Field experiment of pile-soil stress of soft subgrade reinforced by pre-stressed concrete piles

In the field experiment, different cushions were placed in four sections of the pre-stressed concrete pile composition foundation under the same geologic condition. A lot of earth pressure cells were embedded in the soil on the plane of piles top to detect the stress rigorously. The data were achieved and analyzed. The time effect characters of earth pressure and pile-soil ratio were discovered. The data reflects the stress coordination of the piles and soil which can be divided into two processes. The first process is caused by immediate settlement before pile-soil ratio reaches the peak value. The process after the pile-soil ratio reaches the peak value is the second process, which is caused by primary settlement. Reasonable suggestions of the design of cushion were also put forward.