determination of ground surface subsidence of subway twin tunnel in tabriz and comparison of both numerical and experimental methods

low-depth and the soil lands tunnel diggings cause displacement around the tunnel which is horizontal and vertical. this displacement can be reached the surface and cause damage to structures on the surface of land. therefore estimate of how level the ground subsidence making, in effect of the low-depth tunnel digging especially the urban environment it is directly related to people's lives, is of special importance. the study aims to predict the situation of the surface settlement resulting from the twin tunnels digging in urban areas. according to the old texture of tabriz and its surface structure, it is essential to take the effect of digging the underground space on the around, such as the ground settlement into consideration. in this paper, the manner of soil and the ground settlement caused by digging tunnels is studied. first, using different experimental equations, it is estimated the settlement resulting from the twin tunnels excavation of subway in tabriz and then tunnel modeling by software plaxis it is compared the depth of which the land become settled down with the settlement of the empirical equation sand then it was investigated and predicted for tabriz settlement line 1 in the study area.