Paper by Priyam Saxena and Lev Khazanovich from 10th ICCP Quebec 2012
It has been observed by many researchers that the subgrade behavior is load rate dependent. The apparent subgrade stiffness is much higher under the fast moving axle loading than during the slow developing temperature curling and moisture warping. However, traditionally a single k-value is used for both curling and axle load analysis. This paper presents a mathematically rigorous solution for determining stresses and deflections in rigid pavements using separate k-values for slab curling and axle loading. The developed procedure illustrates that, in the event that the k-value for the temperature curling analysis is less than that of the axle loading, the overall stress state is lower under combined axle and thermal loads. At the same time, the paper demonstrates that due to the inherent non-linear behavior of the interaction of the slab and foundation, the use of simple linear superposition of curling and axle loading stresses for two different k-values may result in significant errors. Demonstration for ISCP Board only.