Daraei, Rahman, Bengin M.A. Herki, and Aryan Far H.Sherwani. 2017. “Study on the Rapid Drawdown and Its Effect on Portal Subsidence of Heybat Sultan Twin Tunnels in Kurdistan-Iraq”. Civil Engineering Journal 3 (7):496-507. https://doi.org/10.28991/cej-2017-00000108.