Full Process Research On The Corrosion Of Sewage Pipes

Sulfate attack is one of the most important environmental factors which lead to the damage of the concrete sewage pipe.So,it is very important to study the corrosion behavior of concrete under the attack of sulfate which will guide the design and construction process of the concrete sewage pipe.In this paper,it is going to study the corrosion failure behavior of the concrete sewage pipe by using the methods of theoretical analysis and numerical calculation.(1)Based on finite element software COMSOL and existing mathematical models,the numerical calculation program was developed,which used to implement the numerical calculation of the corrosion failure behavior of concrete under sulfate attack.Meanwhile,this paper analyzed the development of ion erosion and stress with the developed numerical calculation program.(2)Considering the filling effect of the ettringite at the beginning of the sulfate attack,two methods were proposed to improve the existing mathematical model based on the existing research,which are build porosity time-varying function and modify the diffusion coefficient according to the change of the pore structure respectively.Meanwhile,the development law of the porosity and the diffusion coefficient were simulated and analyzed in this paper.(3)One function was established which used to show the change of water level in the sewage pipe.The corrosion failure behavior of the concrete sewage pipe was researched with the proposed porosity time-varying function.Then,the corrosion failure behavior of the tube wall both above and below the water level were analyzed and compared with the results which simulated by the original model.The results show that: the proposed porosity time-varying function which used to improve the existing mathematical model was able to reflect reaction the influence of filling effect to the failure process of concrete sewage pipe.The corrosion rate of the tube wall above the water level is slighter than the area below the water level on the premise that just considering the damage due to the ettringite.