Mechanical Properties and Anchorage Angle Optimization of Rock Mass with a Weak Intercalated Layer

Abstract

A weak intercalated layer has gradually become the key problem in roadway surrounding rock control in deep rock stress environment, and the selection of anchorage angle has a great influence on the stability of the intercalated rock. This study aimed to prepare weak intercalated layer-composited specimens with different dip angles and anchorage angles for the uniaxial compression test. The results showed that the strength curve of the composite specimens exhibited a single-peak variation trend of first decreasing and then increasing from 0° to 90° inclination variation, and the strength and strain reached the lowest value at 60° inclination angle. The failure modes of composite specimens with different dip angles could be divided into single splitting failure, coupled shear failure, and single shear failure. The initial strength of the unanchored specimen was basically the same as that of the anchored specimen, and with the increase in anchorage angle, the uniaxial strength first increased and then decreased. The appropriate anchorage angle range was 0° to 30°. Mainly slip deformation of the specimen occurred when the anchorage angle was smaller than 30°, and the deformation of the specimen mainly depended on the material of the bolt when the anchorage angle was larger than 30°. The strength variation model of the composite anchorage specimen was proposed, taking into account the stress of the bolt, the influence of the dip angle of the intercalated layer, and the anchorage angle of the structural plane.