Research on Calculation Method of the Cushion Thickness in the Rigid Pile Composite Foundation

The paper analyzed the calculating method of the cushion thickness in rigid pile composite foundation.Based on Terzaghi theory,the minimum thickness and the maximum thickness are derived considerding the function of the cushion and its possible failure modes.Moreover,the determination principle of the best cushion thickness is brought forward.The mimimum thickness of the cushion takes the value of pile's upper penetration into the cushion,while the cushion thickness is taken as the maximum thickness when the vertexes of sliding surface contact the bottom of pile cap.Finally,the calculation method of the cushion thickness is verified by using an empirical formula,which can provide a theoretical support for design of the cushion.