Experimental investigation on load transfer characteristics of screw groove pile-geogrid composite foundation

As a new foundation treatment method, the screw groove pile-geogrid composite foundation can effectively reduce the foundation settlement and improve the bearing performance of composite foundation. Laboratory model tests of circular pile-geogrid and screw groove pile-geogrid composite foundation were carried out to analyze the difference of deformation of embankment, pile-soil stress ratio, load sharing ratio, strain of the geogrid and the axial distribution of pile. And to further investigate the mechanical mechanism of the screw groove pile-soil action in the pile-geogrid composite foundation. The results show that the screw groove pile- geogrid composite foundation reduces the settlement of the embankment top surface by about 27.3% when the amount of pile material is only 52.1% of the traditional circular pile, which significantly improves the deformation control effect of the composite foundation. The strain of the geogrid on the screw groove pile-geogrid composite foundation increases significantly in both the transverse and longitudinal directions of the embankment, when compared to the circular pile-geogrid composite foundation, and the flexible raft and tensioned membrane are fully utilized. Under embankment loading, the pile-soil stress ratio of screw groove piles is significantly higher than that of circular pile-geogrid composite foundation, and its load sharing ratio rises by about 11.8%. The screw groove pile utilizes the multi-end bearing of the screw groove structure on the pile side and the superposition of the stress diffusion effect of the reinforced cushion to drive the soil around the pile to carry the load together, which enhances the interaction between the pile-soil-reinforced cushion, greatly improves the utilization rate of the pile material, reduces the amount of cement, and promotes the reduction of carbon emissions.