读者沙龙

时光飞逝,2011年来到。我发现《地球》杂志有了很多可喜的变化：栏目多样了．内容丰富多彩了。图片更漂亮了．文章思想更深刻了,文笔更犀利了。可读性更强了……我很喜欢“地学讲堂”的文章．写出了地学上的许多知识．非常有趣味性。     

天津测震台网综合管理系统的设计与实现

介绍了天津市测震台网综合管理系统开发的背景,分析了系统的架构与设计方案,并对各功能模块进行了详细的描述,同时就软件开发过程中遇到的问题给予了解决方案,阐述了该系统的实现过程并将其加以应用,实际应用表明该系统提高了工作效率,达到了预期目标.     

考虑刚度及边界条件的短索索力求解与试验研究

建立了一个非齐次边界拉索力学模型,基于拉索线性振动理论,推导了考虑拉索抗弯刚度及边界条件的拉索频率方程;根据双曲函数的数理特性对频率方程进行了合理简化,得到了实用的频率简化方程,提出了逆过程求解索力的方法和步骤,并探讨了不同支承刚度对索力的影响。设计了室内拉索试验模型并进行了27种工况索力试验,比较了不同工况下的计算索力与实际索力,验证了本文提出的频率简化方程和逆过程求解方法的实用可靠性。     

基于地震易损性的框架结构的优化方法

给出了一种框架结构地震易损性优化的准则算法．根据优化准则构造了一种修改设计变量的格式,提出了设计方案可行性调整的方法并推导了计算公式,给出了优化算法的计算步骤,并通过一个算例阐述了这种算法的应用。     

大庆油田地震应急预案情景分析

建立了大庆油田地震应急预案情景分析模型,着重分析了大庆油田重要建筑物和特殊结构的分布和危险性,模拟了生命线工程、生产系统受损及次生灾害引发的灾害场景,并对灾害损失状况进行了情景模拟。在GIS平台上可视化表达了地震应急预案的实施效果,展示了地震应急预案实施的情景,检验了预案的可行性。     

背后山古滑坡对汉源老县城震害的影响

通过对背后山地形地貌、地层岩性、地质构造等进行了野外考察,揭示了背后山发育的古滑坡,圈定了古滑坡周界,分析了汶川地震对背后山古滑坡的影响.利用有限元软件ADINA估算了背后山古滑坡的卓越周期,并与汉源老县城附近的强震记录的卓越周期进行了对比,发现可能出现了共振现象.最后探讨了背后山古滑坡对汉源老县城建筑物震害的影响.     

新疆地震台网测震资费管理信息系统的研究与应用

介绍了新疆地震台网测震资费管理信息系统开发的背景,分析了系统的架构与设计方案,及对各功能模块进行了详细的描述,然后阐述了该系统的实现方案并将其加以应用。实践表明,该系统提高了工作效率,达到了预期目标。     

电阻率随位置线性变化时的三维大地电磁模拟

采用积分方程法实现了对三维体电磁散射的数值模拟研究.在分析电张量格林函数的基础上,针对大地电磁情形，进行了数值模拟研究.分析了异常体的横向走向长度对电磁响应的影响,特别对电阻率作线性变化的异常体进行了数值分析,并得到了相应测深曲线.对三维电磁测深进行了分析,考察了地层参数的影响,得到了一些重要结果.     

地震的综合观测与综合分析预报

综述了地震综合观测与综合分析预报的工作概况,首先对日、苏、美、中等四国的这方面状况进行了回顾,并列表作了比较,继而论述了地震预报的探索与实用化问题,文章最后作了某些分析并提出了今后的展望。     

宁夏地区地壳上地幔各向异性研究

本文对国际、国内在地壳上地幔介质各向异性研究领域的发展历史及研究现状进行了简单回顾,交待了宁夏地区的构造环境,阐述了本文所采用的上地幔各向异性分析方法的原理,介绍了地壳各向异性产生的机理并选择了适当的分析方法,首次系统得到了较好的宁夏地区地壳上地幔各向异性测量参数,并进行了解释。     

A comparative study on the rheology and wave dissipation of kaolinite and natural Hendijan Coast mud, the Persian Gulf

The objective of this paper is to investigate the rheological behavior of kaolinite and Hendijan mud, located at the northwest part of the Persian Gulf, and the dissipative role of this muddy bed on surface water waves. A series of laboratory rheological tests was conducted to investigate the rheological response of mud to rotary and cyclic shear rates. While a viscoplastic Bingham model can successfully be applied for continuous controlled shear-stress tests, the rheology of fluid mud displays complex viscoelastic behavior in time-periodic motion. The comparisons of the behavior of natural Hendijan mud with commercial kaolinite show rheological similarities. A large number of laboratory wave-flume experiments were carried out with a focus on the dissipative role of the fluid mud. Assuming four rheological models of viscous, Kelvin-Voigt viscoelastic, Bingham viscoplastic, and viscoelastic-plastic for fluid mud layer, a numerical multi-layered model was applied to analyze the effects of different parameters of surface wave and muddy bed on wave attenuation. The predicted results based on different rheological models generally agree with the obtained wave-flume data implying that the adopted rheological model does not play an important role in the accuracy of prediction.     

Attenuation of seismic waves and the universal rheological model of the Earth’s mantle

Analysis of results of laboratory studies on creep of mantle rocks, data on seismic wave attenuation in the mantle, and rheological micromechanisms shows that the universal, i.e., relevant to all time scales, rheological model of the mantle can be represented as four rheological elements connected in series. These elements account for elasticity, diffusion rheology, high temperature dislocation rheology, and low temperature dislocation rheology. The diffusion rheology element is described in terms of a Newtonian viscous fluid. The high temperature dislocation rheology element is described by the rheological model previously proposed by the author. This model is a combination of a power-law non-Newtonian fluid model for stationary flows and the linear hereditary Andrade model for flows associated with small strains. The low temperature dislocation rheology element is described by the linear hereditary Lomnitz model.     

Seismoelectric and electroseismic responses to a point source in a marine stratified model

We investigate the seismoelectric/electroseismic wavefields excited by a point source in an air/seawater/three-layered porous medium configuration containing a hydrocarbon layer. The results show that if an explosive source for excitation is used, receivers at seafloor can record the coseismic electromagnetic fields accompanying the P, S, fluid acoustic waves and the interface responses converted from the acoustic waves at seafloor interface and from the seismic waves at the interfaces beneath the seafloor. Employing a vertical electric dipole source shows that, with the exception of the interface responses converted from electromagnetic waves at seafloor, the interface responses converted from transmitted electromagnetic waves at the interfaces beneath the seafloor can also be identified. Given that the strength of the explosive source is within excitation capability of industry air guns, the generated interface responses from the hydrocarbon layer can be detected by current electromagnetic sensors considering the low ambient noise at the seafloor. Our results demonstrate the feasibility of the seismoelectric method applied to marine hydrocarbon exploration. Electroseismic modelling results suggest that it is not practical to employ this method to prospect marine hydrocarbon layer due to the weak interface response signal, unless a much larger current is injected into seafloor.     

A study of dissipation of wind-waves by mud at Cassino Beach,Brazil: Prediction and inversion

The impact of a non-rigid seafloor on the wave climate at Cassino Beach, Brazil, May–June 2005 is studied using field measurements and a numerical wave model. The measurements consist of wave data at four locations; rheology and mud thickness from grab samples; and an estimate of the horizontal distribution of mud based on echo-soundings. The dissipation of waves by a non-rigid bottom is represented in the wave model by treating the mud layer as a viscous fluid. Applied for 431 time periods, the model without this type of dissipation has a strong tendency to overpredict nearshore wave energy, except during a period of large storm waves. Two model variations which include this dissipation have a modest tendency to underpredict the nearshore wave energy. An inversion methodology is developed and applied to infer an alternate mud distribution which, when used with the wave model, yields the observed waveheights.     

Mass transport in a thin layer of power-law mud under surface waves

The mass transport velocity in a two-layer system is studied theoretically. The wave motion is driven by a periodic pressure load on the free water surface, and mud in the lower layer is described by a power-law rheological model. Perturbation analysis is performed to the second order to find the mean Eulerian velocity. A numerical iteration method is employed to solve the non-linear governing equation at the leading order. The influence of rheological properties on fluid motion characteristics including the flow field, the surface displacement, the mass transport velocity, and the net discharge rates are investigated based on theoretical results. Theoretical analysis shows that under the action of interfacial shearing, a recirculation structure may appear near the interface in the upper water layer. A higher mass transport velocity at the interface does not necessarily mean a higher discharge rate for a pseudo-plastic fluid mud.     

关于波浪作用下粉土质海床中共振现象的解释

本文详细讨论了粉土质床在波浪作用下所呈现共振现象的力学机制。利用有限深海床下波浪载荷对土层响应的研究，系统地比较了理论计算结果和实验结果。提出在波浪作用下粉土质土层中存在着一硬土层，从而引发Ｂｒａｇｇ共振。     

海沟后退对地幔对流的影响

本文分析了有海底扩张无海沟后退、有海沟后退无海底扩张以及海底扩张与海沟后退共存等３种情况下，俯冲板片运动与海沟迁移的关系．用幂律流体有限元方法计算海沟后退对地幔对流的影响．地幔有效粘度除依赖应力偏张量的第二不变量以外，尚与温度、压力（含流体静压力和流动压力）有关．计算表明，对流环、高流动负压区以及低粘区的个数和位置，均受控于海沟是否后退以及海底是否扩张；温度场与海沟后退无明显关系．流动压力对形成洋中脊和弧后火山、驱动地幔对流以及维持板片的倾斜角度都具有重要意义．     

海沟后退对地幔对流的影响

本文分析了有海底扩张无海沟后退、有海沟后退无海底扩张以及海底扩张与海沟后退共存等３种情况下,俯冲板片运动与海沟迁移的关系．用幂律流体有限元方法计算海沟后退对地幔对流的影响．地幔有效粘度除依赖应力偏张量的第二不变量以外,尚与温度、压力（含流体静压力和流动压力）有关．计算表明,对流环、高流动负压区以及低粘区的个数和位置,均受控于海沟是否后退以及海底是否扩张;温度场与海沟后退无明显关系．流动压力对形成洋中脊和弧后火山、驱动地幔对流以及维持板片的倾斜角度都具有重要意义．     

饱和粉土液化特性的大型振动台模型试验研究

京沪高速铁路徐沪段路基的粉土粘粒含量少于1.5%、粉粒含量约为80%,在强烈地震作用下存在着液化可能性.为充分研究这一饱和粉土地层的液化特性,本文作者利用大型地震模拟振动台,进行了模拟自由场地饱和粉土的地震液化模型试验,试验结果再现了自然地震触发的粉土液化的各种宏观震害现象,揭示了饱和粉土的地震液化规律和特征。试验结果为京沪高速铁路徐沪段路基的抗震设计提供了参考依据。     

EXPERIMENTAL STUDY ON WAVE ENERGY DISSIPATION AND COHESIVE SEDIMENT TRANSPORT IN SILT COAST

EmmmL STonY ON w^rs EareGY DlsSunnox AunCOIIES1VE SEDonT TRANSPORT 1N SirT COASTShaong HUl and Onyx WAI2Abstract:The interahon betwee the wave and fluld mud laye Plays an twrtan fOle in the develOPmen ofsilt coast. Sediment is essenhally transported in the form of rheological flow of mud laye unds thewave achon, and on the other hand, the fluid Inud layer dams the wave consfory. ms papestUdies the laws of wave energy dissiPation and mud bed deformhon, and the moveInen of…