关键词: 锚杆, 岩体反力, 抗剪力, 轴向力, 横向剪切力

Abstract: This study aims to solve the problems on the nonlinear behaviour of rock mass or mortar against the pressure side of the bolt and the dilatancy effect of the structural surface. Theoretical formulas for the axial force and axial deformation, transverse shear force and transverse deformation of anchor bolts were derived, and the formula for the shear resistance of anchor bolts was also established based on the classical beam theory. The validity of the theoretical solutions was verified by the direct shear test on bolted structures. Furthermore, this study performed the effects of joint dilatancy coefficient, joint friction angle, surrounding rock strength and bolt installation angle on the deformation and shear resistance of anchor rods. The results showed that the theoretical calculation results were in good agreement with the experimental results. The higher dilatancy coefficient led to the higher shear resistance of the bolt, but less significant of plastic behaviour. Thus, the shear resistance of bolted joint can be improved by the inherent shear strength of the structural surface. When the strength of surrounding rock decreased, the anchor bolt had to undergo specific deformation to exert a large shearing effect. The higher strength of rock resulted in the yield failure of the bolt within a shorter time, and the damage of the anchor bolt was gradually transformed from the axial tensile failure into tensile shear failure. The optimal installation angle of the bolt increased with the increase of the internal friction angle of the structure. The optimal installation angle of the bolt was estimated within the angle ranging from 30° to 68° in working joint conditions.

Key words: cable bolt, grout reaction force, shear resistance, axial force, transverse shear force