协力桩 (筏 )基础是疏桩基础的一种 ,它的特点是桩稀疏布置 ,因此和传统桩基相比较可大幅度降低基础工程的造价 ,是桩基发展的一种趋势。本文在明确了协力桩 (筏 )基础的概念后 ,详细分析介绍了它的类型、承载特点、设计方法等 ,并对逆作法施工在其中的应用也进行了探讨 The foundation of the third pile (raft) is one kind of sparse pile foundation. Its characteristic is that the piles are sparsely arranged. Therefore, compared with the traditional pile foundation, the cost of the foundation engineering can be greatly reduced, which is a tendency of pile foundation development. After defining the concept of third-party pile-raft foundation, this paper analyzes its type, bearing characteristics, design method and so on in detail, and also discusses the application of reverse-work construction in it