Creep Modelling Study of a Surface Support Liner

Surface supports are widely used in underground excavations. Since conventional surface support liners have inherently-brittle characteristics and require longer curing period, an alternative support system using polymer based surface support liner, thin spray-on liners (TSLs), has been observed to have a promising ductile and fast-curing potential for underground operations. TSLs can exhibit a good performance for highly-stressed, deep, rock bursting conditions as well when used together with rock bolts and wire mesh for reinforcement and retaining purposes. However, uncertainty in the time-dependent behavior of TSLs under sustained constant loading conditions prevents full understanding of TSL support behavior. In this basis, this research aims to reveal the time-dependent creep behaviour of TSLs and to develop different creep models. In this study, creep tests were performed for 2-day cured dogbone TSL specimens under the dead weights (80, 60, 40, and 20 % of the tensile strength) for 23 +/- 2 degrees C laboratory conditions. Descriptive parameters of the TSL creep model were determined by power series, Burger's and multi Kelvin-Voight model. The study results presented the time-dependent behavior of a TSL for different constant loading conditions. In this sense, a TSL creep models constituted for 4 different stress levels. The proposed models create a basement for the future numerical studies.