A method to design and optimize on this composite foundation is provided, include of the size of cap on the top of pile, how to calculate the load on piles and soil, and the concise method with two step for calculating settlement.

• 并提出PTC疏桩复合地基的优化设计思路，桩帽的设计方法，桩、土分担荷载的计算方法，以及沉降计算中简单适用的分部计算法和拟应力修正法。