Estimation of In-Situ Shear Strength Parameters for Subgrade Layer Using Non-destructive Testing
The Falling Weight Deflectometer (FWD) test has been widely used for evaluating the structural condition and load-carrying capacity of asphalt pavement systems as a non-destructive testing device. Conventionally, the in situ stiffness properties of the va
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Abstract The Falling Weight Deflectometer (FWD) test has been widely used for evaluating the structural condition and load-carrying capacity of asphalt pavement systems as a non-destructive testing device. Conventionally, the in situ stiffness properties of the various pavement layers are estimated from the analysis of the surface deflection measurements using a backcalculation procedure. In this pilot study, an innovative and novel approach was investigated for estimating the shear strength parameters (C and ϕ) of the subgrade layer by means of FWD testing. Such parameters become important and necessary when assessing the risk of instantaneous shear failure in asphalt pavement layers under non-standard heavy vehicles. In order to assess the applicability of proposed approach, numerically simulated FWD test as well as measured FWD field data conducted on the APT asphalt pavement sections at the National Airport Pavement Test Facility (NAPTF) were analyzed. The surface deflection measurements from the FWD testing at multiple load levels were used in conjunction with backcalculation process to capture the stress dependent behavior of unbound layers and subsequently used to determine the shear strength parameters of the subgrade layer. It was found that the proposed approach was capable of estimating the in situ shear strength parameters of the subgrade material and the results were consistent with those obtained from conventional laboratory testing. Based on the findings from this study, work is
H. Nabizadeh (&) E.Y. Hajj R.V. Siddharthan S. Elfass P.E. Sebaaly University of Nevada, Reno, Reno, USA e-mail: [email protected] E.Y. Hajj e-mail: [email protected] R.V. Siddharthan e-mail: [email protected] S. Elfass e-mail: [email protected] P.E. Sebaaly e-mail: [email protected] © Springer International Publishing Switzerland 2016 J.P. Aguiar-Moya et al. (eds.), The Roles of Accelerated Pavement Testing in Pavement Sustainability, DOI 10.1007/978-3-319-42797-3_34
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currently undergoing to extend and validate the proposed approach for different type of asphalt pavement structures and subgrade properties. Keywords Shear strength parameters dependent behavior Asphalt pavement
Falling weight deflectometer
Stress
1 Introduction Non-destructive testing (NDT) techniques including lasers, Ground-Penetrating Radar (GPR), Falling Weight Deflectometer (FWD), penetrometers, and seismic technologies have been increasingly utilized in pavement industry for the purpose of quality control and quality assurance (QC/QA) as well as evaluation of pavement performance during its service life (Von Quintus et al. 2009). Among the various NDT techniques, the Falling Weight Deflectometer has attracted substantial attention from highway agencies in the past decades. The FWD simulates pavement responses under a moving truck wheel by applying a stationary dynamic load to the pavement surface. The applied load in conjunction with the measured vertical surface displacements at different radial distances from
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