Finite Element Numerical Simulation Of Key Techniques For Marine Diking

In recent years,with the rapid development of coastal cities,the applications of surcharge preloading method in large-scale projects,such as reclamation project and marine diking,are increasing gradually.These projects have strict standards for control of settlement,high standards of safety and stability,and high requirements for the accuracy of foundation settlement prediction.However,at this stage,the results of numerical model established by the calculation parameters are not ideal enough.The long-term creep effect of soft clay has significant effect on foundation settlement after construction.Traditional construction scheme exists many shortcomings.These problems are increasingly obvious and greatly affect the overall quality and structural stability of the marine diking project.Therefore,it is of great research significance and engineering value to seek a more accurate method for prediction of the final soft foundation settlement and a more reasonable construction scheme.The main contents of this thesis and the research results are as follows:(1)The basic principle of drainage consolidation method is discussed in detail,and the reinforcement mechanism of the surcharge preloading method is analyzed from the change of stress circle,the change of void ratio and the effective stress path.The three components of settlement of soft foundation are analyzed,and the occurrence and duration of each component and the weights of total settlement are discussed.(2)The Chicken Swarm Optimization algorithm is introduced and improved.The inversion model of soil mechanics parameters based on the improved Chicken Swarm Optimization algorithm is established.According to the measured displacements of the dam,the soil mechanics parameters are solved.At the same time,the inversion model of soil mechanics parameters based on particle swarm optimization algorithm is established for contrastive analysis.The soil mechanics parameters sensitivity is analyzed.The soil mechanics parameters in Tianjin coastal area diking during construction are inverted and analyzed.The rationality of the parameters is verified,given the settlement during construction.(3)The microscopic mechanism of creep in soft soil and its influence on engineering are discussed.The creep equation of soil based on the "period of hardening" exponential function law is deduced.Through the creep test and the fitting of the creep parameters,the three important creep parameters(m,n,A)of revised Drucker-Prager model are obtained.The variation regularity of creep parameters between three soil layers is analyzed.The calculation model is established and the location of the maximum settlement point,the ultimate settlement of the foundation,the ultimate settlement of the dam surface and the development direction of settlement are analyzed.The situation of pore water dissipation and soil consolidation are analyzed.(4)The principle and method of traditional offshore diking construction are discussed.The problems are summarized in the traditional construction process.From the view of micro-element,the force of large sand bag is analyzed,and the relationship between the surface tension of sand bag and the perimeter of the bag is demonstrated.Introducing the principle of cutting slope and reducing load,a new type of dam construction scheme using stepped block construction is proposed and the settlement and horizontal displacement of the original construction scheme were compared.The stability of the new construction scheme is analyzed,and the superiority and value of the new construction scheme are demonstrated.