Assessment the Stability of Tunnels in Y Shaped Intersections with Regard to the Intersection Angles, Case Study: Penstock Tunnels of Rudbar Dam

Document Type : Research Article


1 Assistant professor, School of Railway Engineering, Iran University of Science and Technology

2 MSc Student, School of Railway Engineering, Iran University of Science and Technology


Stress analysis and stability control in tunnel intersections is a very complicated issue due to stress concentration and three-dimensional situation. During tunnel construction, increase in load on support, extra tunnel deformations and disordering in rock around of intersection zone is unique and instability may be occur in this sections. In order to control extra deformation and stress, these sections need stronger support system than other sections. Extra deformations and stress values in Y shaped intersections influenced by tunnel intersection angle. The effect of intersection angle on length of extra support has been studied in this paper by three-dimensional modeling of penstock tunnel intersection of Rudbar Dam in FLAC3D. Numerical analysis results for three intersection angles of 60, 75 and 90 show an increase in length of extra support by decreasing in intersection angle.


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