TITLE:
Using Geometry Data from Ground Penetrating Radar to Improve Pavement Layers Auscultation Using Seismic Surface Waves Inversion Method
AUTHORS:
Cheikh Diallo Diene, Mapathe Ndiaye
KEYWORDS:
MASW, GPR, Auscultation, Route, Elastic Properties, Permittivity
JOURNAL NAME:
Open Journal of Civil Engineering,
Vol.12 No.3,
July
29,
2022
ABSTRACT: In order to reduce the unknown
parameters during the inversion of the dispersion curve in the aim to obtain
more precise Vs and VP profiles, the Multi-Channel Analysis of
Surface Waves (MASW) method was combined with the Ground Penetrating Radar
(GPR) method. First, a 2D GPR profile was made on the pavement, then 1D MASW
profiles spaced by 0.2 m apart in the perpendicular direction and centered on
the intersection with the Radar profile. The GPR measurements, made with a 1600
Hz antenna, allowed to calculate the dielectric permittivities then velocities
in order to convert the times profiles to depth. Thus, the thicknesses of the
layers are directly read on the radar profile. MASW measurements were performed
by simulating the Multi-Channel Simulation with One Receiver (MSOR) method in
Land Streamer mode. Six 4.5 Hz pointless geophones are connected to the
seismograph consisting of an Arduino Due microcontroller and a nano-computer
type Raspberry Pi 4. The results of the dispersion analysis showed a
fundamental mode located between approximately 70 Hz and 200 Hz and an inverted
dispersion, characteristic of pavements with
higher frequencies propagating at higher velocities. The results show
that the integration of the number of layers and the thicknesses obtained from
the GPR measurements in the inversion parameters makes it possible to obtain a
more precise Vs and VP velocity profile. All profiles, seismic and radar, have shown that velocities decrease
with depth. The detected heterogeneities appear to be related to
differences in water content inside the pavement.