Simulation And Engineering Application For Resonant Crushing Of Old Cement Concrete Pavement

The old cement concrete pavement in long-term service affects the travel safety due to the serious damage of the pavement and limits its reconstruction effect and reconstruction cost for its high material strength.Therefore,based on the actual project in Guangxi,this dissertation proposes the application of resonance crushing technology to crush the old cement concrete pavement and carry out the design of the pavement with additional layer,to restore the structural performance of the original pavement,guarantee the safety of the passing vehicles,and realize the recycling of the old cement concrete pavement materials at the same time.The dissertation analyzes the resonant petrochemical mechanism of thin plate on elastic foundation,and also calculates the properties of the inherent frequency of the thin plate on elastic foundation.The calculation results show that the excitation frequency（ω₀）and the inherent frequency of the thin slab（ω_n）are controlled at 0.7ω_n≤ω₀≤1.3ω_n,and the effective breaking of the cement concrete slab can be achieved theoretically.The properties of the inherent frequency of the thin cement concrete slab are calculated by the vibration type function and Abaqus simulation.The calculation results show that the initial order inherent frequency of the thin slab under different boundary conditions is about 50 Hz to 100 Hz,and it is also determined that the effect of high frequency and low amplitude excitation force on the original pavement subgrade is weak,which provides a feasible guarantee for resonant crushing in practice.The gradation characteristics,strength mechanism and rebound modulus of the crushed layer section and the backfilled graded gravel section were compared and analyzed by field sampling of the trial crushed section.The pavement temperature field analysis and mechanical response analysis of the resonant crushed pavement structure were carried out through Abaqus finite element analysis,and the simulation results showed that the bottom of the pavement layer under load showed a tensile state,and the crushed layer showed an overall compression characteristic,showing its potential to be more inclined to a flexible base layer,and the overall resonant crushed pavement structure of the asphalt pavement structure was more inclined to a reversed pavement structure.The structural performance and structural strength of the reconstructed pavement were evaluated by Ground Penetrating Rada and Falling Weight Deflectometer,and the results of the study showed that the diseases such as debonding,uncompaction and cavities in the radar spectrum mostly existed in the crushed layer,and the structural strength of the semi-rigid base layer,graded crushed stone base layer and crushed layer was semi-rigid base layer>crushed layer>graded crushed stone base layer.In a comprehensive view,the gradation characteristics and strength characteristics of the old cement concrete crushed layer after resonance crushing disposal show obvious characteristics of flexible base layer,while its disposal as the base layer of the additional layer shows the overall pressure state,which can also better play the flexural and tensile properties of the additional asphalt surface layer.