| A large number of existing surveys have found that the service life and quality of pavement in China have not reached the expected level.The main reason is that the strength of the base layer is insufficient or the strength of the base layer is attenuated too fast during use,thus accelerating the damage of the road panel.Most of the pavements in China use a semi-rigid base layer.However,due to the poor water permeability of the semi-rigid base layer and the weak anti-scour ability,water can not be quickly drained from the base layer to cause water accumulation.Under the action of water,hydrodynamic pressure is generated.Pavement,muddy mud and other phenomena will appear on the road surface,and the degree of bonding between the structural layers will be changed,eventually causing cracks and rutting and other diseases on the road surface.In addition,the road surface dynamic response is more and more obvious,and the traditional static road design is difficult to meet the design requirements.The RCC base has high strength and slab body,which can better adapt to heavy and extremely heavy traffic.Based on this,it is more research significance to carry out the analysis of the dynamic response test of the RCC base course.In this paper,the following researches were carried out by means of on-site drop hammer deflection instrument FWD,Beckman beam BB,vehicle load field test combined with laboratory test:(1)In the test section,the drop-type deflection device(FWD)and the Beckman beam deflection device(BB)are used to measure the deflection of the road surface layer by layer,and it is found that the two have a good linear relationship and use the inverse calculation.The software cacl.4.0 backcalculates the modulus of each asphalt layer layer by layer,and solves the problem that the single layer deflection calculation is not unique.The temperature correction of the layer-by-layer deflection is performed by testing the temperature field measured on the road surface.(2)Using a rotary compactor to form a test piece in the room,perform an indoor dynamic modulus test,and analyze the influence of frequency and temperature on the dynamic modulus to establish a dynamic modulus master curve.The relationship between the layer-by-layer inverse modulus and the indoor dynamic modulus is established,and the two have a good logarithmic relationship.(3)Relying on the on-site test section,the load test of on-site road vehicles is carried out by changing the test conditions such as vehicle type,axle load,tire pressure,vehicle speed,braking and braking,and the horizontal and horizontal strain levels of the road under different working conditions are analyzed and different working conditions are analyzed.The influence of fatigue life on the road surface,combined with the longitudinal and transverse strain time history curves,establishes the relationship between the vehicle load travel speed and the strain time history curve. |
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