Meso-Structure Numerical Simulation Analysis Of Conrete Permeability Characteristics

Porous concrete is a complex medium,which determines the porous concrete with permeation characteristics.In this paper,based on macroscopic scale and scale up multi-scale method,application of f software ADINA,the different porosity concrete continuous media seepage analysis model was established by using Monte Carlo methods.Application structure of graph and Dijkstra algorithm to achieve the pore connectivity of judgment.The random aggregate seepage analysis model was established based on the concrete continuous media model.The relationship between concrete permeability and porosity,pore size,pore connectivity,aggregate delivery rate was studied.That is reasonably determine the permeability coefficient of concrete provides a theoretical basis.Main works and results of this paper included:(1)The models of three-dimensional concrete continuous media,including pore and solid particles elements were established.To study the effects of different porosity and pore connectivity to equivalent permeability coefficient of concrete.The results show that while equivalent pore size is constant,the equivalent permeability coefficient of concrete increases with the increase of total or effective porosity whether considering pore connectivity.In conclusion,when the porosity is less than 0.1,the equivalent permeability coefficient and porosity of a quadratic polynomial relations;equivalent permeability coefficient is directly proportional to porosity with good correlation when the porosity is greater than or equal to 0.1.(2)To study the equivalent permeability of different pore sizes of concrete continuous medium model.The results show that while porosity is constant,the equivalent permeability coefficient of concrete increases with the increase of pore size whether considering pore connectivity.The equivalent permeability coefficient and pore size is directly proportional to the square approximation when ignored pore connectivity.(3)To study the relationship between relative porosity and pore connectivity of all levels of concrete model by the concrete classification calculation and analysis method of approaching step by step.The results show that the pore connectivity enhancement with the increase of relative porosity.Compared with the porosity,the pore connectivity affect the permeability of concrete pores significantly.When the relative porosity is not greater than 0.2,which is impermeable concrete because the pores will no longer be connected.(4)The seepage analysis models of two-dimensioal and two-graded random aggregate concrete were established by based on the concrete macroscopic structure characteristics.To study the pore connectivity and aggregate delivery rate effect on the permeability of concrete.The results show that concrete pore structure of each component affects its permeability,interface is one of the most significant influence on permeability of concrete where the velocity is larger;equivalent permeability coefficient and effective porosity of random aggregates concrete remains a quadratic relationship while aggregate delivery rate is constant,the permeability of concrete aggregate delivery rate increases and enhanced.