Study on Stress Characteristics and Time Effect of Pile Group in High Backfill Site

In order to investigate the effect of creep of the fill around pile on the mechanical properties of the group pile foundation, using the finite difference software FLAC3D, the mechanical properties of $\boldsymbol{2}\times\boldsymbol{2}$ group pile foundation with a fill thickness of 10m and a rock embedded depth of 3m are studied The results show that during the creep of the perimeter fill, the group pile foundation will lead to differential fill and the group pile foundation will lead to differential fill. The results show that during the creep of the perimeter fill, the group pile foundation will lead to differential settlement of the perimeter fill and the inter-pile fill, which will weaken the downward pulling effect of the inter-pile fill on the pile foundation and produce bending moment on the pile cross-section; the variability of the pile internal force, neutral point The variability of the pile internal force, neutral point depth and pile end resistance with time is shown as the creep time increases, the neutral point depth and pile internal force change rapidly in the settling The creep deformation of backfill is a reorganization of its internal structure, which has little effect on the change of soil pressure at its bottom; the effect coefficient of negative frictional resistance effect coefficient of negative frictional resistance group pile calculated by the normative method is on the safe side, which should be optimized in the design with the group pile arrangement and The effect coefficient of negative frictional resistance group pile calculated by the normative method is on the safe side, which should be optimized in the design with the group pile arrangement and pile foundation.