The effect of cracks on the compressibility of rock

Walsh, J. B.

doi:10.1029/jz070i002p00381

Cited by 1,234 publications

(581 citation statements)

References 17 publications

(4 reference statements)

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“…Saturation with fluids ranging widely in viscosity (thus different time scales for fluid flow) tested at different oscillation frequencies from mHz to MHz provides the experimental possibilities to prove the theoretical framework of different fluid flow regimes within the cracked materials. The Peff for crack closure for the glassbead specimens A3-5 agrees with the theoretical estimation of 35 MPa (Walsh, 1965). The shear modulus obtained from the torsional mode forced oscillation shows systematic weakening effects through introducing cracks.…”

Section: Discussionsupporting

confidence: 75%

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An exploratory study of the seismic properties of thermally cracked, fluid- saturated aggregates of sintered glass beads

Olin

Clark

et al. 2013

ASEG Extended Abstracts

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Section: Discussionsupporting

confidence: 75%

“…6). The significant Peff dependence of shear modulus and the crack closure effect at Peff = Eα (Walsh, 1965) (i.e. ~50 GPa × 0.0007 = 35 MPa) can be observed.…”

Section: Representative Results I -Permeabilitymentioning

confidence: 86%

An exploratory study of the seismic properties of thermally cracked, fluid- saturated aggregates of sintered glass beads

Olin

Clark

et al. 2013

ASEG Extended Abstracts

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“…depend on the applied stress [Walsh, 1965;Nut, 1971;Mavko and Nut, 1978]. This dependence is attributed to closing of compliant parts of the pore volume with increasing mean stress [Mavko et al, 1995].…”

Section: It Is Well Known That Seismic Velocities In Crustal Rocksmentioning

confidence: 99%

Source array analysis of coda waves near the 1989 Loma Prieta, California, mainshock: Implications for the mechanism of coseismic velocity changes

Dodge¹,

Beroza²

1997

J. Geophys. Res.

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Abstract. Coda waves are often considered to be generated by backscattering of primary waves from randomly distributed heterogeneifies in the crust; however, modeling and experimental work indicates that much of the coda may be due to scattering near the receiver. Knowing where the coda is generated is important for several reasons. Coda waves have been used to characterize site amplification, scattering and attenuation throughout the crust, and velocity changes associated with large earthquakes; however, a lack of knowledge of where coda waves are generated can lead to ambiguous interpretations. In this study we analyze 26 s of coda waves recorded at up to 78 stations using slowness stacking on two source arrays and find that at nearly all stations, regardless of distance from the source, nearly all the amvals are within one hemisphere, most are strongly clustered near the direct amval, and the clusters are, in general, symmetrically disposed about the array axis (fault plane). This finding suggests that the coda consists primarily of waves scattered near the stations rather than waves scattered throughout the crust. This result holds even at stations very close to the sources where the amount of coda examined is about 6 times the direct S travel time, and it suggests that much of the coseismic velocity decrease associated with the 1989 Loma Pfieta earthquake [Ellsworth et el., 1992] occurred in the shallow crust near the stations. One possible mechanism for inducing such a change is a decrease in the mean stress from the mainshock slip; however, on the basis of static stress modeling, we find that this mechanism would produce a velocity increase in the region where velocity was observed to decrease. We conclude that the velocity decrease was more likely caused by crack opening or crack coalescence due to strong shaking from the mainshock.

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“…The plot of normalized reduced modulus versus the normalized crack length al/hl is shown in Figure 6. For these calculations, the Poisson's ratio of the uncracked and cracked solid was assumed to be the same even tough in actuality they are quite different [ Walsh, 1965]. This assumption is justified here because the magnitude of the stress concentration at the inhomogeneity's tip and related progressive shear faulting process is rather insensitive to the differences in the Poissons ratios.…”

Section: Failure Under Uniaxial Compressionmentioning

confidence: 99%

Compressive failure of rocks by shear faulting

Gupta¹,

Bergström²

1998

J. Geophys. Res.

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Abstract. A model for the compressive failure of rocks via the process of shear faulting is presented. The model addresses the progressive growth of damage that leads to the formation of a critical fault nucleus which grows unstably in its own plane by fracturing the grain boundaries in an increasingly rapid succession. The model uses a two-parameter Weibull-type shear strength distribution for defining the nucleation of initial damage, followed•by the use of stress enhancement factors for addressing the increased probability of failure in the vicinity of already cracked grain boundaries. These factors essentially involve surface averaging of enhanced stresses in the neighboring grains with the appropriate strength distribution as the weighting function. As the stress is further increased, similar correlated fracturing events get preferentially aligned to the crack cluster, resulting in en echelon of cracks.This crack cluster is modeled as an elliptical inhomogeneity within which the cracks interact and lead to material pulverization, the effect of which, mechanistically, is to lower the shear modulus compared with the uncracked material on the outside. The shear stress concentration resulting from this moduli mismatch is calculated and used to compute the stress enhancement factors for defining the nucleation of additional cracking events near the crack cluster. Eventually, the size of the crack cluster becomes suflq. ciently largo t.h•.t it carries a stress concentration high enough to fracture all grain boundary elements in from of it in an increasingly rapid succession. The stress associated with this event is taken as the failure stress.Since the model allows other cracking events to occur within the material volume in accordance with the assumed strength distribution function, formation of other competing but subcritical shear faults naturally occurs. Besides the faulting stress for a prescribed confinement, the model is able to predict the angle of the shear fault fairly well. The model is applied to a variety of rock types, including granite, eclogite, gabbro, aplite, rock salt, sandstone, dunite, limestone, and marble, and the predicted failure envelopes compare rather well with the failure data available in the literature.

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The effect of cracks on the compressibility of rock

Cited by 1,234 publications

References 17 publications

An exploratory study of the seismic properties of thermally cracked, fluid- saturated aggregates of sintered glass beads

An exploratory study of the seismic properties of thermally cracked, fluid- saturated aggregates of sintered glass beads

Source array analysis of coda waves near the 1989 Loma Prieta, California, mainshock: Implications for the mechanism of coseismic velocity changes

Compressive failure of rocks by shear faulting

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