In Situ Tests Comparing the Support Effects of Thin Spray-on Liner and Shotcrete on a Roadway Subjected to Blasting

Shotcrete has been widely used in the support of tunnels and mine roadways, but frequent blasting disturbances can easily cause it to spall from rock surfaces. In previous laboratory tests, it has been shown that thin spray-on liner (TSL) has shown significant potential as an alternative to traditional shotcrete support, but these studies were mainly conducted under static conditions, and doubts remain among many scholars and mine managers regarding the practical application of TSL in the field. The aim of this study is to compare the support effects of TSL and shotcrete under blasting loads and verify the support performance of this new type of skin support material. Through 21 in situ blasting tests, the installation process, support effects, and benefits of the two support methods were analyzed. The results show that compared to shotcrete, TSL provides a better construction environment and lower cost. Under far-field blasting, the downward displacement of the roadway roof supported by TSL is smaller than that of shotcrete, and the wave velocity decrease rate of TSL does not exceed 10% (indicating that the TSL has not been damaged). Under near-field blasting, TSL provides a smaller destruction area than shotcrete. TSL can effectively restrict the movement of the roadway roof, and the damage degree is much lower than that of shotcrete. The tests in this study were only conducted in intact hard rock roadway at a depth of - 520 m. Further research is needed to investigate the support effects of TSL in roadways with different stress environments and the quality of rock masses. Through 21 in situ blasting experiments, the support effects of TSL and shotcrete in hard rock roadways within an underground mine under the influence of blasting loads were validated and compared.A variety of methods, including displacement monitoring, ultrasonic tests, strength tests, and dynamic data tests, were employed to compare the support effectiveness of TSL and shotcrete.Compared to shotcrete, TSL provides a better construction environment and lower cost. Furthermore, the TSL incurs less damage and exhibits a smaller destruction area under blasting loads.In this study, the on-site conditions suitable for TSL application were evaluated, and the reasons for TSL blast-induced damage resistance were analyzed.