2-D analysis of circular tunnel against earthquake loading Mohammad C. Pakbaz a, * , Akbar Yareevand b a Department of Civil Engineering, Shahid Chamran University, Ahwaz, Iran b Department of Civil Engineering, Khuramabad University, Khuramabad, Iran Received 12 February 2004; received in revised form 24 January 2005; accepted 30 January 2005 Available online 14 March 2005 Abstract The use of und