Calculation for settlement of high cap extra-long large diameter pile groups

The settlement of high cap extra-long large diameter pile groups is made up of pile elastic compression and settlement of soil layers under pile end in theory. Methods to calculate pile compression of high cap extra-long large diameter pile groups was deduced or listed. Six methods to calculate settlement of soil layers under pile end were expounded through extra-long large diameter pile groups under south tower of main bridge of Sutong Yangtse River Highway Bridges. The results show that piles' elastic compression should be calculated into the settlement of extra-long large diameter pile groups, including that caused by pile's own weight, and it is little difference between test value and total settlement which is composed of piles' elastic compression calculated through the formula deduced in the paper and theoretic settlement of soil layers under pile end based on Mindlin's additional stress solution, only making 0.06% lower.