Study On Crack Treatment Of Concrete Abutment In The Seasonal Frozen Area Of Northern Hebei

The concrete abutment platform is an important part of the concrete abutment.The cracks in the abutment are an important disease affecting the structure of the concrete abutment.In the northeastern frozen area,the winter is cold and the temperature difference is large,which is prone to freeze-thaw environment.In this climatic condition,the problem of cracks in the concrete abutment body is more prominent.In this paper,the treatment of concrete bridge abutment cracks in the frozen area of Hebei is studied under freezing and thawing conditions.Through on-the-spot investigation,cause analysis,laboratory test and case analysis,the research on the treatment of concrete abutment cracks in the seasonal frozen area of northern Hebei Province is studied.The main research contents and conclusions are as follows:(1)Through the investigation of the cracks in the concrete abutment of the Hebei seasonal frozen area,the summer season in the northern part of the Hebei area is hot and cold in winter,and the temperature difference is large throughout the year.The cracks in the concrete abutment of the Hebei seasonal frozen area mainly include transverse cracks and longitudinal cracks,and the width is between 0.25 and 1.5 mm.These cracks are beyond the crack limit,indicating that the cracks in the concrete abutment of the Hebei seasonal frozen area need to be patched.(2)Analysis on the causes of cracks in the concrete abutment of the Hebei seasonal area.The causes of cracks in the concrete abutment of the Hebei seasonal frozen area are mainly the uneven settlement of the abutment foundation,temperature and shrinkage,and the backfill pressure and upper load.The lateral crack is mainly due to the backfill pressure and the upper load.Larger,longitudinal cracks are mainly due to the fact that the foundation is mostly collapsible loess,which makes the foundation unevenly settled,and the small cracks are due to temperature and shrinkage.(3)Perform a freeze-thaw cycle indoor test.When the freeze-thaw cycle was 150 times,the mass loss rate of the control group reached 5%,showing the characteristics of freeze-thaw damage.At this time,the mass loss rate of the crack repair method was 1.5% lower.According to this rule,when the concrete freeze-thaw damage When the crack repair method is subjected to 25 to 50 freeze-thaw cycles more than the control group.(4)Perform a crack repair laboratory test.By using the control group,surface repair method,epoxy resin repair method,polyurethane repair method,carbon fiber cloth repair method and bolt repair method,the quality loss rate,compressive strength and splitting tensile strength are selected.The crack repair program and analysis of the test results.In summary,the carbon fiber cloth method and the epoxy resin method all exhibit certain advantages in reinforcing concrete test blocks.(5)Based on the experimental data of carbon fiber cloth method and epoxy resin method,the damage prediction model of concrete compressive strength and splitting tensile strength under freezing and thawing conditions was proposed.Through the practical application of the crack repairing scheme on the concrete bridge abutment of a certain highway,it shows that the repair effect is good,and the feasibility of the crack repair method is confirmed.A comprehensive treatment measure for crack repair was proposed.