Analysis of Caving Behaviour Using a Synthetic Rock Mass — Ubiquitous Joint Rock Mass Modelling Technique

Sainsbury, Bre-Anne; Pierce, ME; Ivars, Diego Mas

doi:10.36487/acg_repo/808_136

Cited by 37 publications

(24 citation statements)

References 2 publications

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“…The D Thres value in Equation (6) represents the conditions in which acoustic emissions (scaled microseismicity) may be recorded in a laboratory rock sample associated with the initiation of new fractures and dilation of the sample. It has also been shown to correspond to the point at which measurable microseismicity might be recorded in a mine (Sainsbury et al, 2008). The value is generally between 0.3 and 0.42.…”

Section: Numerical Simulation Of Seismicitymentioning

confidence: 80%

“…Failure of the north slope occurred during 2004, soon after production commenced. Previously numerical simulations were conducted by Sainsbury et al (2008) to provide an assessment of the failure mechanism associated with the failure. The following section provides an assessment of the development of seismicity around the north wall failure area from a review of the microseismic monitoring data and the consideration of the CI.…”

Section: Palabora Cave Developmentmentioning

confidence: 99%

“…This failure has resulted in the dilution of ore reserves and has caused instability in mine infrastructure located on the pit crest. A plan view of the location of the north wall failure is presented in Figure 1 along with a section through the failure area showing the relationship between the mining footprint and the location of the failure -as defined by numerical modelling (Sainsbury et al, 2008). Within the graphic, the mobilised zone has been defined by a simulated displacement greater than, or equal to 2 m. The yield zone has been defined by a location that has lost some or all of its cohesive strength and provides minimal support to the overlying rock mass.…”

Section: Introductionmentioning

confidence: 99%

“…Within the graphic, the mobilised zone has been defined by a simulated displacement greater than, or equal to 2 m. The yield zone has been defined by a location that has lost some or all of its cohesive strength and provides minimal support to the overlying rock mass. A detailed description of each of these cave behavioural regions is provided in Sainsbury et al (2008). A microseismic monitoring system was installed and functional at the mine at the time of the failure.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Microseismic tools for the analysis of the interaction between open pit and underground developments

Reyes-Montes¹,

Sainsbury²,

Pettitt³

et al. 2010

Proceedings of the Second International Symposium on Block and Sublevel Caving

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The transition from surface to underground mining presents a series of technical and operational challenges, in particular those arising from the interaction between the cave and the overlying pit. Seismic monitoring provides a unique means to obtain near real-time information about the development of the fracturing process induced by the mining operations. This paper presents the analysis of temporal, spatial and source size patterns in the seismicity recorded during undercutting and production at the Palabora Mine leading to slope failure in the open pit above, and relates these results to full-scale analysis of the rock mass behaviour in three-dimensional numerical models. Based on the application of the techniques described herein, it is shown that the back analysis of the seismic data provides a prediction technique that could now be employed during the planning stages of a mining operation. It is hoped that by employing these new techniques it would be possible to incorporate results from predicted fracture network behaviour into engineering designs in similar future mining operations and thus provide a means to predict and mitigate against large scale failure as observed at the Palabora Mine.

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Section: Numerical Simulation Of Seismicitymentioning

confidence: 80%

Section: Palabora Cave Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Microseismic tools for the analysis of the interaction between open pit and underground developments

Reyes-Montes¹,

Sainsbury²,

Pettitt³

et al. 2010

Proceedings of the Second International Symposium on Block and Sublevel Caving

Self Cite

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show abstract

“…The numerical modelling technique of embedding a DFN into a bonded assembly of distinct elements, or into a hybrid finite-discrete element code, is called the synthetic rock mass (SRM) method (Mas Ivars et al, 2011). Recent research has shown that the SRM technique can be successfully used to simulate shear strength tests of representative volumes of rock mass (length dimensions in the order of 100 m); the results of SRM tests can be used to derive equivalent material parameters for input into pit scale models constructed with continuum codes such as FLAC3D (Sainsbury et al, 2008).…”

Section: Locationmentioning

confidence: 99%

Combining field methods and numerical modelling to address challenges in characterising discontinuity persistence and intact rock bridges in large open pit slopes

Tuckey¹,

Stead²,

Eberhardt³

2013

Proceedings of the 2013 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering

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Confidence in stability assessments of large rock slopes may be improved by greater understanding the persistence of adverse discontinuities, and the proportion and location of intact rock bridge content within the slope. This paper presents a discussion of the challenges and uncertainty in characterising discontinuity persistence and intact rock bridges, with reference to results from field investigations of open pit slopes at three mines using digital photogrammetry, ground-based LiDAR, and modified 2D window mapping methods. A conceptual numerical model is then devised, where a distinct element numerical code was applied to investigate the influence of rock bridges on brittle rock mass failure and dilation in a model large open pit slope. Distinction between co-planar or out-of-plane intact rock bridges, and larger 'rock mass bridges' between more persistent discontinuities is considered necessary and the authors suggest that a fracture network engineering approach tailored to large open pits may be helpful for their characterisation. With modified trace mapping procedures, intact rock bridges may be quantified in terms of an intensity parameter R 21 that describes the total length of inferred rock bridge traces per unit area within a mapping window. An analogous blast-induced damage intensity factor B 21 is also introduced, that describes the total length of blast-induced fracture traces per unit area in a mapping window. For numerical models, a damage intensity parameter D 21 is applied, which quantifies the intensity of fracturing that develops inside a modelled slope. Large rock slope failures rarely occur entirely along completely continuous, pre-existing basal sliding surfaces. Even if major pre-existing structures exist, deformation and failure of large slopes in hard rock is more likely to involve a combination of shearing and dilation of pre-existing discontinuities such as joints, with a degree of stress-induced brittle fracturing of intact rock (Sjöberg, 1999). The process of brittle crack initiation, propagation and coalescence is progressive (Eberhardt et al., 2004), and may be characterised by a time-dependent degradation of rock mass strength in localised zones of stress concentration, that may eventually lead to (1) the formation of a continuous sliding surface and (2) the development of kinematic freedom and finally slope failure (Stead et al., 2006). The potential complexity of slope failure mechanisms increases with the scale of the slope. In open pit mines, inter-ramp or overall slope failure surfaces may have irregular or step-path geometry, involving rupture through several structural domains with different shear strength properties and different local failure mechanisms. McMahon (1979) introduced the step-path simulation method during investigations for the Bougainville open pit mine in Papua New Guinea with the probabilistic STEPSIM code. Later, the probabilistic step-path simulation approach was further developed for a slope optimisation study at Ok Tedi mine, resulting in the STEPSIM4...

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Characterisation of confinement effect on jointed rock pillars using a Synthetic Rock Mass approach

Zhang

Zhao

2016

Num Anal Meth Geomechanics

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Confinement effect on jointed rock pillars is numerically characterised in this research using a Synthetic Rock Mass (SRM) approach. The SRM is an integrated model incorporating a discrete fracture network within a Particle Flow Code 3D particle assembly. In this paper, the confinement effect on a 3D jointed pillar SRM model is investigated in a series of simulations, including biaxial compression tests and true and conventional triaxial compression tests. The numerical results suggest that the applied confining stresses generally result in higher pillar strengths and ductile post-peak responses. More brittle post-peak behaviour is simulated in the biaxial and true triaxial tests when the pillar is confined by a high stress in one lateral direction and by a zero/low stress in the other lateral direction. This phenomenon is attributed to significant lateral pillar dilation in the less confined direction. Detailed pillar failure modes are monitored in the uniaxial and triaxial tests. Axial splitting fractures and long shear zones cutting through the pillar are simulated when the pillar is able to dilate in the direction of least confinement. Localised shearing along joints and failed rock blocks is the dominant failure mode when the pillar dilation is resisted by the applied confining stresses. The pillar remains relatively intact with limited cracking in the pillar core in the highly confined triaxial tests.

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Analysis of Caving Behaviour Using a Synthetic Rock Mass — Ubiquitous Joint Rock Mass Modelling Technique

Cited by 37 publications

References 2 publications

Microseismic tools for the analysis of the interaction between open pit and underground developments

Microseismic tools for the analysis of the interaction between open pit and underground developments

Combining field methods and numerical modelling to address challenges in characterising discontinuity persistence and intact rock bridges in large open pit slopes

Characterisation of confinement effect on jointed rock pillars using a Synthetic Rock Mass approach

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