Experimental and Numerical Study on Anchorage Strength and Deformation Properties of Blocky Rock Mass

Abstract

This study experimentally and numerically investigated the anchorage properties, bolt force evolution, deformation and stress fields of blocky rock mass with various dip angles of joint surfaces under an applied axial load. The results show that due to bolt reinforcement, the axial stress-strain curves of anchorage blocky rock mass show typical strain-hardening characteristics, and compared with models without anchorage, the peak strength and elastic modulus increase by 21.56% and 20.0%, respectively. With an increase in axial stress, the lateral strain continuously increases, and restriction effects of bolts reduce the overall deformation of model surfaces. The axial stressstrain curves of anchorage blocky rock mass in the simulations present a “double peak strength” phenomenon due to bolt reinforcement, and the peak strength, second peak strength, residual strength, surface displacement field, as well as the principal stress fields all depend on the dip angles of joint surfaces. As a result of the bolt reinforcement effects, cone-shaped compression zones are produced in the models, and compression zones of adjacent bolts superimpose with each other to form anchorage belts, improving the overall bearing capacity of anchorage models. Obvious stress concentration can be observed at both bolt end and anchorage section. Not only the role of bolt support transfers the blocky rock mass to be a three-dimensional stress state through compression effects, but also it improves both tensile strength and shear resistance of both joint surfaces and the overall blocky rock mass.