DOI: 10.15986j.1006-7930.2019.03.003
通过有限元软件模拟了上拔荷载作用下斜桩的承载变形性状并与直桩进行比较,分析了桩身倾角对桩顶位移、极限抗拔承载力、桩身弯矩、剪力及轴力的影响,研究了斜桩-土接触压力、桩侧摩阻力的分布特征,探讨了长径比与斜桩有效桩长的关系.结果表明:在上拔荷载作用下,斜桩桩顶的上拔位移均大于相应直桩.桩身倾角及上拔荷载越大,上拔位移和水平位移越大; 斜桩极限抗拔承载力大于直桩,且在15～20°之间存在一个最佳倾角使斜桩的极限抗拔承载力达到最大; 桩身最大弯矩均出现在z/L=0.1处,最大剪力均出现在桩顶截面处.在z/L=0.4以下区域,桩身弯矩及剪力几乎全部为零.同一桩身相对深度处,桩身剪力及弯矩都随着倾角的增大而增大; 直桩及各斜桩桩端存在真空吸力.倾角对桩身轴力的影响不大; 桩-土接触压力的大小与桩身倾角的大小有关.桩与土沿深度方向脱离的范围随着倾角的增大而增大; 斜桩左、右两侧摩阻力分布相差较大,其大小与倾角的大小有关; 上拔荷载作用下斜桩存在有效桩长.倾角的大小对有效桩长影响不大.
The finite element software was used to simulate the load-bearing deformation behavior of the slanted piles under upward loading and compared with the vertical piles. The displacement of the pile top, ultimate pull-out capacity, bending moment, shear force and shaft of the pile were analyzed. The influence of force was studied on the distribution characteristics of slant pile-soil contact pressure and pile side friction resistance, and the relationship between length-diameter ratio and effective pile length of slanted pile was discussed. The results show that under the action of uplifting load, the uplift displacement of inclined pile top is larger than that of corresponding vertical pile.The greater the inclination angle and updraft load of the pile, the larger the uplift displacement and horizontal displacement; the ultimate pullout capacity of the inclined pile is greater than that of the vertical pile, and there is an optimal inclination angle between 10° and 20° so that the ultimate resistance of the inclined pile. Pulling load capacity reaches the maximum; the maximum bending moment of the pile appears at z/L=0.1, and the maximum shear force appears at the top of the pile section. In the area below z/L=0.4, the bending moment and shear force of the pile are almost zero. At the relative depth of the same pile body, the shear force and bending moment of the pile increase with the increase of the inclination angle; The vacuum suction force exists at the pile end of the vertical pile and each inclined pile. The dip angle has little effect on the axial force of the pile body; The pile-soil contact pressure is related to the size of the pile body inclination angle. The range of separation between pile and soil in depth direction increases with the increase of inclination angle; The distribution of friction resistance on the left and right sides of the inclined pile is quite different, and its size is related to the size of the inclination angle; Effective for the inclined pile under upward loading Pile length. The size of the dip has little effect on the effective pile length.
