The demand for specific earth retaining wall methods is increasing along with the advancement and overcrowding of underground space use such as the presence of adjacent structures in an urban area. To cope with this, the method named earth stepped-twin retaining wall is increasingly being applied. However, there is a concern about the workplace if the earth pressure causes a heaving and pressing phenomenon from both ends of the retaining wall in the earth stepped-twin retaining wall. Therefore, we proposed the application of an anchor method that contains the inner and outer walls by using numerical simulation. The effects of the difference in soil properties, the horizontal distance between the outer and inner walls, and the depth of the outer wall embedment on the anchor were investigated. The results of this study show that the wall deflection of the inner wall could improve by adopting the anchor support. Besides, it was found that the inner wall can be efficiently suppressed by adopting the hybrid system with anchors and struts according to the soil properties, horizontal distance, and the depth of the outer wall.

The demand for specific earth retaining wall method is increasing, along with the advancement and overcrowding of underground space use, such as the presence of close structures, in an urban area. The method is named stepped-twin retaining wall. The feature of this method is to have inner and outer retaining walls and excavate the ground by two-step in order to minimize the effect of the excavation on neighboring existing structures. However, the design of the earth retaining wall is currently carried out by individual engineers based on their own experience. Therefore, it is crucial that the standard method of retaining wall using a two-step construction is established. As the first step toward the standardization, evaluation of factors affecting the ground behavior of the earth retaining wall was carried out. In particular, we picked up four major considerable factors, which are horizontal distance between the outer and inner walls, depth of outer wall embedment, mechanical properties of soil. The evaluation was done by using two dimensional FEM analysis and the results were summarized to make clear the effect of each factor.