Omid Ahrami - phd Student ,Civil Engineering Department, Science and Research Branch Islamic Azad University, Iran
Meysam Fadaee - Assistant professor, Civil Engineering Department, Science and Research Branch Islamic Azad University, Iran
Zoubin Malekpour - M.S.c Student ,Civil Engineering Department, Islamic Azad University of Zanjan, Iran
Hamid Malekpour - M.S.c graduate ,Civil Engineering Department, Tehran University technical faculty , Iran

Underground facilities are an integral part of the infrastructure of modern society and are used for a wide range of applications ,including subway and railway ,highways and water transport .Underground spaces and tunnels that are in seismic region must be resistant against static and dynamic loads .With pay attention to seismic design importance of underground structures, in this article first it will be tried to present a suitable investigation about difference between surface structures design and underground constructions norms and its efficient factors for arriving at a conclusion . one of the most important effective items in tunnel’s Seismic design is tunnel rigidity ratio and its environment .According to researches it is shown that deformations and forces come in to tunnel in earthquake timely are dependent on relative rigidity structure and its ground environmental that it can be a basic parameter for tunnels and underground structures design

tunnel , interaction , structure , seismic , free field