Development and evolution theoretical model for phase field and particle field of saturated steel-concrete structure under stray electric field

Abstract

The invention discloses a phase field and particle field development and evolution theoretical model of a saturated steel-concrete structure under a stray electric field. Compared with a traditional isothermal adsorption empirical model, the theoretical model takes thermodynamics as a theoretical basis. The method comprises the following steps: firstly, through minimization of Gibbs free energy of a system, based on three thermodynamic models, namely a pure phase dissolution deposition equilibrium model, a solid solution model (an ideal solid solution and a non-ideal binary solid solution) and a double electrode layer complex reaction equilibrium model, obtaining initial values and interaction of lower phase and pore liquid particles of the cement-based system; secondly, performing coupling of the thermodynamic model and the finite element model through an operator splitting method, and then calculating a phase field and a particle field. Therefore, a scientific basis and a theoretical model are provided for accurately calculating the particle field and the phase field of the pore liquid in the concrete under the action of the stray electric field.

Description

technical field [0001] The invention belongs to the field of civil engineering materials, and relates to a theoretical model for the development and evolution of an internal phase field and a particle field of a water-saturated steel-concrete structure under the action of a stray electric field. Background technique [0002] In recent years, electrified rail transit has developed rapidly in my country and even in the world, which not only relieves the pressure of transportation, but also meets the requirements of sustainable development strategies, and has become one of the most important modes of transportation for people's daily travel. Corresponding rail transit infrastructure is in the period of large-scale construction, and these infrastructures mainly based on reinforced concrete structures are the premise and guarantee for the safe operation of rail transit. However, the stray electric field formed by the rail transit power supply system will have a huge impact on the...

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Problems solved by technology

However, the stray electric field formed by the rail transit power supply system will have a huge impact on the durability of reinforced concrete structures, and pose a potential threat to the service safety of rail transit infrastructure.

[0003] The impact of stray electric fields on the durability of reinforced concrete structures is mainly reflected in the following two points: First, the impact on the electrochemical corrosion behavior of steel bars is mainly manifested in the reduction of cross-sectional area of ​​steel bars, the accumulation of corrosion products and the adhesion of steel-concrete interface. Second, the impact on the distribution of pore liquid particles in the porous concrete material is mainly manifested as the diffusion and migration of pore liquid particles under the electric field formed by stray currents. On the one hand, it may cause erosion of local areas. Excessive concentration of reactive ions (such as chloride ions) or alkali metal ions (such as sodium ions and potassium ions) will cause corrosion of steel bars or alkali-aggregate reactions. On the other hand, ions will break the original thermodynamics during electromigration. Equilibrium, and tends to establish a new equilibrium, which often leads to the dissolution or deposition of hydration product phases or even the formation of new phases, and the phase change process will also affect the transport process of particles in concrete

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