Pile-soil stress ratio of deformable pile-supported and geosynthetics-reinforced embankments

For deformable pile-supported and geosynthetics-reinforced embankments, a load transfer model for common coordination working mechanism of embankment-net-pile-soil is established. Soil arching effect of the embankment and mutual coordination working mechanism of pile-soil are analyzed based on the modified load transfer model for embankments and the assumed distribution of skin friction on piles. According to the force equilibrium, a new formula for pile-soil stress ratios and the differential settlement between piles and soil is deduced under the coupling of soil arching effect, tensioned membrane effect and mutual coordination working mechanism of pile-soil. The model is verified through practical projects, and the relationships of the pile-soil stress ratios with correlative influence factors are analyzed. It is found that the pile-soil stress ratios will first increase and then decrease with the increase of angle of internal friction of fill, will increase with the increase of the pile modulus of compressibility and the fill modulus of compressibility, and will decrease with the increase of the soil modulus of compressibility between piles and the pile space. With the increase of the tensile strength of geo-grids, the pile-soil stress ratios on net will decrease, and those below net will increase. The latter is larger than the former, and the relative difference between them will increase with the increase of the tensile strength of geo-grids, the fill modulus of compressibility, the unit weight and the height of fill. The theoretical value of the pile-soil stress ratios and the differential settlement between piles and soil are close to the observed ones.