Abstract:Based on BISAR software,a comparative study was made of the subgrade working area depth.A full analysis was made of the effects of pavement structure rigidity,subgrade rigidity and vehicle load on the subgrade working area depth.A mistake in converting the pavement structure layers’ thickness into equivalent subgrade thickness in original subgrade textbook was disclosed,which may lead to some illogical results by using the ratio of vehicle load adding stress to road deadweight stress to define the subgrade working area.Finally,this paper presents a proposal to replace the road deadweight stress with soil terminal strength in defining subgrade working area.
