Analytical-numerical solution for stress distribution around tunnel reinforced by radial fully grouted rockbolts

作者:Ranjbarnia Masoud*; Oreste Pierpaolo; Fahimifar Ahmad; Arya Amir
来源:International Journal for Numerical and Analytical Methods in Geomechanics, 2016, 40(13): 1844-1862.
DOI:10.1002/nag.2517

摘要

This paper presents an analytical-numerical approach to obtain the distribution of stresses and deformations around a reinforced tunnel. The increase in the radial stress of the reinforced tunnel, based on the performance of a bolt, is modeled by a function, which its maximum value is in the vicinity of the bolt periphery and it exponentially decreases in the far distance from the bolt. On the basis of this approach, the shear stiffness between the bolt and the rock mass and the shear stress distribution around the bolt within the rock mass are also analytically obtained. The results are compared with those obtained by the assumption of 'uniform increase of radial stress' method, which is made by the previous studies. The analyses show when the bolts' spacing is large, the safety factor must be increased if the 'uniform increase of radial stress' method is used for the design. Finally, a procedure is introduced to calculate the non-equal deformation of the rock mass between the bolts at any radius that can be useful to compute the bending moment in shotcrete layer in New Austrian Tunnelling Method (NATM) approach.

  • 出版日期2016-9