Analysis of soil arching of composite foundations with long and short piles

Unequal settlements between the piles and the soil will result in soil arching of embankments. Pressure test results (or monitoring in situ) show that the fill load concentrates toward the pipe pile cap and the mixed piles, the earth pressure on the pile cap platform is 4.5 times the average one on the soil-area between piles, and that on the mixed pile top is 1.7 times that on the soil-area between piles. The pile cap platform, the soil-area between piles and the mixed piles share 25%, 69% and 6% of the total fill load. The bearing capacity of the piles and the soil-area between piles do not give full play, that is, the bearing load on the pipe piles is only 40 % of their capacity, and the soil-area between piles is only 25 %, indicating that there is still potential to be tapped. The replacement ratio is the main factor for the increase of proportion of pile bearing load, and the main way is to raise the replacement ratio of piles and the size of the pile cap.