Experiment of pile-soil stress ratio of DJM pile composite foundation in Chengdao

Key words:  soft clay of Chengdao  DJM pile composite foundation  pillow  pile-soil stress ratio  bearing performance  experiment

Abstract:

Pile-soil stress ratio is a very important indicator to reflect the level of the together-work of the pile and soil，also a major parameter calculating bearing capacity of composite foundation and settlement, and it is interrelated with the physical and mechanical properties of the soil，whose influencing factor is also complicated. Combined with a large-scale project，the large stress ratio test to the DJM pile conposite foundation in the soft clay of Chengdao was conducted. The regulations of the pile-soil stress ratio of DJM pile composite foundation with the change of load，time，thickness and stiffness of pillow in Chengdao region were obtained. TTie finite element analysis was carried out, and these two results were compared. TTie results show that there is no time effect to the pile-soil stress ratio of DJM pile composite foundation. Hie pile-soil stress ratio of DJM pile composite foundation is negative correlation to the thickness of pillow. Tlie pillow with a certain thickness could coordinate the work of the pile-soil，and the best thickness range should be confirmed by experiments. The pile-soil stress ratio of DJM pile composite foundation is positive correlation to the elastic modulus of pillow. Pile-soil stress ratio would never change when the elastic modulus reaches a certain value. Tlie pillow material with proper elastic modulus should be chosen based on the pile material. Tlie numerical value of the pile-soil stress ratio of DJM pile composite foundation in this region mainly distributed from 6.5 to 9.0.