Study on settlement calculation method of rigid-flexible pile

Basing on Mindlin stress solution, referencing the idea from Geddes stress solution and using the numerical integral function of NIntegrate in Mathematica software, the numerical computational methods for vertical additional stress coefficient at random point in the ground under the uniform tip load of the rigid pile with circular tip and the flexible pile with annular tip were achieved. A numerical method of calculating the vertical additional stress coefficient of flexible pile skin friction acting at any point in the ground was obtained. One loading case of the skin friction is rectangular distribution from top to bottom along the pile body and uniform distribution along circumference of the pile section; the other one is triangular distribution from top to bottom along the pile body and uniform distribution along circumference of the pile section. The computational method for settlement of the rigid-flexible pile was established, based on the hypothesis that the rigid pile and the flexible pile have compatible deformation and the Mindlin stress solution. The computational method has been tested and verified by the data of in-site static loading test. The settlement calculated from the case that the skin friction is triangular distribution is smaller than that computed from the case that the skin friction is rectangular distribution from top to bottom along the pile body, and the difference is small. The Mindlin stress solution is better applied to calculate the settlement of the rigid-flexibly pile which is in the elastic stage; the settlement is relatively small when the settlement is in the plastic stage.