Peridynamic Simulation Of Chloride Transport In Concrete

The erosion of chloride ions leads to a decline in the durability of reinforced concrete,which can cause huge economic losses and energy waste.It has become a very prominent issue in the marine engineering field.The establishment of a calculation model for the chloride ion erosion process is of great significance for the study of the durability failure process of reinforced concrete.Peridynamics is a numerical calculation method based on non-local model,which has prominent advantages in solving the problem of non-continuous media mechanics.In this paper,the peridynamics method was used to study the transport of chloride ions in concrete under the effects of diffusion and wet-dry cycles.The main work is as follows:1.Summarized the basic theory of chloride ion erosion in concrete and peridynamicsThe basic theory of chloride ion erosion mechanism and peridynamics in concrete is introduced.The research status of chloride ion transmission and peridynamics theory at home and abroad are reviewed.The meanings of various parameters in the peridynamics equation are introduced,and the calculation model for describing chloride diffusion under specific conditions is discussed.2.Established a model of chloride ion diffusion process based on peridynamics theoryAccording to the classical diffusion theory and the peridynamics theory,the peridynamics equations for the diffusion problem are established.The material parameters and boundary conditions in the classical diffusion theory are transformed into the expressions of the peridynamics model.The variations of chloride ion concentration in the diffusion one-dimensional and two-dimensional homogeneous concrete models were simulated and compared with the corresponding analytical solutions to verify the accuracy of the established peridynamics model.It provides the basis for further study of chloride transport in concrete.3.The proposed multi-scale model of peridynamicsThe limitations of the traditional uniform peridynamics model are discussed,as well as its problems in the construction of concrete meso-scale models.Based on the traditional uniform peridynamics model,a multi-scale peridynamics modeling method is proposed.Using the proposed multi-scale peridynamics method,a concrete multi-phase meso-scale model including mortar,aggregate and ITZ layer was established to simulate the diffusion process of chloride ion in concrete.The effect of the diffusion coefficient and thickness of the ITZ layer on the diffusion process of chloride ions was analyzed.4.The study of the process of chloride ions eroding concrete under the effect of wet-dry cyclesA multi-scale peridynamics wet-dry cycle model was established to simulate the moisture transport process in concrete.Based on the concrete multi-phase meso-scopic model,the effect of wet-dry cycle on the chloride ion erosion process in concrete was studied,and the concentration change of chloride ion with water capillary absorption in concrete was calculated.A peridynamics model for the transport of chloride ions in concrete under the joint action of the wet-dry cycle and diffusion process was established.The erosion process of chloride ions under complex environmental conditions was simulated and laid the foundation for studying the durability of concrete.