geotechnicalconsiderationsinminebackfillinginaustralia-外文文献(编辑修改稿)

geotechnicalconsiderationsinminebackfillinginaustralia-外文文献(编辑修改稿)内容摘要：

sion 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 effort 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 Duffieldet 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 cores havedemonstrated the scatter of results, but more importantly, have highlighted a distinct variation in brickperformance when saturated, as it would occur in themines. Two identical cylindrical cores were cut from 29porous barricade bricks. One of the brick cores fromeach of the individual bricks was tested dry, and theother core was tested after having been saturatedfor either 7 or 90 days. The strength and deformationparameters (namely, the uniaxial strength, Young’smodulus, and the axial failure strain) for the wet anddry cores are shown in Figs. 7e9.Firstly, the extreme scatter between all results reitertheaverageuniaxialpressivestrengthofdrybrickstofallbetween6and10 MPa,whenthebrickmanufacturersguarantee minimum of 10 MPa. It can also be seen fromthis figure that there is a distinct loss of pressivestrength as a result of wetting the brick. There was nosignificant difference between 7 and 90 days soaking,implying that the strength loss occurs immediatelyupon wetting. This loss appears to be in the order ofapproximately 25%, which is notable considering thatbricksaregenerallyexposedtosaturatedconditionswhenplaced underground, and all manufacturer strengthspecifications are based on bricks that are tested dry.The stiffness also appears to be reduced by wetting(Fig. 8). The Young’s modulus of the dry cores rangedbetween 1 and MPa. The length of time the brickswere wetted did not have a significant impact onthe magnitude of the reduction in stiffness. The peakfailure axial strain was not reduced by wetting (Fig. 9).The cores in general failed under an axial strain of lessthan 1%.The porous bricks are designed to be free drainingand therefore, their permeability is at least an order ofmagnitude greater than that of hydraulic fill. The02468101214086421012Uniaxial pressive strength of dry core (MPa)Uniaxial pressive strengthof wet core (MPa)90 days7 days14Production 14 (2020) 1168e1175Fig. 7. Uniaxial strength of dry and wet bricks.barricade bricks have pro。