Top: Testing of various types of shotcrete on static and dynamic response; Bottom: Diesel-electric hybrid loader prototype
The CANMET Mining and Mineral Sciences Laboratories (MMSL) are federal government research laboratories within Natural Resources Canada. They provide research and scientific advice to the mining and minerals industries, and to provincial/territorial and federal government departments involved in promoting or regulating these industries.
The following is a brief synopsis highlighting some of the innovative research projects currently being spearheaded by CANMET-MMSL in their effort to improve health, safety and productivity in the mine environment.
The influence of various fibre types on the static and dynamic response of shotcrete
As mines continue to dig deeper and in-situ stresses increase, the need to understand ground support system responses and to improve upon them is imperative. Currently in the mining industry, shotcrete is used primarily in permanent openings, such as shaft stations, refuge stations and vehicle bays, although there is a trend towards its increased usage throughout the mining cycle. In some instances, it has even become the support of choice.
Incorporating fibres into the shotcrete mixture minimizes the necessity for the labour-intensive process of mesh installation, thus reducing cycle time. These fibres impart fracture toughness and crack growth resistance to the shotcrete, which has traditionally been the role of the mesh. Using fibre-reinforced shotcrete (FRS) also enhances safety, as it allows workers to apply support while remaining away from unsupported ground.
However, there are many different types and geometries of fibre currently available, each performing differently. CANMET-MMSL will prepare, test and evaluate shotcrete properties related specifically to these fibres, including the differing types, materials, geometries and proportions. The aim is to supply sound scientific data to mining engineers, to enable them to determine the appropriate fibres required for safe ground support at their site. This project will provide an opportunity to enhance the effectiveness of ground support systems, as well as provide a platform for CANMET-MMSL to develop future research into determining and quantifying the response of FRS with respect to dynamic forces, such as those caused by rockburst events.
Dynamic performance of ground support elements
Increasingly, the dynamic capabilities of ground support has become one of the key design considerations when selecting yielding elements for highly stressed, burst-prone or high deformation environments. Since 2003, CANMET-MMSL’s Ground Control Program has been evaluating the dynamic performance of various ground support elements to fulfill its mandate related to the safety of underground workers. In addition to its continued testing of tendons, CANMET-MMSL has spearheaded a new project to gather all information available regarding the dynamic parameters of ground support elements. The objective is to provide the mining industry with concise and up-to-date data regarding dynamic tendon support. It is anticipated that this information will facilitate support selection and design as well as identify existing gaps in the information. Under the leadership of CANMET-MMSL, its self-developed testing protocols are currently being assessed by the American Society for Testing and Materials Inc. The acceptance of the standard test procedure will become official at the beginning of 2008.