【正文】 porous bricks(Fig. 2). The access drives, which are made large enoughto permit the entry of machinery during mining, areblocked by the barricades during filling. The drives areoften located at more than one level. Initially, the drives0102030405060708090100 1 10 100 1000 10000Grain size (181。 Geotechnical1. IntroductionIn the mining industry, when underground ore bodiesare extracted, verylarge voids are created,which must beuse of the waste rock or tailings that are consideredbyproducts of the mining operation. This is an e?ectivemeans of tailing disposal because it negates the needfor constructing large tailing dams at the surface. Thebackfilling ofunderground voids also improveslocal andregional stability, enabling safer and more e?cientis a major issue in Australia, where 10 million cubicmetres of underground voids are generated annually asa result of mining [1].There are two basic types of backfilling strategies.The first, uncemented backfilling, does not make use ofcan be studied using soil mechanics theories. A typicalexample of uncemented backfilling is the use ofhydraulic fills that are placed in the form of slurry intothe underground voids. The second category, cementedbackfilling, makes use of a small percentage of bindersuch as Portland cement or a blend of Portland cementwith another pozzolan such as fly ash, gypsum or blastfurnace slag.The purpose of this paper is to analyse the findingsfrom an extensive laboratory test programme carriedout in Australia on hydraulic fills and several barricadebricks. Hydraulic fills are uncemented techniques, andare one of the most widely used backfilling strategies inAustralia. More than 20 di?erent hydraulic fills,representing a wide range of mines in Australia, werestudied at James Cook University (JCU). The grain sizedistributions for all of these fills lie within a narrowGeotechnical considerations inN. Sivakugana,*, . RankineaSchool of Engineering, James CookbCannington Mine, BHP Billiton, .Received 1 March 2020。 Backfills。b,Universit1C211 2020 Elsevier Ltd. All rights reserved.Keywords: Hydraulic fills。 Mining。 Paste fills。 received in revisedAvailable onlineAbstractMine backfilling can play a significant role in the overall operationsafety is a prime consideration, hydraulic systems are the most monmines worldwide have mainly been attributed to a lack of understandingdescribes the findings from an extensive laboratory test programmeand several barricade bricks. A limited description of paste backfillsan investigative tool is highlighted.Journal of Cleaner Productionbinding agents such as cement, and their characteristics* Corresponding author. Fax: C61 7 47751184.Email address: (N. Sivakugan).09596526/$ see front matter C211 2020 Elsevier Ltd. All rights reserved.doi:mine backfilling in Australia. Rankinea, . Rankineay, Townsville 4811, AustraliaBox 5874, Townsville 4810, Australiaform 2 June 2020。m)Percent finer by weight Australian hydraulic fillsCemented hydraulic fillPaste fillFig. 1. Typical grain size distribution curves for hydraulic fills,cemented hydraulic fills and paste fills.N. Sivakugan et al. / Journal of Cleanerlocated at upper levels act as exit points for the decantedwater, and also serve as drains when the hydraulic fillrises in the stope.. Drainage considerationsDrainage is the most important issue that must beconsidered when designing hydraulic fill stopes. Therehave been several accidents (namely, trapped miners andmachinery) worldwide caused by wet hydraulic fillrushing through horizontal access drives (Fig. 2).Several reasons, including poor quality barricade bricks,liquefaction, and piping within the hydraulic fill areattributed to such failures [2]. Therefore, permeability ofthe hydraulic fill in the stope is a critical parameter inthe design。1222。2222。1Cy222。1C2552y222。1C255y222。3222。s modulus of wet core (GPa)Young39。2020. p. 161e5.[7] ASTM D 4254e91. Standard test method for minimum indexdensity and unit weight of soils and calculation of relative density.Annual book of ASTM standards. .: American Society ofTesting Materials。1175N. Sivakugan et al. / Journal of Cleaner Production 14 (2020) 1168e1175barricade walls.Paste fill contains at least 15% of grains finer than20 mm, and the e?ective grain size (D10) is in the order of5 mm. The 3e6% binder improves the strength and thusstability significantly. The large fine content within thepaste fill enables most of the water to be held to thesurface of the grains, and therefore drainage is not aconcern in paste backfilling.AcknowledgementsSeveral mines have contributed cash and inkindto the research discussed in this paper. Their supportis gratefully acknowledged. Senior Technical O?cersMr. Warren O’Donnell and Mr. Stuart Petersen assistedin most of the laboratory test work carried out on thebricks and hydraulic fills. Our regular discussions withMr. Richard Cowling of Cowling Associates were veryvaluable throughout our mining research.References[1] Grice T. Recent mine developments in Australia. In: Proceedingsof the 7th international symposium on mining with backfill(MINEFILL)。 1998. p. 111e6.[3] Herget G, De Korompay V. In situ drainage properties ofhydraulic backfills. Research and innovations, CIM specialvolume。 2020.p. 218e24.[5] Kuganathan K. Mine backfilling, backfill drainage and bulkheadconstruction e a safety first approach. Australia’s miningmonthly February, 2020。97(SM9):1207e25.[10] Clark IH. The properties of hydraulically placed backfill. In:Proceedings of backfill in South African mines. Johannesburg:SAIMM。March/April, 2020. p. 45e50.[12] Robinsky EI. Thickened discharge e a new approach to tailingsdisposal. Canadian Mining and Metallurgical Bulletin 19