Abstract
On the basis of a refined Shear-lag model, a constitutive equation is proposed to estimate the axial force of rock bolt according to the displacement of surrounding matrix. Coupling and decoupling behaviors of reinforcement in pullout tests, around an underground opening and opening joints are discussed respectively. For pullout test, the distribution of axial force and shear stress is compared with former research and test results, and a back analysis method is suggested to estimate the shear strength of the interface and the ultimate capacity of the rock bolt. As an example, the behavior of rock bolts intersecting multizone around a tunnel is analyzed, and the neutral location of rock bolts is discussed further. For a rock bolt intersecting joints, more than one neutral point may appear according to analysis.
