Mechanics Performance Study On Cast-in-place Concrete Based On The Vehicle Bridge Coupling Vibration

In the process of bridge maintenance and repair,the repairing concrete is a kind of heterogeneous material,during the maintenance period,It will inevitably be interrupted by the outside world or even the impact of continuity,This has an adverse effect on the mechanical properties of concrete,and then affect the quality of bridge maintenance and reinforcement.Therefore,it is of great significance to study the law of the influence of the bridge vibration caused by traffic load on the performance of concrete in order to solve the problem of the maintenance and reinforcement of the bridge under the condition of uninterrupted traffic.Aiming at this problem,In this paper,the influence of driving vibration on the mechanical properties of cast-in-place concrete under the action of vehicle bridge coupling is studied.The main research work and conclusions are as follows:In this paper,the influence of driving vibration on the mechanical properties of fresh concrete is studied under the simulation of vehicle-bridge interaction.First of all,through the investigation of bridge disease and dynamic response characteristics,the main diseases of different types and span bridges are summarized,and it is considered that the destruction of concrete structures is the most common form of the disease;Through literature and practical tests,common medium and small span Bridges natural frequencies in the range of 2Hz?13Hz,the maximum dynamic deflection range is 1mm?11mm.Secondly,through the selection of pavement layer as the representative of the cement concrete mix optimization design and verification,the design of the concrete mix to meet the actual work performance and mechanical performance requirements,then,the orthogonal test scheme is designed,and the vibration frequency,amplitude,vibration time and vibration application time are four influencing factors and the three factors are selected for vibration test.It is found that the influence of vibration time on the mechanical properties of concrete after vibration is the most important one,in addition,the frequency,amplitude and vibration time is longer,the greater the influence on the mechanical properties of concrete,and concrete in different stages of hardening effect applying vibration on concrete performance are not the same,before the initial setting of vibration must enhance the compressive strength of concrete,applying vibration between initial setting and final setting will reduce the strength of the concrete splitting and bending,but after the final set vibration has a little influence on mechanical properties of concrete.In addition,the mechanical properties of the concrete were improved and the anti-vibration effect was improved by adjusting the original concrete mix ratio and adding the steel fiber with the volume ratio of 0.85%and the 0.15%polypropylene fiber.Finally,in order to test the changes of concrete after vibration of the internal structure by homogeneity test,non-uniform coefficient test results show that concrete non-uniform coefficient increases obviously after vibration,and the addition of fiber group uneven coefficient is relatively small;At the same time,through the analysis of the image,i.t is found that the vibration before the initial setting could reduce the number of concrete holes to a certain extent,and the pore size also decreases,Besides,adding fiber can improve the pore structure of concrete;The ultrasonic testing found that the vibration velocity of concrete decreased obviously,which has a certain effect on the concrete structure,but not uniformity can be improved after adding hybrid fiber concrete in a certain extent,but with the growth of the age,the pores of concrete internal defects and to a certain "repair".