This study investigated the relationship between bolt rib spacing and anchorage performance under different conditions of surrounding rock. Based on the thick-walled cylinder theory

pull-out tests were carried out on sinistral rebar bolt specimens with the spacing of 12

24

36

and 48 mm

which were anchored in the steel sleeves with wall thicknesses of 4.5 and 6.0 mm

respectively. Results of the drawing force

the displacement of drawing force more than 100 kN

the circumferential strain of the sleeves and energy dissipation were obtained. Experimental results show that the displacement of drawing force more than 100 kN

the circumferential strain and the energy dissipation value of the sleeve increase with increasing the rib spacing in different sleeves (different surrounding rock conditions)

respectively. The pulling force of anchor rod is found to be the highest when the rib spacing is 24 mm. While with the same rib spacing

the stronger the surrounding rock is

the larger the pulling force is. The circumferential strain of the sleeve with a 4.5 mm thick wall is larger than that of 6.0 mm

which indicates that the effect of surrounding rock is significant on the deformation ability of bolts. Moreover

the anchorage performance can be improved by increasing the rib spacing under different surrounding rock conditions.