横向荷载对基桩竖向承载力的影响分析

Effect of Transverse Load on Vertical Load Capacity of Piles

为研究横向荷载对基桩竖向承载力的影响,首先利用m法假设下轴横向受荷桩桩身挠曲方程的幂级数解,得到桩周土对桩身抗力沿桩轴向的分布,在此基础上利用横向受荷桩桩侧土体应力分布弹性解,求得桩周所受法向压力的变化量,进而得到桩侧阻力极限值的变化量沿桩轴向的分布,将此变化量积分得到由横向荷载引起的桩侧极限摩阻力的变化量,由于横向荷载对桩端阻力影响不大,故此即为基桩竖向承载力的变化量,横向受荷桩的竖向承载力即为此变化值与无横向荷载作用时基桩的竖向承载力之和。然后将导得的计算公式对某试验进行分析,其结果表明计算值与实测值吻合较好,最后对横向荷载下基桩极限侧阻力变化量的影响因素进行了分析。分析结果进一步证明了横向荷载对基桩竖向承载力有一定影响,在工程设计中值得注意。

In order to analyse the effect of transverse load on vertical load capacity of piles, the distribution of soil reaction along pile axis was obtained by using the power series solution of deflection equation of piles subjected to both transverse load and axial load based on m method. Then with the elastic analytic solution of stress distribution in the soil surrounding piles subjected to transverse load, the variation of normal pressure acted on the pile was derived and the distribution of the variation of limit skin friction along pile axis was obtained, and this variation was integrated to get the variation of the ultimate skin friction due to transverse load. This variation equals the variation of the vertical capacity since transverse loading has little effect on the ultimate base resistance, the vertical load capacity of piles subjected to transverse load is the sum of the vertical load capacity of piles not subjected to transverse load and the variation of the ultimate skin friction. After that, an experiment was analyzed by using the established formula.The result shows that the calculated values are close to the tested values.At last, the influencing factors of the variation of ultimate skin friction of piles subjected to transverse load were analysed, and the result further confirms that transverse load has some influences on vertical load capacity and it is noteworthy during the design of pile foundation.