Study On Computation And Prediction Method Of Load-bearing Characteristics Of Rigid Piles Composite Foundation

Through the replacement function of pile, rigid pile composite foundation enhances the bearing capacity better than natural ground while cost less than pile foundation. So it has been widely applied in the civil engineering and brought tremendous social and economical interest. But the study on its calculation is relatively behind the engineering practice. Therefore, the research of bearing capacity and settlement characteristics of rigid pile composite foundation, which has both academic value and appliance signification, has been the focus on the basic engineering research area in foundations.Based on the recent research, we systematically studied on the bearing capacity and settlement characteristics of rigid pile composite foundation, and developed the optimization design mode. In virtue of the theory and method in artificial intelligence domain, the author has studied the bearing capacity and settlement, and developed the models to predict them. The validity of the models has also been proved by the engineering practice. Here follows the main research work and achievements presented in this thesis:(1) Studying the bearing capacity and settlement design theory of the long-short-pile foundation based on composite foundation design theory, we discussed bearing capacity and settlement calculation mode according to different foundation style, and summarized application scope of the long-short-pile foundation from engineering appliance. The long-short-pile foundation is especially suitable for ground with relative thick compressed layer. Through the comparison of calculation results and the detected data in the factual engineering, the reliability of long-short-pile composite foundation engineering application under soft ground has been proved.(2) Based on Finite element analysis, single pile CFG composite foundation model and long-short-pile foundation model were established in the paper. Through the systematical analysis of the influences of the pile-soil module ratio, cushion, and replacement ratio on rigid pile composite foundation characteristic, we also get some regularity conclusion of pile-soil.(3) The prediction of bearing capacity of rigid pile composite foundation was studied using intelligent methods, and two prediction models were presented. The first one was to apply genetic algorithms to determine the original weights and construct BP algorithm model for predicting single pile bearing capacity, which is to use genetic algorithms to optimize the original weights and threshold distribution, and then construct the BP network prediction model according to the trait of global searching for ensuring the prediction more accurate. The second model for predicting bearing capacity was based on simulated annealing algorithm, which can get approximate solution of combinatorial optimization problems. This method takes advantage of multiplicative principle, nonlinear and simulated annealing algorithm to construct single pile bearing capacity prediction. The engineering samples have proved both of these two methods valid and practical, and the latter was more accurate than the former.(4) Settlement prediction model of rigid pile composite foundation was studied using the intelligent methods, and two have been presented. The first method is to utilize polynomial approach method to estimate the unknown parameter, which was to use differential coefficient on discrete observation spots of the polynomial instead of the difference in common method, and got three estimated values of the time-response equation through least squares method to construct and promote grey model. The second method presented settlement prediction model of rigid pile composite foundation through combining multivariate nonlinear regression and genetic algorithm. The engineering samples have proved both of these two methods valid and practical, and the latter one is more accurate than the former.(5) Based on analyzing the disposal method that PKPM CAD software adopted to deal with every engineering detail, we combine foundation optimization design and PKPM together, and present optimization design structure of rigid pile composite foundation based on PKPM. The optimization design system of rigid pile composite foundation was achieved through MVC model, which verified the feasibility of the optimization design structure. We also talk about the various operations and primary functional realization technology of data conversion, display layer, control layer and data layer on PKPM.