考虑剪切变形影响的桩基m法计算理论

Calculating theory of m method assumption for piles with shear deformation effect

考虑桩基的剪切变形影响,利用单广义位移深梁理论,建立了桩基m法的计算方法,导出了水平位移、转角、弯矩和剪力的初参数表达式和无量纲参数函数的统一表达式,根据桩底边界条件建立了初参数解的计算公式;给出了无量纲参数函数随换算深度和弯剪刚度比的变化图形。研究表明,换算深度小于3.0时,弯剪刚度比对无量纲参数函数影响较小,换算深度大于4.0时,弯剪刚度比对无量纲参数函数影响的趋势非常明显,桩基剪切变形的影响程度与桩的边界条件有关。算例结果表明,桩身的剪切变形有增大桩顶水平位移、提高弯矩零点位置、改变弯矩分布特征、扩大桩侧土压力大小等影响。

Considering the shear deformation effect of piles,the calculating theory of m method assumption for piles was presented by using the single generalized displacement theory of deep beam.The initial parameter formulae to horizontal displacement,slope,moment and shear force were derived.The unified non-dimensional functions were also put forward.According to the boundary conditions,the initial parameters solutions were determined.The changing figures of non-dimensional functions with converting length and ratio of bend stiffness to shear stiffness were plotted.Some conclusions were summarized that when the converting length was less than 3.0,there was little influence of the ratio of bending stiffness to shear stiffness on the non-dimensional functions,while the converting length was greater than 3.0,the influence of the ratio of bending stiffness to shear stiffness on the non-dimensional functions became obvious;the influencing degree of the shear deformation effect was related to the boundary conditions.Example results showed that shear deformation can enlarge the horizontal displacement at the top,lift theposition of zero moment,change moment distribution and magnify the soil pressure on pile.