Geotechnical Assessment of Polymetric Materials as Skin Reinforcement in Underground Mines
Jan Nemcik, Ian Porter, Ernest Baafi, Christopher Lukey and Geoffrey Spinks
Faculty of Engineering
University of Wollongong
Wollongong NSW 2522
Current advances in roof support automation require a fast and effective skin reinforcement of underground mine roadways. To satisfy these needs a strong and tough glass fibre polymeric alternative is emerging as a logical substitute to the old steel mesh support system.
This paper investigates the polymer properties obtained from laboratory tests and utilises computational models to predict the optimum polymer performance needed for effective roadway skin reinforcement. In particular, emphasis is placed on developing a strong and resistant shell that minimises movement along the fractured rock and coal surfaces found between the roof bolt anchors. Strong surface adhesion and the strength of the reinforced polymer skin can provide the necessary toughening mechanism required to enhance roadway surface support by forming a reinforced polymer/rock surface layer. The fractured rock mass in its undisturbed phase is relatively stiff while confinement stresses exist. However, any dilation that occurs due to displacement along the rough surfaces of the fractured rock causes strata softening, bulking and movement into the mine opening. The ÃÂÃÂ¿polymer SkinÃÂÃÂ¿ provides an active resistance to any movement along the fractured rock surface as soon as any movement begins to occur. Even partial de-bonding of the polymer from the rock surface may not significantly disturb this mechanism. Severe roof movement that may occur in overloaded roadways may totally de-bond the polymer from the fractured rock mass. However, the tough nature of the polymer mesh will further resist the loading of strata in a manner similar to that of steel mesh, while the polymer fibre yielding mechanism will give an audible warning similar to the audible yield of the old wooden prop system.