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Received: February Accepted: July
DOI: ./mice.
INDUSTRIAL APPLICATION
Modeling and validation of impact forces for
back-calculation of pavement surface moduli
Mohan Zhao Yu Liu Hainian Wang Xinnan Xu Shaojie Xu
Key Laboratory of Special Area Highway
Engineering of Ministry of Education,
Chang’an University, Xi’an, China
Correspondence
Yu Liu, Key Laboratory of Special Area
Highway Engineering of Ministry of
Education, Chang’an University, Xi’an
, China.
Email: yul@chd.edu.cn
Funding information
National Natural Science Foundation of
China, Grant/Award Number:
Abstract
When an impact load is sufficiently small, its influence on the pavement struc-
ture is mainly from the surface layer material. To explore the influence depth
of an impact load and back-calculation of the pavement surface modulus, both
numerical calculation and experimental testing were conducted, and the results
are presented in this paper. The numerical calculation was performed through
a DEM-FDM-coupled model. After a new modulus back-calculation algorithm
is formed by analyzing the numerical modeling results, experimental tests were
also conducted for verification, and the results were analyzed. The max value
of the falling weight impact force was closely related to the elastic modulus of
the material, and the influence depth was controllable. Finally, it is proved that
the method can be used to calculate the surface layer modulus and estimate the
surface layer thickness.
1 INTRODUCTION
Since the s, falling weight deflectometer (FWD) mea-
surements have been extensively used for evaluating
pavement situ conditions (Uddin et al., ). With FWD
testing, the pavement surface deflection is measured to
evaluate the overall bearing capability of pavement or
to back-calculate the pavement layer modulus (Goktepe
et al., ;Saric&Pozder,). In practice, the layer
modulus back-calculation is a matching process combin-
ing mechanical analysis with multi-layered elastic system
theory and comparing measured and calculated deflec-
tions.
The earliest simplified method was to perform modu-
lus back-calculation by compiling a nomogram or table.
Although the speed of back-calculation is relatively fast,
it has not been widely used due to the poor accuracy of
the back-calculation results (Tutumluer & Sarker, ).
In contrast, the iterative method has been widely used
due to its good computational accuracy and applicability
© Computer-Aided Civil and Infrastructure Engineering.
(Harichandran et al., ), and researchers have devel-
oped various back-calculation software programs based on
this method, such as CHEVDEF, BISDEF, and ELSDEF.
However, the iterative method requires a long calculation
time; simultaneously, it depends on the value of the initial
seed and the presence of problems such as local conver-
gence and the uniqueness of the solution (X. Zhang & Sun,
). To further improve the computational efficiency,
the database search method was proposed (Gopalakrish-
nan & Khaitan, ). Since this method is much faster
and more stable, it is suitable for road network surveys,
and the MODULUS software based on this method was
developed in the Strategic Highway Research Program.
However, the disadvantage of this method is that the
database should be established in advance. At the same
time, interpolation often induces large errors for data that
are not in the database (Zha, ). With the populariza-
tion of computer-aided engineering, the artificial neural
network (ANN; Sharma & Das, ) method and genetic
algorithm (GA; Fwa et al., ) method were proposed for
1238 wileyonlinelibrary.com/journal/mice Comput Aided Civ Inf. ;:–.
