关键词: 沉桩深度, 隧道, 圆孔扩张理论, 桩-土相互作用, 静压桩

Abstract: This article begins with simulation of the static pressure pile driving process with FLAC3D based on the cavity expansion theory, and compares the results of numerical simulation and analytical calculation. The calculated values and the trends of numerical simulations and analytical solutions are consistent. Therefore, simulation of the effect of pile driving friction on the displacement penetration method helps produce results close to practice in the entire pile driven process calculation. The pile driving calculation of the resultant effects on the deformation and inner force of the nearby tunnel with depth of 4, 8, 12, 16 and 20 m draws the conclusion that static pressure pile driving has an obvious effect on the deformation of the nearby tunnels. As the depths increases, displacement of the tunnel structure increases, which mainly consists of the displacement in the horizontal direction. The maximum tunnel structure displacement reaches 11.55 mm when the pile driving depth is 20 m. Meanwhile, the pile driving process results in tunnel deflection: counterclockwise (away from the pile) deflection when the pile driving depth is 4, 8, 12 and 16 m; clockwise (toward the pile) deflection when the pile driving depth is 20 m. As the pile driving depth increases, the additional bending moment distribution of the tunnel structure changes gradually from vertically axial symmetry to laterally axial symmetry. The tunnel bending moment turns counterclockwise (toward the tunnel) after pile driving and for most tunnel structures, the absolute values of bending moment tend to decrease.

Key words:  the depth of pile driving, cavity expansion theory, pile-soil interaction, tunnel, static pressure pile