COUPLING MODEL OF BOLT REINFORCEMENT SYSTEM AND APPLICATION
杆状支护系统的耦合模型及应用

A normal analytical model for reinforcement is proposed, on the basis of refined Shear-Lag model, to describe the mechanical coupling at the interface between reinforcement and rock/soil mass. Coupling and decoupling behavior of reinforcement in pullout test is analyzed, and a new method is suggested to evaluate actual shear strength of interface between reinforcement and rock/soil mass. Average shear force is smaller than actual shear strength. The difference is related not only to the embed length of reinforcement, but also to the deformation modulus of matrix material. Interaction influence of anchor length and matrix's deformation modulus is often ignored in normal pullout test, which may leads to large deviation. Rational anchor length is suggested for pullout test. Analysis of bolt around tunnel shows that there is a pullout area, neutral point and anchor area along bolt. The position of neutral point is not only determined by geometry of tunnel, but also influenced by the rock mass properties. Theoretical prediction coincides well with testing data.