An investigation in squeezing potential in the second segment of Azad tunnel

Quick estimation of possible problems is very important for tunnel excavation through anisotropic and low strength rock masses like shale and schist. This paper deals with the squeezing problem in the second segment of Azad tunnel in KordestanProvince which passes through phyllite and slate weak rock masses with squeezing potential. For this purpose four experimental methods were used. According to the obtained results, squeezing value and strain of tunnel wall in the critical section with maximum overburden (760 m) was determined and then support pressure has been calculated by using Hoek & Marinos equation. At final, the results of above experimental methods has been used for estimating of starting squeezing depth nomination in this segment of tunnel, and this depth has been estimated 180 m.