Abstract：The mechanical mechanism，working behavior and deformation property of settlement-controlled composite pile foundations are analyzed；and the expressions for the pile number of the composite pile foundations are deduced. A new method calculating the settlement of the composite pile foundations，i.e. modified deep foundation layer-wise summation method，is put forward. The foundation settlements of two engineering examples are calculated by the method. The results show that the foundation settlements obtained by the modified deep foundation layer-wise summation method are much less than those of shallow natural foundation. Furthermore，the composite pile foundation settlements accord with in-situ monitoring results，correspond to the practical situation and meet the requirement of current design code of building foundation. Under this condition，the number of the piles can be cut down，and the foundation¢s bearing capacity can exert fully. Consequently，the cost of construction can be saved and the quality of engineering can be more easily assured by the cooperation between the pile and soil.
