Study On Back Analysis Method With Genetic Algorithm Of The Deep Foundation Pit's Design Parameters And Its Excavation Dynamic Prediction

As a complex Geotechnical engineering problem,deep foundation pit engineering'retaining is a dynamic process of design and constructure. Pile-anchor supporting as one of the structures in many retaining structures, because of its convenience in construction, security, economic, big stiffness and small deformation, is widely applied at home and abroad. Usually , There are many parameters in the design process which could not be determined. So the paper firstly introduce genetic algorithm into the back analysis method about deep foundation pit'design parameters based on many predecessors' research work. Then the paper makes a series of research work on the optimization solution and dynamic prediction of the supporting structure's soil parameters and pile-anchor'stiffness. Finally, all of the research works has been realized on computer.According to the current situation and requirement in the aspect of finite element method and the dynamic excavation back analysis of deep foundation pit' supporting structure, the paper do some work as follows:(1) Based on the elastic foundation finite element theory, the program of finite element RSBK was developed with FORTRAN language which applied to the deep foundation pit'design and analysis. The inner-force and displacement of the structure can be computed with the program. (2) On the basis of the characteristic and basic principle of the genetic alogrithm, a nonlinear model parameter identification program was developed, then a back analysis procedure thinking about the deep foundation pit retaining structure'design parameters was put forward, lastly, a dynamic optimization parameter identification program GABR about the elestic foundation finite element model of the deep foundation pit'retaining structure was developed. The program could identify the soil parameters and the pile-anchor stiffness parameters simultaneously and reached ideal effect with the check of a project case. (3) Using the program GABR into someone pit with pile-anchor supporting structure which was widely used at home and abroad. A lot of back analysis and further discuss about the design parameters were done. Finally the reasonable value of the control parameters and the number and types of the identification parameters, the techniques and rules of the parameters'selection were researched. The results of the research provides importment references for the similar projects in the area. (4) The dynamic prediction and implementation procedure of the deep foundation pit was researched. The research results was used into one of the big deep foundation pits in Qingdao. A comprehensive forecast method was used in the project and the feasibility of the method was checked through the project. It achieves ideal effect.In this thesis , the results can be used into the similarly finite element model of other structure system. At the same time,the conclusions may be reference for some engineering practice in Qingdao.