RIPRAP STABILITY ON STEEP SLOPES

ＲＩＰＲＡＰＳＴＡＢＩＬＩＴＹＯＮＳＴＥＥＰＳＬＯＰＥＳＨｏｗａｒｄＨ．ＣＨＡＮＧ１ＡＢＳＴＲＡＣＴＳｔｅｅｐｃｈａｎｎｅｌｓｌｏｐｅｓａｒｅｏｆｔｅｎｌｉｎｅｄｗｉｔｈｒｉｐｒａｐａｓａｐｒｏｔｅｃｔｉｏｎａｇａｉｎｓｔｐｏｔｅｎｔｉａｌｅｒｏｓｉ...     

SEDIMENT RESUSPENSION IN THE CHANGJIANG ESTUARY

ＳＥＤＩＭＥＮＴＲＥＳＵＳＰＥＮＳＩＯＮＩＮＴＨＥＣＨＡＮＧＪＩＡＮＧＥＳＴＵＡＲＹＳＨＩＷｅｉｒｏｎｇ１ａｎｄＬＩＪｉｕｆａ２Ａｂｓｔｒａｃｔ：Ａｓｐｅｃｉｆｉｃｖａｒｉａｔｉｏｎｐａｔｔｅｒｎｏｆｔｈｅｎｅａｒｂｏｔｔｏｍｓｕｓｐｅｎｄｅｄｓｅｄ...     

国际地震学和地球内部物理学协会（IASPEI）亚洲区域大会及其地震CT论文简介

国际地震学和地球内部物理学协会（ＩＡＳＰＥＩ）亚洲区域大会及其地震ＣＴ论文简介ＭａｎｙＳｅｉｓｍｉｃＴｏｍｏｇｒａｐｈｙＡｒｔｉｃｔｅｓＰｒｅｓｅｎｔｅｄｉｎｔｈｅＩＡＳＰＥＩＲｅｇｉｏｎａｌＡｓｓｅｍｂｌｙｉｎＡｓｉａ［本刊讯］为纪念唐山大地震２０...     

SOME FACTS AND ISSUES ABOUT TGP

ＳＯＭＥＦＡＣＴＳＡＮＤＩＳＳＵＥＳＡＢＯＵＴＴＧＰ￥ＬＩＮＢｉｎｇｎａｎ（Ｐ．Ｎ．Ｌｉｎ）（ＰｒｅｓｉｄｅｎｔＥｍｅｒｉｔｕｓｏｆＩＷＨＲ，ＣｈａｉｒｍａｎｏｆＡｄｖｉｓｏｒｙＢｏａｒｄ，ＩＲＴＣＥＳ．）Ａｂｓｔｒａｃｔ：Ｔｈｉｓａｒｔｉｃｌｅｐｏ...     

SEDIMENT TRANSPORT : THEORY AND PRACTICE

ＳＥＤＩＭＥＮＴＴＲＡＮＳＰＯＲＴ：ＴＨＥＯＲＹＡＮＤＰＲＡＣＴＩＣＥＢｙＣｈｉｈＴｅｄＹＡＮＧＰｕｂｌｉｓｈｅｒ：ＭｃＧｒａｗＨｉｌＩｎｃ．,ＮｅｗＹｏｒｋ;３９６ｐａｇｅｓ,１９９６,ｈａｒｄｃｏｖｅｒＴｈｅｍｏｎｏｇｒａｐｈｉｓｔｈｅｒｅｓｕｌ...     

震源区介质Q值变化物理机制的模拟实验研究

利用较大岩石样品,实验研究了加载时同时向样品内注水过程中穿过样品超声波波速和尾波Ｑｃ值的变化特征。结果表明,在压力作用下,岩石破坏前通过岩石的尾波Ｑｃ值下降,如果有压力水进入,则岩石的尾波值Ｑｃ会大幅下降。因此,我们可以认为,地壳岩石破坏发生地震前的尾波下降的物理机制是岩石在压力产生扩容裂隙及流体进入裂隙双重作用的结果。     

THE ROLE PLAYED BY WASH LOAD DEPOSITION IN THE FORMATION OF DIFFERENT RIVER PATTERNS

ＴＨＥＲＯＬＥＰＬＡＹＥＤＢＹＷＡＳＨＬＯＡＤＤＥＰＯＳＩＴＩＯＮＩＮＴＨＥＦＯＲＭＡＴＩＯＮＯＦＤＩＦＦＥＲＥＮＴＲＩＶＥＲＰＡＴＴＥＲＮＳＴｈｅｌｏｗｅｒｌａｙｅｒｏｆｔｈｅｂｅｄｍａｔｅｒｉａｌｃｏｎｓｉｓｔｓｏｆｔｉｎｅｓａｎｄａｎｄｔｈｅｕｐｐｅｒｌａｙｅｒｃｏｎｓｉｓｔｓｏｆａｍｉｘｔｕｒｅｏｆｃｌａｙ（１０％）ａｎｄｔｉｎｅｓａｎｄ（９０％）．ＮＡＴＵＲＡＬＲＩＶＥＲＳｌ．ＣｈａｎｇｅｏｆｃｈａｎｎｅｌｐａｔｔｅｒｎｓａｌｏｎｇａｒｉｖｅｒｃｏｕｒｓｅＩｔｉｓｃｏｍｍｏｎｔｈａｔｉｎｔｈｅｕｐｐｅｒＰａｒｔｏｆａｎａｌｌｕｖｉａｌｒｉｖｅｒｔｈｅｌｏｎｇｉｔｕｄｉｎａｌｓｌｏｐｅｉｓｓｔｅｅｐａｎｄｔｈｅｒｉｖｅｒｃａｒｒｉｅｓｈｅａｖｙｓｅｄｉｍｅｎｔｌｏａｄ．Ｄｕｅｔｏｔｈｅｓｔｅｅｐｓｌｏｐｅａｎｄａｓｓｏｃｉａｔｅｄｈｉｇｈｖｅｌｏｃｉｔｙｃｌａｙｓｅｔｔｌｅｓｌｉｔｔｌｅｅｖｅｎｏｎｔｌｏｏｄｐｌａｉｎ．Ｆｌｏｏｄｐｌａｉｎｏｒｒｉｖｅｒｈａｎｋｃｏｎｓｉｓｔｓｏｆｓｉｌｔａｎｄｔｉｎｅｓａｎｄ．Ｔｈｅｒｉｖｅｒｂｅｈａｖｅｓａｓａｗａｎｄｅｒｉｎｇｏｎｅ．Ｐａｓｓｉｎｇａｃｅｒｔ     

THE PANTANAL:AN ECOSYSTEM IN NEED OF PROTECTION

ＴＨＥＰＡＮＴＡＮＡＬ：ＡＮＥＣＯＳＹＳＴＥＭＩＮＮＥＥＤＯＦＰＲＯＴＥＣＴＩＯＮ￥ＭａｒｅＰ．Ｂｏｒｄａｓ（Ｐｒｏｆｅｓｓｏｒ，ＤｅｐａｒｔｍｅｎｔｏｆＨｙｄｒａｕｌｉｃｓ，ＩｎｓｔｉｔｕｔｅｏｆＨｙｄｒａｕｌｉｃＲｅｓｅａｒｃｈ（ＩＰＨ），Ｆｅｄ...     

Uncertainties in estimation of extrapolated annual occurrence rate of earthquakes using logical tree

ＵｎｃｅｒｔａｉｎｔｉｅｓｉｎｅｓｔｉｍａｔｉｏｎｏｆｅｘｔｒａｐｏｌａｔｅｄａｎｎｕａｌｏｃｃｕｒｅｎｃｅｒａｔｅｏｆｅａｒｔｈｑｕａｋｅｓｕｓｉｎｇｌｏｇｉｃａｌｔｒｅＺＨＩ－ＸＩＡＮＹＡＮＧ１）（杨智娴）ＰＥＩ－ＺＨＥＮＺＨＡＮＧ２）（张培...     

INFLUENCE OF CONSTRUCTIONAL ELEMENTS ON SEDIMENT TRANSPORT

ＩＮＦＬＵＥＮＣＥＯＦＣＯＮＳＴＲＵＣＴＩＯＮＡＬＥＬＥＭＥＮＴＳＯＮＳＥＤＩＭＥＮＴＴＲＡＮＳＰＯＲＴ￥ＳｉｌｋｅＷｉｅｐｒｅｃｈｔａｎｄＷｉｌｈｅｌｍＢｅｃｈｔｅｌｅｒ（ＲｅｓｅａｒｃｈＡｓｓｏｃｉａｔｅ，ＩｎｓｔｉｔｕｔｅｆｏｒＨｙｄｒａｕｌｉ...     

地震地电阻率各向异性变化数值模拟

将APE模式中差应力与裂隙的演化理论与前期研究中建立的张量形式的各向异性电性模型相结合,推导出了裂隙演化参数(密度、孔压、纵横比、闭合角)与电导率关系的动态方程,用数值模拟方法研究了饱水岩石在水平向应力作用下电阻率的各向异性变化．并结合实验和观钡5结果,讨论了电阻率各向异性变化的可能机理。     

含裂隙介质中的视电阻率各向异性变化

我国50多年的视电阻率连续观测结果表明,大地震前近震中区域的视电阻率呈现出与主压应力方位有关的各向异性变化,即:垂直于主压应力方向观测的变化幅度最大,平行方向最小或不明显,斜交方向介于二者之间.目前我国定点台站视电阻率观测的探测范围主要在浅层沉积层以内,通常含有较多的含水裂隙.本文将地下岩土介质简化为由固体基质和含流体/气体裂隙组成的固液气三相介质,且基质、流体和气体具有标量形式的电阻率,推导出了包含基质和流体电阻率、裂隙率、饱和度和裂隙面积率因子的电阻率张量表达式.以裂隙的扩展/闭合表示应力作用下裂隙的变化,得到了电阻率随裂隙变化的微分形式,电阻率变化对裂隙体积变化放大系数的表达式和裂隙横向变化对纵向电阻率影响的横向权系数的表达式.在此基础上得到了介质电阻率和视电阻率的各向异性变化特征:对于含水裂隙介质,无论裂隙如何变化,均是最小主轴方向电阻率的变化幅度大于其他方向;对于含水孔隙介质,沿孔隙主要变化方向的主轴电阻率变化幅度大于其他方向.对于各向异性变化,视电阻率和介质电阻率存在π/2的方向差异.相较于含水岩石,无水岩石介质电阻率的各向异性变化不显著.本文提出的电阻率表达式可以对实验室和野外实际观测的许多结果做出合理的解释.     

无限长源二维各向异性地层中CSAMT有限元模拟

可控源音频大地电磁测深法(CSAMT)基本上是基于电性各向同性理论的假设,而实际地层普遍表现为电性各向异性现象,因此研究各向异性地层条件下CSAMT方法的电磁响应具有重要的理论意义和应用价值.本文从有源Maxwell方程出发,推导出了二维各向异性地层条件下无限长线源频率域的电磁场响应,得到了一组平行于线源方向的电场分量E_x和磁场分量H_x的偏微分方程,并采用有限元法进行求解.模型的计算结果表明:不论是对均匀半空间还是一维层状介质中的各向异性二维体模型的计算,均能从结果中明显地看出各向同性背景场和各向异性异常体的存在;在计算中通过改变各向异性系数或各向异性旋转角,其结果在视电阻率和相位曲线上均存在显著区别.计算结果表明了在各向异性地层中,仍然采用各向同性的假设进行CSAMT资料的处理与解释,可能会带来比较严重的误差,这种情况下必须采用基于各向异性的地质模型对CSAMT资料进行处理和解释.研究结果对于提高CSAMT方法的勘探效果和应用水平具有重要的指导意义.     

CSAMT单分量数据解释方法

可控源音频大地电磁法(CSAMT)一直沿用大地电磁法(MT)的办法,通过计算电场分量与磁场分量的比值,求取卡尼亚视电阻率.而CSAMT场源已知,电场分量和磁场分量都与地下电阻率存在一定的关系,可以单独采用CSAMT电场分量或者磁场分量提取地下介质的视电阻率.本文通过分析电场分量与磁场分量的数据特性,提出利用CSAMT电场单分量数据进行视电阻率的计算,用改进的广义逆矩阵反演方法,使初始模型中的地电层数等于频道个数,克服了以往反演计算中层数较少的问题;实现全场区电场分量视电阻率曲线的拟合反演.同时对单分量视相位计算方法进行分析,结合山西大同地区积水采空区探测及数据解释结果,论证本文提出的单分量解释方法的有效性.     

山西临汾地震台地电阻率异常分析与探讨

对山西临汾地震台地电阻率观测数据在临汾及其周边地区发生4．0级以上地震时的异常变化、异常形态进行了对比分析,认为,临汾中心地震台地电阻率对于捕捉该区地震前兆异常信息有积极的意义;对2008年4月以来临汾中心地震台地电阻率观测数据的变化情况、变化形态做了分析,其结果可为场源外区域地电异常的研究提供依据和参考。     

吉林省地电阻率震兆异常分析研究

应用吉林省内榆树、 四平两个地电阻率台站观测资料, 采用形态法、 归一化变化速率法和各向异性度法, 分析研究了1999年汪清M_S7.0深震以及2006年乾安—前郭M_S5.0浅源地震前的地电阻率异常变化. 结果表明, 震前地电阻率出现长趋势下降变化或短临异常变化, 表现为: ① 汪清M_S7.0深震前, 榆树台和四平台地电阻率月均值曲线上均显示出震前持续2年尺度的中期下降异常; ② 汪清M_S7.0深震以及乾安—前郭M_S5.0浅源中强震前, 榆树台和四平台地电阻率变化速率均大于异常指标; ③ 乾安—前郭M_S5.0地震前, 四平台地电阻率各向异性度曲线显示出明显的低值异常变化, 而榆树台各向异性度S曲线则出现破年变变化. 上述异常变化的原因可能为, 太平洋板块向NW方向挤压, 导致震源区及附近最大主压应力方位(或近于该方位)NW向的挤压作用突出, 引起介质内部导电流体快速进入或重新分布, 从而使地电阻率出现长趋势下降变化和各向异性变化.      

Sensitivity and inversion of marine electromagnetic data in a vertically anisotropic stratified earth

The controlled‐source electromagnetic (CSEM) and magnetotelluric method (MT) are two techniques that can be jointly used to explore the resistivity structure of the earth. Such methods have, in recent years, been applied in marine environments to the exploration and appraisal of hydrocarbons. In many situations the electric properties of the earth are anisotropic, with differences between resistivity in the vertical direction typically much higher than those in the horizontal direction. In cases such as this, the two modes of the time‐harmonic electromagnetic field are altered in different ways, implying that the sensitivity to the earth resistivity may vary significantly from one particular resistivity component (scalar, horizontal or vertical) to another, depending on the measurement configuration (range, azimuth, frequency or water depth). In this paper, we examine the sensitivity of the electromagnetic field to a vertically anisotropic earth for a typical set of configurations, compare inversion results of synthetic data characterizing a vertically anisotropic earth obtained using the isotropic and anisotropic assumptions and show that correctly accounting for anisotropy can prevent artefacts in inversion results.     

Forward modeling of marine DC resistivity method for a layered anisotropic earth

Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell’s equations for an anisotropic model, we introduce scalar potentials based on the divergence-free characteristic of the electric and magnetic (EM) fields. We then continue the EM fields down into the deep earth and upward into the seawater and couple them at the ocean bottom to the transmitting source. By studying both the DC apparent resistivity curves and their polar plots, we can resolve the anisotropy of the ocean bottom. Forward modeling of a high-resistivity thin layer in an anisotropic half-space demonstrates that the marine DC resistivity method in shallow water is very sensitive to the resistive reservoir but is not influenced by airwaves. As such, it is very suitable for oil and gas exploration in shallowwater areas but, to date, most modeling algorithms for studying marine DC resistivity are based on isotropic models. In this paper, we investigate one-dimensional anisotropic forward modeling for marine DC resistivity method, prove the algorithm to have high accuracy, and thus provide a theoretical basis for 2D and 3D forward modeling.     

Apparent resistivity over a three layer earth with an inhomogeneous interstratum

Summary The theory of resistivity sounding on a three layer earth comprising an inhomogeneous interstratum has been presented. The electrical conductivity in the intermediate layer, embedded between two layers of uniform conductivity, is assumed to follow either generalised power law or exponential variation. A point source of current is placed on the surface. The electric potential functions on the ground surface have been obtained. The expressions for apparent resistivity over the above models for the Wenner and Schlumberger electrode configurations have been derived.     

剪切和摩擦滑动大模型的视电阻率变化幅度和各向异性

用石英砂、河砂和水泥模压制成1m×1m×0.3m的均匀和非均匀介质模型，对模型进行剪切和摩擦滑动实验，观测模型不同位置和不同方位的视电阻率变化幅度和各向异性特征. 均匀介质模型实验结果为：电阻率变化与测线的位置有关，距裂隙近的测线，电阻率变化幅度大，从百分之几到百分之几十；距裂隙远的测线，电阻率变化幅度小，从百分之几到不变. 对于非均匀介质模型，电阻率变化幅度要小一些，最大也只有百分之几. 电阻率变化除与测线的位置有关外，还与测线的方位有关，同一测点不同方位的测线，电阻率变化幅度不同，有的差别很大. 剪切与摩擦滑动两种加载方式的电阻率变化幅度数量级相同. 裂隙穿过部位及其附近测点的电阻率变化各向异性主轴方位解与剪切和摩擦滑动的实际裂隙方位吻合较好.