A modified approach for prediction of strength and post yield behaviour for high GSI rockmasses in strong, brittle ground

Diederichs,; Carvalho, J.; Carter, T.G.

doi:10.1201/noe0415444019-c31

Cited by 22 publications

(17 citation statements)

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“…We use representative rock mass properties based on past investigations in the study area [ Girod , ; Girod and Thelin , ; Willenberg , ; Yugsi , ], as well as available literature values for the microcrack initiation and extensional fracture limits in intact crystalline rock [ Diederichs et al ., ; Leith et al ., ]. These properties are summarized in Table and are used to define the three behavioral thresholds required to plot a material‐specific trilinear fracture envelope (Figure ) for the orthogneiss (Randa augengneiss) dominant in our chosen cross section (see section 4.1).…”

Section: Modeling Strategymentioning

confidence: 99%

“…Unlike Diederichs et al . [], however, who apply the envelope to determine plastic yield limits for numerical models, we use the envelope to assess likely modes of bedrock fracture in a model limited by long‐term bedrock strength criteria: namely tensile fracture, new microcrack development, and Byerlee's empirical friction law [see Anderson [, ]; Byerlee []; Brace and Kohlstedt []; Leith et al . [].…”

Section: Modeling Strategymentioning

confidence: 99%

“…The envelope consists of three key behavioral thresholds: (1) the microcrack initiation threshold, (2) the extensional fracture limit, and (3) the empirical Hoek-Brown shear failure envelope. Unlike Diederichs et al [2007], however, who apply the envelope to determine plastic yield limits for numerical models, we use the envelope to assess likely modes of bedrock fracture in a model limited by long-term bedrock strength criteria: namely tensile fracture, new microcrack development, and Byerlee's empirical friction law [see Anderson [1905Anderson [ , 1951; Byerlee [1978]; Brace and Kohlstedt [1980]; Leith et al [2013].…”

Section: Trilinear Fracture Envelopementioning

confidence: 99%

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Subglacial extensional fracture development and implications for Alpine Valley evolution

Leith

Moore

Amann³

et al. 2014

JGR Earth Surface

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[1] Bedrock stresses induced through exhumation and tectonic processes play a key role in the topographic evolution of alpine valleys. Using a finite difference model combining the effects of tectonics, erosion, and long-term bedrock strength, we assess the development of near-surface in situ stresses and predict bedrock behavior in response to glacial erosion in an Alpine Valley (the Matter Valley, southern Switzerland). Initial stresses are derived from the regional tectonic history, which is characterized by ongoing transtensional or extensional strain throughout exhumation of the brittle crust. We find that bedrock stresses beneath glacial ice in an initial V-shaped topography are sufficient to induce localized extensional fracturing in a zone extending laterally 600 m from the valley axis. The limit of this zone is reflected in the landscape today by a valley "shoulder," separating linear upper mountain slopes from the deep U-shaped inner valley. We propose that this extensional fracture development enhanced glacial quarrying between the valley shoulder and axis and identify a positive feedback where enhanced quarrying promoted valley incision, which in turn increased in situ stress concentrations near the valley floor, assisting erosion and further driving rapid U-shaped valley development. During interglacial periods, these stresses were relieved through brittle strain or topographic modification, and without significant erosion to reach more highly stressed bedrock, subsequent glaciation caused a reduction in differential stress and suppressed extensional fracturing. A combination of stress relief during interglacial periods, and increased ice accumulation rates in highly incised valleys, will reduce the likelihood of repeat enhanced erosion events.

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Section: Modeling Strategymentioning

confidence: 99%

Section: Modeling Strategymentioning

confidence: 99%

Section: Trilinear Fracture Envelopementioning

confidence: 99%

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Subglacial extensional fracture development and implications for Alpine Valley evolution

Leith

Moore

Amann³

et al. 2014

JGR Earth Surface

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“…strain hardening of the mine pillars. The strain hardening behaviour of mine pillars produced by the CSFH model is unrealistic for rock substance [16]. Outcome of the CSFH modeling of the mine also did not conform with actual ground conditions.…”

Section: Discussionmentioning

confidence: 99%

3D-Numerical simulation of a mine using cohesion-softening, friction-softening and hardening behavior

Rajmeny¹,

Jain²,

Vakili³

2016

Proceedings of the Conference on Recent Advances in Rock Engineering (RARE 2016)

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Abstract-Numerical modeling is a potent tool to evaluate stability and to assist in long term planning of a mine along with predictive modeling of planned mining situations. However, selection of proper input properties regarding the rock mass still intrigues the Rock Mechanics community. A well-documented case study of a hard rock mine situated in moderately high stress regime practicing sublevel open stoping has been simulated using 3D finite difference method (FLAC3D). The mine was modeled using three types of constitutive material modelMohr-Coulomb with strain-softening post peak, bi-linear MohrCoulomb with strain-softening post peak, Mohr-Coulomb with cohesion softening/friction hardening (CSFH) post peak. Outcome of all approaches have been compared with actual ground conditions. The comparison revealed that the numerical models using the bi-linear Mohr-Coulomb with strain-softening post peak provides most realistic match to the observations in the mine including instability of the crown pillars.

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“…For very heterogeneous rock types the spalling limit is often < 10 but may be > 10 in homogeneous materials [46] [36].…”

Section: Beobachtungen Von Fasergipseinlagen Im Gebirgementioning

confidence: 99%

Role of brittle fracture on swelling behaviour of weak rock tunnels: hypothesis and qualitative evidence /

Steiner¹,

Kaiser

Spaun³

2010

Geomechanics and Tunnelling

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Underground construction in rock prone to swelling behaviour may result in long-term problems, especially in the invert, if the structure cannot resist swelling pressures. Swelling phenomena are not only a consequence of ground conditions but are strongly influenced by excavation and construction procedures. Evidence of brittle failure observed in the field will be presented and analyzed to prove that brittle failure is the trigger effect of swelling phenomena in shale and clay-anhydrite rocks. Brittle fractures have also been observed in laboratory swelling tests. Brittle failure can create cracks that form pathways for water, leading to changes in the stress-state, and as a consequence trigger swelling phenomena. In clay-anhydrite rock, the swelling pressure is caused by the crystallization pressure of gypsum. The excavation and construction procedures used for the tunnel are a decisive factor for controlling swelling behaviour.

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A modified approach for prediction of strength and post yield behaviour for high GSI rockmasses in strong, brittle ground

Cited by 22 publications

References 0 publications

Subglacial extensional fracture development and implications for Alpine Valley evolution

Subglacial extensional fracture development and implications for Alpine Valley evolution

3D-Numerical simulation of a mine using cohesion-softening, friction-softening and hardening behavior

Role of brittle fracture on swelling behaviour of weak rock tunnels: hypothesis and qualitative evidence /

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