engleski

Effect of traffic load on behaviour of flexible pavements – examples from Croatia

In the last ten years, Croatia invested considerable monetary funds in road building. The pavement structure design of all built roads was done in accordance with the Croatian regulations (HRN U.C4.012 standard). The traffic load, as one of the key parameters in design, was calculated according to the HRN U.C4.010 standard, and expressed by the number of equivalent standard 82 kN axle load. The applicable Croatian and European law regulations allows axle loads higher than the standard, and appearance of axle loads higher than those allowed by the law is not rare on Croatian roads. The paper considers the effect of the axle loads on behaviour of several types of flexible pavements characteristic for Croatia, whereby parameters like type of the axle, the type of tyres and the inflation pressure were taken into account. The calculations of critical stresses and strains (tensile on the bottom of asphalt and cement stabilized layer, vertical compressive on the top of the subgrade) were performed for selected pavements by the CIRCLY software. Based on the calculated values of stresses and strains, equivalency factors, which represent a relative effect of particular levels and ways of load transfer on the structure, were determined. The obtained results show that the effect of the considered input parameters (loads, types of axles, types of tyres, inflation pressure) is not negligible. It is indicated that the existing equivalency factors of particular vehicle types, which are used to determine the traffic load, i.e. the number of the standard equivalent 82 kN axle load during design of new or estimation of the residual life of the existing flexible pavements, should be revised.

LEF; ESAL; flexible pavement; fatigue criteria; rutting criteria

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