Effect of Road Surface Irregularities and Structural Variability on Dynamic Pressures under Flexible Roads

摘要

As part of a program of research to obtain data for rational pavement design, measurements are being made of the vertical component of the dynamic stress generated in the soil subgrade by vehicles travelling along road surfaces. In addition to the main factors which control the stress, such as vehicle speed, wheel load and road temperature, other factors, often random in character, can cause large variations in the soil stresses. These factors include variations of the dynamic wheel load resulting from the characteristics of the vehicle as it travels over road surface irregularities, and non-uniformity of the soil and other road materials. They were considered relatively unimportant in earlier work where there were often considerable differences in the load-spreading properties of the various constructions examined in a particular experiment. The present work indicates that, under certain circumstances, these uncontrolled factors can cause the soil stress to vary by up to plus or minus 35 per cent under the same nominal construction. (Author)