Ashkan Rahmani and Vahid Hosseinitoudeshki
Abstract
This paper presents numerical analysis of the effect of KARSTIFICATION on the axial force of lining in tunnels excavated in the limestone by means of elasto-plastic finite element method. In numerical analysis, a 2D finite element program with software Phase 2 is utilized. The circular tunnels are modeled with diameter of 6, 8, 10, 12 and 14 meters and reinforced with lining. Then, the effect of circular and rhombus karsts is investigated on the axial force of lining. The results of the evaluations show that by increasing distance of karsts from the tunnel, the axial force changes of lining have decreased and the maximum of these changes has occurred by circular karstification at the bottom of tunnels. Furthermore, by increasing diameter of tunnels, the ratio of the axial force changes of lining due to karstification has reduced.