Overload influence on unsealed gravel road performance

Abstract

The unsealed gravel roads are fundamental to flow the rural production and to provide the rural population access to urban centers, allowing a better economic and social life quality for this portion of the population. One of the main problems found in this type of road is the rutting, which are caused by the axle overload. In Brazil, traffic with overload is a common practice due to the lack of weight control on the majority of brazilian roads. Therefore, this research aims to evaluate the effect of load increase per axle on vertical stress on top of the subgrade and on the reduction of lifespan through the load equivalency factor (LEF) on two unpaved roads located in a settlement in the city of São Gabriel, RS. Those evaluations were made through the analysis of the vertical stresses on top of the subgrade and the through the LEF, using mathematics methods and SisPav software, with the AEMC tool. The analysis were always made for loads of 8,2 tf (standard), 10 tf and 12 tf and the study concluded that increased loading on the axle generates an increase in the vertical stresses on top of the subgrade, and automatically occasions decrease on the N number and increase of LEF, making the projections of lifespan of the analysed roads have a reduction of approximately 60% for 10 tf load and of 80% for 12 tf load).