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By P J. Bangerter, J Pan

Optimising for Net Present Value (NPV) with a strategic optimiser such as COMET, Prober-E, Blaser or Minemax has hitherto lacked a dynamic method for analysing the so-called third-order outcomes (such as Carbon emissions) of optimisation within life-of-mine planning. Optimisation, per se, has natural effects on carbon emissions in a life-of-mine plan. Contemporary strategic planning employs a mathematical optimiser to make sense of non-linear data (ie a block model) and produces a best-NPV optimised mining schedule, within a set of constraints. The very act of optimisation influences emissions, and in a dynamic way.

Aug 2, 2023

By J Seery, N Savage, A Wilson, L Nicholas

Geological modelling provides a means of spatially representing the three dimensional distribution of geological information to downstream stakeholders. The geologist completing the modelling work intimately understands the varying degrees of confidence, assumptions and extrapolation required to honour the data. Geological models are often taken and used by stakeholders without fully understanding this modelling process. This can lead to confusion amongst stakeholders when the geological model shows variable reconciliation. A method for visually communicating the confidence of the spatial distribution of geological models has been created by the Rio Tinto Iron Ore structural geology group for use primarily in geotechnical engineering investigations. A numeric confidence rating is assigned to each geological data point used in the creation of a geological surface. This is based on data type, collection method and reliability to indicate potential error in distance from its modelled location. In regions of sparse data, confidence ratings are inserted based upon the geologistÆs experience and knowledge of the geology, whereas mapped geological contacts or drill hole intersections are assigned a higher confidence rating. A regular grid of points is registered to the geological surface and each of these grid points is assigned a confidence rating using an inverse distance weighting using a nearest neighbour approach. The resulting grid is colour coded according to the confidence rating to provide a visual representation of the variable confidence of the geological surface in three dimensions. Subjectivity and bias from the geologist is minimised by critically analysing the input geological data and then applying this methodology to represent the confidence in the spatial characteristics of geological models. Understanding of this confidence enables mining professionals to make informed decisions and identify areas that require further geological investigative work. CITATION:Savage, N, Nicholas, L, Wilson, A and Seery, J, 2013. Visual communication of geological confidence - a move toward a less subjective approach, in Proceedings Iron Ore 2013 , pp 169-174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

Distillation of the large and growing greenhouse literature indicates that: ò Global warming has occurred over the past century or more; ò Build-up of CO2 (and lesser greenhouse gases) in the atmosphere is a fact; ò This build-up is likely to cause further global warming. It does not appear possible to conclude that the observed C02 build up and observed global warming are linked; nor is it yet possible to forecast global or regional climate variation with conviction. The dominant greenhouse gas is C02 with about half the warming potential of those gases emitted by man's activities; and about 80% of anthropogenic C02 emissions are from the burning of fossil fuels. Fossil-fuel C02 emissions arg divided about equally between the developed countries of OECD and the rest of the world. However C02 output growth over the past decade was about 4% for OECD and some 40% elsewhere. Population growth and pressure for better living standards will ensure continued higher growth outside OECD. Uncertainty about the impact of increasing C02 emissions on climate, and the long lead-times involved in limiting the increase in atmospheric C02 concentrations, are good reasons for taking action now. Australia accounts for about 275 million tonnes a year or just over 1% of the CO2 emitted from the world's consumption of fossil fuels, and the fight to control global emissions will be won or lost elsewhere. Australia's participation will be by wise conselt and by example. In view of the uncertainties involved, it appears premature to take actions that might place an additional financial burden on our hard-pressed country. However, much can be done now that makes good economic sense and has the added benefit of limiting the growth in Australia's CO2 emissions. Natural gas emits less C02 per unit of energy when burned than either coal or oil. Furthermore, new gas-fired power stations utilise energy at considerably higher efficiency than is the case today with coal or oil. Because of much lower capital costs, there is a compelling economic case for permitting natural gas to compete freely with coal in the Australian power generation market.

Jan 1, 1989

By D C. Ford

The Argyle AK1 orebody was discovered in 1979 and subsequently found to be a large, economically viable reserve with high grade diamondiferous ore. Production began via an open pit operation at the end of 1985 and has continued for some 25 years to present day. This, however, will come to an end in the next few years with production moving to an underground operation via block-cave mining methods.A series of studies from 2001 - 2005 was carried out; diamond drilling commenced after approval in 2006, from an exploration drive to determine the likelihood of the current proposed block cave operation.In 2006, development of the block cave project began, in order to realise the part of the orebody below the extent of the open pit mining operation.Development of the block cave technique, comprising an undercut level beneath the target zone of the orebody with subsequent extraction level 15 - 20 m beneath, relies largely on a number of block-caving parameters (hydraulic radius, rock type, structure and orientation of stress and grade of the orebody). These all have an influence on cave ability and eventual profit of the operation. Evaluation of further potential for taking this orebody beyond the block cave phase with options such as sublevel-caving are being considered for the UG-2 portion of the resource/reserve. Diamond drilling for this work is currently under revise.The challenges faced in transitioning form the surface operations to the underground, comprising a changing workforce, converging development drives, underground aquifers, major excavations and transportation of ore via automation are intriguing.

Aug 22, 2011

By H Arvidson, V Chamberlain, R Marinho, B Parsons, T Rowl, M Noppé, M Mattera

With the introduction of CRIRSCO (2019) based mineral asset disclosure, Regulation S-K part 1300, 2019 (S-K1300) by the United States (US) Securities and Exchange Commission (SEC), applicable to companies listed on the New York Stock Exchange from 2021, Mineral Resource is now required to be reported Exclusive of Mineral Reserve, referred to here as ‘Exclusive Mineral Resource’ (EMR). EMR is equivalent to reporting Mineral Resource additional to Mineral Reserve, which has been permitted in jurisdictions outside the US for many years. Despite this, there are no practical guidelines in the literature or relevant reporting codes and rules for Competent/Qualified Persons to refer to, which creates a risk that disclosure of EMR estimates across the industry will be inconsistent and potentially ambiguous for analysts, investors, potential investors, and other stakeholders.With the introduction of CRIRSCO (2019) based mineral asset disclosure, Regulation S-K part 1300, 2019 (S-K1300) by the United States (US) Securities and Exchange Commission (SEC), applicable to companies listed on the New York Stock Exchange from 2021, Mineral Resource is now required to be reported Exclusive of Mineral Reserve, referred to here as ‘Exclusive Mineral Resource’ (EMR). EMR is equivalent to reporting Mineral Resource additional to Mineral Reserve, which has been permitted in jurisdictions outside the US for many years. Despite this, there are no practical guidelines in the literature or relevant reporting codes and rules for Competent/Qualified Persons to refer to, which creates a risk that disclosure of EMR estimates across the industry will be inconsistent and potentially ambiguous for analysts, investors, potential investors, and other stakeholders.

May 24, 2023

By S Juras

To our geologists at Eldorado Gold Corporation, the release of the gold assays on a new ore zone causes a flurry of excitement. But to our metallurgists, that news is often greeted with the question ‘What’s the sulfur grade’? In our company, we operate and manage projects whose end-product will either be auriferous sulfide flotation concentrate or gold doré. Almost all of the steps in the ore processing are related to sulfur (in this paper specifically sulfide sulfur). So why do we geologists wait until late in a project or into production before collecting sulfur data for mine planning and ore control purposes?Gold deposits associated with sulfides commonly use a metallurgical process that begins with a flotation step to recover gold into a smaller mass known as flotation concentrate. Often, this step solely targets the sulfide minerals with gold only coming along for the ‘ride’. As a result, the gold grade in the concentrate is primarily influenced by the ratio of gold to sulfur in the feed. Should this concentrate require a refractory process downstream (eg pressure oxidation), knowing sulfur grade is critical as sulfur controls heat balance in the process. Regardless, we need sulfur models to be as robust as gold models, and created much earlier in the project evaluation process.Sulfur models require quality data collected at the same density as gold samples. Analytical methods must match expected grade ranges and quality assurance quality control (QA/QC) protocols and must be of the same integrity as in use for gold. Sulfur models will then be created by their own data analyses, interpolation protocols and validation. Furthermore, ore control systems should be designed for regular sulfur monitoring to ensure and enhance downstream value. Given time it should become habitual for geologists to likewise ask, ‘And what’s the sulfur grade’, or more specifically, ‘What’s the gold to sulfur ratio’?CITATION:Juras, S, 2017. Sulfur – the new geometallurgical grade in gold-sulfide deposits, in Proceedings Tenth International Mining Geology Conference 2017, pp 199–202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By F Ramos

Conventional techniques for resource estimation generally involve the laborious analysis of variograms and the specification of parameters for covariance functions. In large deposits, construction of resource models and their update require significant amount of manual work, expert knowledge and time. In this paper we take a machine learning view to the problem of resource estimation. This is a non-parametric Bayesian method, leading to automatic parameter estimation (learning). Through Bayesian learning, the parameters of the model can be obtained by optimising a quantity known as the marginal likelihood. The main advantage of this approach over conventional maximum likelihood estimators is that the objective function incorporates the OccamÆs razor principle. This allows the comparison of different statistical models û for example, models designed with different covariance functions û and naturally penalises complexity, thus avoiding overfitting. Our technique presents significant flexibility for the definition of mean and covariance functions and permits the usage of more sophisticated models.The second contribution of this work is the formulation of a data fusion mechanism that continuously updates the resource model. As mining progresses, more information becomes available. For example, the hardness of the rocks can be measured while drilling blast holes, grades of ore and contaminants are obtained from cone logging. This information is in general available at a finer spatial resolution but can be more uncertain. The data fusion mechanism can seamlessly estimate the uncertainties of the different types of information and fuse them as new measurements are acquired. This procedure can significantly improve the quality of the resource model, defining new grounds for stochastic mine planning. We demonstrate the effectiveness of our approach in estimating iron ore deposits by integrating information about different grades.

Sep 26, 2011

By H Arvidson, B Spence, S Helm

Mining is the art of disturbing ground. All phases of a mine’s life cycle from exploration to building and operating a mine, through closure, has a physical impact on the earth. There is currently increasing public and stakeholder awareness owing to a wide range of issues including heritage protection, environmental stewardship, and social impacts therefore ground disturbance must be conducted in a way that honours and respects all agreements, regulations, legislation, and social expectations. A comprehensive ground disturbance permitting process has been developed through consultation with major mining companies and Traditional Owner groups. It operates from strategic business planning through to closure and rehabilitation. Adherence to the principles and process of permitting helps to minimise risk by ensuring that mining companies conduct their business in an inclusive, professional, reliable, and consistent manner that stakeholders reasonably expect, and that mining companies can be proud of. Built on a geographical information system, supplemented with a specialist database, this process allows request, review, and approval by subject matter experts, to operate in a common environment that is transparent, facilitates collaboration, improves efficiencies, and reduces the risk of error or omission. The application of new technology can effectively highlight changes that naturally occur in today’s dynamic ESG domain and provides the perfect platform to record actual disturbance against authorised and planned allowances. The social license to operate demands that strong governance of the ground disturbance process, described herein, can be demonstrated to any interested stakeholder, and mining companies recognise that this principle is central to the betterment of the mining industry.

Sep 18, 2023

By M Brockman, M Cowan, A Robeson

"Sunrise Dam Gold Mine (SDGM) is located 820 km from Perth, 220 km from Kalgoorlie—Boulder and 55 km south of Laverton in Western Australia. The SDGM main pit had successfully operated since 1997 and was due to be completed during 2012. An opportunity existed to extract the high-grade crown pillar – 600 kt @ 7 g/t for 135 koz by either open pit or underground methods.The crown pillar was the 60 m (vertically) thick remaining part of the high-grade Cosmo orebody between the top of the paste filled underground mine stopes and the planned base of the final open pit shell.There were two major difficulties being considered when choosing the underground or open pit options:a major wall failure in the upper section of the main pit wall directly above the crown pillar restricting access from the base of the open pit to the top of the crown pillarimpact of a high rainfall event while the crown pillar was being mined from either surface or underground resulting in flooding of the underground mine workings.This paper will discuss the following issues:the process to identify and evaluate the risks in both options using knowledge based modelling software; this technique allowed the evaluation of a complex set of assumptions to arrive at the preferred optionremediation of the Watu failurethe selection of the preferred option and the challenges encountered before, during and after the extraction of the crown pillarthe planning and geotechnical work to ensure the safe extraction of the crown pillarsuccessful outcomes transitioning from open pit operation to a solely underground operation.Citation:Robeson, A, Cowan, M and Brockman, M, 2016. A Case Study on the Assessment, Planning and Extraction of the Crown Pillar at Sunrise Dam Gold Mine, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 115–136 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By K White, C Ferguson, M Harding

Understanding watercourses and river processes at a landscape scale is vital for managing risk to mining infrastructure and operations as well as minimising future environmental impacts beyond the life of the mine. Recognising this, Iluka Resources Limited engaged Alluvium Consulting Australia to identify and characterise watercourses across several neighbouring mineral tenements in the Eucla Basin, South Australia (Alluvium, 2013, 2014a, 2014b). The objective of the studies was to inform planning for risk management during mine planning and operation and appropriate landscape rehabilitation for mine closure.Mining operations in the area are by open cut extraction of mineral sands. The extracted resource is processed on-site before leaving the site for export. Several pits are to be developed in stages with simultaneous backfilling and surface reinstatement. Mining is initially taking place in the Jacinth tenement, where up to 100 km of watercourses may be directly or indirectly impacted (refer to Figure 1).The total study area (shown in Figure 1) is approximately 330 km2 and spans three smaller areas that were the focus of separate investigations during mine planning.CITATION:Ferguson, C, White, K, Harding, M and Hardie, R, 2016. Landscape-scale assessment of watercourses in remote arid South Australia to inform mine planning to mine closure, in Proceedings Life-of-Mine 2016 Conference, pp 200–204 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By D François-Bongarçon

The link between geostatistics and Theory of Sampling (TOS) is examined again in view of new findings made while trying to compare predicted sampling variances and estimated grades (using geostatistics) on the same material, and this provides an important consistency requirement whenever calculations are made that involve both theories in a comparative way. It also briefly explores the relationship to De Wijs fractal model of mineralisation and eventually provides new support for the use of consistency theory for calibrating TOS variance formulas.CITATION:François-Bongarçon, D, 2017. Theory of Sampling and geostatistics – the ultimate link, in Proceedings Eighth World Conference on Sampling and Blending , pp 391–394 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By M Behrens

The Melbourne Main Sewer Replacement (MMSR) is a major urban infrastructure project involving approximately 2.3 km of tunnelling and construction works. The works extend from Docklands Precinct, on the southwest edge of the city, southwards to connect with the Hobsons Bay Main Sewer in Port Melbourne. The tunnel boring machine (TBM) tunnelled section of the works terminates at the Yarra River where the delta geology and alignment requirements precluded the use of underground tunnelling methods. The 132 m long river crossing works involve a cut-and-cover excavation within a staged fl ooded cofferdam construction to construct an immersed tube tunnel as an extension of the TBM works.This paper reports on the development of the staged construction method and highlights the geotechnical and structural design aspects involved in building a new sewer in the Yarra River to close the gap between the new TBM driven and pipe-jacked tunnels.

Mar 8, 2011

By B W. Atkinson

Full-stream mechanised sampling apparatus, that collect a full cross-sectional increment from the complete screen discharge, will always be the preferred option for sampling screen overflows. However, the reality is that provisions for automated sampling are rarely, if ever, provided at the discharges of individual screens within beneficiation plants.Sampling from the discharge of high capacity vibrating screens, especially multi-slope screens, is subject to sampling bias, due to the stratification of the ore that occurs on the vibrating screen deck. The stratification in the vibrating bed translates to a stratified falling stream at the discharge end of the screen, typically with smaller particles at the back of the falling stream and large particles at the front of the falling stream (Figure 1).The chemical and physical characteristics of heterogeneous ore (mineral or coal) particles vary significantly with particle size. If samples do not correctly reflect the source material size distribution, they will be biased and the resulting analytical/assay data will not reflect the actual physical nor chemical characteristics of the source material.Prior published data for coal preparation research (Australian Coal Association Research Program) has demonstrated that a bias appears to exist for samples collected from high capacity multi-slope screens.A new form of sampling scoop has been developed with the aim of overcoming this issue.Bias was evaluated at a coal preparation plant by comparing the desliming screen overflow size distribution to that for æreferenceÆ coal preparation plant feed samples collected using the recognised stopped-belt technique. The study procured 20 sets of comparison samples in order to ensure statistical relevance.Two forms of sampling device were employed for the multislope screen discharge.A conventional square aperture scoop was demonstrated to exhibit a significant coarse bias, in that the resulting samples exhibited a significantly coarser size distribution compared to the reference samples. In other words it was evident that the conventional scoop æfavouredÆ material from the front of the falling stream.A new æcollapsibleÆ sample scoop was evaluated in parallel, and its samples were found to exhibit no relevant bias.CITATION:Atkinson, B W and Swanson, A R, 2012. A new method for sampling from high capacity screens, in Proceedings Sampling 2012 , pp 89-94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By C Jones

Ridgeway Deeps is a block cave (BC) located down dip of the operating Ridgeway sublevel cave (SLC) mine. The BC is located approximately 210 m vertically below the lowest SLC level and approximately 1100 m below surface. Due to the mine layout containing a number of common pieces of key infrastructure the activities of both were interlinked.When investigating project construction options for the BC, a number of potential risks were identified including a conflict of priorities between operational and project deliverables and the varying safety and work methods between an owner mining approach in the SLC and a potential contractor workforce in the BC. This led to a review of the construction philosophy and the opportunity to utilise the existing SLC workforce as the basis of all activities in the mine. It was identified that a number of synergies existed with the current SLC operators and mine supervision including common work practices and the opportunity to build on the unique SLC skills of the operators and supervisors which could then be used at other Newcrest caving mines.With the commitment to this philosophy of building on the existing SLC crews and supervision the number of employees reporting through the superintendent underground operations grew from 95 to 245. This increase led to a restructuring of the reporting and work requirements of the superintendent, foremen and shift bosses. In order for the foreman and shift bosses to focus on running the larger crew numbers for the full 12 hour shift the mine superintendent became a pseudo human resources manager taking over all non-mine focused activities including overtime allocation and work and behavioural performance management. In simple terms, ensuring there were competent bums on seats when and where required. As the additional workers were recruited to top up the existing employee numbers, their employment history was used to place them in the most suitable roles. For example, those with building industry experience were placed on the civil construction crews and those with a farming background were used as truck drivers, nippers or on the service crews. To cope with the increased number of new starters a number of key personnel were seconded from the crews into the training group to act as on shift trainers. This initially caused a reduction in mine performance as the main operators were reassigned but it proved a valid move as the time for new operators to reach acceptable levels was significantly reduced with safe operating standards being maintained. This paper discusses how the Ridgeway Deeps Project was delivered on time and under budget whilst at the same time retaining its position globally as an operation to be benchmarked against.

Mar 21, 2011

By P K. Seccombe

The McKinnons gold deposit is hosted by weakly deformed, Palaeozoic metasedimentary rocks of the Cobar Basin in the western Lachlan Fold Belt of New South Wales. Mineralisation comprised a largely supergene resource of 1.7 Mt of ore, grading 1.7 g/t gold, established over structurally controlled, primary gold and base-metal mineralisation in underlying, carbonate-rich meta-siltstones and sandstones of Early Devonian age. Mineralisation was associated with at least two major fluid cycles. The first cycle was characterised by four stages of vein formation. Early quartz and carbonate veins (Stages 1 and 2) and quartz-pyrite breccias (Stage-3) occurred prior to, or early in, the main regional deformation (D1). Continued D1 deformation produced syntectonic, carbonate-base-metal veins (Stage-4), primarily in dilatant zones adjacent to fold axes. The second cycle of mineralisation was an epithermal-style event, driven by a shallow, syn-D2 or post-tectonic intrusion, defined by aeromagnetic imaging. The intrusion may have exploited a jog, controlled along the basin margin by basement faults. Mineralisation produced gold-pyrite veins, associated with pervasive quartz-sericite-adularia and chlorite-sericite alteration. Highest primary gold grades are confined to quartz-adularia boiling zones. The McKinnons deposit offers an important example of mineralisation formed by multiple processes. Early-stage, base-metal mineralisation at McKinnons reflects structurally focussed, basin dewatering and metamorphic processes, typical of other deposits in the Cobar Basin. By contrast, late-stage gold mineralisation at McKinnons is magmatically driven and of epithermal style. Recognition of overprinting distinctive geological events is critical, not only in modelling ore formation, but in developing a versatile exploration concept.

Jan 1, 1999

BHP is the world's largest copper concentrate producer with production from mines at Escondida (Chile), Ok Tedi (Papua New Guinea), and Island Copper (Canada). The entire concentrate production is further processed into refined copper by third-party smelters around the world. In anticipation of an expansion in the global copper concentrate production capacity and a corresponding increase in treatment and refining charges by copper smelters, BHP has continuously evaluated various opportunities for downstream copper processing. An expansion in the Escondida mine production, combined with BHP's interest in processing some of its concentrate production on-shore in Chile, ultimately resulted in the development of the Escondida Leach Process. This process was specifically developed for higher grade concentrates, such as from Escondida. An ammoniacal lixiviant and air are used under ambient conditions to leach less than one-half of the contained copper values. After solid-liquid separation, the solution is subjected to solvent extraction regenerating the ammoniacal lixiviant and the copper loaded organic phase is stripped in spent electrolyte returned from the electrowinning plant where ultra-high quality SX-EW copper is produced. The solid leach residue can, if required, be upgraded by flotation to produce a high-grade copper concentrate with improved fuel values and a pyrite tail for disposal. After an 18-month bench and pilot plant scale program and an engineering feasibility study, Minera Escondida Limitada decided to build an 80 000 tonnes of copper per year facility near Antofagasta, Chile. The installed investment cost amounted to around $160 million. The plant went into commercial production in November 1994 and better than 99.9995 per cent Cu cathodes were produced right from the start. BHP believes that the process and the commercial plant are an excellent example of a novel approach advancing the science of copper metallurgy in harmony with present demands for environmentally sound processes and high quality products.

Jan 1, 1995

By J Greberg

This paper discusses the use of simulation in the mine planning process. A case study on the Newcrest Cadia East project is presented, and the challenges and possibilities for using simulation as a tool for mine planning and scheduling is discussed.The simulation study presented in this paper was performed during the project’s prefeasibility stage, and focused on the planning and scheduling of the development of panels in the future mine. The Cadia East project will be the largest underground operation in Australia and the first using panel caving. Simulation was used in order to optimise the development of panels; it was mainly used in order to verify the plans for the development process and allocate resources in an optimal way. The work was performed as an iterative process and adjustments to the plans were made according to simulation results. Bottlenecks were identified and different scenarios were tested.The results from the simulation study shows how different operational constraints affect the planned development process and how changes in priorities can be necessary in order to maintain a high development speed. Furthermore the study shows how changes in planned mine layout requires changed strategies, and how this was solved using the simulation tool.In this paper the authors critically discusses the use of simulation in mining operations: what are the limitations and challenges of using simulation as a tool for mine planning and scheduling, what are the benefits, and what do we aim for in the future?

Nov 22, 2011

We live in a world in crisis. One where the tides of change run ever faster. Where the only thing we can be sure of is change itself. The challenge we face, therefore, is not how to resist the forces that move us nor even to try to predict where they will lead us, but to harness their energy and use their momentum to find new and innovative solutions to problems that can seem intractable. Indeed, crisis is often the catalyst which energises a business to change its technology and to form a partnership with a company which specialises in pioneering new technology.

Jan 1, 1993

Large deposits present computational challenges to todayÆs commercial orebody modelling systems that are based on conventional block models. We describe a system that is specifically engineered to model and visualise large deposits. Central to the system is linear octree encoding of conventional block models and real-time conversion of three-dimensional (3D) meshes to linear octrees. We provide both methodological treatment and practical experience in implementing such a system. A commercial implementation is also presented to demonstrate the validity of the approach.

Sep 26, 2011

By A Purwodihardjo

Evaluation of the construction method used for the pedestrian underpass construction at Ipswich Road, Brisbane, Australia is presented in this paper. The pedestrian underpass was constructed through the existing railway embankment between Harrogate and O’Keefe Streets on the eastern side of Ipswich Road. This underpass construction is part of the CLEM7 tunnel project (formerly known as the North-South Bypass Tunnel) which is the longest toll road in Australia at a total length of 6.8 km. The jacked box construction technique was initially identified as a preferred option during the tender and concept design phases. However at the final design stage, the cut and cover technique was selected as this method can reduce the construction time and cost significantly. The design and construction teams effectively managed the challenges, complexities and risks associated with undertaking cut and cover tunnel through the existing heavily utilised rail embankment. The on-site construction time for the underpass using the cut and cover technique was reduced to less than 42 hours.

Mar 8, 2011