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1.
Nicholas W. Hayman Lucie Ducloué Kate L. Foco Karen E. Daniels 《Pure and Applied Geophysics》2011,168(12):2239-2257
It is a long-standing question whether granular fault material such as gouge plays a major role in controlling fault dynamics
such as seismicity and slip-periodicity. In both natural and experimental faults, granular materials resist shear and accommodate
strain via interparticle friction, fracture toughness, fluid pressure, dilation, and interparticle rearrangements. Here, we
isolate the effects of particle rearrangements on granular deformation through laboratory experiments. Within a sheared photoelastic
granular aggregate at constant volume, we simultaneously visualize both particle-scale kinematics and interparticle forces,
the latter taking the form of force-chains. We observe stick-slip deformation and associated force drops during an overall
strengthening of the shear zone. This strengthening regime provides insight into granular rheology and conditions of stick-slip
periodicity, and may be qualitatively analogous to slip that accompanies longer term interseismic strengthening of natural
faults. Of particular note is the observation that increasing the packing density increases the stiffness of the granular
aggregate and decreases the damping (increases time-scales) during slip events. At relatively loose packing density, the slip
displacements during the events follow an approximately power-law distribution, as opposed to an exponential distribution
at higher packing density. The system exhibits switching between quasi-periodic and aperiodic slip behavior at all packing
densities. Higher packing densities favor quasi-periodic behavior, with a longer time interval between aperiodic events than
between quasi-periodic events. This difference in the time-scale of aperiodic stick-slip deformation is reflected in both
the kinematics of interparticle slip and the force-chain dynamics: all major force-chain reorganizations are associated with
aperiodic events. Our experiments conceptually link observations of natural fault dynamics with current models for granular
stick-slip dynamics. We find that the stick-slip dynamics are consistent with a driven harmonic oscillator model with damping
provided by an effective viscosity, and that shear-transformation-zone, jamming, and crackling noise theories provide insight
into the effective stiffness and patterns of shear localization during deformation. 相似文献
2.
利用双轴伺服控制加载装置,采用3块花岗闪长岩标本组成的含有2个滑动面的直剪结构,开展了摩擦滑动实验。实验中通过在剪切方向上叠加正弦波状的位移扰动,研究了剪应力扰动对断层粘滑失稳的影响。研究表明,在恒定的正应力和位移速率下,标本表现出较为规则的粘滑;当在剪切方向叠加位移扰动后,随扰动振幅的增加,粘滑发生时间与扰动的相关性增大,粘滑的应力降和时间间隔的分布趋于离散,其中扰动能产生明显影响的临界振幅大致为0.05MPa;粘滑应力降和时间间隔随扰动振幅增大而逐渐离散的现象在较高正应力下更为明显,而相同扰动振幅下粘滑失稳发生时间与扰动的相关性也随正应力增加而增大;扰动周期对摩擦性状的影响不明显。研究结果意味着,地震引起的同震剪应力的变化不仅会引起邻近断层上地震发生时间的变化,也可能引起地震强度的变化 相似文献
3.
4.
THE GEOLOGICAL AND ROCK MECHANICAL DISTINCTION EVIDENCE BETWEEN STICK-SLIP AND CREEP IN HOST ROCK SEGMENTS OF FAULT 
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下载免费PDF全文 ZHOU Yong-sheng 《地震地质》2019,41(5):1266-1272
Paleo-seismic and fault activity are hard to distinguish in host rock areas compared with soft sedimentary segments of fault. However, fault frictional experiments could obtain the conditions of stable and unstable slide, as well as the microstructures of fault gouge, which offer some identification marks between stick-slip and creep of fault.
We summarized geological and rock mechanical distinction evidence between stick-slip and creep in host rock segments of fault, and analyzed the physical mechanisms which controlled the behavior of stick-slip and creep. The chemical composition of fault gouge is most important to control stick-slip and creep. Gouge composed by weak minerals, such as clay mineral, has velocity weakening behavior, which causes stable slide of fault. Gouge with rock-forming minerals, such as calcite, quartz, feldspar, pyroxene, has stick-slip behavior under condition of focal depth. To the gouge with same chemical composition, the deformation mechanism controls the frictional slip. It is essential condition to stick slip for brittle fracture companied by dilatation, but creep is controlled by compaction and cataclasis as well as ductile shear with foliation and small fold. However, under fluid conditions, pressure solution which healed the fractures and caused strength recovery of fault, is the original reason of unstable slide, and also resulted in locking of fault with high pore pressure in core of fault zone. Contrast with that, rock-forming minerals altered to phyllosilicates in the gouges by fluid flow through degenerative reaction and hydrolysis reaction, which produced low friction fault and transformations to creep. The creep process progressively developed several wide shear zones including of R, Y, T, P shear plane that comprise gouge zones embedded into wide damage zones, which caused small earthquake distributed along wide fault zones with focal mechanism covered by normal fault, strike-slip fault and reverse fault. However, the stick-slip produced mirror-like slide surfaces with very narrow gouges along R shear plane and Y shear plane, which caused small earthquake distributed along narrow fault zones with single kind of focal mechanism. 相似文献
5.
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
6.
Frictional heat generation and seismic radiation in a foam rubber model of earthquakes 总被引：1，自引：0，他引：1
Results from a study of stick-slip particle motion at the interface between two stressed foam rubber blocks indicate that normal vibrations and interface separation are an important part of the stick-slip process in foam rubber. The dimension of the dynamic slip pulse is small compared to the dimension of the model (approximately 10 cm vs. 200 cm) consistent with the abrupt-locking slip pulse model ofBrune (1970, 1976), andHeaton (1990). A comparison of frictional heat generation between stable-sliding and stick-slip foam rubber models indicates a linear relation between the temperature increase on the fault surface (for a given distance of slip) and the driving shear force for the stable-sliding model, while for the stick-slip model there is essentially no variation in frictional heat generation with an increase in shear stress. We performed experiments to investigate the ratio of normal motion to shear motion at different levels of normal stress in the stick-slip foam rubber model. Preliminary result indicate that the normal component of the particle motion increases more rapidly with increasing normal stress than the shear component. The phenomenon of interface separation and normal vibrations may thus explain some of the most frustrating problems in earthquake mechanics, e.g., the heat flow paradox, the long-term weakness of major active faults, and anomalousP-wave radiation. 相似文献
7.
Cheng Haixu Wu Kaitong Zhang LiuCenter for Analysis Prediction SSB Beijing China Institute of Geology SSB Beijing China 《中国地震研究》1995,(2)
In this paper,compression tests of intact granite samples have been made in a triaxial testing machine with solid confining pressure.From the tests,the influences of confining pressure and loading rate(axial strain rate)on the deformation and fracture process of rock samples,on the stress drop and recurrence interval of stick-slip events,and on the geometric distribution of the main fracture have been studied.The experimental results show that the loading rate influences the stress drop and recurrence interval of stick-slip events greatly.At lower loading rates,the stress drop of stick-slip events is greater,their recurrence interval is longer and shows no regularity in distribution.When the loading rate goes higher,the stress drop will become smaller and the recurrence interval will tend to be constant and stick-slip events show a quasi-periodicity.At lower confining pressures and strain rates,the main fracture may evolve into 2 X-shaped conjugate shear faults; whereas at higher confining pressures and 相似文献
8.
用双剪法对济南辉长岩和点苍山大理岩进行了摩擦滑动实验.实验中的应力变化方式有两种.A 型实验:先使断层面上的正应力增加到一定值,然后保持正应力不变,并增加剪应力使断层发生粘滑;B 型实验:先使断层面上的正应力增加到一定的值,保持正应力不变,并增加剪应力到断层发生粘滑前的某一应力状态,再保持剪应力不变,减小正应力直到粘滑发生.实验表明,B 型实验中岩石的摩擦强度高于 A 型实验.A 型实验中粘滑发生前有声发射率增加的前兆,B 型实验中粘滑发生前看不到声发射率的明显增加.由实验得到一个启示,即闭锁断层的开锁可能采取两种形式:一种是冲开闭锁,即以剪应力的增加使断层发生错动;另一种是解开闭锁,即以正应力的减小使断层发生错动.断层的粘滑采取哪种形式,由断层带的应力变化途径决定. 相似文献
9.
Hartmut Spetzler Guennadi Sobolev Anatoli Koltsov Arno Zang Ivan C. Getting 《Pure and Applied Geophysics》1991,137(1-2):95-112
In this paper we report results obtained from various friction experiments under direct and oblique shear loading conditions. We used four rock types of varying brittleness (quartzite, anhydrite, limestone, pyrophyllite) with different surface roughness. The observations concentrate on the time span several milliseconds before dynamic failure occurs. During this period a premonitory, unstable phase of slip (slip 2) occurs. This differs importantly from a premonitory, stable process (slip 1) with durations of hundreds of seconds. On smooth surfaces slip 2 is usually observed with ductile rocks and less reliably with brittle rocks. Slip 2 is mostly accompanied by acoustic emissions, which increase in rate of occurrence and in magnitude until the stick-slip event. Foreshocks are observed during approximately 50% of the slip 2 events on rough surfaces. Foreshocks far exceed the acoustic noise level, which is also prevalent before stick-slip events on rough surfaces. In the direct shear experiment, where two faults are being loaded simultaneously, in about 20% of the cases precursory slip 2 was observed on the opposite side on which the final stick-slip event occurred. 相似文献
10.
11.
Eiichi Fukuyama Shiqing Xu Futoshi Yamashita Kazuo Mizoguchi 《Journal of Seismology》2016,20(4):1207-1215
We investigated the shear strain field ahead of a supershear rupture. The strain array data along the sliding fault surfaces were obtained during the large-scale biaxial friction experiments at the National Research Institute for Earth Science and Disaster Resilience. These friction experiments were done using a pair of meter-scale metagabbro rock specimens whose simulated fault area was 1.5 m?×?0.1 m. A 2.6-MPa normal stress was applied with loading velocity of 0.1 mm/s. Near-fault strain was measured by 32 two-component semiconductor strain gauges installed at an interval of 50 mm and 10 mm off the fault and recorded at an interval of 1 MHz. Many stick-slip events were observed in the experiments. We chose ten unilateral rupture events that propagated with supershear rupture velocity without preceding foreshocks. Focusing on the rupture front, stress concentration was observed and sharp stress drop occurred immediately inside the ruptured area. The temporal variation of strain array data is converted to the spatial variation of strain assuming a constant rupture velocity. We picked up the peak strain and zero-crossing strain locations to measure the cohesive zone length. By compiling the stick-slip event data, the cohesive zone length is about 50 mm although it scattered among the events. We could not see any systematic variation at the location but some dependence on the rupture velocity. The cohesive zone length decreases as the rupture velocity increases, especially larger than \( \sqrt{2} \) times the shear wave velocity. This feature is consistent with the theoretical prediction. 相似文献
12.
Nonlinear earthquake response analysis and energy calculation for seismic slit shear wall structures
Based on the concept of structural passive control, a new type of slit shear wall, with improved seismic performance when
compared to an ordinary solid shear wall, was proposed by the authors in 1996. The idea has been verified by a series of pseudo-static
and dynamic tests. In this paper a macro numerical model is developed for the wall element and the energy dissipation device.
Then, nonlinear time history analysis is carried out for a 10-story slit shear wall model tested on a shaking table. Furthermore,
the seismic input energy and the individual energy dissipated by the components are calculated by a method based on Newmark-β
assumptions for this shear wall model, and the advantages of this shear wall are further demonstrated by the calculation results
from the viewpoint of energy. Finally, according to the seismic damage criterion on the basis of plastic accumulative energy
and maximum response, the optimal analysis is carried out to select design parameters for the energy dissipation device. 相似文献
13.
The nucleation process of stick-slip instability was analyzed based on the experimental measurements of strain and fault slip on homogeneous and non-homogeneous faults. The results show that the nucleation process of stick-slip on the homogeneous fault is of weak slip-weakening behavior under constant loading point velocity. The existence of a short "weak segment" on the fault makes slip-weakening phenomenon in nucleation process more obvious, while the existence of a long "weak segment" on the fault makes the nucleation process changed. The nucleation is characterized by accelerating slip in a local region and rapid increase of shear stress along the fault in this case, which is more coincident with the rate and state friction law. During the period when fault is locked, increasing of shear stress causes lateral elastic dilation near the fault, and the rebound of the dilation at the time of instability causes an instantaneous increase of normal stress in the fault plane, which is an important factor making fault be rapidly locked and its strength recovered. 相似文献
14.
Shengli Ma Liqiang Liu Jin Ma Kaiying Wang Xiaoyan Hu Tianchang Liu Xiuquan Wu 《中国科学D辑(英文版)》2003,46(2):56-66
The nucleation process of stick-slip instability was analyzed based on the experimental measurements of strain and fault slip on homogeneous and non-homogeneous faults. The results show that the nucleation process of stick-slip on the homogeneous fault is of weak slip-weakening behavior under constant loading point velocity. The existence of a short “weak segment” on the fault makes slip-weakening phenomenon in nucleation process more obvious, while the existence of a long “weak segment” on the fault makes the nucleation process changed. The nucleation is characterized by accelerating slip in a local region and rapid increase of shear stress along the fault in this case, which is more coincident with the rate and state friction law. During the period when fault is locked, increasing of shear stress causes lateral elastic dilation near the fault, and the rebound of the dilation at the time of instability causes an instantaneous increase of normal stress in the fault plane, which is an important factor making fault be rapidly locked and its strength recovered. 相似文献
15.
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
16.
Hideki Mukoyoshi Tetsuro Hirono Hidetoshi Hara Kotaro Sekine Noriyoshi Tsuchiya Arito Sakaguchi Wonn Soh 《Island Arc》2009,18(2):333-351
To understand the characteristics of deformation of an out-of-sequence thrust (OST) and the style of fluid flow along it, we investigated the Nobeoka Tectonic Line, which has been interpreted as a deep OST (7–9 km), in the Shimanto accretionary complex, Southwest Japan. The shear zone in the footwall differs significantly in the along-strike direction not only in thickness, which varied from 100 to 300 m, but also in lithology and mineral vein development. These variations might reflect primarily differences in lithology; that is, the sandstone-dominant shear zone with a large amount of mineral veins precipitated in microcracks is relatively thick, whereas the shale-dominant shear zone with a small amount of veins and with textures indicating highly pressurized pore fluid, is thinner. By comparison with characteristics of a shallow OST (3–5 km), we conclude that the shallow OST has experienced repeated brittle failure with rapid slip and focused fluid flow whereas the deep OST has experienced both brittle and ductile deformation, followed by fluid flow of various styles, depending on the lithology. 相似文献
17.
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
18.
V. V. Adushkin G. G. Kocharyan V. A. Novikov 《Izvestiya Physics of the Solid Earth》2016,52(5):637-647
We present the data of the laboratory experiments on studying the regularities of gradual transition from the stick-slip behavior to aseismic creeping on the interblock boundary. The experiments show that small variations in the material composition in the principal slip zones of the faults may cause a significant change in the fraction of seismic energy radiated during the dynamic unloading of the adjacent segment of the rock mass. The experiments simulate interblock sliding regimes with the values of the scaled kinetic energy differing by a few orders of magnitude and relatively small distinctions in the strength of the contacts and in the amplitude of the released shear stresses. The results of the experiments show that the slip mode and the fraction of the deformation energy that goes into the seismic radiation are determined by the ratio of two parameters—the stiffness of the fault and the stiffness of the enclosing rock mass. An important implication of the study for solving the engineering tasks is that for bringing a stressed segment of a fault or a crack into a slip mode with low-intensity radiation of seismic energy, the anthropogenic impact should be aimed at diminishing the stiffness of the fault zone rather than at releasing the excessive stresses. 相似文献
19.
The sources for thirteen deep focus earthquakes ofm
b≥5.5 andh>400 km in Northwest Pacific region were studied using waveform fitting and shear fracture source model. The source parameters
were obtained as follows: focal depth, faulting plane, slip direction, rupture velocity, rupture length, rupture direction
and scalar moment tensor. It was found that all these earthquake sources can be interpreted as shear faulting and have simple
source time functions. The strike direction of faulting plane for most deep focus earthquakes coincides with that of the subduction
zone, especially in the deep part of the subduction zone, it results in the tendency of reducing the dip angle of the subduction
zone. The multiple point source model was also used to study the source process. The waveform fitting is better than the shear
fracture model, but the general rupture direction which coincides with that from unilateral shear source model can not be
obtained from the multiple point source model.
This study is supported by the National Science Foundation of China and the Chinese Joint Seismological Science Foundation. 相似文献
20.
The Bloody Bluff fault zone, which divides the New England Avalon zone and Nashoba zone, contains at least two shear zones that are within Avalonian rocks. The Rice Road shear zone (sinistral, strike-slip) affects the Westboro Formation and is intruded by the 630 Ma Dedham Granite. The Rice Road shear zone, and equivalent pre-granite mylonites appearing in drill cores, parallel the terrane boundary, and may have controlled the later mylonitization. The Nobscot shear zone (dextral, strike-slip) is a prograde shear zone cutting a granite assumed to be related to the surrounding 630 Ma plutons. Similar shear zones have been seen cutting Late Proterozoic plutons in the New England Avalon zone, and represent a series of en echelon strike-slip shears. The Burlington mylonite zone (shear sense equivocal) is part of the terrane boundary. This is a retrograde shear zone that forms the southeastern border of the Wolfpen lens, a lenticular body of sheared and altered metamorphic and intrusive rock that has been assumed to be part of the New England Avalon zone. Microstructural characteristics indicate that the Burlington mylonite zone was active after the Nobscot shear zone. In particular, quartz in the Nobscot shear zone was dynamically recrystallized by a combination of grain boundary migration and rotation recrystallization processes, thought to occur during shearing at upper-greenschist conditions. In contrast, quartz in the Burlington mylonite zone was recrystallized predominantly by rotation recrystallization, indicating lower-greenschist, retrograde, deformation. The two shear zones are too close for these differences to be a result of a simple thermal field gradient.While mineral assemblages in most of the study area indicate no metamorphic grade higher than upper-greenschist temperatures, the Wolfpen lens contains amphibolites with assemblages formed at temperatures above the oligoclase isograd, indicating mid-amphibolite facies metamorphism. As metamorphic contrast is one of the key features differentiating the Nashoba zone from the New England Avalon zone, the Wolfpen lens cannot be assumed to be part of Avalon. It may be a small block of rocks of intermediate grade between the two terranes. 相似文献