大面积路堤荷载下带承台桩的荷载传递分析

Analysis on load transfer for caped piles under large area of embankment

提出用迭代法分析大面积路堤荷载下带承台桩荷载传递特性的计算方法。将大面积路堤桩中的任意一根桩及其代表的桩间土看作一个存在相互作用力的柱杆系统,单个柱杆用荷载传递法分析,柱杆之间的相互影响用迭代法分析。该方法可简便地考虑桩、土、承台和路堤的相互作用,地基土的分层特性和桩身荷载传递函数的非线性。假定传递函数分别为线弹性全塑性和指数曲线的模型时,对双层地基中的路堤桩进行了算例分析,得到荷载分担比、等沉面、中性点、沉降、轴力、摩阻力等结果。讨论桩顶荷载分担比、中性点位置随填土高度、桩长和承台置换率的变化规律。计算桩顶荷载分担比与模型试验的中央桩实测结果大体一致,荷载传递特性与数值模拟结果也大体一致。

An iterative method to analyze the load transfer of caped piles under large area of embankment was presented. An individual pile with the surrounding soil in large scale pile groups was taken as a column system with interactions. An individual pile column was analyzed by using a load transfer method, while the interaction was analyzed through an iterative process. The pile-soil-cap-embankment interaction and the nonlinearity of load transfer curve for layered soils may be conveniently taken into account. Regarding the load transfer curve as ideal elastoplastic or exponential curve, an embankment caped pile in layered soils is analyzed to obtain the stress ratio, equal-settlement surface, neutral point, displacement, axial force, and skin frictional resistance. Factors influencing the pile efficacy and neutral point location were studied, including fill thickness, pile length, replacement ratio of cap, etc. The calculated pile efficacy is agreement with the measured value for the central pile of 3×3 pile group, and so is the load transfer characteristics.