Numerical Calculation of Reducing Negative Shaft Resistance of Group Piles with Asphalt Coats

In this paper, the finite difference software FLAC3D is used to simulate the reduction effect of asphalt coat pouring on piles of a bridge. The numerical simulation uses contact parameters to simulate the interaction of the coat between piles and soil. In several cases stack loads, distribution of axial forces along piles and settlements on the caps of piles are computed. The action of asphalt to reduce the negative shaft resistance is analyzed. The results show that the finite difference software FLAC3D can be used to simulate negative shaft resistance of group piles and reducing action of asphalt coats. Asphalts coats of group piles play roles of obviously covered curtain. The neutral point position of the corner pile is the lowest and the range of negative shaft resistances is the largest. The neutral point position of the center pile is the highest and the negative shaft resistance range of it is the least. These results answer to the practice engineering rules. This paper concludes that as stack loads increase, the neutral point position gradually moves downwards. The larger stack loads are, the more obvious reducing effect of negative shaft resistances and settlements on the caps of piles are. The conclusions offer guidance to the design and calculation of group piles.