Modelling brittle failure of rock

Hajiabdolmajid, V.; Kaiser, Peter K.; Martin, C. Derek

doi:10.1016/s1365-1609(02)00051-5

Cited by 488 publications

(230 citation statements)

References 12 publications

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“…This condition may lead to a more systematic use of damage detection methods such as acoustic monitoring in laboratory tests. Concerning the brittle Hoek-Brown parameters, rock characterisation could also be deepened in order to take into account factors such as rock brittleness (Hajiabdolmajid et al, 2002) in the evaluation of the damage threshold.…”

Section: Resultsmentioning

confidence: 99%

“…In the field, the obtained brittle rock-mass strength then depends on various factors such as rock brittleness (Hajiabdolmajid et al, 2002(Hajiabdolmajid et al, /2003, pre-existing damage, rock-mass heterogeneity and jointing, feedback confinement due to size effects or stress rotation, and more.…”

Section: The Mechanisms Of Brittle Failure In Laboratory Tests and Nementioning

confidence: 99%

“…However, no quantitative correlation between depth and damage could be inferred from these test results. In fact several other factors should have been considered such as the natural dispersion of test results, coring effects, orientation of foliation, variations in rock granulometry and the brittleness index (Hajiabdolmajid et al, 2002).…”

Section: Uniaxial Compressive Strength Assessmentmentioning

confidence: 99%

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Brittle Rock Failure in the Steg Lateral Adit of the Lötschberg Base Tunnel

et al. 2008

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This is the accepted author's version of an article protected by copyright. The rights are held by Springer-Verlag Wien.The final publication is available at http://link.springer.com. Summary During the crossing of brittle rock formations at the Lötschberg base tunnel, failure phenomena have been observed both at the tunnel face and at the walls. A detailed analysis has been undertaken to explain these behaviours, based on the recent developments of Canadian research on brittle failure mechanisms. At the tunnel walls, a very good agreement is found between calculated and observed damage and between two prediction methods i.e. a semi-empirical failure criterion and elastic calculations with the "brittle Hoek-Brown parameters". Near the face, due to the 3D nature of the stress conditions, some limitations of these approaches have been highlighted, and the growth of wall failure has been analysed. This research allowed a better understanding of the brittle rock mass behaviour at the Lötschberg base tunnel and showed that brittle failure processes dominate the behaviour of deep, highly stressed excavations in massive to moderately jointed rock. It also illustrates where improvements to the adopted approaches are required.

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Section: Resultsmentioning

confidence: 99%

Section: The Mechanisms Of Brittle Failure In Laboratory Tests and Nementioning

confidence: 99%

Section: Uniaxial Compressive Strength Assessmentmentioning

confidence: 99%

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Brittle Rock Failure in the Steg Lateral Adit of the Lötschberg Base Tunnel

et al. 2008

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“…13). Logically, it is difficult if not impossible, to prepare for imminent failure that is sudden and dominantly brittle in nature [25,26]. Under the three CSRs, SLO had predictions that followed an irregular path, though predictions gradually approached T f (Fig.…”

Section: Shikotsumentioning

confidence: 99%

A new practical method for prediction of geomechanical failure-time

Mufundirwa

Fujii

Kodama

2010

International Journal of Rock Mechanics and Mining Sciences

102

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Can we predict failure-time of geo-hazards? This question, poses a traditional rock mechanics problem. It is a challenge to date in the rock mechanics field to precisely predict failure-time of geo-hazards, and geo-hazards still pose major threat to life and major loss in terms of economics. The focal point of our research is to predict failure-time of geo-hazards. Firstly, we evaluated the validity of the INVerse-velocity (INV) method to predict failure-time of rock mass and landslides. And as a merit, the method utilizes rates of displacement (du/dt) or strain (d /dt) to predict the actual failure-time (T f ), so the value of total displacement or strain before "failure" is not crucial. Secondly, we developed a new method for computing failure-time predictions based on the SLOpe (gradient) to predict T f , termed the SLO method, which will be described in detail in the paper. And in tally, a simple conceptualised model representing "safe" and "unsafe" predictions was proposed.To validate these hypotheses, prediction of rock mass failure, Asamushi and Vaiont landslides (in situ studies) was conducted.Furthermore, laboratory conditions were incorporated into the research, which are: (i) predictions using circumferential strain c and axial strain a from uniaxial compression creep test on Shikotsu welded tuff (SWT); and (ii) predictions of failure-time for Inada granite under Brazilian creep tests. It was realized that SLO method is better than the INV method; SLO gave safe predictions in all the cases. In contrast, INV tends to give unsafe predictions (predicted failure-time T fp > T f ). Our findings reveal that predictions using c are better than using a for SWT, and notably, given failure with very short tertiary creep, the methods tend to show limited reliability. However, SLO method could find extensive application in predicting failure-time of geo-hazards, for instance, roof wall failure in mines etc.; this method is promising in reducing fatalities and damage to property which industry and society still face at present.

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“…Hajiabdolmajid, Kaiser, and Martin (2002) successfully simulated damage around the Mine-by tunnel using a cohesion-weakening and frictional-strengthening strainsoftening (CWFS) model implemented in the FLAC program ( Figure 19). The model was implemented using user-defined FISH functions.…”

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confidence: 99%

Calibration of a numerical model for bore-and-fill mining

Roberts¹

2017

J. South. Afr. Inst. Min. Metall.

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Tau Tona mine has historically experienced damaging seismicity during attempts to extract its high-grade, highly stressed shaft pillar (Murphy, 2012). In an attempt to reduce the potential for seismic events a new mining method that involves the boring of largediameter holes on-reef has been trialled. The rationale behind reef boring is that it reduces the effective stoping height, thus limiting the influence of the excavation on the surrounding rock mass. This is particularly important in the shaft pillar, as high deformation and closure are associated with increased seismic hazard.Optimization of the boring sequence and in-hole support enable the extraction of as much of the reef as possible, while minimizing waste rock mining. Support must be installed in such a way that workers are never required to enter the holes. Filling the holes with a stiff, strong material will achieve these goals. Concrete, for example, has low porosity, can be engineered to have high strength and stiffness, and is easily poured or pumped into the holes from service excavations.This paper describes how observations and measurements at a reef-boring pilot site were used to calibrate nonlinear numerical models. Initial models were calibrated based on observations of breakout and additional fracturing that was exposed when a raise was mined along the axis of an existing hole. A novel criterion for simulating breakout was developed, based on displacement into the hole and parallel to the minor stress axis. This criterion was used with the calibrated model to simulate the drilling and filling of a sequence of five holes. Some of these holes were instrumented with stress-change gauges and some were scanned and surveyed. The in situ data was compared with modelled outcomes.The feasibility of reef boring was considered by Jager, Westcott, and Cook (1975). They analysed various reefs in terms of deviation from planarity, presenting charts and tables to indicate optimal hole diameters in different mining areas. Adams (1978) describes stoping using a raiseboring machine on the Carbon Leader Reef (CLR) at West Driefontein mine. Holes were drilled adjacent to each other to create a continuous slot between reef drives. Pilot holes were bored and then used to guide a raisebore reamer from the upper reef drive. The completed slot is shown in Figure 1. Calibration of a numerical model for bore-and-fill mining by D. RobertsBore-and-fill mining was implemented at a pilot site in Tau Tona mine's shaft pillar on 97 level. Observations, scan data, and measurements from this site were used to calibrate an inelastic numerical model of bore-andfill mining within the Carbon Leader Reef (CLR).Borehole breakout was found to occur around holes at the site as they were bored. A strike-parallel exposure showed that fracturing within the Carbon Leader stratum extended far beyond the breakout (up to 1.2 m from the hole sidewall). This was confirmed by borehole camera observations in a hole drilled on-reef through a bored-and-filled hole.A Mohr-Coulomb strain-softeni...

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Modelling brittle failure of rock

Cited by 488 publications

References 12 publications

Brittle Rock Failure in the Steg Lateral Adit of the Lötschberg Base Tunnel

Brittle Rock Failure in the Steg Lateral Adit of the Lötschberg Base Tunnel

A new practical method for prediction of geomechanical failure-time

Calibration of a numerical model for bore-and-fill mining

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