通过弹塑性有限元数值模拟，分析了软基条件下考虑新老路基相互作用的高速公路拓宽变形性状。计算结果表明：①新路基填筑使路基沉降呈现老路中心沉降小、拓宽路基沉降变形大的反盆形分布形式；②随填土高度的增加，路基沉降增大，路基顶部最大沉降点逐渐外移，在新路基顶面相对位置由新路基中心向新路基路肩移动；③随着路基加宽宽度的增大，路基沉降增大，新路基最大沉降点逐渐外移，在新路基顶面相对位置由新路基路肩向新路基中心移动；④新路基预压期越长，路基工后沉降越小；⑤新路基填筑速率越大，路基工后沉降越大。深入了解加宽路基的沉降变形性状，有助于确定合理的软基处理和路基拼接方案，为路基拼接优化处理提供参考。

Elastic-plastic finite element numerical simulation is performed to analyze the deformation characteristics of highway widened on soft clay ground when the interaction between new subgrade and old subgrade is considered. The results indicate that the construction of new subgrade leads to small settlement at the old road center and large settlement on the new subgrade, which exhibits a reverse basin shape. The subgrade settlement increases with the rise of subgrade height, and the maximum settlement at the top of new subgrade moves outward from the new subgrade center to new subgrade shoulder. The settlement also increases with the expansion of new subgrade width, and the maximum settlement at the top of new subgrade moves outward from the new subgrade shoulder to new subgrade center. Settlement after the construction would reduce as the precompaction period of new subgrade elongates, while increase as the construction shortens. A good insight into the settlement deformation behavior is contributive  to the determining of soft clay subgrade treatment and splicing scheme.