Numerical Investigation on the Interaction between a U-Shaped Pile Supporting Structure and an Adjacent Gravity Retaining Wall in River Dredging

Abstract

There is significant interaction between the new supporting structure and the existing adjacent retaining wall in the dredging and excavation project of urban rivers. In addition, the three factors, the spatial location, the stiffness of the structures, and the soil conditions of the two sides of the interaction will exert effects on the bearing properties of the two structures. Combined with an actual dredging project, FLAC3D software was applied to analyze the influencing rule of U-shaped concrete sheet pile (USCSP) section size, pile length, retaining wall height, and pile–wall spacing on the supporting structure and the bearing properties of the existing gravity retaining wall during dredging excavation. The results are that when the length of the sheet pile increases, the horizontal displacement of the pile gradually decreases, the horizontal displacement of the existing retaining wall declines, and the earth pressure at the wall’s back rises. With the increase in the section size of the sheet pile, its bending resistance enhances gradually, and the horizontal displacement of the existing retaining wall reduces, while the earth pressure slightly increases. When the pile–wall spacing grows, the interaction between the supporting structure and the retaining wall is gradually weakened under the process of excavation, the horizontal displacements of the sheet pile and the retaining wall decrease continuously, and the earth pressure at the retaining wall’s bottom continues to strengthen. Moreover, with the retaining wall growing, the passive resistance from the soil in front of the wall is greater for keeping the stability of the retaining wall, and the horizontal displacement and the stress of the sheet pile increase significantly after excavation. The above results indicate that the characteristics of the pile–wall interaction should be deeply considered in designing and constructing such projects in order to determine the overall stability of the retaining pile and the existing retaining wall. In this study, FLAC3D software was used to analyze the influence of various factors on the structure in order to provide reference for ensuring the safety of the whole structure.