An Investigation into the Effect of Foliation Orientation on Displacement of Tunnels Excavated in Metamorphic Rocks


1 Geotechnical Engineering, Department of Civil Engineering, University of Mohaghegh Ardabili, Ardabil, Iran.

2 Geotechnical Engineering, Department of Civil Engineering, Islamic Azad University, Zanjan Branch, Zanjan, Iran.

3 Department of Civil Engineering, Islamic AzadU niversity, Zanjan Branch, Zanjan, Iran.


Rocks show a different behavior towards excavation due to their continuity or discontinuity, elastic or inelastic behavior, isotropy or anisotropy and homogenous or heterogeneous nature and the response behavior of tunnels has always been a concern for geotechnical engineers during excavation operations in a variety of stones. Anisotropic rocks have different properties in different directions and also in different locations. In the present study, the effect of foliation orientation on the displacement of tunnels excavated in metamorphic rocks is evaluated. Hence the tunnel excavation is modeled for a metamorphic rock medium in different directions of foliation plane. The results show that the vertical displacement of tunnel crown is seen at a distance of 4 to 6 m from the critical tunnel face in all samples, where more than 60% of deformations occur. It should be noted that 20% of deformations are reported at a distance of 6 to 15 m along the excavation face section.