【正文】 anerUnited States. The in situ measurements showed relativedensity values ranging from 44 to 66% at four di?erentmines.The laboratory exercise also showed that the hydraulic fill slurry settles to a dry density (g/cm3) of timesthe specific gravity (Gs) for a wide range of tailings withspecific gravity values ranging from to . Drydensity (rd) and void ratio (e) are related by:rdZGsrw1Ce240。D 240。 2020. p. 351e7.[2] Bloss ML, Chen J. Drainage research at Mount Isa MinesLimited 1992e1997. In: Proceedings of Minefill ’98. Brisbane(Australia)。68:47e53.[13] Jewell RJ. Introduction. In: Jewell RJ, Fourie AB, Lord ER,editors. Paste and thickened tailings: a guide. Perth (Australia):U。 1978. p. 117e23.[4] Rankine KJ, Sivakugan N, Rankine KS. Laboratory tests formine fills and barricade bricks. In: Farquhar G, Kelsey P,Marsh J, Fellows D, editors. Proceedings of the 9th AustraliaNew Zealand conference on geomechanics. Auckland。Young’s modulus is a crucial parameter in deformation calculations using most constitutive models. TheRelative Density, Dr ( )Void ratio, e Densest possiblestateLoosest possiblestate 0100Hydraulic fillsin mines50eminimumemaximumFig. 3. Relative density of the hydraulic fills sedimented in thelaboratory.Production 14 (2020) 1168e1175oedometer tests on the hydraulic fills showed significantproperty test, as in a paction test, is to determineoptimum water content. In Fig. 5, the optimum waterFig. 4. Scanning electron micrograph of a hydraulic fill sample.creep settlements that took place on the pletion ofconsolidation settlements. This has yet to be verifiedquantitatively and on a fullscale stope.. Direct shear testDirect shear tests are carried out to determine thepeak and residual friction angle of the hydraulic fill. Thetests are carried out on reconstituted hydraulic fillsrepresenting the in situ grain packing in the stope, whichcan be at relative densities of 40e70%. Since there isno clay fraction, cohesion is zero. Direct shear testsconducted at JCU reveal that the friction anglesdetermined from direct shear tests are significantlyhigher than those determined for mon granularsoils. This can be attributed to the very angular grainsthat result from crushing the rock waste, which interlockmore than the mon granular soils. The angulargrains can be seen in the scanning electron micrographsof the hydraulic fill samples (Fig. 4).1230 10203Dry density (t/m3) 5 min vibration5 min vibrationMaximum dry densityNo vibration (free settling under self weight)Intergranularcontact existsFig. 5. Placement property curvecontent of the fill is 14%, with the maximum dry densityof t/m3. This water content can also be estimatedfrom a maximum dry density test and the saturationline as 12%. These curves are useful in assessing thecontractive or dilative behaviour of hydraulic fills atvarious water contents. For example, when the fill inFig. 5 is subjected to vibratory loading (., due toblasting) at 14% water content and a dry density of t/m3, it will densify, whilst the same fill at 8% watercontent and dry density of t/m3will bee looser.3. Barricade bricks for hydraulic fill minesBarricade failure in underground mining operationsis a primary safety concern because of the potentialconsequences of failure. Between 1980 and 1997, 11barricade failures were recorded at Mount Isa Mines inboth hydraulic and cemented hydraulic fills [5]. In 2020,a barricade failure at the Normandy Bronzewing Minein Western Australia resulted in a triple fatality, and two0405060Minimum dry density. Placement property testA placement property test for hydraulic fills wasproposed by Clark [10]. This is essentially a pactiontest, where the pactive e?ort is applied through5 min of vibration on a vibrating table. Porosity at theend of vibration is plotted against the water content.Alternatively, dry density can be plotted against watercontent, as shown in Fig. 5. Here a is the air content,and the contours of aZ0, 3, 10, 20 and 30% are shownin the figure. The shaded region is where the hydraulicfill can exist whilst maintaining intergranular contact.The slurry follows a saturation line when settling underits selfweight, with the density increasing with somevibratory loading.One of the main applications of the placement1171N. Sivakugan et al. / Journal of Cleaner Production 14 (2020) 1168e1175of a hydraulic fill sample.permeable brick failures were reported later that sameyear as a result of hydraulic fill containment at theOsborne Mine in Queensland [1].The specialized barricade bricks often used for thecontainment of hydraulic fill in underground mines aregenerally constructed of a mortar posed of mixtureof gravel, sand, cement and water at the approximateratio of 40:40:5:1, respectively. Fig. 6 shows a photograph of (a), a barricade brick and (b), an underground,the walls have been constructed in a vertical plane,but the recent industry trend has been to increase wallstrength by constructing them in a curved manner, withthe convex toward the hydraulic fill as shown in Fig. 6b.Although it is known within the mining industrythat the porous bricks used in underground barricadeconstruction are prone to variability in strength properties [5], the manufacturers often guarantee a minimumFig. 6. Porous brick barricade. (a) A brick, (b) brick barricade under1172 N. Sivakugan et al. / Journal of Cleanerconstruction in a mine.value for uniaxial pressive strength for the bricks inthe order of 10 MPa [11]. Kuganathan [5] and Du?eldet al. [11] have reported uniaxial pressive strengthvalues from 5 MPa to over 26 MPa.A series of uniaxial pressive strength testsundertaken on a large sample of brick cor