NOVEL HYBRID FRP TUBULAR STANDING SUPPORTS FOR UNDERGROUND MINES

With the depletion of shallow coal resources, more and more coal mines have been extended to deeper mining levels with large deformation of the surrounding rock. The potential risk of roof falls cannot be simply addressed by traditional reinforcement systems (i.e. rock bolt and cable bolt) owing to their insufficient deformation capacities. It is therefore important to utilise a combination of secondary standing supports and roof bolting systems to maintain the stability of overlying strata. There are various secondary standing supports being used in underground mines. Among these existing standing supports (e.g. timber chock, concrete crib, cluster prop and so on), the pumpable standing support and the Can® support are the two most popular commercial products in the market. Due to the insufficient strength of the fabric container in pumpable standing supports, the strain-softening behaviour associated with unexpected load shedding events is believed to be the main restriction for the wide application of the pumpable standing support from a design perspective. The use of a steel container in the Can® support makes it possible to sustain integrity with a large deformation capacity even in some critical geological and mining conditions. However, the transportation and ventilation issues caused by the setting of the Can® support with a large cross-sectional area have attracted much attention from coal operators. This thesis focuses on the development of a novel standing support incorporating the emerging material, namely fibre-reinforced polymer (FRP) composite, as a potential alternative to the existing available standing support when considering the high strength-to-weight ratio and linear tensile behaviour of the FRP composite.