Empirical selection of ground support for dynamic conditions using charting of support performance at Hamlet mine

Mikula, Peter; Gebremedhin, Belay

doi:10.36487/acg_rep/1704_42_mikula

Cited by 6 publications

(7 citation statements)

References 5 publications

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“…The system was created in conjunction with the extensometer and stress measurements, all of which served to better understand the crosscut behaviour and interpret the damage progression in a way that reflected the actual mechanisms driving it. This system is fully described in Jones & Saiang (2022a, 2022b and is similar in function to others published (Kaiser et al 1992;Lawson & Zahl 2012;Duan et al 2015;Mikula & Gebremedhin 2017).…”

Section: Damage Mappingmentioning

confidence: 71%

Empirical damage prediction in sublevel cave crosscuts at the Malmberget mine

Jones¹,

Saiang²

2022

Caving 2022: Fifth International Conference on Block and Sublevel Caving

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Building on the empirical research completed in the footwall contact zone of LKAB's Malmberget mine, a method has been developed for predicting damage in the crosscut entries of the mine layout. Three-dimensional stress measurements combined with analyses of measured and observed damage in the crosscuts have allowed new interpretations of the crosscut performance. Stress analysis focused on the relative differential stresses measured in the area of interest. These stress changes were then linked directly to observed changes in the entry condition according to the Entry Condition Rating (ECR) system, a damage mapping system developed for the mine. A bilinear model was used to describe the entry condition rate of change such that the peak measured differential stress corresponds to increased degradation rates. These bilinear degradation rate trends are shown to be directly related to the geotechnical qualities of the rock using the Geologic Strength Index (GSI) of the monitored locations, irrespective of lithology. The final step was to develop an empirical model that allows prediction of a crosscut's future ECR based on changes in the relative differential stress and the GSI of the crosscut. In combination with simple numerical modelling tools the model can be used to predict ahead of time when additional reinforcement will be necessary.

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Section: Damage Mappingmentioning

confidence: 71%

Empirical damage prediction in sublevel cave crosscuts at the Malmberget mine

Jones¹,

Saiang²

2022

Caving 2022: Fifth International Conference on Block and Sublevel Caving

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“…Early empirical chart work was reported by Mikula (2012). Mikula & Gebremedhin (2017) provided a detailed discussion of several advantages and limitation of the empirical chart method. Some key aspects are summarised here.…”

Section: Advantages and Limitations Of The Empirical Chart Approachmentioning

confidence: 99%

Empirical charting for dynamic ground support at Flying Fox and Spotted Quoll mines

Graham,

Waheed,

Mikula

2023

Ground Support 2023: Proceedings of the 10th International Conference on Ground Support in Mining

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Empirical charting of ground support performance in dynamic conditions using easily available mine site data is a method applied at Flying Fox and Spotted Quoll nickel mines in Western Australia. The focus is on identifying the limiting largest seismic event magnitude for which a given ground support scheme would be expected to sustain damage to a tolerable level.The method has been used previously with success at Long Shaft and Hamlet mines to guide the selection of support in dynamic conditions. Charting defines the relationships between three easily determined factors: the dynamic disturbance (via the seismic event magnitude); the level of ground support damage caused; and the type of installed ground support. Most Flying Fox and Spotted Quoll events are crush events, for which the use of magnitude as a proxy for the dynamic disturbance is suitable.At the mines, installed ground support is broadly classified into three schemes: conventional friction bolt and mesh; fibrecrete with mesh and bolts; and custom high-performance seismic. At Flying Fox mine, 224 data points were available for the preparation of charts for these schemes, while at Spotted Quoll there were 137 data points. Events as large as ML2.2 at Flying Fox and ML2.9 at Spotted Quoll were recorded. Despite the two mines being only 6 km apart, their geomechanical environments were different and a corresponding difference in the empirical charts was evident.Strong advantages of the empirical approach are recognition of the site-installed bolts, seismicity, geology and support performance. This makes the results calibrated to the mine. The approach does not require estimation of ground motion or site effect (for crush-type events) at the precise location of a support element, nor estimation of energy and load capacities of elements during dynamic disturbances. However, the approach has limitations as described in the paper, and the charts are not transferable between mine sites. Empirical charting should provide site engineers with a defensible support selection method for seismic conditions described by an expected or forecast upper event magnitude. The process is simple, transparent and attractive in that it takes into account all of the factors that can negatively impact the actual capacities versus design capacities. It is hoped that the descriptions in this paper will encourage engineers to explore similar work for their sites.

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“…Kaiser et al (1995) also proposed support and shotcrete damage scales, which are useful to capture. Mikula & Gebremedhin (2017) proposed a simplified support damage scale, consisting of just three levels of damage (acceptable, tolerable and intolerable) corresponding to S0-1, S2-3 and S4-5 respectively. This is a practical scale to use because it helps to categorise damage by the level of rehabilitation required.…”

Section: Support Damagementioning

confidence: 99%

Development of a single-pass detailed damage mapping application

Cumming-Potvin

Potvin

Wesseloo

et al. 2019

Proceedings of the Ninth International Symposium on Ground Support in Mining and Underground Construction

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High-quality data is crucial in back-analysis of rockburst data and the development of empirical design methods. Data collection and reporting is currently predominantly a manual process (creating a two-pass system) with limited organisation or standardisation. To facilitate the collection, management and analysis of high-quality rockburst damage data, a damage mapping application was developed. This application is designed for offline use with tablet devices, creating a single-pass system. The data captured by the application includes information on location, rock mass conditions, installed ground support and corrosion, falls of ground, damage and photos. The application was designed with four goals in mind: consistency, speed, comprehensiveness and simplicity. To achieve these goals, a number of custom-made widgets were employed for optimal data input. Once input is complete, the data is synchronised to a server on the mine network and is then available for further analysis with an mXrap app.

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Empirical selection of ground support for dynamic conditions using charting of support performance at Hamlet mine

Cited by 6 publications

References 5 publications

Empirical damage prediction in sublevel cave crosscuts at the Malmberget mine

Empirical damage prediction in sublevel cave crosscuts at the Malmberget mine

Empirical charting for dynamic ground support at Flying Fox and Spotted Quoll mines

Development of a single-pass detailed damage mapping application

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