Abstract：The interaction mechanism of pile and soil in complicated ground is studied in detail. The limitation and applicability of different methods for solving this problem are analyzed and compared，based on which a new practical model of pile-soil system in multi-layer medium is set up. In combination with improved Mindlin solution，load transfer method，linear deformation layer model，mirror imagine method，optimization and back analysis method，a new generalized elastic theory method is presented to calculate and analyze complicated ground model. The optimization and back analysis program can not only be used to calculate and modify load-settlement curve of a pile，but also to analyze geo-mechanical parameters of ground-pile system on the basis of static load test results of a pile. The values of parameters can be used to supervise the design about bearing performance of a pile. The method and program are validated with engineering cases and proved to be satisfactory.
