| With the continuous development of our society and the rapid economic growth,my country’s aviation industry has achieved unprecedently rapid development.The annual passenger traffic and cargo traffic continue to rise,and the aircraft load also keep increasing.As an important foundation of the aviation industry,the quality of airport runway definitely cannot be ignored.During actual engineering operation,due to objective or human factors,there are always void under the pavement deck.With the cyclic action of the aircraft load,the void problem may get worse,becoming slab corner fractures,plate breakages and other problems.Early detection and early treatment of void problem is required.How to detect and identify whether void exist and the specific location and depth of void has important engineering significance for the detection and maintenance of airport pavements.With the widespread use of heavy hammer deflection gauges and the development of polymer grouting technology,the maintenance method that combine the non-destructive testing and polymer grouting have been continuously improved.At present,the most mature method to determine the position and depth of the void is the combination of a hammer deflection instrument and a ground penetrating radar.In some ways,the heavy workload and the manual identification limite the applicaion of the polymer grouting.Therefore,this paper studies the void repair of airport cement concrete pavement and evaluates its effect.The specific research results are as follows:1.Using finite element software,a three-dimensional model of the void structure of the airport pavement can be established,to calculate the stress distribution of the pavement panel under geostatic stress and aircraft loading stress,to study the stress character with different void areas and different positions along the joints.The calculation result shows that under the geostatic stress,besides the stress concentration in the central void area,stress concentration also occur at the void edge,the critical surface of the void area and the non-void area;under the aircraft loading stress,Stress concentration occurs in the central void area,and a panel with a large void area has a larger stress peak than a small void area.2.The void beneath slab model under the action of HWD is established,to establish the void evaluation method based on the deflection basin data by studying the change-rule of the deflection basin data with different void sizes and different depths.The data results show that the numerical changes of the indexes BLI,MLI,and LLI based on the deflection basin curve can reflect the approximate depth of the void problem,and can provide a reference for the polymer grouting construction for void repairing.3.Through field test,polymer grouting repairs were carried out on the structural layer with void or loose problems beneath road surface.According to the test result,the deflection value of the grouting center decreased in 8 places and increased in 2places.After grouting,the void with original intercept greater than 50μm tends to be stable and qualified,and the load transfer capacity basically stay unchanged,the deflection ratio of the central plate and the plate angle has a large decline,and the waveform of three-dimensional radar image after grouting is relatively regular,even without reflection signal,proving that the vacant and loose positions are filled and squeezed tightly after grouting,and the effect is obvious.4.Comparison of ground penetrating radar data through field test and evaluation index based on deflection basin index,select 3 test panels with different void depths from the 10 test panels,and then basing to the ground penetrating radar images of voids at different depths,combinning the deflection basin data of the heavy hammer deflection meter,the result shows that the void evaluation method basing on the deflection basin data can be used for the repair evaluation of the road surface. |
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