Numerical Calculation Of Interaction For Pile-raft Foundation And Case Analysis In Taiyuan

In recent years pile-raft foundation becomes more popular due to its adaptability and high bearing capacity with the development of high-rise building. Determining the settlement of pile-raft foundation and load distribution between pile and raft are the focus and the difficulty in geotechnical engineering.In this paper, based on the review of general development situation and fundamental theory of interaction of pile-raft foundation, following research works are achieved:a. Comparison has been made between calculated result of settlement for single pile and the result of static load test, parameter involved in calculation model have been modified to meet the need of calculation for group piles, so we can make good use of known information.b. Limit compression layer model has been used to consider muti-layer of soil, rectangular plate element has been applied to analysis the raft, compression modulus Es is obtained through modifying Esi.2, which has been fitted and proved by collected data about soil modulus in different depths fromTaiyuan, additional stress of ground among piles and that of pile tip are calculated by Boussinesq' stress solution and Mindlin' solution based on elastic theory respectively. The settlement is obtained according to the layerwise summation method. The calculating model for interaction of pile-raft foundation is built based on above mechanism and calculation program is established accordingly by using MATLAB software.c. Influence of several design parameters on the settlement of group pile, the contact pressure distribution on the top of the pile and load distribution of pile and raft, have been analyzed respectively, thus the mechanism of interaction of pile-raft foundation is discussed. In this paper, variation regular of contact pressure on the top of pile with different relative rigidity ratio of pile against raft is presented and the result that settlement distribution is characteristic of boiler bottom is obtained. All those analysis above may provide designer with reliable theoretical evidence to decide arrangement of pile and choose optimum thickness of raft.d. At the end of the paper, the applications of the method are introduced on three projects. Comparison has been made between measured data and the result of calculation. It is shown that the method of this paper is plausible and practical.