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1.
断层黏滑是一种摩擦失稳,能够诱发地震、矿震等诸多地质灾害.目前,断层黏滑(包括断层亚失稳)研究,主要集中在实验方面和基于连续方法或非连续方法的数值模拟方面.为了弥补连续方法和非连续方法各自的不足,一些兼具二者优势的连续-非连续方法应运而生.为了检验引入速率-状态依赖摩擦定律的自主开发的拉格朗日元与离散元耦合连续-非连续方法的正确性并探究断层倾角对断层黏滑的影响,首先,模拟了滑块-底板模型的滑动-保持-滑动实验;然后,模拟了双轴压缩岩样的断层倾角的影响,重点考察了断层黏滑过程中亚失稳阶段摩擦系数的演化规律.研究发现,随着断层倾角的增大,岩样上表面平均差应力的绝对值-时步数目曲线的锯齿形由规则向不规则变化;初次黏滑发生时的时步数目、平均应力降、平均黏滑周期和平均峰值应力均减小.当断层处于黏滑前阶段时,断层面各处的摩擦系数和剪应力相差较小.当断层进入亚失稳阶段后,断层面上摩擦系数的平均值下降速度加快,这可作为断层进入亚失稳阶段的特征之一.引入速率-状态依赖摩擦定律后的拉格朗日元与离散元耦合连续-非连续方法的断层黏滑结果能与现有结果（例如,断层黏滑实验结果）基本吻合,但更加丰富,这在一定程度上... 相似文献
2.
原有三维非连续变形分析(DDA)方法采用常摩擦系数的Mohr-Coulomb定律作为切向破坏准则,然而当描述更大尺度构造块体的运动与变形时,常摩擦系数不再适用.速度-状态摩擦本构定律能够定量描述地震周期各阶段断层面剪应力变化,解释发震断层行为.本文将速度-状态摩擦定律与三维DDA方法相结合,首先推导了计算摩擦系数的实用公式,随后通过滑动-保持-滑动实验与速度步进实验算例对改进的三维DDA方法进行了验证.结果表明,应用速度-状态摩擦本构定律的三维DDA方法能够比较准确地模拟静摩擦的时间依赖性与动摩擦的速度依赖性,解决了将三维DDA方法在地学中应用的基本问题. 相似文献
3.
利用速率-状态摩擦定律(Rate-and State-Dependent Friction Law:简称RSF定律),结合McKenzie-Brune摩擦生热模型,本文分别从Ruina提出的RSF定律和Chester-Higgs提出的RSF定律出发,通过一维弹簧-滑块模型,采用四阶变步长的Dormand-Prince算法,对断层演化过程进行了数值模拟,探讨了摩擦生热对断层演化进程的影响.模拟结果显示,与Ruina-模型相比,Chester-Higgs-模型在断层高速滑动时存有更大的摩擦强度,表明摩擦生热对断层具有一定的强化作用,且同临界滑移距离的取值相关.而且,Chester-Higgs-模型在失稳时的断层面温度远远低于Ruina-模型,表明摩擦生热在断层演化过程中能抑制断层面温度的剧烈升高,且正应力和临界滑移距离越大,两种模型的温差越为明显,而断层的刚度和尺度则对温度的影响很小.模拟两种模型周期演化过程的结果表明,在相同的初始条件下,Chester-Higgs-模型给出的断层失稳周期明显比Ruina-模型更短,说明摩擦生热对断层自身演化最显著的影响是较大地缩短了地震重复发生周期.当断层进入周期性演化后,Chester-Higgs-模型给出的摩擦强度大于Ruina-模型,且对第一次非周期性失稳的摩擦强度和剩余应力的继承性更好.另外,由ChesterHiggs-模型给出的静态应力降远小于Ruina-模型给出的结果,所对应的单个事件的滑移量也小于Ruina-模型. 相似文献
4.
利用双轴伺服控制加载装置,采用三块花岗闪长岩标本组成的含有两个滑动面的直剪结构,开展了摩擦滑动实验.实验中通过在垂直滑动面的载荷上叠加正弦波状和方波状的扰动,研究了正应力扰动对断层黏滑失稳的影响.研究表明,在恒定的正应力和位移速率下,标本表现为规则的黏滑,叠加正应力扰动后,随扰动振幅的增加黏滑发生时间与扰动的相关性增大,黏滑应力降和时间间隔的分布趋于离散.黏滑应力降和时间间隔的平均值随平均正应力的增加呈线性增长,扰动叠加后黏滑应力降的离散度随平均正应力的增加而增大;黏滑应力降和时间间隔主要受应力变化幅度的影响,而与应力变化的速率关系不大.剪应力和正应力扰动都会对断层黏滑失稳产生影响,而正应力扰动的影响更明显.这两种扰动对断层黏滑失稳影响的机制存在差异,剪应力扰动只是改变断层滑动的推动力,而正应力扰动则改变了断层面上凹凸体的接触状态. 相似文献
5.
地震是断层的摩擦失稳过程.摩擦本构关系对断层的破裂成核、破裂传播、破裂速度、能量释放、破裂终止等起着至关重要的控制作用.为了比较不同摩擦关系在断层自发破裂动力学过程中的影响,文中引入目前应用最为广泛的4种典型摩擦本构关系,它们分别是：滑移弱化摩擦关系,速率弱化摩擦关系,以及速率-状态相依摩擦关系中的老化定律和滑动定律.研究中利用有限单元方法对上述4种摩擦关系控制的断层自发破裂过程分别进行模拟计算,模拟结果显示：当模型参数相同时,不同摩擦关系模拟的破裂行为总体上具有一致性,都可以产生亚剪切破裂或超剪切破裂,并且破裂传播速度的大小与摩擦本构关系的类型无关.此外,它们之间还存在着较大的差异：（1）速率弱化摩擦关系可以模拟脉冲型破裂;而其他3个摩擦关系只能模拟裂纹性破裂.（2）不同摩擦关系模拟的超剪切破裂转换长度不同,速率-状态相关摩擦关系的老化定律相比其他摩擦关系需要更大的转换长度才能实现亚剪切破裂转变为超剪切破裂;而速率弱化的摩擦关系的超剪切转换长度可以为0,即不需要转换距离就直接产生超剪切破裂.（3）速率弱化摩擦关系模拟的破裂速度自成核后很快就达到稳定值;而其他类型摩擦关系模拟的破裂传播则要经历由缓慢破裂到逐渐加速直至达到稳定破裂的过程.值得特别指出的是,本文所使用的4种摩擦关系都不能完整地反映实际大地震破裂过程的摩擦属性,需要进一步深入研究. 相似文献
6.
《地震地质》2016,(1)
实验室断层黏滑伴随有温度变化,温度不但与摩擦滑动有关,还与样本的应力状态相关。文中利用红外热像仪进行全场观测,研究平直断层黏滑不同阶段的热场演化。实验不仅观测到了峰值前后从应力积累转变为释放导致的温度由升转降的现象,还观测到了失稳后断层升温和块体降温的相反变化。更重要的是通过分析沿断层各个部位的温度随时间的变化,发现了识别失稳部位的温度前兆:失稳部位的温度从强偏离线性阶段开始,一直是相对高值,在亚失稳阶段升温速率突然增大,远高于其他部位。分离摩擦和应力的作用后,发现亚失稳阶段失稳部位的升温发生于围岩上而非断层带上,说明断层处于闭锁状态而相邻的围岩区域处于应力集中状态,推测满足这2个条件的部位可能是未来的失稳部位。此现象或许有助于野外发震位置的判断。 相似文献
7.
实验研究断层黏滑过程的变形演化,尤其是失稳黏滑瞬间的断层位移演化特征,对于了解地震从孕育到发生的全过程具有重要意义.本文基于数字散斑相关方法(digital speckle correlation method, DSCM),用三套图像采集系统(两套低速和一套高速图像采集系统)搭建了断层黏滑过程的多观测区域、多时间尺度的变形场测量系统,并用此系统对一种花岗岩双剪滑动模型的黏滑过程进行了实验研究.对间黏滑期和黏滑期断层位移演化特征进行深入分析的结果表明:间黏滑期断层位移演化体现出空间上的非均匀性和时间上的"趋同化"特征,断层滑动趋同化也许是断层错动匀阻化的一种宏观表现形式;断层黏滑动态过程持续时间非常短(本文300 mm断层黏滑过程持续时间约在1 ms量级),黏滑失稳前会出现预滑,预滑出现到黏滑失稳发生所经历的时间与黏滑失稳过程所用时间相差一个量级;断层的一次黏滑由若干个滑动速度不同的、小的失稳滑动组成,黏滑失稳过程中断层的滑动速度呈现出波动性,整个滑动过程中断层经历了多个高速滑动和低速滑动的交错. 相似文献
8.
在实验室内利用超声尾波观测大尺度(1.5 m)岩石断层的黏滑过程.利用基于尾波干涉的观测方法,我们获得了高达10~(-6)的相对波速变化的观测精度,这相当于~10 kPa的应力变化.利用高精度的测量,我们获取两种不同加载速率下(1μm·s~(-1),10μm·s~(-1))黏滑过程三个阶段(恢复、加载和滑动)基于波速变化的特征量.我们更进一步获取了断层失稳阶段波速变化的时空演化过程.最后讨论了该观测方法需要改进的地方.以上研究结果表明作为一种对现有实验观测手段的有益补充,利用超声尾波观测实验室大尺度岩石断层的动力学过程是可行的. 相似文献
9.
文中总结了基岩断层带黏滑与蠕滑的地质标志与岩石力学实验证据,分析了控制黏滑与蠕滑的物理机制。断层带内的矿物组成、矿物变形机制、流体作用和断层带变形方式等是控制黏滑与蠕滑的主要因素。富含黏土矿物的断层泥具有速度强化型摩擦滑动,控制着断层蠕滑,而以方解石、石英、长石及辉石等造岩矿物为主的断层泥在大陆浅源地震的震源深度条件下具备黏滑条件。脆性破裂伴随的扩容过程是断层黏滑的必要条件,而压实、碎裂和塑性剪切变形形成的叶理和小褶皱对应于蠕滑。在流体作用下,压溶使孔隙和微裂隙愈合,有利于断层强度的恢复和断层闭锁,既是断层发生不稳定滑动的根源,也是断层带局部存在高压流体的条件,而在流体作用下的退变质反应与水解反应生成黏土矿物和层状及环状硅酸盐矿物,不仅降低了断层带的强度,还导致断层向蠕滑转变。断层带内均匀分布多个剪切面和较宽的变形带对应于蠕滑,局部化的R剪切及Y剪切、窄变形带和摩擦镜面对应于黏滑。 相似文献
10.
为了深入理解断层带摩擦滑动速度依赖性转换及其机制,利用双轴摩擦实验对干燥及含水条件下岩盐断层带摩擦的速度依赖性进行了实验研究,并观测了摩擦滑动过程中的声发射,分析了断层带的微观结构.实验结果表明,干燥岩盐断层带在0.1~100 μm/s的速度范围内表现为速度弱化,增大σ2会使断层带向速度强化转变;含水条件下岩盐断层带在1~100 μm/s的速度范围内表现为速度弱化,而在0.1~0.01 μm/s的速度范围内表现为速度强化,速度依赖性转换出现在0.1~1 μm/s,其中断层表现为振荡或应力释放时间较长的黏滑事件;岩盐断层带在干燥条件下表现出很强的声发射活动,每个黏滑均对应一丛声发射事件,而在含水条件下一次黏滑只对应一个声发射事件.显微观察表明,局部化的脆性破裂是速度弱化域的主要变形机制,分布式的碎裂流动是干燥岩盐断层带在速度强化域的变形机制,颗粒边界迁移以及压溶作用的塑性变形是含水条件下岩盐断层带在速度强化域的主要变形机制,而脆性破裂和塑性变形共同控制着速度依赖性转换域断层带的变形.水的存在促进岩盐发生塑性变形,进而导致断层带从速度弱化向速度强化转换.上述结果有助于理解断层带上地震活动的特征和慢地震的机制. 相似文献
11.
12.
The determination of the coefficient of viscosity of eruptive products gives useful elements to the knowledge of possible variations of composition and physical conditions of the magmas. 相似文献
13.
Studia Geophysica et Geodaetica - 相似文献
14.
Geomagnetism and Aeronomy - The magnetic evolution of the active region of the Sun at the level of the photosphere has been studied. Magnetic synoptic maps of the 2007 Kitt Peak Observatory were... 相似文献
15.
V. E. Pavlov T. Yu. Tolmacheva R. V. Veselovskiy A. V. Latyshev A. M. Fetisova I. V. Bigun 《Izvestiya Physics of the Solid Earth》2017,53(5):702-713
Until recently, the existing data prevented the geophysicists from accurately dating the Bysy-Yuryakh stratum, which outcrops in the middle reach of the Kotuy River, constraining the time of its formation to a wide interval from the end of the Late Cambrian to the beginning of the Silurian. The obtained paleomagnetic data unambiguously correlate the Bysy-Yuryakh stratum to the Nyaian regional stage and constrain its formation, at least a considerable part of it, by the Tremadocian. This result perfectly agrees with the data on the Bysy-Yuryakh conodonts studied in this work and yields a spectacular example of the successful application of paleomagnetic studies in solving important tasks of stratigraphy and, correspondingly, petroleum geology. Within the Bysy-Yuryakh stratum, we revealed a large normal-polarity interval corresponding to the long (>1 Ma) period when the geomagnetic reversals were absent. This result, in combination with the data for the Tremadocian and Middle–Upper Cambrian sequences of the other regions, indicates that (1) the rate of occurrence of the geomagnetic reversals on the eve of the Ordovician Moyero superchron of reversed polarity was at most one reversal per Ma; (2) the superchron does not switch on instantaneously but is preceded by a certain gradual change in the operation conditions of the dynamo mechanism which, inter alia, manifests itself by the reduction of the frequency of geomagnetic reversals with the approach of the superchron. This finding supports the views according to which a process preparing the establishment of the superchrons takes place at the core–mantle boundary. 相似文献
16.
Josef Vykutil 《Studia Geophysica et Geodaetica》1968,12(2):217-220
Резюме Дается вывод формул для вычислений длины хорды, длины и азимутов нормаляных сечений и длины геодезической линии эллипсоида.
Применяются тригонометрические функции данных величин и постоянные принятого ргфгргнц-эллипсоида, что является целесообразным
при использовании вычислителQjных машин, особенно автоматов. Рабочие формулы рекомендуются в форме (8–11).
Dedicated to Professor František Fiala on His 85th Birthday
Address: Veveři 95, Brno. 相似文献
Dedicated to Professor František Fiala on His 85th Birthday
Address: Veveři 95, Brno. 相似文献
17.
Summary A simple model is proposed suitable for studying the effect of the ground layer of the atmosphere, polluted by aerosol, on the albedo. This model is founded on solving the equation of transfer of radiative energy. The numerical results are discussed, particular attention being paid to the analysis of errors due to neglecting the multiple reflection of solar radiation on the aerosol particles. A method which would also include the multiple reflection is proposed, and the conditions under which the presence of the aerosol is responsible for an increase or decrease of the solar radiation balance on the Earth's surface, are analysed. 相似文献
18.
Prof. Dr. W. A. Heiskanen 《Pure and Applied Geophysics》1958,41(1):1-18
Summary The author mentions the aims of the World-wide gravity project he established in the Ohio State University in Columbus, in 1950. He outlines the practical procedure of the gravimetric computations of the undulationsN and the vertical deflection components and and emphasizes that only by the global international cooperation and additional gravity observations at sea carried out during the last decade it has been possible to gather to Columbus the needed gravity material. Since there exist still large gravimetrically unsurveyed areas it is of vital significance to study what gravity anomalies are best to be used for these regions. The given figures concerning the accuracy of theN, and , estimated theoretically and obtained in practice, indicate that in the gravimetrically well surveyed parts of the world like in Europe and the United States we can get gravimetrically on basis of existing gravity material theN-values with accuracy of about 5–10 meters, and and with the accuracy of about 1. The geoid undulationsN are already computed in Columbus for more than 6000 points of the northern hemisphere. The sample maps show the interesting geoid of Europe and vicinity between the latitudes 60° and 30° and longitude 5° W and 30° E, drafted on basis of more than 1000N-values computed at the corners of 1°×1° squares. It is interesting to realize that the geoid undulations in all this area are positive, the extreme values being between 40 and 50 meters. The geophysical significance of the geoid maps of this kind is pointed out. 相似文献
19.
Ivanka Jakubcová Věra Marvanová Miloš Pick Antonín Novotný Reviewer Z. Šimon 《Studia Geophysica et Geodaetica》1982,26(2):193-196
Summary The results of two different methods of the determination of the non-linearity of the gravimeter scale are compared; the economy is discussed as well. 相似文献
20.
Atmospheric temperature and humidity fields as well as information on other meteorological parameters are nowadays retrieved from radiance measurements recorded by operational meteorological satellites. Up to now, the inversion procedures used only take into account crude information on the topography of the Earth’s surface. However, the applied radiative transfer codes have to consider the Earth’s surface as the lower boundary of the atmospheric model and, therefore, need a more precise mean elevation and a classification of the roughness of the Earth’s surface. The influence of the topography of the Earth surface on retrieved temperature profiles is studied by using a physico-statistical inversion method. An objective analysis is made of the more precise mean elevation and derivation of roughness parameters using a new high-resolution digital elevation model (DEM) with a resolution of 500 m×500 m. By means of a geomorphological process and a newly developed topography rejection test, areas with a high surface roughness are localized and singled out. The influence of topography on the retrieved temperature profiles is illustrated by case studies. Changes are found predominantly in areas with a high variation of topography. Using the new high-resolution DEM and the topography rejection test, the geographical position of the calculated temperature profiles tends to be shifted towards areas with a small vertical variation of topography. The mean elevation determined by the new elevation model better characterizes the area observed. Hence, the temperature profiles can be calculated down to lower atmospheric levels. Furthermore, a guess profile better describing the atmospheric situation is selected by the more precise elevation. In addition, the temperature profiles obtained near the coast are improved considerably by the more precise determination of the surface property ‘sea’ and ‘land,’ respectively. Integration of an independent physical information such as topography leads, on average, to a slight improvement of the results of the physico-statistical inversion procedure. In some cases, however, significant improvements have been achieved regarding the desired accuracy of temperature profiles of the order of 1 K. In future, the spatial resolution of new high-resolution sounding instrumentation on the next generation of operational meteorological satellites will be increased. To exploit the resolving power of this new instrumentation, the different variation of the topography of the Earth surface, especially in regions with a high variation of topography, can be taken into account more precisely by using a high-resolution DEM. 相似文献