AUGUST 2021 CURRENT PROJECTS This report is a summary of current projects for the months May, June and July 2021 ACARP CONTACTS PROGRAM MANAGEMENT PROJECT ADMINISTRATION Australian Coal Research Limited Australian Research Administration Pty Ltd Suite 3, Level 9 Level 12, 167 Eagle Street Brisbane Qld 4000 307 Queen Street PO Box 7148 Riverside Centre Qld 4001 Brisbane Qld 4000 Phone: 07 3225 3600 Phone: 07 3607 3824 Anne Mabardi RESEARCH COORDINATORS Ian Neill [email protected] Executive Director Peter Bergin [email protected] Patrick Tyrrell Underground NSW [email protected] [email protected] Marilyn Keenan Levy Administrator Nicole Youngman Cam Davidson [email protected] [email protected] Open Cut – Mining [email protected] Ashley Conroy Technical Market Support [email protected] Nerrida Scott Coal Preparation [email protected] David Drakeley [email protected] www.acarp.com.au DISCLAIMER No person, corporation or other organisation (“person”) should rely on the contents of this report and each should obtain independent advice from a qualified person with respect to the information contained in this report. 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ACARP Current Projects Report August 2021 Underground Projects C27020 UNDERGROUND Management of Coal Bursts and Pillar Burst in Deep Mines Coal Burst University of Adelaide C25004 Giang Nguyen Murat Karakus Review of Australian and International Coal Burst Experience and Control Technologies Value: $380,240 Report Expected: September 2021 University of New South Wales Industry Monitor/s: Coal Burst Task Group Ismet Canbulat ACARP Contact: Peter Bergin Value: $404,000 We are currently in the finishing stage of this project, Report Expected: August 2021 which collaborates the theoretical framework with the Industry Monitor/s: Coal Burst Task Group numerical modelling approach to evaluate the burst ACARP Contact: Patrick Tyrrell potential of coal. This project utilises the longwall mining scenario in the coal seam under the geological A draft report is with the industry monitor(s) for review. arrangements with Coal Cliff Sandstone (upper) and Loddon Sandstone (lower) rock mass layers, delineated C26066 in (Yardimci and Karakus 2020). The majority of the key Energy, Burst Mechanics Required for Coal Bursts project objectives have been successfully achieved. and Energy Release Mechanisms For instance, a theoretical framework for laboratory University of New South Wales scale coal burst assessment is developed and applied to Ismet Canbulat the cuboidal coal specimen under true triaxial loading- Winton Gale unloading conditions imitating the coal exposed to the in-situ polyaxial stress with unloading effect after Value: $357,500 excavation. The coal specimen's strength, elastic, and Report Expected: August 2021 fracture properties, determined from laboratory Industry Monitor/s: Coal Burst Task Group experiments (including uniaxial compression and AUSBIT ACARP Contact: Peter Bergin – Adelaide University Snapback Indirect Tensile Strength test), were utilised to develop the burst envelop for A draft report is with the industry monitor(s) for review. rocks/coal from the above three in-situ geological units. In-situ horizontal stress ratio (k) in Australian mining C26068 conditions was determined from the detailed literature Use of Real Time Rib Drilling Data to Determine review. This theoretical assessment indicates the coal the Propensity for Coal Bursts During Roadway burst potential in the in-situ coal seam, ie burst index Development ( )>1. In comparison, the rock specimens from the upper (ie coal Cliff Sandstone) and lower (Loddon sandstone) ₽ Dynamic Efficiency geological strata demonstrate zero/no burst tendency. Peter Mastalir These theoretical predictions were further verified via the numerical strain burst experiments conducted on Value: $150,000 specimens from all three geological units. Additionally, Report Expected: June 2022 the experimental data from coal burst experiments Industry Monitor/s: Coal Burst Task Group conducted in China is also considered to validate the ACARP Contact: Peter Bergin laboratory scale theoretical and numerical results. This project is on hold due to the following reasons: The numerical framework utilised in this study includes • COVID-19 (access restrictions); and developing a cohesive contact model with elastoplastic- damage coupling (Verma 2020). It was implemented in • Mine site 2 has agreed in principle to take up project. the hybrid numerical modelling framework, ie 3DEC- Itasca. In addition to the laboratory scale strain bursts The estimated date to restart work is October 2021. numerical experiments, the applications of the developed numerical framework were further extended to conduct the field scale burst evaluation, providing an additional layer of verification to our theoretical burst prediction. In this view, the sample scale coal and rock properties were upscaled to field-scale rock mass using the Hoek-Brown criterion (Hoek et al. 2002; Hoek and Brown 2019). For field-scale coal mining simulation, two approaches were adopted: continuum and Page 1 ACARP Current Projects Report August 2021 Underground Projects discontinuum. In the first approach, the coal and rock C27041 layers, interacting via rock joints, are considered Ground Support Requirements in Coal Burst continuum blocks. The stress state and resultant Prone Mines deformation at the excavation face indicate burst occurrence in the coal seam immediately after the University of New South Wales excavation. The movable shield equipped with a canopy Ismet Canbulat as a portable roof support system is idealised as a steel platen structure across the excavation face. In the second Value: $150,000 approach, each geological unit is further discretised into Report Expected: September 2021 deformable tetrahedral blocks interacting via a cohesive Industry Monitor/s: Coal Burst Task Group contact model. It provide an exlicit rock damage and ACARP Contact: Peter Bergin failure/bursting scenario on coal seam mining face, further verifying the results from field scale continuum The objectives of this project are to: approach. • Review the international best-practice ground control systems in burst prone mines; The results obtained are promising, as per our • Evaluate and characterise ground support principles expectations, marking the achievements of the key and considerations; objectives of this study. Few results from continuum • Assess yielding support technologies and determine simulation are further refined for better clarity. We are the energy absorption requirements for the ground currently drafting research article/s aimed towards top support systems for coal burst control; international mining journals to publish the key results • Identify engineering principals and failure from this study. We are also planning to finalise the mechanisms of yielding support; and to project report to include the key results obtained during • Establish functional requirements of appropriate and this project's second half/extended duration. effective ground support technologies for coal burst control that are in line with Australian experience, The final report for this project is being drafted and will regulations, mine design, and operational practices. be submitted to the industry monitors for review. The project has been impacted by the lack of access to a C27039 numerical modelling code that is located at UNSW, due True Triaxial Strength of Coal Measure Rocks and to COVID-19 lockdowns. its Impact on Stability of the Roadways and Coal Burst Assessment Work undertaken during the quarter includes: • A database of currently available yielding roof bolts SCT Operations and mesh has been compiled; Mahdi Zoorabadi • A risk based approach has been developed to identify Winton Gale the risk categories (ie risk zoning) in development and longwall faces. This approach has been enhanced Value: $187,000 with the outcomes of C26066; Report Expected: August 2021 • The framework for coal burst management plan, Industry Monitor/s: Coal Burst Task Group which was proposed as part of C25004, has been ACARP Contact: Peter Bergin updated to reflect the new risk based approach; • A new analytical model has been developed that A draft report is with the industry monitor(s) for review. assesses the ground support requirements in the case of a coal burst event. This methodology considers roof bolts, mesh, straps and cables. The final program that contains the gas expansion energy, strain energy and seismic energy as well as the assessment of the support adequacy is being compiled and will be made available shortly; • Using the above methods, the mines sites will be able to determine the safe distances in remote mining and ground support requirements under coal burst prone conditions; and • Final report is being compiled. Page 2 ACARP Current