| In recent years,the reinforced concrete urban integrated pipe gallery has become an important underground structure for urban construction,used to lay various pipelines such as electricity,communication,municipal administration,gas,water supply and drainage,and its structural design life is usually 100 years.At present,the relevant researches mainly focus on impermeability and chemical resistance.There are few research results that considered the comprehensive effects of impermeability,chemical resistance,alternating temperature changes and complex stress states.Therefore,this article took the reinforced concrete urban integrated pipe gallery structure as the background,which studied the impermeability,chloride ion permeability,sulfate ion corrosion resistance,heat resistance and stress deformation behavior of concrete-coating system of plain concrete,polyurethane surface film-forming coating and cement-based permeable crystalline coating by means of literature summary,and analyzed the suitability and advantages of the coating type to the environment,indoor experiment and numerical simulation,in order to furnish reference foundation for the design and maintenance of reinforced concrete city utility tunnel structure.The principal research content and achievement are as follows:(1)Considering factors such as coating type,coating thickness,etc.,the concrete-coating system was tested against water penetration by the water penetration height method to compare and analyze the anti-seepage effects of plain concrete,PWC coating,and CCCW coating,and to analyze the influence of coating thickness on anti-seepage effect.The results showed that both polyurethane surface film-forming coatings and cement-based permeable crystalline coatings had significant waterproof effects,and the water penetration depth decreased with the increase of the coating thickness;for the same coating thickness,the water penetration depth of the CCCW coating was less than that of the PWC Coating.(2)Considering factors such as coating type and coating thickness,the electric flux technique was used to finish the chloride ion penetration resistance test of the concrete-coating system,and the chloride ion penetration resistance of plain concrete,PWC coating and CCCW coating were compared and analyzed,and the influence law of the thickness of the coating on the resistance to chloride ion permeability was analyzed.The outcomes indicated that both PWC coating and CCCW coating could effectively resist the penetration of chloride ions,and the resistance of PWC coating to chloride ion penetration was better than that of CCCW coating;within a certain thickness range,the coating thickness increased and the resistance to chloride ion penetration increased.However,when it increased to a certain thickness,the electric flux of concrete was not significantly reduced;for PWC coating,1.0mm thickness could achieve satisfactory resistance to chloride ion penetration,and for CCCW coating,1.2mm coating thickness could achieve satisfactory resistance to chlorine Ion penetration effect.(3)Considering factors such as coating type,coating thickness,etc.,the concrete-coating system was examined on the sulfate ion corrosion resistance test by the dry-wet cycle approach,and the effects of sulfate resistance of plain concrete,PWC coating,and CCCW coating was compared and analyzed,and analyzed the effect regulation of coating thickness on the corrosion resistance of sulfate ions.The outcomes indicated that both PWC coating and CCCW coating could effectively reduce sulfate ion erosion,and the resistance to sulfate ion erosion was better as the thickness increased;the mass loss and compressive corrosion resistance coefficient of PWC coating specimens were less than that of CCCW coating.It showed that the sulfate corrosion resistance of PWC coating was better than that of CCCW coating;when the thickness of PWC coating was greater than1.0mm and the thickness of CCCW coating was greater than 1.2mm,the thickness of the coating increased,and the change of concrete quality loss and compression corrosion resistance coefficient was no longer obvious.Therefore,1.0mm thick PWC coating and1.2mm thick CCCW coating could obtain satisfactory resistance to sulfate ion erosion.(4)In order to study the influence of temperature changes on the deformation coordination of the concrete-coating system,concrete specimens with a PWC coating thickness of 1.0 mm and a CCCW coating thickness of 1.2 mm were designed and manufactured.The three conditions of monotonous rise,monotonic temperature drop,and temperature rise and fall cycles were tested to compare and analyze the temperature deformation coordination and expansion and contraction of PWC coating,CCCW coating and concrete under temperature changes.The test results showed that the PWC coating was greatly affected by the temperature,the thermal expansion coefficient of the CCCW coating was closer to that of concrete,and the CCCW coating had better temperature deformation consistency with the concrete.(5)The concrete specimens with PWC coating thickness of 1.0mm and CCCW coating thickness of 1.2mm were designed and manufactured.The uniaxial monotonic loading and uniaxial cyclic loading tests were finished on the MTS universal testing machine to compare and analyze the loading deformation process and destruction form,and to study the deformation characteristics of concrete and coating under stress conditions.The test results showed that in the case of monotonic loading,the peak stresses of the coating schemes were slightly different,but the peak strains were significantly different;when cyclic loading was carried out at stress levels of 20%,50%,and 75% compressive strength,the peak cyclic load increased.The residual deformation and peak strain of the specimens also increased.During the cyclic loading process,the more cyclic loading times,the greater the peak strain of all specimens;whether monotonous loading or cyclic loading,the CCCW coating had better consistency with concrete deformation. |
