Reliability Analysis And Optimization Design Of Foundation Engineering Based On FEM

There are many indeterminate factors in foundation engineering, traditional method to solve this problem in engineering design is safety factor method. There is defect in safety factor method, its results cannot evaluate safety degree of the engineering completely and clearly, and usually result in great risk or waste in engineering design. Reliability design method, which is more scientific and reasonable, can make up the defect of safety factor method, and more reasonable safety evaluation indicator can be obtained. Therefore, there is important theoretical and practical meaning to study the application of reliability calculation method in geotechnical engineering.This thesis weightily studies the reliability analysis and optimization design of foundation engineering based on FEM, by means of theory analysis, test analysis and numerical simulation. Following are the primary contents.Firstly, the basic concept and the usually used calculation methods of structural reliability are introduced. An easier method for solving the structural reliability is brought out based on the theory of error diffusion. Calculating the reliability of settlement of the expensive soil roadbed, comparing with the result of JC method, it indicates that this new method is more simple and reliable, and the precision of the result can meet the request of the project.Secondly, two sample methods of Monte Carlo method are introduced. Through the cement composite soil test, the complication of the orthotropic test method in the geotechnical test is studied, the research indicates that the orthotropic test can decrease quantity of the test. Based on the combination of Monte Carlo sample method and the orthotropic test, an upgraded method is brought out, which can increase the simulation efficiency.Thirdly, Monte Carlo method and the finite element analysis are combined, and by means of the ANSYS software, using the method of Monte Carlo-FEM, the structural reliability analysis is accomplished on computer. The raft foundation-engineering example indicates that this method can expediently analyze the reliability of the foundation and evidently increase the simulation efficiency and precision.Lastly, using the theory of optimization design and FEM, recurring to ANSYS, optimization design of raft foundation is studied.