عنوان مقاله [English]
نویسنده [English]چکیده [English]
A gravity retaining wall is designed in cross sections for unit length in plane strain condition. But there are some friction forces between tunnel portal wall and trench and gallery which they can help the structure to be stable and this is the main difference between a tunnel portal wall and a regular gravity retaining wall. The friction forces can be calculated by reaction of the contact surfaces. With respect to the variation of thickness of the portal wall, stress and then force distribution in the surfaces will be nonlinear. Therefore based on the force distribution’s equations have been calculated the value and location of the friction forces by integrating of the formulations. Three different heights of the portal wall and regular gravity wall have been designed. The heights were 6, 7.5 and 9.5 meters and a horizontal acceleration (0.2g) has been considered as an earthquake event. The results of the calculations show that the portal walls with 6 to 9.5 meters height can be designed about 36 to 52 percent lighter than regular gravity retaining walls.