Numerical studies of the influence of microstructure on rock failure in uniaxial compression — Part II: constraint, slenderness and size effect

In this paper, a Material Failure Process Analysis code (MFPA2D) was employed to investigate the interaction of end effect zone of specimen with the wing crack propagation inside the brittle specimen containing pre-existing flaws under uniaxial compression comparing with the experimental results. The numerical results show that the shorter the distance between the pre-existing flaw and the specimen's end , the slower the crack propagation process and the shorter wing propagation length is , and vice versa. In addition, the end effect zone was also influenced by the wing crack propagation.

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Numerical Studies of the Influence of Heterogeneity on Rock Failure and Induced Earthquake Precursors

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.2648 ◽

2005 ◽

Vol 297-300 ◽

pp. 2648-2653

Author(s):

Ming Ruo Jiao ◽

Chun An Tang ◽

W.F. Sun ◽

Shu Hong Wang

Keyword(s):

Numerical Simulations ◽

Rock Failure ◽

Earthquake Precursors ◽

Numerical Results ◽

Mechanical Heterogeneity ◽

Induced Earthquake ◽

Numerical Studies ◽

Good Agreement

A series of numerical simulations were performed to investigate the effects of geometric and mechanical heterogeneity of pre-existing faults of rocks on their failure and induced earthquake precursors. The numerical results revealed that rock failures with the different heterogeneity produce the different earthquake precursors, which are in a good agreement with those of observations in nature.

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Comparative analysis of acoustic and electromagnetic emissions of rocks

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/929/1/012013 ◽

2021 ◽

Vol 929 (1) ◽

pp. 012013

Author(s):

V N Klyuchkin ◽

V A Novikov ◽

V I Okunev ◽

V A Zeigarnik

Keyword(s):

Comparative Analysis ◽

Uniaxial Compression ◽

High Stress ◽

Electromagnetic Emission ◽

Rock Failure ◽

Dynamic Rupture ◽

Block Model ◽

Rock Samples ◽

Electromagnetic Emissions ◽

Electromagnetic Signals

Abstract Comparative analysis of acoustic and electromagnetic emissions recorded during the intact rock samples deformation and dynamic rupture of simulated crustal fault is presented. Specialized machines for uniaxial compression and shear tests of rock samples with identical data acquisition systems for both test cases were employed. Increase of acoustic emission was observed accompanied by significant rise of intensity and amplitude of electromagnetic signals at high stress of the rock samples under the uniaxial compression or dynamic failure in the spring-block model. Such correlation is consistent with the previous conclusions that an increase of electromagnetic emission may be considered as a rock failure precursor. Any specific characteristics of the detected electromagnetic signals to be used for prediction of impending rock failure or the earthquake fault rupture were not found. The similarity of electromagnetic signals and their spectra obtained at the press equipment and the spring-block model suggests that in both cases, the signals observed are generated by the crack formations and shear. The electromagnetic emission appeared only in dry samples. The samples saturated by water with the salinity of over 0.1% demonstrated no electromagnetic emission.

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