矿的时空、成因联系和耦合关系,厘定多期成矿作用叠加改造及其对成矿产物的影响;从整装勘查区乃至区域成矿带巨量金聚集的角度,深化巨量成矿物质来源研究;全面分析阳山整装勘查区内典型金矿床特点,并通过与国内外典型矿床的对比研究,确立区内金矿床的成因类型和勘查类型;以区内复杂构造演化为脉络及其对成矿的控制研究,提炼主要控矿因素和找矿勘查标志;面向找矿突破的总体目标,全面总结勘查区、矿田和矿床等不同层次的成矿规律,系统全面评价勘查区资源潜力和找矿勘查方向。