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Title: Application of shakedown theory in the structural design of bituminous pavements
Author: Liu, Shu
ISNI:       0000 0004 5989 0757
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2016
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Excessive rutting, one of the major distress modes of bituminous pavements, is mainly caused by the accumulation of load-induced permanent deformation. However, current pavement design approaches against the excessive rutting are mainly developed using the theory of elasticity. Recently, a new pavement design approach based on the shakedown concept has attracted lots of attention because it can consider plastic properties of pavement materials. However, most of the existing shakedown solutions were developed for pavement foundations composed of granular materials and soils. Very limited work has been reported on bituminous pavements. Besides, current studies usually assume homogeneous, isotropic pavement materials obeying an associated plastic flow rule (termed as standard materials in the present study), which may not be realistic for pavement materials. In the present research, a step-by-step numerical approach was used to obtain numerical shakedown limits of pavement structures under repeated moving loads. Both two-dimensional and three-dimensional problems were considered. It was found that, under the assumption of standard materials, the obtained numerical shakedown limits and residual stress fields agreed well with the available theoretical data. A static (i.e. lower bound) shakedown approach for pavements with anisotropic, heterogeneous materials was developed based on Melan’s lower bound theorem and the critical residual stress method of Yu and Wang (2012). The influence of material plastic flow rules on pavement shakedown limits was also evaluated both numerically and theoretically. It was found that neglect of the inherent material properties (i.e. anisotropy, heterogeneity and non-associated plastic flow) could overestimate the real shakedown limits of bituminous pavements. A series of tests were conducted to validate the shakedown concept for the responses of bituminous pavements under traffic loads. Two distinct phenomena corresponding to shakedown and non-shakedown were observed. Triaxial tests and uniaxial compression tests were also undertaken to obtain the stiffness and strength parameters, from which the theoretical shakedown limits can be calculated. Comparison between the experimental results and the theoretical solutions revealed that the current 3D shakedown approach for standard materials may overestimate capacities of bituminous pavements. Finally, the lower bound shakedown approach was employed to design a typical bituminous pavement. A direct comparison was made between the shakedown-based design and the current UK design method. It demonstrated that the shakedown-based design for bituminous pavements can be conducted considering the maximum contact pressure and a relatively high air temperature.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TE Highway engineering. Roads and pavements