Laboratory investigation of support mechanism of thin spray-on liner for pillar reinforcement

Thin spray-on liners (TSLs) are attracting attention as effective rock support reinforcement in underground mines. They have the potential to increase roadway development rates and provide resistance at small rock surface displacements. To study the reinforcement provided by a TSL when applied onto a pillar surface, the support mechanism of TSL-coated rock samples was investigated, thereby providing a basis for studying the effect of TSL confinement on rock pillars. A polymeric material liner was applied to three types of rock (siltstone, sandstone and granite), and details of the sample preparation and loading procedures are presented. The results of rock failure tests indicate that significant strength improvement and enhancement of post-failure characteristics developed for the TSL-encapsulated samples. TSL reinforcement of the weaker rocks appears to be better than that of the stronger rocks. It is concluded that effective rock reinforcement occurs in the case when the tensile strength of the TSL material is greater than the tensile strength of the rock; the TSL reinforcement of stronger rock types may not be as effective. The test results obtained are consistent and conclusive.