竖向荷载作用下斜桩荷载传递性状试验研究

Experimental study of load transfer behavior of batter piles under vertical loads

通过模型试验研究了竖向荷载作用下砂土中斜桩的荷载传递性状,分析了桩身倾角及长径比对斜桩桩身轴力、弯矩、剪力、桩侧摩阻力及端阻比的影响。试验结果表明：在桩顶竖向荷载作用下,斜桩桩身轴力均小于相应直桩桩身轴力,桩身倾角越大,轴力沿深度衰减得越快,桩长径比越大,轴力沿深度衰减得也越快;斜桩桩身最大弯矩随桩身倾角及长径比的增加而增加,最大弯矩出现的深度与桩身倾角无关,只与长径比相关;不论桩身倾角及长径比的大小,斜桩桩身最大剪力均出现在桩顶截面处,桩身最大剪力随着桩身倾角的增加而增大;桩身倾角越大,斜桩最大摩阻力越大,长径比越大,斜桩最大摩阻力越小,斜桩最大摩阻力出现在桩顶下1/4～1/5桩长处;斜桩端阻比随着桩顶竖向荷载的增加而增大,随着桩身倾角及长径比的增加而减小。

A series of model tests is conducted to explore the load transfer behavior of batter piles embedded in sand under vertical loads. The effects of inclined angle of pile and ratio of pile length to its diameter（L/D） on pile shaft axial force, bending moment, shear force, skin friction and the ratio of tip resistance to the pile head load are analyzed. The results show that： the axial force of batter pile subjected to vertical load is less than that of vertical pile; the greater the pile inclination and the ratio of L/D are, the faster the axial force attenuates along the depth. The maximum bending moment of batter pile increases with the increasing of inclined angle as well as the ratio of L/D; but the depth at which the maximum bending moment occurs is only associated with the ratio of L/D. No matter what the magnitudes of the inclined angle and the ratio of L/D are, the maximum shear force always occurs at the pile top; and the maximum shear force increases with the increasing of the pile shaft inclined angle. The larger the pile inclination and the L/D are, the greater the maximum frictional resistance is, the smaller the maximum frictional resistance of the batter pile is; the maximum frictional resistance of the batter pile always occurs at a depth of 1/4-1/5 pile length below the pile head. The end resistance ratio of batter piles increases with the increase of vertical load of the pile, and decreases with the increase of inclination angle and the L/D.