Civil Engineering

Anisotropic and foliated rock masses, the behaviour of which are dominated by closely spaced planes of
weakness, present particular difficulties in the assessment of pit slope stability. Various numerical modelling
techniques are available that explicitly simulate the joints and discontinuities within an anisotropic rock
mass. However, due to the computational intensity of these numerical techniques, it is not practical to
explicitly simulate the joint fabric of an entire three-dimensional pit slope for routine stability assessment. In
order to simulate the effects of anisotropic rock mass strength and deformation behaviour on pit slope
stability, a modelling methodology has been developed to account for rock mass anisotropy and scale
effects using a continuum based ubiquitous joint constitutive model. This paper outlines the anisotropic
modelling methodology and presents a series of demonstration models that have been used to validate the
technique.

Microseismic monitoring, the engineering application of earthquake seismology, provides an insight into the location and extent of fracturing induced by the caving process. The spatial characteristics of the observed microseismicity provide valuable validation for the back analysis of the cave process
through numerical models (e.g. Pierce et al. 2006, Sainsbury et al., 2008). It also provides a tool for the validation of predictive cave models that aim to forecast the extent and location of the seismogenic zone and the evolution of damaged rock mass properties.
A case study is presented using Northparkes Mine microseismic (MS) events located by forward calculating P- and S-wave travel times using ray-tracing and wavefront  construction techniques through velocity structures that mimic heterogeneity and damage in the rock. By using these models it
is expected to get a better resolution of the extent, position and structure of the seismogenic zone. Conversely, the location of high-quality events provides a means to validate the fit of strain models.

The transition from surface to underground mining presents a series of technical and operational challenges, in particular those arising from the interaction between the cave and the overlying pit. Seismic monitoring provides a unique means to obtain near real-time information about the development of the fracturing process induced by the mining operations. This paper presents the analysis of temporal, spatial and source
size patterns in the seismicity recorded during undercutting and production at the Palabora Mine leading to slope failure in the open pit above, and relates these results to full-scale analysis of the rock mass behaviour in three-dimensional numerical models. Based on the application of the techniques described herein, it is shown that the back analysis of the seismic data provides a prediction technique that could now be employed during the planning stages of a mining operation. It is hoped that by employing these new techniques it would be possible to incorporate results from predicted fracture network behaviour into engineering designs in similar future mining operations and thus provide a means to predict and mitigate against large scale failure as observed at the Palabora Mine.

Highly skilled engineers drive many Australian industries including mining – a crucial Australian industry - in their pursuit of economic returns around the globe. Understanding the globalised context of Australian mining highlights the challenges of attracting highly skilled engineers to the often remote locations of Australia’s mining landscape. Despite the investment of educational and training resources over several decades, women’s engagement and progression in mining has been limited: only 13.4% of the country’s mining workforce are women. In Australia only 0.5% of mining’s managerial roles and Board positions are currently held by women.
The recent Women in Industry Awards (2015) suggest that women’s success in mining required them to be determined, tenacious, to take risks and to back themselves. Being knowledgeable and enjoying working in and mentoring a committed team was also key. The language of success in this industry suggests that women have overcome many hurdles and barriers along the way, yet these trials are rarely mentioned in reports, interviews or articles. The scarcity of women in the mining engineering industry suggests that understanding these hurdles, and the strategies that successful women adopt, may prove beneficial in encouraging girls and women to consider this profession and to support their on-going success.

The capacity of ground support components which have been affected by corrosion is reduced and may ultimately lead to failure of the component and the strata. In order to maintain an effective, long-term ground support system, significant campaigns of rehabilitation are often required in corrosion affected areas. The most common corrosion protection for steel ground support utilises sacrificial systems such as galvanising. Galvanising has previously been proven to be susceptible to some corrosion processes. Stainless steel is the most effective in resistance to corrosion, but can be cost prohibitive, and its mechanical properties often make it unsuited for use in ground support components Providing an outer protective plastic coating to bolts has proven to be an effective means of protecting the inner steel bar from corrosion. However, these support systems tend to be heavy, and require post cement grouting to provide full encapsulation. In comparison to a standard bolt/resin system, they are slow to install and expensive. These systems have also been shown to reduce overall load transfer performance of the bolting system. In order to provide a higher level of corrosion protection whilst maintaining current installation practises and bolting cycle times, Minova has developed the Enduro™ steel ground support range. The Enduro™ range consists of standard Minova steel ground support components which have been treated with a unique coating process. The Enduro™ coating has been tested in the harshest of conditions, both underground and in controlled laboratory conditions. It has been proven to effectively resist or eliminate the formation of corrosion, even in the most aggressive environments. This paper outlines the laboratory and underground corrosion performance testing carried out on Enduro™ ground support products.

Anisotropic and foliated rock masses present particular difficulties in the assessment of pit slope stability. Although many attempts have been made to describe the strength of rock masses that exhibit a preferred orientation of weakness, no general methodology has emerged throughout the literature
to simulate anisotropic behaviour in a three-dimensional numerical model of pit slope stability. In order to simulate the effect of the anisotropic shale rock mass on pit slope stability at MMG Limited’s (MMG) Century Mine, the Ubiquitous Joint Rock Mass (UJRM) method has been applied. This paper  outlines the methodology that was used to assist mine personnel in the management of complex anisotropic slope instability that jeopardised the recovery of 1.8 million tonnes of zinc ore.