Experiences gained from gas and water inflow toward the tunnel, case study: Aspar anticline, kermanshah, Iran

Abstract

Groundwater and gas inflow toward the tunnel being excavated in Aspar Anticline (at the west of Kermanshah, Iran) cause some problems during construction. Aspar Anticline consists of limestone units from Illam Formation which in Iran is known as a resource formation for Petroleum and natural gas. Detailed investigations (based on result of physical and chemical tests performed on different samples taken from the water and air of the Tunnel) show that about 1 lit H2S gas can be solved in 100 lit water and enter to the Tunnel. It is obvious that solved gas can released in Tunnel by decreasing water pressure and disturbance of water. This study shows that there is a strong relationship between geological and hydrogeological parameters and concentration of gas in the tunnel. These parameters can be considered as indices for identifying potential of gas and water inflow toward the tunnel before excavation. Also, in this paper, the problems related to gassy and water inflow in the tunnel, being constructed with double shield TBM machine are discussed. © ISRM International Symposium - 5th Asian Rock Mechanics Symposium 2008, ARMS 2008. All rights reserved.