Characteristics of in-situ dynamic stresses of pavement subgrade under portable falling weight deflectometer test

This paper has summarised and enhanced the understanding on the dynamic stress characteristics within soil subgrade material under PFWD tests, by in-situ measurement of vertical and confining stresses. Besides, several crucial findings were yielded, (1) The different natures of the PFWD applied stress and soil stress indicate the variations of vertical stresses within the soil mass are influenced by other factors apart from the applied stress alone; (2) Beyond the distance of one times the PFWD plate diameter from the source of load, the E(PFWD) stays fairly constant, this corresponds to a vertical stress ratio (stress measured/stress applied by PFWD) of about 0.2; (3) The horizontal confining stresses are highest at the location of the source of load and reduce dramatically away from the source; (4) The drop height of mass was found to impose a moderate influence on the EPFWD, which is different from the findings provided by some of the previous researchers and (5) The confining stress has the strongest correlation with E(PFWD), being followed by vertical stress and deviator stress.