The bearing capacity of super-long and large-diameter bored pile tip is influenced by the facts including construction process,depth effect,size effect and so on.

The analysis of pile tip settlement measuring and the data of pile testing,has ex-pressed that the stress-strain process of upper loads on pile shaft and foundation soil has elastic deformation characteristics of both pile and foundation soil.

Axial pull-out test of core concrete of prestressed concrete pipe piles and analysis of stress at the pile end;

The paper introduced the design and construction of pile end bearing layer strengthening for assuring the engineering quality.

In the limited formula of explosive-enlarged hole pile, there are some unclear expressions of the mechanism in bearing load.