| Because of the advantages of high stiffness, good stability, superior carrying capacity, long service life, convenient construction work etc., Cement concrete pavement is attracting more and more attention in road-builders of different countries. However, by virtue of the gradual decrease of using properties of Cement concrete pavement, various damages appear gradually. The most common one is the cavity of cement concrete cement. How to adopt an effctive approach to examine cavity beneath concrete slab, and to precisely distinguished cavity areas and location, is the key work of pavement M & R。The thesis proposes the detection of void for Cement Concrete Pav-ement with the method of acoustics-vibration. The technique of acoustic-cs-vibration can determine the quality of samples through measuring the acoustic characteristics of the vibration wave which generated by filliping the test cases. In practical project,The concrete slab can be regarded as the acoustic oscillator, void as the perturbation of its resonant modes. By employing the software of ANSYS, it makes modal analysis for concrete slab and builds the rela-tionship between the vibration frequencies of concrete pavement and void. It provides the theoretical basis for void detection method. The method of void detection works as follows:firstly, create test system on the sound c-haracteristics of the perturbation of harmonic oscillator and process self-vibration signal of the concrete slab samples which was collected by the test system using the software of Matlab; Then, extract the free vibration frequency of concrete slab; Finally, Make the void area determination of concrete pavement through adaptive neural network. The acquisition and analysis on the sound signal, including the using of adaptive neural netw-ork, is based on Matlab software void. With the related experimental data, the experiment achieved good results by the detection method of acous-tics-vibration.Conclusion shows that acoustic-vibration combined with BP neural netw-ork system can be strict, rapid recognition of the vacancy of concrete sl-abs, and it provides the theory and application basis for research of other common damages of concrete slabs(for crack, void and so on), the res-earch results provide a new thought and theory basis for evaluating the v-acancy of concrete slabs, it has larger theoretical meaning and enginee-ring value. |
