Analytical model for grouted rock bolt in tunnel design

Abstract

An analytical model for the grouted rock bolt in NATM tunneling design is proposed. Typical distributions of axial loads are presented considering the debonding at the interface between rock bolt and rock mass. The parameters study shows that: 1) The position of maximum axial force is not only related with the length of rock bolt and internal radius of tunnel, but also strongly influenced by physical properties of rock mass. 2) Maximum axial load and its position in rock bolt tends to be constant when anchor length of bolt is long enough, which means it is not good only to increase the length of rock bolt under certain condition. 3) Young's modulus of rock mass influences the working of bolt significantly.