Abstract: The construction of resin anchor bolts in soft surrounding rock tunnels is complex and inefficient. To address the limitations of traditional resin bolts, two technical schemes involving prestressed hollow bolts with built-in resin are proposed. Their applicability in soft surrounding rocks is examined via working principle analysis, structural design, and field testing. The results reveal the following: (1) Under normal broken surrounding rock conditions, the installation qualification rate of prestressed hollow bolts with built-in resin is 81.9%, significantly higher than that of traditional resin bolts (50%); (2) The net operation times for 3 m and 4 m prestressed hollow bolts with built-in resin are 4.62 min and 5.55 min, respectively; (3) Considering the preparation time for the trolley, the total operation time is controlled within 6－6.5 min and 7－7.5 min, respectively; (4) The self-drilling prestressed hollow bolt with built-in resin achieves self-drilling and pretightening for severely broken surrounding rocks through long prestressed bolts, enabling timely support of the surrounding rock. The construction efficiency of this type of bolt is comparable to that of traditional bolts.

Key words: railway tunnel, built-in resin, prestressed hollow bolt, anchorage support, soft surrounding rock, self-drilling bolt