Research On The Influence Of Slice-Cracks Technology On Mechanical Behavior Of Asphalt Overlay On Existing Cement Concrete Pavement

Slice-cracks recycling and reinforcement technology is a new type of cement pavement reconstruction technology.Slice-cracks of cement pavement makes the cement slab crack evenly,and structural layers with even strength can be obtained after grouting reinforcement.Practice has proved that the residual strength of the road treated with this technology is large,and diseases such as reflection cracks and interface slide can be effectively suppressed base on the cement pavement with cracks.However,there is no mature and complete construction specification of slice-cracks recycling and reinforcement in China.The relevant mechanics mechanism,design and construction index is still incomplete.In view of this situation,based on the G106 national road reconstruction project,the coupling method of discontinuum-continuum is applied to the study on the relevant mechanical behavior of the asphalt overlay structure on the existing cement concrete pavement,the main research is as follows:(1)Through the establishment of a slice-cracks existing cement concrete pavement structure model and its corresponding asphalt overlay structure model,the road surface deflection and the distribution of shear stress under different crack distribution forms was analyzed.The analysis results show that the road surface deflection is related to the intersection of cracks.When the intersection of the cracks is located in the cement concrete slab,the greater the spacing between the cracks,the more obvious the unevenness of the road surface deflection,the greater the maximum deflection of the road surface.The strength and uniformity performed best when the crack spacing is 0.2m.The cracks penetrating the cement slab will make the deflection increase significantly.The smaller the crack spacing,the closer the location of the maximum shear stress in the asphalt overlay is to the road surface,and the greater the shear stress.(2)In order to analyze the formation mechanism of reflection cracks in asphalt overlay paved on slice-cracks cement pavement,the mechanical analysis model of the joint and crack tip were established.The results show that the crack spacing is 0.2m,the shear stress of the joint tip is the smallest and the impact of the crushing direction is minimal.As the distance from initial crack to the joint reducing,the shear stress at the joint tip can be effectively reduced.The crack tip stress concentration is more obvious than the joints.When the crack spacing is 0.2m or 0.25 m,the stress at the crack tip and the road surface deflection are the best on the whole.Decreasing the length of cracks can effectively use the strength of cement concrete,and the stress concentration in the cement layer can ensure a larger strength reserve space.(3)Based on the actual form of road surface groove,the mechanical analysis model for asphalt overlay over the cement pavement with grooves was established.The effects of different groove distributions on the horizontal displacement of the road surface and the maximum shear stress at the groove were analyzed.The results show that the groove spacing is in the range of 0.3~0.8m,the horizontal displacement of the road surface and the maximum shear stress at the groove can meet the engineering requirements.Depth of groove is most suitable in 0.15~0.30 cm.Outside this range,horizontal displacement is not ideal and the maximum shear stress will increase significantly.And the side slope of the groove with a small angle is more advantageous.