Experimental and numerical analysis of thin spray-on liner materials for use in underground mines

Steel mesh that is currently used in underground coal mines is of a passive nature and in most cases does not contribute to roadway skin reinforcement. Steel mesh is a safety device that is only effective in supporting detached pieces of rock or severely fractured rock mass experiencing large displacements. As a relatively new form of rock support Thin Spray-on Liners (TSLs) are currently being investigated as an effective skin support technology. Research indicates that TSLs may provide superior rock skin control. Being a pro-active support technique, it is known that a TSL is able to provide resistance to even small rock movements and thus significantly improve rock skin stability. TSLs have the potential to increase roadway development rates because their application in conjunction with rock bolts can be automated. In addition, TSLs can be sprayed remotely, thereby improving personnel safety while providing resistance to small rock deformations. TSL materials have thus been attracting attention from both research organisations and industry. In order to investigate and compare the compressive strength of glass fibre reinforced TSL developed at the University of Wollongong, a compression test was developed using cube samples of 40 mm in size. The effect of a small amount of glass fibre in the polymer matrix was tested. The test results indicate that the compressive strength and the material stiffness of the cube samples increased with the increase of glass fibre. All samples exhibited a ductile stress strain curve as they had a yield point and a fracture point. The ductile TSL yield characteristics are very important as sudden brittle failure is considered unsafe for mining practices.