Wind Erosion Mechanism Of Concrete Based On Groove Shape

During the long-term service of the concrete structural,wind erosion of concrete wall surface is a common maintenance problem.Specifically,the wind erosion not only affects the overall aesthetics of the concrete structure,but also with the continuous stripping of the wall surface material,leading to worsening cracks and honeycomb hemp surfaces,and even causing quality problems such as exposed steel bar.In the engineering application,the measures such as improved the mix ratio or covered the protective coating are always selected to prevent wind erosion.However,the above methods need to pay a relatively expensive cost.Since in the natural environment,especially in desert areas,animals and plants resist the long-term erosion induced by sandstorm through the rich grooves contour of their body surface.Therefore,in the present work,the non-smooth groove wall surface common in engineering design is selected as the research object.Hence,system research of the wind erosion resistance of groove concrete wall surfaces is conducted numerically.The aim of this work is to find effective ways to improve the wind erosion resistance of the concrete wall surface without changing the material properties and provide relevant theoretical information.The main work of this paper can be summarized as follows.Firstly,the RNG k-? turbulence model was selected as the continuous phase model which combined with the DPM discrete phase model was used to realize the coupling of kinetic energy and turbulence under the condition of gas-solid two-phase flow.Moreover,the FLUENT universal model was selected as the erosion model,combined with the designed applicable computing domain,a three-dimensional numerical model which is applicable for studying the wind erosion resistance of groove concrete wall surfaces was developed.Hence,the numerical parameters were set based on the data of wind erosion experiments,and the reliability of the established numerical model was verified by comparing numerical values with experimental results.The arc-shaped grooves were selected for the wall contour design,and the smooth wall surface was compared to analyze the wind erosion resistance.The study found that when the erosion angle is low,the anti-wind erosion performance of the arc-shaped groove wall surface is inferior to that of the smooth wall surface,which is consistent with the experiment of the flat grinding method.However,with the increase of the erosion angle,the anti-wind erosion ability of the arc-shaped groove wall surface is significantly improved and is better than that of the smooth wall surface,and the maximum increase can reach 25.434%.This phenomenon not only originates from the change of the near-wall flow field,but also from the change of the damage mechanism caused by the angle of gravel incidence.Although the size of the expanded grooves cannot have a substantial effect on the applicable erosion angle,it can affect the overall wind erosion rate.Secondly,the wind erosion resistance of the concrete wall surfaces which with the single arc-shaped groove and multi arc-shaped groove forms were systematically studied,and the results were compared and analyzed with the smooth wall surface under the same numerical conditions.It is found that,under the condition of low erosion angle,the wind erosion resistance of single arc-shaped groove wall surface is worse than the smooth wall surface,which is consistent with the results of the flat grinding experiments.However,under the condition of high erosion angle,the wind erosion resistance of single arc-shaped groove wall surface is improved significantly,which becomes better than the smooth wall surface and the maximum increase can up to 25.434%.The main cause for this phenomenon not only originates from the change of the near-wall flow field,but also from the change of the damage mechanism caused by the incident erosion angle.In addition,we also found that although expand the size of the groove can not have a substantial effect to the applicable erosion angle,it can affect the overall wind erosion rate to a certain extent.Moreover,the wind erosion resistance of single arc-shaped groove and multi arc-shaped groove wall surface were compared.It is found that the wind erosion resistance of multi arc-shaped groove wall surface will vary in specific numbers,but overall is basically consistent with the single arc-shaped groove wall surface.The main cause for this phenomenon is that the vortex inside the groove has relatively better stability,which make the flow field near the groove area shows an independent development according to the groove spacing,so there is less interaction between the flow field develops in each groove.In addition,because the low-velocity flow field exists only in the near-wall area between the grooves,the gravel can not obtain enough space to adjust the movement trajectory.Therefore,the groove spacing is not a dominant factor which hinders the practical use of the multi arc-shaped groove wall surface.Finally,system research of the wind erosion resistance of the inclined groove concrete wall surfaces was conducted.It is found that the wind erosion characteristics of the inclined groove wall surface is similar to the arc-shaped groove wall surface.The applicable erosion angle of the inclined groove wall surface is obviously related to the inclination angle of the groove wall.Specifically,when the inclination angle of the groove wall is 90°,the applicable erosion angle is relatively wide,while it is relatively narrow at 30°.In addition,when the inclined angle of the groove wall is relatively low,the vortex inside the groove is likely suppressed in the groove bottom area,resulting in the inability to effectively expand the space for deceleration and energy reduction by increasing the groove depth.