【正文】 b,Universit1C211 2020 Elsevier Ltd. All rights reserved.Keywords: Hydraulic fills。 Mining。 Backfills。 Paste fills。 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。 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。 accepted 3 June 202026 April 2020of a mine operation. In the Australian mining industry, wherebackfills deployed. Many accidents reported at hydraulic fillof their behaviour and barricade bricks. This papercarried out in Australia on more than 20 di?erent hydraulic fillsis also provided, and the usefulness of numerical modelling as4 (2020) 1168e1175band as shown in Fig. 1. Along with them, the grain sizedistribution curves for a paste fill and a cementedhydraulic fill are also shown. It can be seen that thecemented hydraulic fill falls within the same band as thehydraulic fill. The addition of a very small percentage ofcement has a limited e?ect on grain size distribution.Paste fills generally have a much larger fine fraction thanhydraulic fills or cemented hydraulic fills, but havenegligible colloidal fraction finer than 2 mm.2. Hydraulic backfillsHydraulic fills are simply silty sands or sandy siltswithout clay fraction, and are classified as ML or SMunder the Unified Soil Classification System. The clayfraction is removed through a process known as desliming, whereby the entire fill material is circulatedthrough hydrocyclones and the fine fraction is removedand then sent to the tailings dam. The remaininghydraulic fill fraction is reticulated in the form of slurrythrough pipelines to underground voids.Over the past decade there has been a steady increasein the solid content of the hydraulic fill slurry placed inmines in an attempt to reduce the quantity of water thatmust be drained and increase the proportion of solids.The challenge posed by a high solid content is that itbees di?cult to transport the slurry through thepipelines due to rheological considerations. Currently,solid contents of 75e80% are mon, althougheven at 75% solid content, assuming a specific gravityof for the solid grains, 50% of slurry volume iswater. Therefore, there is opportunity for a substantialamount of water to be drained from the hydraulic fillstope.To contain the fill, the horizontal access drivescreated during mining are generally blocked by barricades constructed from specially made 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。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 b