Application of integrated geophysical technique for the mapping
Application of Integrated Geophysical Technique for
the mapping of old Foundation Pilings at Penang
Mohd Nawawi and Amin E. Khalil
PPSF, Universiti Sains Malaysia
• Problem statement
• Site Layout
• Planned Geophysical techniques
• Methods overview
• Survey layout.
The site under investigation is planned for new
development project at Pulau Pinang state. 20 years ago
another project was established at the site. However, the
project as cancelled and the buildings were removed and
the foundations was buried. These buried foundation
piles decelerated the construction of the new project.
This is motivation of the present work.
The site is a connection center where various
land and marine transportation exist. These
1- The ferry that connects Penang island with
2- The railway station (KTM) that connect the
other Malaysian states.
3- Rapid Penang bus station.
4- Asphaltic roads and a flyover bridge.
Foundation Piles can be
detected through these
1. Density contrast.
2. Shear wave velocity.
3. Magnetic properties due to iron bars.
5. Dielectric constant
Hence the following
3.Multichannel Analysis of Surface waves.
4.Time domain electromagnetic
5.Ground Penetrating Radar GPR
Although density contrast exist
between concrete piling and
surrounding soil, the area is too
noisy that we couldn’t carry out
a reliable gravity survey. As a
result the gravity method was
excluded from the survey
Example in figure
MASW (Multichannel analysis of
Two problems when
test MASW at the
problems are the
high noise and low
resolution of the
method. Hence, the
The method gave good
result as shown in the
The technique uses
aligned vertically at
a spacing of 1m. The
subtraction gives the
vertical gradient of
magnetic field. The
the near surface
The technique produce
profiles similar to
electromagnetic pulse is
sent to the subsurface,
the reflected energy
surfaces is then
• Old foundation piling decelerate the
establishment of new development project
• Near surface geophysical methods were
employed to solve the problem.
• Magnetic gradiometer and GPR showed
good example for detecting old foundation
• Other methods couldn’t be applied because
of the site conditions