New Materials And Applications For Repairing Typical Diseases And Protecting Structures In Hydraulic Engineering

The working conditions of hydraulic structures are harsh and complex,and various kinds of diseases gradually appear in the service process of most hydraulic structures.Conventional materials can not fully meet the engineering requirements,and the repair effect is not good.In this paper,two typical diseases of hydraulic concrete structure erosion and metal structure corrosion are studied,and their damage and protection mechanism are analyzed.Through indoor tests,the existing materials are improved,and a new repair scheme is proposed and construction parameters are obtained.Finally,field application research is carried out.T he main research results are as follows:(1)The erosion damage mechanism and corrosion damage mechanism were described respectively,and the factors affecting the erosion effect and corrosion rate were analyzed.The formula of the compound abrasive particle abrasion amount under the erosion action was summarized.According to the established stress model of the erosion repair thin layer,the stress and strain solutions of the repair layer under the action of curing shrinkage and temperature are deduced.Furthermore,the adhesive property,abrasion resistance,deformation coordination and other aspects of the repair or protection materials are required.(2)Aiming at the erosion damage of hydraulic concrete,the combined repair material of"epoxy interface agent+underwater anti-abrasion mortar+flexible nano-ceramic coating" was selected to repair.The dry bond strength between the composite repair material and concrete was above 4.0 MPa,and the anti-abrasive strength was up to 2545.2 h/(kg/m2).Reinforced cracking test and mechanical analysis of repair structure show that the composite repair material can adapt to the deformation of concrete,and will not crack or peel damage under-200℃～40℃environment,and the integrity is good.(3)Aiming at the problem of hydraulic metal corrosion,based on the semi-finished epoxy anticorrosive coating,the composite protection scheme of " nano titanium composite heavy anticorrosive coating+ceramic anticorrosive and abrasion-resistant coating" was determined through component study and ratio test.The adhesion of the bottom coating and the surface coating can reach 11.14 MPa and 10.07 MPa,respectively.The surface coating has no significant change in color after 60 artificial agings accelerated cycles.The abrasion resistance of the composite protective structure can reach 635.85 h/(kg/m2).Other performance indicators meet the standard requirements.(4)Through the test and application,the construction technology suitable for the new composite protective material is summarized,and the construction parameters such as the operation time of the bottom coating and the surface coating at different temperatures and the maximum coating thickness are obtained.To solve the problems of difficult coating and high environmental protection requirements for arc gate in service,a construction scheme based on movable scaffold+buoy platform+fixed scaffold was put forward,which could meet the requirements of safety construction and environmental protection at the same time.(5)Concrete erosion composite repair material and metal corrosion composite protection material are used in concrete erosion damage in the flow passage of No.2 unit of Gaotan Hydropower Station and No.2 curved gate of Don gping Hydropower Plant combined with related construction technology.After the completion of the inspection,it is found that the repaired surface is smooth and the repair effect is good,and the erosion damaged repaired structure has no serious wear and tear after several times of drainage and grinding test in a year,so it can be applied to similar projects.