Calculation of composite foundation settlement by using Mindlin solution;

By using Mindlin solution and boundary element method,the calculation formulas of superimposed stress of surrounding soil induced by bulkhead pressure and friction force during the propulsion of shield tunneling are deduced.

Considering the condition of rigidity or flexibility foundation plate,a comparison between Mindlin solution and Boussinesq solution results is made with the load condition of centralized load or.

Based on Mindlin displacement solution,the formulas for settlement of 18 and 64 extra long and large diameter pile groups are deduced according to the hypotheses that resistance to pile end is concentrated force and skin friction of pile is linear increasing distributed force.

Based on the concept of effective length of flexible pile,the displacements for top of pile and surface of soil between piles were formulated by elastic theory and Mindlin displacement solution.

According to the principle of layer-wise summation method,the elastic theory method based on the Mindlin displacement solution is extended,an approximate method for calculating the settlement of single pile in lay- ered soils is established.