Study On Detection Technology Of Pavement Void Based On Spectrum Characteristic Analysis

Cement concrete pavement as a typical form of pavement structure has been widely used at home and abroad.Because of the void of pavement slab,the early damage of cement concrete pavement is serious,and it is not easy to repair.Therefore,it is one of the key problems in pavement maintenance that how to effectively determine whether there is void under the pavement structure.There are many factors affecting void under the pavement slab,and it is very complex.Therefore,in view of the actual needs of pavement maintenance management,this paper devotes itself to developing a technical means that can accurately and effectively identify the void under the cement concrete slab.Based on the theory of thin plate vibration,the void model of cement concrete pavement slab is established by using ABAQUS finite element software.The different boundary conditions of cement concrete pavement slab,coefficient of foundation bed,void shape and void area are calculated and analyzed numerically.The results show that the worse the boundary force transmission device is,the lower the natural frequency is.The foundation quality is positively correlated with the fundamental frequency of the pavement vibration.The void shape of the pavement has little effect on the natural frequency,but the larger the void area is,the more the natural frequency of the pavement decreases.Based on the theory of frequency spectrum analysis of sound,the pavement slab is regarded as an acoustic harmonic oscillator and the void is regarded as an interference factor to the vibration of the pavement slab.The response of the acoustic signal of the cement concrete pavement slab after the input excitation is processed and analyzed by using the software of matlab,and the time-domain and frequency-domain diagrams of the acoustic signal are obtained.The relationship between different void conditions and frequency spectrum is calculated.The natural frequency and frequency decline rate are set as the characteristic parameters for identifying void.The void of cement concrete pavement is determined by BP adaptive neural network.Engineering application shows that the detection technology of road void based on spectrum characteristic analysis has good practicability.The research results of this paper provide a new technical way for the void identification of cement concrete pavement,and have a certain guiding role for the maintenance and management of cement concrete pavement.