PCC桩是一种适合软土地区加固的刚性桩，以大面积PCC桩复合地基中的一个桩-土-垫层单元为研究对象，考虑桩-土-垫层的共同作用，提出了PCC桩复合地基桩土应力比的一种计算方法。该方法假定桩土界面的摩阻力与桩土相对位移为理想弹塑性关系、同一水平面上桩间土与桩芯土沉降相同、桩端土符合Winkler地基模型，考虑桩-土-垫层的协同作用机理，推导出了PCC桩复合地基桩土应力比和沉降的计算公式，并根据推导出的公式对桩土应力比的影响因素进行了分析，为PCC桩复合地基优化设计提供参考和依据。

The cast-in-situ concrete thin-wall pipe pile (PCC pile) is a kind of rigid pile suitable for reinforcing soft foundation. A new method of calculating the pile-soil stress ratio of PCC pile composite foundation is presented taking the combined action of pile-soil-cushion into account. The relationship of frictional resistance and relative displacement between the pile shaft and the surrounding soil is idealized as perfectly elastoplasticity; meanwhile, settlement of soil between the piles and inside the piles at the same depth is assumed to be equal, and the soil at the pile tip is considered to be in conformity with Winkler ground model. Based on these assumptions, the calculation formulas for pile-soil stress ratio and settlement are derived through analyzing the pile-soil-cushion interaction. The influencing factors of pile-soil stress ratio are discussed according to the obtained formulas, which are beneficial to the optimal design for PCC pile composite foundation.