ABSTRACT FOR ICMST 2015 Laboratory investigation on the tensile bond strength of thin spray-on liners

摘要

Steel mesh acts as a passive skin support that restricts the movement of loose rocks in order to protect the safety of personnel working at the face.However, as a passive support method, it can be effective in supporting the roof only when the roof deforms and significant displacements occur.The installation of steel mesh in underground coal mines is labor intensive and is difficult to automate.In order to solve this problem, the application of Thin Spray-on liner (TSL) has been proposed.This type of support material can be sprayed onto a rock surface and thus it can be automated.The TSL is a pro-active support method forming a strong composite layer of TSL-Rock material that can restrict the movement of fractured fragments immediately after application.To assess its geotechnical function in strata surface reinforcement, tensile bond strength must be evaluated as it is one of the most important TSL properties that contribute to the quality of reinforcement.In this study, modifications and improvements were made in the process of sample preparation.The effect of loading rates, TSL thickness, rock types and environmental conditions on the tensile bond strength of polyester-based TSL material were investigated.The test results indicate that for low loading rates ranging from 0.5 mm/min to 2 mm/min the effect of loading rates can be ignored while for higher loading rates of up to 10 mm/min, the tensile bond strength increases.The data analyses indicate that the tensile bond strength of the polymer-based TSL material is inversely proportional to the square root of the TSL thickness.The results also demonstrate that TSL material adheres better to dry rocks while adhesion to wet rocks decreased to approximately 65-75％ of the dry adhesion.The data indicate that the tensile bond strength may increase with the tensile strength of rock substrates.