Three-dimensional spatial stress state of highway subgrade under vehicle load: experimental evidence and evaluation model

ABSTRACTIn this study, field tests of highway subgrade dynamic response were conducted using a self-developed regular dodecahedron soil pressure sensor (RDSPS). The RDSPS can be used to quantify the total stress of the subgrade soil element. The effects of different axle loads, speeds, and vehicle types on the dynamic response of the subgrade were investigated. The spatial distribution law of the vertical dynamic stress of the highway subgrade was examined. An estimation model for the vertical dynamic stress and the influence depth of vehicle load was developed. The results suggest that, under the action of a moving traffic load, the principal stress axis continues to rotate. Both vehicle speed and axle load have an impact on the dynamic response of the subgrade; however, for newly built highways, the impact of the vehicle axle load on the dynamic stress is more significant. The vertical dynamic stress increases linearly with the speed or axle load of the vehicle. The attenuation law of the vertical dynamic stress caused by different types of vehicles on the subgrade along the depth direction is basically consistent, and the attenuation speed changes from fast to slow, with the fastest attenuation rate in the base layer.KEYWORDS: Highway subgrade; dynamic response; three-dimensional stress state; field testing; influence depth AcknowledgmentsThis work is supported by the Natural Science Foundations of Shandong province, China (No. ZR2020ME242) and the National Natural Science Foundation of China (No. 52178429, and No. 52027813).Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was supported by National Natural Science Foundation of China: [Grant Number 52027813]; Natural Science Foundations of Shandong province: [Grant Number ZR2020ME242].