Investigating the behaviour of fibre reinforced polymers and steel mesh when supporting coal mine roof strata subject to buckling

To improve ground skin support in highly stressed underground mines, new types of thin spray-on liners (TSL) are currently under development to replace steel mesh. To test these products, three different types of support material were tested for their ability to resist buckling failure, a mode of failure typically experienced by strata in highly stressed mine roadways. Steel mesh, as currently used for skin support, and two types of glass fibre-reinforced polymeric TSL materials were tested and compared. One of the TSL materials FRP Y was specifically designed for coal mining application. Four hydrostone slabs, cast to promote buckling, were bolted together to mimic laminated roof strata, coated with each material and tested in compression. Test results indicated that due to the strong bond, specimens reinforced with TSL materials had greater stiffness and peak strength than specimens with no support or those supported with steel mesh. On average, the specimens supported with steel mesh were approximately 1.7 times stronger than the unsupported control specimens while the specimens supported with FRP X and FRP Y were 3.2 and 2.3 times stronger, respectively. Experiments clearly indicate that the bonding characteristics of the TSL material formed a composite layer with the rock skin thus increasing the specimen’s ability to resist rock skin failure.