A Multi-Perspective Analytical Study On Pavement Acceleration For Pavement Structure,Pavement Materials And Vehicle Information

As a component of pavement dynamic responses,pavement acceleration response has great research value due to its close relationship with road service condition and vehicle information.On the one hand,according to physical definitions,acceleration is closely related to the mechanical state,displacement and modulus of an object,so pavement acceleration can reflect the stress condition and deformation of pavement structure and the stiffness of pavement materials from the side.On the other hand,in terms of causes,pavement acceleration is just induced by moving vehicles,so the relevant vehicle information can be also obtained by analyzing pavement acceleration.In view of such facts,this dissertation focused on pavement acceleration,and the analytical study was conducted from the perspectives of pavement structure,pavement materials and vehicle information.Firstly,the laws on the distribution and response of pavement acceleration field under moving load were investigated systematically.Relied on an actual road section,the corresponding three-dimensional finite element model was established,and the reliability of such road model was verified by comparing the measured and simulated values of vertical acceleration.Combining the distribution nephograms and time-history curves of three-directional accelerations,the laws on the distribution and response of pavement acceleration field were discussed detailedly.Based on the orthogonal test,the influencing degrees of vehicle load,vehicle speed,upper layer modulus and upper layer damping ratio on the acceleration response of intact pavement without damage were analyzed,and the relevant sensitivity ranking was obtained accordingly.Secondly,the acceleration responses of pavement structure with different crack damage forms were further studied.Under the premise of controlling variables,a total of fourteen conditions,including the typical crack damage forms of different crack positions,crack lengths,crack numbers and crack distances and whether crack extends or not,were considered.Based on the vertical acceleration peak of intact pavement without damage,the change rate of vertical acceleration peak was proposed as the evaluation index to describe the specific effects brought by different crack damage forms.The relevant results verified the potential application of pavement acceleration in crack damage monitoring,which provides a new idea for the crack damage monitoring during road service period.Thirdly,the issue of using acceleration integration to reflect pavement displacement was discussed.Through the indoor shaking table vibration test and the outdoor vehicle-induced pavement vibration test,the acceleration signals under standard sinusoidal vibration mode and actual vehicle-induced vibration mode were obtained.On this basis,the calculation results of direct integration,indirect integration,time-domain integration and frequency-domain integration were compared,and the integration method suitable for processing pavement acceleration data was determined preliminarily.Combining the straight track loading test,the feasibility of utilizing acceleration integration to obtain pavement displacement was further verified.Fourthly,from the perspective of pavement materials,the change laws on the acceleration signals of asphalt mixture specimens under typical loading modes were studied experimentally.Based on the actual test condition,the splitting fatigue test and the OT(Overlay Tester)tension test were selected as the representative tests with load controlling mode and displacement controlling mode,respectively.By collecting and analyzing the acceleration signals of asphalt mixture specimens in the whole loading process,the relevant change laws under such two loading modes were explained detailedly,so as to describe the mechanical failure process of asphalt mixture specimens qualitatively using acceleration signals.Finally,from the perspective of vehicle information,the analytical study on pavement acceleration was conducted continually.According to the current relevant specification in China,the pavement acceleration signals under different vehicle types were obtained by the help of finite element simulation.On this basis,the discussions on such vehicle-induced pavement acceleration signals were carried out in both time domain and frequency domain.The relationships among the time-domain and frequency-domain features of pavement acceleration and the axle numbers,speeds,axle distances and axle loads of moving vehicles were analyzed emphatically,and then a new vehicle information acquisition method based on the low-frequency distribution of pavement acceleration and suitable for the vehicles with two or three axles was proposed.Relied on a demonstration road section in Yunnan Province,the pavement acceleration measurement was conducted to further verify the practical application of pavement acceleration in vehicle information acquisition.In summary,pavement acceleration contains very rich physical information,and is worthy of analyzing more comprehensively and deeply;it is hoped that this dissertation can improve the understanding on pavement acceleration,and also provide a valuable reference for future relevant studies.