Rapid Maintenance Technology For Grassroots Diseases Of Guangzhou Airport Expressway

With the rapid development of the economy,people’s requirements for the quality of traffic are getting higher and higher,and road traffic is the most popular mode of travel.The quality of roads is related to the efficiency and safety of people’s travel.With the operation of the roads,various degrees of damage will occur in the roads,especially in the highways with large traffic volume.This invisible disease needs to be discovered and treated in time,otherwise the internal diseases will gradually reduce the carrying capacity of the roads.Driving comfort even harms people’s driving safety.Since the traditional excavation planing and milling method is time-consuming and labor-intensive,it takes a long time to close the road and has a great impact on traffic.This method obviously does not apply to some major roads with large traffic volume.Therefore,it is necessary to study grouting technology with short construction time,low construction cost and little impact on traffic.Based on the Guangzhou Airport Expressway project,based on the understanding and analysis of the research status at home and abroad,this paper has carried out field test research on the process,detection method and evaluation method of grouting effect of road base layer disease.The parameters are grouting depth,grouting hole distance,grouting pressure and grouting time.The choice of grouting depth is related to the location of the internal disease of the road.The depth should be selected to ensure that the grout can completely fill the void inside the road.The arrangement of the grouting holes should be selected according to the form of the road surface disease.The hole spacing can be calculated according to the spherical diffusion theory,or 1.5～2m according to the engineering experience.Grouting pressure is generally 1～1.5MPa.When grouting,an experienced operator should be selected to grout.Consider the overflow state of the slurry and the rising pressure of the grouting gun to determine whether the grouting is full.After confirming that the internal void of the road has reached saturation,the grouting gun should be closed and stabilized.Press for 10 to 20 seconds to prevent slurry backflow.The project adopts self-developed geopolymer grouting material,which can achieve final condensation and strength up to 2.3Mpa after 3 hours of construction,and has strong fluidity and no expansion,and will not damage the original road structure.The slurry is neutral,does not contain heavy metal substances,does not pollute the environment around the construction area,and can realize construction and development for 3 hours.He invisible disease of the road needs to be measured by means of detection.Although the core of drilling is the most direct and accurate way,this method will destroy the overall structure of the road,so it should not be used more.At present,engineers and technicians mainly use ground penetrating radar and drop hammer deflection tester to detect the approximate location of road internal diseases and evaluate the effect of grouting.These two methods are simple and efficient,but they also have their drawbacks.In order to improve the accuracy of detection,impact imaging method is adopted.To comprehensively analyze and analyze the internal diseases of the road.The engineering practice shows that the part with large impact response strength in the impact response intensity distribution map has a large amount of pulp,and the small amount of the small amount of the grout is small,and the distribution of the impact response intensity is very good corresponding to the distribution of the disease on the site.Grouting by geopolymer can make the impact response intensity distribution of the road more uniform,indicating that the grouting technology can effectively control the void inside the road.After the grouting of the geopolymer,the strong reflection surface of the radar image disappears and the level is more distinct.After grouting,the deflection data is significantly reduced.The PSSI of the pavement structure strength index before grouting is evaluated as the sub-,medium-,and good road sections.After the filling of the geopolymer slurry,the structural strength of the road sections is obviously improved,and the grades are excellent and good.Moreover,the pavement strength coefficient SSI of each segment reached 0.8 or more after grouting,indicating the effectiveness of geopolymer grouting technology in treating road internal diseases.