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遥感图象的解译结果表明，环形构造与中强地震的关系密切。通过对环形构造控震作用的研究，指出了环形构造的控震模式及环形构造对地震构造环境的分析和地震预报的意义。 相似文献
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地震学家对遥感图象上的线性构造带和网络状构造格局及其与地震的关系很感兴趣,但对环形构造——遥感图象一种比较特殊的构造形态及其与地震的关系并没有引起足够的重视。多年来,笔者利用遥感图象初步分析了我国西北地区的地震构造环境,本文就环形构造在地震研究中的作用,谈几点认识。 相似文献
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环形构造是地表常见的地质构造之一。其活动构造与地震的关系颇为密切。在冀东地震区进行这项工作,对地震研究确有很大意义。一、冀东环形构造的标志所谓环形构造是指在地表上出现围绕某一中心或类核心区,呈连续或断续的弧形、环形、放射状分布的同代、异代的地质体或地质构造现象;它有正向和反向的;其规模不一,形态各异,有园形、椭园形及园锥形,乃至等轴多角形。据此,我们利用1:100O0 相似文献
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概述了已于1982年7月出版发行的《中国活动构造典型卫星影象集》。该集选辑了我国30个省、市、自治区的157幅假彩色合成和黑白的活动构造典型照片,并附有简要文字说明,基本上反映了活动断裂、新生代褶皱、活动构造盆地、活动环形构造、新生代火山、地震构造等各种类型的影象。 相似文献
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本文依据深部地球物理场、区域大地构造、地表活动断裂、地震活动等，划分了中国大陆的地震构造带，同时分析了地震构造带的活动特征和孕震构造条件，在此基础上，具体地把地震构造带的概念应用于地震危险区分析之中，探讨了地震危险区及地震前兆异常与地震构造带的关系，本文提出以地震构造带研究作为地震监测和预报工作的基础，将地震构造带作为系统性的活动构造条件应用于地震危险区划分之中。 相似文献
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地震构造是强震发生的必要基础，强震的孕育和发生与构造密切相关。强震的孕育和发生不仅与震中周围构造有关，而且与孕震区所在的整个构造带有关。这就表明整个构造带的地震活动性与未来强震都有关联，因此，我们在做测震学参数异常预测地震时，必须考虑整个构造带的地震活动。过去我们常以震中周围地区的地震活动资料来做测震学参数的异常分析，可能会丢失部分信息。本文进行了地震构造分区和构造单元的划分，把加卸载响应比参数和张家口一渤海边界带有机结合，对基于活动地块边界带的加卸载响应比参数在海城地震预测中的应用进行了研究，结果预测效果很好。这种方法对边界带的地震危险性判定有某种参考价值。 相似文献
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对雷琼凹陷地震地质的认识 总被引：1，自引：0，他引：1
本文试图通过多波段卫片判读,结合深部物探,地表地质调查等资料进一步认识区域内新生代构造,了解活动断层和地震危险区。 一、构造展布与活动性 区域内比较清晰的构造主要是断裂构造和环形构造,区域内不同地段各组构造在不同波段卫星象片中具不同程度显示(图1 a、b、c、d)。 相似文献
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应用双差地震定位法对首都圈及其邻区1980～2004年发生的地震进行重新定位，进行首都圈的地震构造成因分析表明：重定位的地震表现为与区域构造更为密切的“井”字形活动分布，地震震源分布证实了人工地震勘探所推断的深大断裂的存在；首都圈地区的地震多发生于地壳的中、上部，可能存在局域构造块体运动变形和深部构造动力作用的二种不同地震构造成因；地震活动图像表明中强震易发生在上下地壳相交的脆－韧性转换带中，并揭示了首都圈地区潜在的地震空区和陡倾角的隐伏断层. 相似文献
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绕流对称性破缺往往对柔细结构产生很大的作用效应,诱发结构振动,严重影响其可靠性和安全性。基于圆柱平面绕流模型,系统分析了实际流体圆柱绕流纵向对称性破缺以及各种情况的横向对称性破缺现象。为了更加深入地理解理论分析的结果,利用Fluent软件对圆柱绕流模型进行了计算机模拟,详细分析了雷诺数为10、20、40、100、200、2000、20000时的绕流情况,结果显示,当雷诺数为200时,流场开始出现横向对称性破缺。在此基础上,以Tacoma大桥风振致毁事故为例,分情况探讨了旋涡同步交替脱落导致的桥面起伏性振动,以及旋涡异步交替脱落导致的桥面扭振。分析结果表明,绕流对称性破缺是诱发大桥振动破坏的直接原因。 相似文献
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地下水单井综合观测的"循环法"及其原理 总被引：2，自引：1，他引：1
主要介绍在地下水前兆观测中采用“循环法”实现静水位-水化学单吉综合观测技术方案,该方法通过设置一循环系统,在保持静水位状态观测的同时,位于井口处的循环回路上部可获取深部含水层水化学观测,从而为实现同时满足水位和水化学观测要求的单井综合观测提供了基础,还变该方法在水化学观测方面的工作原理给出了定量描述,推导了井孔观测系统的水化学平衡方程,为该方法的有效性给出了理论证明,同时还简要介绍了有关实验验证结果。 相似文献
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Gin-Show Liou 《地震工程与结构动力学》1994,23(2):193-210
A systematic procedure is presented for generating dynamic stiffness matrices for two independent circular foundations on an elastic half-space medium. With the technique reported in References 1–3, the analytic solution of three-dimensional (3D) wave equations satisfying the prescribed traction due to the vibration of one circular foundation can be found. Since there are two analytic solutions for two prescribed tractions due to the vibrations of two circular foundations, the principle of superposition must be used to obtain the total solution. The interaction stresses (prescribed tractions) are assumed to be piecewise linear in the r-directions of both cylindrical co-ordinates for the two circular foundations. Then, the variational principle and the reciprocal theorem are employed to generate the dynamic stiffness matrices for the two foundations. In the process of employing the variational principle, a co-ordinate transformation matrix between two cylindrical co-ordinate systems is introduced. Some numerical results of dynamic stiffness matrices for the interaction of two identical rigid circular foundations are presented in order to show the effectiveness and efficiency of the present method, and some elaborations for its future extensions are also discussed. 相似文献
15.
Watercourse morphology is affected by local scouring when the flow interferes with anthropic structures. Controlling the scour hole size is of predominant importance to guarantee bridge safety as well as to limit the variations of river morphology. A combined countermeasure against bridge pier scour is proposed and tested in order to reduce the maximum scour depth and deviate it away from the bridge foundation. In the first part of the laboratory campaign, combination of two countermeasures (bed-sill and collar) was evaluated for a circular pier under clear-water and live-bed steady flow conditions. The proposed combined countermeasure exhibited an efficiency of about 64% in terms of scour depth reduction. Afterwards, it was tested in unsteady flow conditions, first for a circular pier, then in the case of a rectangular pier with round nose and tail, two circular in-line piers and two rectangular in-line piers, under a hydrograph with a peak flow velocity slightly above the threshold condition of sediment motion. Results showed that the combined countermeasure had an efficiency of about 63% for a single circular pier; however, higher efficiency (about 75%) was obtained in applications to rectangular pier and two in-line circular or rectangular piers. 相似文献
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半无限空间中圆形孔洞周围SH波的散射 总被引：14，自引：5，他引：14
建立了求解在含有圆形孔洞的弹性半空间中SH波散射与圆形孔洞附近动应力集中问题的解析方法。利用SH波散射的对称性和多极坐标的方法，构造了一个可以预先满足半空间自由表面上应力自由边界条件的圆形孔洞对SH波散射的波函数。利用这一波函数，则可将该问题转化成对一个圆形孔洞散射的求解问题。该问题的解答最终又可归结为对一组无究代数方程组的求解问题，并可利用截断有限项的方法对其进行计算，最后给出了有关圆形也洞附近动应力集中问题的算例和数值结果，并讨论了波数与圆孔至自由边界距离变化对动应力集中的影响。 相似文献
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Transient electromagnetic surveys with unimodal transverse magnetic field: ideas and results 
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下载免费PDF全文 Vladimir S. Mogilatov Arkadiy V. Zlobinskiy Boris P. Balashov 《Geophysical Prospecting》2017,65(5):1380-1397
The theory behind transient electromagnetic surveys can be well described in terms of transverse magnetic and transverse electric modes. Soundings using transverse magnetic and transverse electric modes require different source configurations. In this study, we consider an alternating transverse magnetic field excitation by a circular electric dipole. The circular electric dipole transmitter is a horizontal analogue of the vertical electric dipole. Offshore surveys using circular electric dipole might represent an alternative to the conventional marine controlled‐source electromagnetic method at shallow sea and/or for exploring relatively small targets. Field acquisition is carried out by recording either electric or magnetic responses. Electric responses bear information on the 1D structure of a layered earth and successfully resolve high‐resistivity targets in marine surveys. Land‐based circular electric dipole soundings are affected by induced polarisation. On the contrary, magnetic responses are absent on the surface of a 1D earth, and as a result, they are very sensitive to any and even very small 3D conductivity perturbations. In addition, they are sensitive to induced polarisation or some other polarisation effects in the subsurface. At present, circular electric dipole transmitters and magnetic receivers are successfully used in on‐land mineral and petroleum exploration. 相似文献
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Jose A. Carnicero M. Concepción Ausín Michael P. Wiper 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(8):1991-2002
This paper proposes a nonparametric approach to estimating the dependence relationships between circular variables and other circular or linear variables using copulas. The proposed method is based on the use of Bernstein copulas which are a very flexible class of non-parametric copulas which allows for the approximation of any kind of dependence structure, including non symmetric relationships. In particular, we present a simple procedure to adapt Bernstein copulas to the circular framework and guarantee that the constructed bivariate distributions are strictly continuous. We provide two illustrative case studies, the first on the relation between wind direction and quantity of rainfall in the North of Spain and the second on the dependence between the wind directions in two nearby buoys at the Atlantic ocean. 相似文献
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Comparison between Shannon and Tsallis entropies for prediction of shear stress distribution in open channels 总被引：2，自引：1，他引：1
Hossein Bonakdari Zohreh Sheikh Mohtaram Tooshmalani 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(1):1-11
The concept of Tsallis entropy was applied to model the probability distribution functions for the shear stress magnitudes in circular channels (with filling ratios of 0.506, 0.666, 0.826), circular with flat bed (filling ratios of 0.333, 0.666), rectangular channel (1.34, 2, 3.94, 7.37 aspect ratios) and compound channel (with relative depths of 0.324, 0.46). The equation for the shear stress distribution was obtained according to the entropy maximization principle, and is able to estimate the shear stress distribution as much on the walls as the channel bed. The approach is also compared with the predictions obtained based on the Shannon entropy concept. By comparing the two prediction models, this study highlights the application of Tsallis entropy to estimate the shear stress distribution of open channels. Although the results of the two models are similar in the circular cross-section, the differences between them are more significant in circular with flat bed and rectangular channels. For a wide range of filling ratio values, experimental data are used to illustrate the accuracy and reliability of the proposed model. 相似文献
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Phil Dyke 《Ocean Dynamics》2005,55(3-4):238-247
Wave trapping and induced flow around an island is examined. The exactly circular island solutions are reprised and the solutions
extended, and shown to apply to a stratified sea. The homogeneous solutions are then used to deduce the wave trapping and
flow around a near circular island. It turns out that the cotidal pattern for a perfectly circular island is relatively immune
to variations in geometry and radially dependent depth variations. This helps explain the similarity in the behaviour of the
tides around various islands (the Pribilof Islands near Alaska, Oahu in Hawaii, Cook Island off north west Australia, Bermuda
off the eastern coast of the USA, and Bear Island in the Norwegian Sea). The dominant steady drift and its rate of decay off-shore
is also calculated. 相似文献