Quasi-static fault growth and shear fracture energy in granite

Lockner, D. A.; Byerlee, J. D.; Kuksenko, V. S.; Пономарев, А. В.; Sidorin, A. Ya.

doi:10.1038/350039a0

Cited by 939 publications

(584 citation statements)

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“…Second, in the shallow crust a combination of tensile and shear mode cracks may lead to fault rupturing. Third, the controlled variation of the propagation velocity of the fault allows us to bridge the gap between previously published laboratory acoustic emission results on dynamic fracture [Lei et al, 2000] and quasi-static rate-controlled tests [Lockner et al, 1991 ]. A second study with a series of confined asymmetric tests is under way which focuses on the process zone in different materials.…”

Section: Two Different Types Of Aue Granitementioning

confidence: 99%

Fracture process zone in granite

Zang¹,

Wagner²,

Stanchits³

et al. 2000

J. Geophys. Res.

198

116

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Abstract. In uniaxial compression tests performed on Aue granite cores (diameter 50 mm, length 100 mm), a steel loading plate was used to induce the formation of a discrete shear fracture. A zone of distributed microcracks surrounds the tip of the propagating fracture. This process zone is imaged by locating acoustic emission events using 12 piezoceramic sensors attached to the samples. Propagation velocity of the process zone is varied by using the rate of acoustic emissions to control the applied axial force. The resulting velocities range from 2 mm/s in displacement-controlled tests to 2 lam/s in tests controlled by acoustic emission rate. Wave velocities and amplitudes are monitored during fault formation. P waves transmitted through the approaching process zone show a drop in amplitude of 26 dB, and ultrasonic velocities are reduced by 10%. The width of the process zone is -9 times the grain diameter inferred from acoustic data but is only 2 times the grain size from optical crack inspection. The process zone of fast propagating fractures is wider than for slow ones. The density of microcracks and acoustic emissions increases approaching the main fracture. Shear displacement scales linearly with fracture length. Fault plane solutions from acoustic events show similar orientation of nodal planes on both sides of the shear fracture. The ratio of the process zone width to the fault length in Aue granite ranges from 0.01 to 0.1 inferred from crack data and acoustic emissions, respectively. The fracture surface energy is estimated from microstructure analysis to be -2 J. A lower bound estimate for the energy dissipated by acoustic events is 0.1 J.

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Section: Two Different Types Of Aue Granitementioning

confidence: 99%

Fracture process zone in granite

Zang¹,

Wagner²,

Stanchits³

et al. 2000

J. Geophys. Res.

198

116

View full text Add to dashboard Cite

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“…In the case of JS sample the slip was different from stable sliding under quasi-constant differential stress usually observed after postpeak strain softening and Satoh et al [1990] concluded that the most plausible mechanisms of fault development was shear linking of an axial crack array [Wong, 1982]. In triaxial compression experiments on granite and sandstone samples by controlling axial stress to maintain constant AE rate, the fault growth and shear fracture have been followed quasi-statically [Lockner et al, 1991[Lockner et al, , 1992. In that case the postpeak weakening curve corresponds to propagation of the macroscopic fault plane across the sample, and microcracking, as determined by AE locations, remained uniformly distributed in the central portion of the granite samples until after peak stress.…”

Section: P Wave Velocitiesmentioning

confidence: 99%

Comparison of the microfracture localization in granite between fracturation and slip of a preexisting macroscopic healed joint by acoustic emission measurements

Jouinaux¹,

Masuda²,

Lei³

et al. 2001

J. Geophys. Res.

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“…This can be described by including plastic strain rate as a source term in Eq. (2). Then, the relevant (inhomogeneous) wave equation describing the acoustic emission process takes the form…”

Section: A General Framework For Acoustic Emission During Plasticmentioning

confidence: 99%

“…The method involves recording the arrival times of a wave at multiple transducers which in turn determines the distances of the AE source from the transducers. This procedure is akin to that adopted in fracture studies on rock samples [2,13]. This method has been used to explain the power law distribution of the amplitudes of the AE signals in the deformation studies of ice samples [12,13].…”

Section: Introductionmentioning

confidence: 99%

“…A good example from the geological scale is the acoustic emission (AE) during volcanic activity [1]. Varied laboratory scale examples such as AE from crack nucleation and propagation in fracture of solids [2][3][4], thermal cycling of martensites [5][6][7], peeling of an adhesive tape [8][9][10][11] and collective dislocation motion can be cited [12][13][14]. Clearly, while the sources that lead to AE signals in such widely different situations are necessarily different, they are generally attributed to the release of stored elastic energy in the system.…”

Section: Introductionmentioning

confidence: 99%

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General framework for acoustic emission during plastic deformation

2015

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Despite the long history, so far there is no general theoretical framework for calculating the acoustic emission spectrum accompanying any plastic deformation. We set up a discrete wave equation with plastic strain rate as a source term and include the Rayleigh-dissipation function to represent dissipation accompanying acoustic emission. We devise a method of bridging the widely separated time scales of plastic deformation and elastic degrees of freedom. While this equation is applicable to any type of plastic deformation, it should be supplemented by evolution equations for the dislocation microstructure for calculating the plastic strain rate. The efficacy of the framework is illustrated by considering three distinct cases of plastic deformation. The first one is the acoustic emission during a typical continuous yield exhibiting a smooth stress-strain curve. We first construct an appropriate set of evolution equations for two types of dislocation densities and then show that the shape of the model stress-strain curve and accompanying acoustic emission spectrum match very well with experimental results. The second and the third are the more complex cases of the Portevin-Le Chatelier bands and the Lüders band. These two cases are dealt with in the context of the Ananthakrishna model since the model predicts the three types of the Portevin-Le Chatelier bands and also Lüders-like bands. Our results show that for the type-C bands where the serration amplitude is large, the acoustic emission spectrum consist of well separated bursts of acoustic emission. At higher strain rates of hopping type-B bands, the burst type acoustic emission spectrum tends to overlap forming a nearly continuous background with some sharp acoustic emission bursts. The latter can be identified with the nucleation of new bands. The acoustic emission spectrum associated with the continuously propagating type-A band is continuous. These predictions are consistent with experimental results. More importantly, our study shows that the low amplitude continuous acoustic emission spectrum seen in both the type-B and A band regimes is directly correlated to small amplitude serrations induced by propagating bands. The acoustic emission spectrum of the Lüders-like band matches with recent experiments as well. In all of these cases, acoustic emission signals are burst-like reflecting the intermittent character of dislocation mediated plastic flow.

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Quasi-static fault growth and shear fracture energy in granite

Cited by 939 publications

References 10 publications

Fracture process zone in granite

Fracture process zone in granite

Comparison of the microfracture localization in granite between fracturation and slip of a preexisting macroscopic healed joint by acoustic emission measurements

General framework for acoustic emission during plastic deformation

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