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  • Articles  (114)
  • Engineering  (104)
  • Friction  (10)
  • Marine Geosciences and Applied Geophysics
  • diatoms
  • 1975-1979  (114)
  • Geosciences  (114)
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  • Articles  (114)
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  • 1
    Electronic Resource
    Electronic Resource
    Mineralogy and physical nature of clay gouge (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 655-689 
    Details
    ISSN: 1420-9136
    Keywords: Fault gouge ; Friction ; Earthquake faulting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Fault gouges have been observed in the surface outcrops, in shallow excavations, and in deep (300 meters below the surface) tunnels and mines in fault zones. The 2-microns fractions in these fault gouges may compose a few percent to more than fifty percent of the total mass in the outcrops, and the mineralogy of the 2-microns fractions consists of a variety of clays (the common ones are montmorillonite, illite, kaolinite, chlorite, vermiculite and mixed-layer clays) and some quartz, feldspars, etc. Although we cannot yet conclude directly from the studies of gouges that similar gouges exist at depths where many large shallow earthquakes are generated, there is a strong possibility that they do, based on (1) available equilibrium data on various clays — for example, kaolinite has been found to exist at 4 kb and 375°C (±15°C) (Thompson, 1970) and montmorillonite + kaolite has been found to exist at 450°C and 4 kb (Velde, 1969); (2) the compatibility of laboratory velocity data in gouge (Wang et al., 1977) with those in a model for central California (Healy andPeake, 1975); (3) the capability of clays to undergo sudden earthquake-like displacements (Summers andByerlee, 1977); (4) the petrology of intrafault cataclastic rocks in old fault zones (Kasza, 1977); and (5) the compatibility of gouge mineralogy with the mineralogy of hydrothermal clay deposits. If clay gouges are indeed significant components of the fault zone at depth, then the mechanical properties of clays under confining pressures up to 4 kb are important in the behavior of faults. Very few experiments have been performed under such high pressures. But from the physical makeup of clays, we can infer that (1) the range of possible behavior includes stable sliding with vermiculite and montmorillonite (asByerlee andSummers, 1977, have proven) to stick-slip-like behavior with kaolinite, chlorite, etc.; (2) the absence or presence of water will greatly affect the strengths of gouges — it is possible that water may reduce the strength of gouge to a fairly small value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876531
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  • 2
    Electronic Resource
    Electronic Resource
    Time-dependent friction and the mechanics of stick-slip (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 790-806 
    Details
    ISSN: 1420-9136
    Keywords: Stick-slip ; Friction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Time-dependent increase of static friction is characteristic of rock friction undera variety of experimental circumstances. Data presented here show an analogous velocity-dependent effect. A theor of friction is proposed that establishes a common basis for static and sliding friction. Creep at points of contact causes increases in friction that are proportional to the logarithm of the time that the population of points of contact exist. For static friction that time is the time of stationary contact. For sliding friction the time of contact is determined by the critical displacement required to change the population of contacts and the slip velocity. An analysis of a one-dimensional spring and slider system shows that experimental observations establishing the transition from stable sliding to stick-slip to be a function of normal stress, stiffness and surface finish are a consequence of time-dependent friction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876539
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  • 3
    Electronic Resource
    Electronic Resource
    Volume changes during fracture and frictional sliding: A review (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 603-614 
    Details
    ISSN: 1420-9136
    Keywords: Compaction ; Dilatancy ; Fracture ; Friction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Volume changes in geologic materials have been measured with strain gauges, cantilever displacement gauges, or through observation of either pore or total volume. When porosity is less than 0.05, compaction is small or absent; apart from elastic strains in the minerals, dilatancy predominates, beginning at 50 to 75 percent of the fracture stress difference. When initial porosity exceeds about 0.05, compaction and dilatancy may overlap. The onset of dilatancy has not been identified, but most of the dilatancy occurs within about 10 percent of the fracture stress difference. In low porosity rocks, dilatancy increases initial porosity by a factor of 2 or more; in porous rocks or granular aggregates the increase is only 20 to 50 percent. However, the actual pore volume increase is larger in rocks of high initial porosity. Hence, earthquake precursors which depend on the magnitude of dilatancy should be more pronounced in porous rocks or in fault gouge. In contrast, precursors which are based on fractional changes in some porosity-related property may be more pronounced in rocks of low initial porosity. Future work is particularly needed on constitutive relations suitable for major classes of rocks, on the effects of stress cycling in porous rocks, on the effects of high temperature and pore fluids on dilatancy and compaction, and on the degree of localization of strain prior to fracture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876527
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  • 4
    Electronic Resource
    Electronic Resource
    Electrical resistivity changes in rocks during frictional sliding and fracture (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 717-731 
    Details
    ISSN: 1420-9136
    Keywords: Electrical resistivity ; Fracture ; Friction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Significant changes of electrical resistivity of saturated rocks and water pressure along sliding surface occurred during stick-slips in our direct shear experiment. Two types of changes of electrical resistivity occurred. In the first, resistivity decreased with increasing shear stress, reached minimum together with a sudden release of shear stress and returned to a higher value immediately afterwards. In the second, resistivity again decreased with increasing stress but, in contrast to the first type of changes, it decreased further upon the sudden drop of shear stress. The magnitude and the direction of the changes of water pressure on the sliding surface during stick-slip were not uniform, indicating local variations of surface deformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876534
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  • 5
    Electronic Resource
    Electronic Resource
    Friction of rocks (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 615-626 
    Details
    ISSN: 1420-9136
    Keywords: Rock mechanics ; Friction ; Faulting surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Experimental results in the published literature show that at low normal stress the shear stress required to slide one rock over another varies widely between experiments. This is because at low stress rock friction is strongly dependent on surface roughness. At high normal stress that effect is diminished and the friction is nearly independent of rock type. If the sliding surfaces are separated by gouge composed of Montmorillonite or vermiculite the friction can be very low.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876528
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  • 6
    Electronic Resource
    Electronic Resource
    Aspects of asperity-surface interaction and surface damage of rocks during experimental frictional sliding (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 705-716 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; Frictional Heating ; Surface damage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Mechanisms for the dissipation of energy during the frictional sliding of rocks includes brittle fracture, plastic deformation, frictional heating, and elastic distortion. The first three energy sinks are manifested by surface damage during frictional sliding. Normal load, temperature, and the velocity of the sliding surfaces as well as surface roughness and hardness all influence the nature of surface damage which includes the generation of structures such as wear grooves, gouge, and welded particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876533
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  • 7
    Electronic Resource
    Electronic Resource
    Rock friction-effect of confining pressure, temperature, and pore pressure (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 690-704 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; Pressure ; Temperature ; Water ; Stress ; Gouge ; Joints ; Faults
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper reviews many of the mechanical properties of faulted and jointed rock under pressure and temperature and in the presence of water. At low effective confining pressures (below about 1 kilobar), the friction strength is quite variable and depends on the frictional resistance between gouge particles or asperities and on the dilatancy of the fault. At higher pressures the friction strength is nearly independent of mineralogy, temperature, and rate, at least for rocks whose friction strength is less than the failure strength. Water tends to slightly weaken the fault. The type of sliding motion, whether stick-slip or stable sliding, is much more affected by environmental and mineralogical factors. In general, stick-slip is dominant at high pressures and low temperatures, in the presence of strong minerals such as quartz and feldspar, in the absence of gouge, for lower surface roughness, and perhaps in the presence of water. The microscopic deformation mechanisms are poorly understood. At low temperatures, cataclasis dominates in rocks containing mostly quartz or feldspar, and plastic deformation in rocks containing mostly calcite or platy silicates. At high temperature most minerals deform plastically, producing a greater temperature-and rate-dependence of the friction strength. Glass has been found in some sliding surfaces in sandstone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876532
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  • 8
    Electronic Resource
    Electronic Resource
    Seismic velocity changes during fracture and frictional sliding (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 732-742 
    Details
    ISSN: 1420-9136
    Keywords: Velocity changes ; Fracture ; Friction ; Holography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Fracture and frictional sliding are considered as phenomena involving brittle failure. Brittle failure is preceded by the formation of small (subcritical) cracks. In non-water-saturated rock, the distribution, shape and size of these suberitical cracks determine the change in the physical properties prior to failure. A model is proposed which suggests that the spatial and temporal distribution, shape and size of subcritical cracks within a stressed rock depend upon the rate of deformation and the volatile content. As a rock is stressed beyond about 50 percent of its ultimate failure stress, dilatancy is initiated. With increasing stress a broad zone of cracks develops within the dilatant region. The seismic velocities through this zone decrease markedly and the cracks grow more numerous., changing in size and shape. Before brittle failure of the rock occurs, the subcritical cracks interact, leading to a concentration of the zone. During the stage when the zone narrows, the seismic velocities in crease in the surrounding volume due to local rotation of stresses and consequent closure of some cracks. In most laboratory experiments the stage during which the velocity increases and the now intense deformation zone becomes narrow is very short and difficult to observe experimentally. At very low strain rates and with volatiles present, the crack growth and subsequent interaction lead to the narrowing of the intense deformation zone and therefore to an observable increase in velocity. The above is based upon an interpretation of a number of experiments. Using optical holography we have observed the development and subsequent intensification of a deformation zone. Ultrasonic velocity measurements showed a distinct anomaly (decrease followed by an increase) before failure. The anomaly was only detectable at our lowest experimental strain rates (3×10−8/sec).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876535
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  • 9
    Electronic Resource
    Electronic Resource
    Rupture and particle velocity during frictional sliding (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 954-963 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; Rupture and Particle velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Laboratory measurements of rupture and particle velocity are in surprisingly good agreement with seismic values, providing further evidence that stick-slip friction is a suitable mechanism for shallow earthquakes. A simple theory is developed to explain the linear relationship observed between average particle velocity and stress drop for stick-slip events. Both stick-slip ruptures and cracks in brittle material commonly propagate at velocities roughly comparable to theS wave velocity of the material. Rupture normally begins relatively slowly and accelerates to a steady velocity in a few centimeters. Observations suggest that stick-slip ruptures can propagate atS wave speeds or occasionally greater and that cracks in pre-stressed glass can also propagate faster than theS waves. Fracture and thus rupture velocity of intact rock specimens is greatly influenced by the inhomogeneous structure of rock. Fracture may be modeled by coalescence of many cracks rather than growth of a single crack.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876549
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  • 10
    Electronic Resource
    Electronic Resource
    Nonuniform friction as a physical basis for earthquake mechanics (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 964-989 
    Details
    ISSN: 1420-9136
    Keywords: Friction ; Earthquake mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A review of simple models and observations suggests that the main first-order features of active faulting-mechanical instability, the frequency-magnitude relations, seismic and aseismie slip, seismic radiation, incoherency and rupture stoppage — may be explained by a single characteristic of crustal faults: the spatial variation of the effective frictional stress, which resists slippage on faults. Faultoffset data suggest that rupture propagation ceases in regions of high resistance which act, as barriers. In these regions slippage is associated with negative stress drop. The spacing λ and the amplitudeA(λ) of the barriers, as inferred from the frequency-magnitude and moment relation for earthquakes, obeys a simple statistical relationA(λ)∼λp. On the scale of particle motion, this variability of frictional stress provides a mechanical instability which may be associated with the concept of dynamic friction. Invariably, the rapid particle motion in the model is always preceded by accelerated creep. The particle acceleration is highly irregular, giving rise to an almost random acceleration record on the fault. The particle displacement is relatively smooth, giving rise to simple displacement time function in the far field. Rupture propagation time is approximately proportional to the gradient of frictional stress along the fault. Consequently sharp changes of this stress may cause multiple events and other long period irregularities in the fault motion. The power density spectrum associated with the frictional stress implies that stress may be related to a Poisson distribution of lengths. The autocorrelation of such type of distribution yields a correlation lengthk L −1 , similar perhaps toHaskell's (1964) andAki's (1967) correlation lengths inferred from spectral analysis of seismic waves. The partial incoherency of faulting implies that preseismic deformation may be significantly incoherent, consequently the prediction of small moderate earthquakes may be subject to inherent uncertainties. We conclude that frictional stress heterogeneities may be necessary and sufficient to explain active faulting associated with small and moderate earthquakes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876550
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