Yokota, Y, Yamamoto, T, Date, K & Mori, T 2013, 'Quality improvement of rockbolting', in Y Potvin & B Brady (eds), Ground Support 2013: Proceedings of the Seventh International Symposium on Ground Support in Mining and Underground Construction, Australian Centre for Geomechanics, Perth, pp. 667-679, https://doi.org/10.36487/ACG_rep/1304_47_Yokota
(https://papers.acg.uwa.edu.au/p/1304_47_Yokota/)
Abstract: Recently, owing to advances in tunnel support and reinforcement techniques, NATM (New Austrian Tunnelling Method) has been increasingly used even for large section tunnels, squeezing tunnels and shallow tunnels in urban areas. Therefore, the authors have focused on improving the quality of rockbolting and have developed a technique for diagnosing the installation condition of rockbolts using ultrasonic waves, high-friction anchored rockbolts using checkered steel pipes and a simplified axial force measurement device using a light emitting converter (LEC). This paper presents the details of each development and actual applications of these new techniques to several sites. All results confirmed the effectiveness of these three techniques.