Tree root pile for underpinning and reinforcing of existing building foundation and construction method of tree root pile

The invention discloses a tree root pile for underpinning and reinforcing of an existing building foundation and a construction method of the tree root pile. In a traditional tree root pile underpinning structure, a section of expanding pile body is formed at the bottom of a foundation to be underpinned, and interface shearing and friction type connection between a traditional tree root pile and an existing building foundation are changed into pressure-bearing type connection between the expanding pile body and the bottom of the existing building foundation. Therefore, the force transmission between the tree root pile and the existing building foundation is more direct and reliable, and the settlement of the existing building after underpinning can be reduced. 本发明公开了一种用于即有建筑物基础托换加固的树根桩及其施工方法，在传统树根桩托换结构中，在拟托换基础底部，形成一段扩径桩体，将传统树根桩与即有建筑物基础之间的界面剪切、摩擦型连接，变为扩径桩体与即有建筑物基础底部之间的承压型连接。使树根桩与即有建筑物基础之间的力的传递更直接、更可靠，并可减少托换后即有建筑物的沉降。