| Compaction degree is a key indicator of pavement performance.The quality of compaction directly determines the service life of the road,and insufficient compaction will promote the occurrence of some terrible problems.The traditional compaction detection technology cannot meet the requirements of non-destructive,safe,comprehensive,real-time and continuous.The traditional compaction detection technology has been unable to achieve the detection technical level of emerging asphalt pavement.Therefore,it is of great practical significance to develop an intelligent continuous detection technology for pavement compaction to improve pavement compaction quality and compaction efficiency.Based on the above reasons,this paper relies on the national highway 212 line Huishui Cangxi to Shuanglong section highway project in Langzhong.The in-depth research is about the vibration compaction mechanism and characteristics,road roller-bituminous mixture,vibration compaction simulation model,on-site vibration acceleration signal acquisition and processing,vibration acceleration-the impact of compaction relationship research and the continuous intelligent system of compaction degree.(1)Through the analysis of vibration compaction mechanism and compaction characteristics,combined with the compaction construction process of asphalt pavement.it is concluded that the essence of vibration compaction is to combine and squeeze the particles of each component of the mixture again and narrow the pores between the particles through the action of external force.The defects of traditional detection methods are analyzed.It is found that the traditional compaction detection technology can not take into account the non-destructive,safe,comprehensive,real-time and continuous.(2)Based on Newton ’s Second Law Theory,the compaction equipment is equivalently decomposed into spring and damping,and a two-degree-of-freedom ’road roller-bituminous’ dynamic model is established.The dynamic equation is solved under linear,nonlinear and general conditions.The relationship between the vibration acceleration and the mixture stiffness is obtained.The Matlab is used to establish the ’road roller-bituminous ’ simulation model.The stiffness and damping parameters are changed to obtain the variation law of vibration acceleration,velocity and displacement with time.It is found that the vibration acceleration increases with the increase of asphalt mixture stiffness,that is,there is a positive correlation between them.Therefore,the vibration acceleration feedback signal can be used to characterize the degree of compaction.(3)The vibration acceleration acquisition system was built by using DH5902 acquisition equipment and 1A941 E acceleration sensor.The vibration accelerations of the upper layer(AR-SMA-13),the middle layer(AC-20)and the lower layer(AC-25)were collected and stored respectively.The measured data are filtered,and the number of periods for solving the effective value of vibration acceleration is determined according to the standard deviation value corresponding to each period after reducing the error.The compaction degree of the experimental section is measured by the traditional core drilling sampling method.The measured compaction degree value and the effective value of vibration acceleration are corresponding to each other and linearly fitted..And the relationship between the vibration acceleration and compaction degree of the upper,middle and lower layers is obtained.The simulation results are compared with the measured results to verify the rationality of the simulation model.(4)The study of the correlation between vibration acceleration and compaction degree of upper,middle and lower surface layers under different thickness,rolling speed and rolling temperature conditions concludes that the compaction efficiency decreases with the increase of thickness,that is,the greater the thickness is,the more difficult the compaction will be.By analyzing the fitting curves corresponding to each relationship,it can be seen that the compaction efficiency decreases with the increase of thickness.And it is more difficult to meet the compaction requirements.The change of rolling speed within the specified range has no obvious effect on the compaction effect.In order to ensure the construction efficiency,the compaction operation should be completed at high temperature as much as possible within the specified temperature range,and the compaction effect will be more excellent.(5)Aiming at the evaluation of the compaction quality of asphalt pavement,a real-time evaluation system of compaction degree is established by using Labview.The real-time detection of the compaction degree of asphalt pavement is realized and the compaction quality is quickly evaluated by the test results.It is found that there is no significant difference between the results of the evaluation system and the measured data,which demonstrates the accuracy of the evaluation system. |
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