中文摘要：

在一定简化的基础上，根据位移、应力连续条件，将路堤填土、加固区和下卧层作为统一的整体，提出了考虑桩顶上刺、桩土相互作用和桩端下刺的路堤荷载下复合地基加固区计算模型，并建立了模型的有限差分解法。基于三维数值模拟结果，采用考虑复合地基下卧层应力集中效应的下卧层附加应力计算方法，从而建立路堤荷载下复合地基沉降计算方法。计算实例表明，复合模量法计算结果偏小，而应力修正法偏大，所提方法最接近实测结果，具有较好的适用性。

英文摘要：

Based on some simplifications, the embankment, improved area and substratum are treated as a whole with continuous displacements and stresses. A settlement calculation model for the improved area of the composite foundation under embankment load is developed, especially taking the penetration of the pile top, the interaction between column and surrounding soil, and the penetration of the pile end into account. And a finite difference method is presented to solve the calculation model. Based on 3D numerical simulation results, a simplified method is used to calculate additional stresses in substratum of the composite foundation under embankment load, with the stress concentration phenomenon taken into consideration. Then the settlement calculation method of the composite foundation under embankment load is presented. The computational results indicate that the settlement calculated with composite modulus method is smaller while that with a modified stress method is far lager than observed data, and the result calculated with the proposed methods agrees well with observed data.