By analyzing the seismic survey data of portal structure of highway tunnels in Wenchuan Earthquake,the results show that the structure outside the tunnels is more influenced by the secondary disasters,and impacted by seismic inertia force significantly;and that there is almost no structural damage of tunnel portal section in hard rock,while more serious damage occurs in soft rock.Through three-dimensional finite difference numerical simulation and analysis of typical field damage,seismic damage mechanism of...