Abstract: This paper presents the optimization results of double-row piles as the deep excavation supporting structures for a case history in Nanning, Guangxi. A three-dimension numerical model of the supporting structure of double-row piles to analyze the deformation characteristics under various conditions was established by commercial finite difference software FLAC3D. The results indicated that the increasing the row spacing can effectively reduce the excavation induced risk and the horizontal displacement of the piles. The horizontal displacement in the double row soldier pile is gradually increasing with the decrease of the pile length and the diameter of the rare-row piles but the deflection value is within the allowed range. Therefore, the length and the diameter of the rare-row piles can be appropriately reduced if the safety of the excavation can be ensured.

Key words: deep excavation design software, doublerow piles, parametric analysis, design optimization