1、翻译部分英文原文Geotechnical considerations in mine backfilling in Australia N. Sivakugan a,*,R.M. Rankine b, K.J. Rankine a, K.S. Rankine a a School of Engineering, James Cook University, Townsville 4811, Australia b Cannington Mine, BHP Billiton, P.O. Box 5874, Townsville 4810, AustraliaAbstract :Mine bac
2、kfilling can play a significant role in the overall operation of a mine operation. In the Australian mining industry, where safety is a prime consideration, hydraulic systems are the most common backfills deployed.Many accidents reported at hydraulic fill mines worldwide have mainly been attributed
3、to a lack of understanding of their behaviour and barricade bricks.This paper describes the findings from an extensive laboratory test programme carried out in Australia on more than 20 different hydraulic fills and several barricade bricks. A limited description of paste backfills is also provided,
4、 and the usefulness of numerical modelling as an investigative tool is highlighted. Keywords: Hydraulic fills; Mining; Backfills; Paste fills; Geotechnical1IntroductionIn the mining industry, when underground ore bodies are extracted, very large voids are created, which must be backfilled. The backf
5、illing strategies deployed often make use of the waste rock or tailings that are considered by-products of the mining operation. This is an effective means of tailing disposal because it negates the need for constructing large tailing dams at the surface. The backfilling of underground voids also im
6、proves local and regional stability, enabling safer and more efficient mining of the surrounding areas. The need for backfilling is a major issue in Australia, where 10 million cubic metres of underground voids are generated annually as a result of mining 1. There are two basic types of backfilling
7、strategies. The first, uncemented backfilling, does not make use of binding agents such as cement, and their characteristics can be studied using soil mechanics theories. A typical example of uncemented backfilling is the use of hydraulic fills that are placed in the form of slurry into the undergro
8、und voids. The second category, cemented backfilling, makes use of a small percentage of binder such as Portland cement or a blend of Portland cement with another pozzolan such as fly ash, gypsum or blast furnace slag. The purpose of this paper is to analyse the findings from an extensive laboratory
9、 test programme carried out in Australia on hydraulic fills and several barricade bricks. Hydraulic fills are uncemented techniques, and are one of the most widely used backfilling strategies in Australia. More than 20 different hydraulic fills, representing a wide range of mines in Australia, were
10、studied at James Cook University (JCU). The grain sizer distributions for all of these fills lie within a narrow band as shown in Fig. 1. Along with them, the grain size distribution curves for a paste fill and a cemented hydraulic fill are also shown. It can be seen that the cemented hydraulic fill
11、 falls within the same band as the hydraulic fill. The addition of a very small percentage of cement has a limited effect on grain size distribution. Paste fills generally have a much larger fine fraction than hydraulic fills or cemented hydraulic fills, but have negligible colloidal fraction finer
12、than 2 m. Fig. 1. Typical grain size distribution curves for hydraulic fills,cementedhydraulic fills and paste fills.2Hydraulic backfills Hydraulic fills are simply silty sands or sandy silts without clay fraction, and are classified as ML or SM under the Unified Soil Classification System. The clay
13、 fraction is removed through a process known as desliming, whereby the entire fill material is circulated through hydrocyclones and the fine fraction is removed and then sent to the tailings dam. The remaining hydraulic fill fraction is reticulated in the form of slurry through pipelines to undergro
14、und voids. Over the past decade there has been a steady increase in the solid content of the hydraulic fill slurry placed in mines in an attempt to reduce the quantity of water that must be drained and increase the proportion of solids. The challenge posed by a high solid content is that it becomes
15、difficult to transport the slurry through the pipelines due to rheological considerations. Currently, solid contents of 75-80% are common, although even at 75% solid content, assuming a specific gravity of 3.00 for the solid grains, 50% of slurry volume is water. Therefore, there is opportunity for
16、a substantial amount of water to be drained from the hydraulic fill stope. To contain the fill, the horizontal access drives created during mining are generally blocked by barricades constructed from specially made porous bricks (Fig. 2). The access drives, which are made large enough to permit the entry of machinery during mining, are blocked by the barricades during filling. The drives are often located at more than one level. Initially,
