Crack extension caused by internal gas pressure compared with extension caused by tensile stress

McHugh, Stuart

doi:10.1007/bf00963386

Cited by 86 publications

(36 citation statements)

References 9 publications

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“…In fact, the stress wave can only initiate limited cracking and crushing of the rock near the borehole which would not exceed more than several hole diameters (Kutter and Fairhurst 1971). Based on some field and laboratory experiments, McHugh (1983) concluded that the effect of gas pressure could be more noticeable than the effect of stress wave. The same result was confirmed by Daehnke et al (1997).…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of rock fracturing by gas pressure using the extended finite element method

2015

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High energy gas fracturing is a simple approach of applying high pressure gas to stimulate wells by generating several radial cracks without creating any other damages to the wells. In this paper, a numerical algorithm is proposed to quantitatively simulate propagation of these fractures around a pressurized hole as a quasi-static phenomenon. The gas flow through the cracks is assumed as a one-dimensional transient flow, governed by equations of conservation of mass and momentum. The fractured medium is modeled with the extended finite element method, and the stress intensity factor is calculated by the simple, though sufficiently accurate, displacement extrapolation method. To evaluate the proposed algorithm, two field tests are simulated and the unknown parameters are determined through calibration. Sensitivity analyses are performed on the main effective parameters. Considering that the level of uncertainty is very high in these types of engineering problems, the results show a good agreement with the experimental data. They are also consistent with the theory that the final crack length is mainly determined by the gas pressure rather than the initial crack length produced by the stress waves.

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Section: Introductionmentioning

confidence: 99%

Numerical analysis of rock fracturing by gas pressure using the extended finite element method

2015

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“…In the meantime, stress wave (or shock wave) and explosion gas pressure are produced and loaded on the surrounding rock mass. The stress wave propagates at a higher velocity for a shorter duration in comparison to the explosion gas pressure [23,24]. The explosion gas pressure can cause further extension and propagation of the cracks around the blasthole that are created by the stress wave.…”

Section: Introductionmentioning

confidence: 99%

“…Substitute 10% for in (23), then the damage variable D is equated to 0.19. Correspondingly, the critical rock mass damage variable is = 0.19.…”

Section: Determination Of Damage Thresholdmentioning

confidence: 99%

Blast Induced Crack Propagation and Damage Accumulation in Rock Mass Containing Initial Damage

Wang

Zhao

et al. 2018

Shock and Vibration

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Blast induced rock mass damage and crack propagation play important roles in structure safety and stability in mining, quarrying, and civil constructions. This paper focuses on the effect of small blasthole diameter blast on crack propagation and damage accumulation in water-bearing rock mass containing initial damage composed of inherent geological discontinuities and previous multiblast induced damage. To elucidate this effect, theoretical analysis of calculation method for several important blast influencing factors is firstly presented. Secondly, definition of a practical damage variable using ratio of longitudinal wave velocity in rock mass before blast occurrence to that after blast occurrence and derivation of a damage accumulation calculation equation accounting for initial damage and blasting effect are described. Lastly, a detailed description of the conducted in situ blast tests and plan layout of the sonic wave monitoring holes is reported. The results indicate that blast activates and then extends the initial cracks in rock mass, leading to accumulation of rock mass damage. The rock mass damage accumulation can be conveniently quantified using the proposed damage variable. When the damage variable reaches its threshold of 0.19, occurrence of damage in the surrounding rock mass is indicated. It is also found that the blast induced rock mass damage extent and the blast induced vibration velocities decrease nonlinearly with increasing the distance between blast source and monitoring position.

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“…This process continues as the gas pressure attempts to establish a state of equilibrium concentration whereby the gas has moved to a more dispersed lower energy state through the host medium or vented to the atmosphere. Gas expansion can be attributed with increasing the length of cracks in some tests by a factor of five (McHugh, 1983). The pressures resulting from gas expansion can go through positive and negative cycles.…”

Section: Breakage Due To Gas Expansionmentioning

confidence: 99%

“…Specifically those that quantify properties not specified explicitly by the iDamage model. For instance, the McHugh model is predicated on the assumption gas expansion is the dominant rock breakage mechanism (McHugh, 1983).…”

Section: Recommendationsmentioning

confidence: 99%

Evaluation of a blast damage model based on stress attenuation criteria

Lewis¹

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Crack extension caused by internal gas pressure compared with extension caused by tensile stress

Cited by 86 publications

References 9 publications

Numerical analysis of rock fracturing by gas pressure using the extended finite element method

Numerical analysis of rock fracturing by gas pressure using the extended finite element method

Blast Induced Crack Propagation and Damage Accumulation in Rock Mass Containing Initial Damage

Evaluation of a blast damage model based on stress attenuation criteria

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