Study Of Concrete Pavement Materials And Structure Under Heavy-load Transportation

The heavy-load transportation is a worldwide problem, which has come to attention at home and abroad and has been researched. In this study, the construction techniques of cement concrete pavement under heavy-load transportation were researched from the two aspects of materials and makeup of pavement.1. The characteristic and mechanism of initial failures on cement concrete pavements underheavy-load transportation have been analyzed in this paper. Based on this, the countermeasure against cement concrete pavement destroying was addressed herein from pavement's material and makeup. Setting dowel in concrete transverse joints and pavement structural drainage system, choosing the base material of good performance at aspect of anti-pumping, can effectively prevent pavements pumping damages; Increasing the thickness or raising the flexure strength of concrete slab can prevent the initial fatigue failures.2. In order to building up anti-destroying capability of the given pavement thickness under heavy load, reducing the wastes of raw and processed materials, the high performance pavement concrete, which has a very good road performances, was developed applying to cement concrete pavement under heavy-load transportation.3. The calculation method of composite resilient modulus of foundation in present specification of cement concrete pavement design for highway is based on the principles of the deflections equivalency at the top of base. The method can't reflect the characteristics of large rigidity of semi-rigid base, which results in the very larger difference between a loading or thermal stresses computed value and a theoretically correct value. In this study, the calculation method of composite resilient modulus of foundation was founded on the equivalent principles of the flexure stresses of concrete slabs and stresses induced concrete slab due to thermally warped or curled.4. Concrete slabs was assumed to be an infinite thin plate resting on elastic foundation, when loading stresses in double-layered plain concrete pavements adopted in present specification of cement concrete pavement design for highway are analyzed. The assumption can't calculate the vertical compressing deflection and the level cutting deflection, and exaggerates the function of base supporting. This brings about the error of loading stresses computed value in double-layered plain concrete pavements. The applied calculation method of loading stresses in double-layered plain concrete pavements was founded in the study5. For the sake of convenient for application and avoiding consulting a nomogram forthermal stresses calculation, through a great deal of calculation for different pavement construct, this paper presents experiential formula for the coefficient of thermal stresses, which has precision in use.6. The results indicated that the influence of temperature variations on load transfer efficiency is very large, application of negative temperature gradient make for reducing deflections at joints and LTE of a specific pavement is time dependant. The influence of dowel bars at transverse joints on loading stresses and thermal stresses at the critical load position can be ignored, and the influence coefficient of dowel bars at longitudinal joints on thermal stresses is 1.02— 1.05.7. In this study, three dimensional finite element models were developed simulating stressesinduced in doweled joints due to thermal and load. The results indicate that excessive contact stresses at the interfaces between steel dowels and the surrounding concrete occurs due to thermal and load, and crack at dowel/concrete interface form. This leads to the development of dowel looseness and distress in concrete transverse joints. New load-transferring device pilot studies indicate that the protecting sleeves significantly reduce the magnitude of such contact stresses and enhance durability of load transfer efficiency. Finally, this paper presents the design method of the protecting sleeves.8. Based on analysis of pavement condition and damaged mechanism on cement concretepavements under heavy-load transportation, according to research of the characteristic of heavy-load transportation, material properties and structural composition design of cement concrete pavement, this paper presents the principia of structural composition design and the typical structure of cement concrete pavement under heavy-load transportation9. Considering the failures characteristic on cement concrete pavements under heavy-load transportation, in this study, a design method of concrete pavements, which aims for preventing concrete pavement fatiguing and pumping distress and destroying under the once or more effect of loads, is primarily put forward.