Comparative analysis of the performance of Thin Spray-on Liner with shotcrete and mesh support

In order to study the effect of different surface protection components, such as Thin Spray-on Liner (TSL), in the support system of prestressed bolts on the critical rock mass, based on the similarity theory, physical modeling tests were designed and carried out for the support of the critical rock mass by the combination of NPR bolts and PR bolts with three types of surface protection components, such as TSL, sprayed concrete, and metal mesh, respectively. The test results show that the three types of surface protection components can significantly increase the threshold value of crack development of the critical rock specimen and effectively improve the peak bearing capacity of the critical rock body, and at the same time, the NPR bolts with higher strength and elongation have a more significant effect on the improvement of the peak bearing capacity of the critical rock specimen. In addition, TSL and spray-mixed support and specimen surface can realize close fit, in the loading of the early support response is more timely, in the late loading, compared with the spray-mixed material in the rupture of debris collapse, TSL in the occurrence of tearing can still be tightly adhered to the specimen proximity surface of the rock specimen, to prevent specimen debris fall. For the phenomenon of TSL coating rupture in the experiments, the energy balance equation was established to analyze the connection between the actual energy absorption effect and the theoretical value of the combination of TSL and bolts under the pre-stressed bolts support system, and it was found that the combination of pre-stressed bolts and TSL greatly improved the actual energy absorption effect of the support system as a whole, and the analytical results of the various experimental subgroups showed better results than the theoretical values. The analysis results of the subgroups show a good fit.