geo physical investigations

1. DEPARTMENT OF CIVIL ENGINEERING
CASE STUDY ON
GEOPHYSICAL
INVESTIGATIONS

2. CONTENTS:
 Introduction
 Literature
 Methodology
 Summary of case studies
 Conclusion

3. INTRODUCTION
I. Geophysical Investigation is an indirect
approach to the investigation of ground or built
structure.
II. Geophysical techniques can be used to
measure the variation of the physical properties
of sub surface material.
III. These investigations are carried out quickly.
This means large area can be investigated in are
reasonable short period and hence the time is
saved

4. OBJECTIVES:
 To study previous Investigations of case studies solved in
different locations.
 Review on geophysical Investigations methods.

5. METHODOLOGY
Collecting data on actual existing work
Gathering information about methods used
Overview of Case studies
Conclusion

6. Author Title Case study review Conclusion
Nazli lsmail
Muhammad
Yanis
Firas sarhan
Abdullah
Mapping buried
ancient structure
using gravity method
: A case study from
Cot Sidi Abdullah
,North Aceh
 The study area is situated in kuta
krueng village ,samudera sub
dist,north aceh.
 Gravity data where collected on a
suspected buried structure of cot sidi
Abdullah.
 The data were acquired using CG5
AutoGrav. The AutoGrav is a
microprocessor-based automated
gravity meterthat has measurement
range of over 8000mGals and a reading
resolution of 0.001mGal.
 This accurate specification enables the
AutoGrav to be used for detailed
archaeological surveys.
 The accient structure of cot sidi
Abdullah has been successfully
mapped using gravity method.
 The method is considerably fast,
cost effective and non-invasive to
be applied for archaeological
investigation.
Table 1: Gravity method (Geophysical investigation)
References:
1.T.Muhammad,Daulah Shalihiyah di sumatera ,Lhokseumawe:CISAH,2011.
2.J.M.Reynolds,An Introduction to applied and environmental geophysics,1st ed.,UK:Geo-sciences Ltd,1997.

7. Map of Cot Sidi Abdullah(A) and Sidi Abdullah’s tomb(B). Grid shows area of data
measurement.Blue indicates Water area , green is building and grey is footpath.

8. Author Title Case study review Conclusion
Momoh,L.O
O.Akintorinwa
M.O. Olorunfemi
Geophysical
Investigation of
Highway Failure – A
case study from the
basement complex
Terrain of
Southwestern
Nigeria
 The study area is situated in Ilesha-Owena
highway is located within the lagos-Ibadan-
akure highway in the northern part of osun
state,southwestern Nigeria
 Three geophysical traverses study highway
segments.To detemine the lateral and vertical
variation in ground apparent resistivity
beneath each specific traverse line as
opposed to the schlumberger VES that
entailed 1-D vertical probing of the
subsurface .Both arrays utilized multiple
electrode spacings for variable depth
mapping.A base station was established for
the three traverses.Base station readings
were taken before commencement of
measurement and immediately after all the
traverses had been occupied to enable
diurnal and offset corrections.The GEONICS
EM 16 VLF-EM Unit was used for the EM data
collection along the three highway segments
investigated.
In this work, geophysical
investigation of
stable/unstable segments of
Ilesa-Ife highway has been
carried out as a means of
establishing the geological
factors that may have
influenced the incessant
failure of the highway,results
from geophysical survey
conducted to investigate
causes of highway failures
identifies the possible causes
of the highway pavement
failure in a typical basement
complex area.
Table 2: Magnetic method ( geophysical investigation)
References:
1. Adeleye,A.O.,2005.Geotechnical Investigation of Sub-grade soil along sections of Ibadan-Ife
highway unpublished M.Sc. Project ,Obafemi Awolowo university,Ile-Ife,pp:181
2. Ajayi,L.A1987.thought on road failures in Nigeria.R.E.,1989

9. Fig: soil map of the study area (modified after
smyth and Montgomery,1962)
Fig: Geological Map of the area around the investigated
Highway

10. Author Title Case study review Conclusion
Aigbedion Isaac
Samuel O Salufu
Application of
electrical
Geophysical
method in site
selection for viable
area for agriculture
practices: A case
study of Ukpenu-
Ibhiese and
Iruekpen edo State-
Nigeria
 Electrical geophysical
method was applied , to
select viable area with
essential soil nutrients for
plant’s growth.
 The result of the electrical
resistivity geophysical
method showed that
southwest and northwest of
the area has resistivity
values that ranged between
80ohm to 170ohm while
the remaining part of the
area has higher values than
170ohmm,ranged from
580ohmm to 950ohmm.
Electrical geophysical
method has been applied
and its result compared to
conventional soil test
analysis in this study, to
select area with viable soil
nutrients for the purpose of
crop cultivation
Table 3: Electrical Method (Geophysical Investigation)
Reference:
1. Sheriff. Sheriff RE. Enclopedic dictionary of exploration geophysics, 3rd edn. Society of
exploration Geophysicists, Tulsa.1991;2002

12. Author Title Case study review Conclusion
B.Siemon
M.Ibs-von seht
S.Frank
Airborne
Radiometric peat
mapping A case
study from a bog in
Germany
• This case study uses
helicopter-borne
radiometric data to
investigate a bog in
Germany.
• It requires scaling of the
relative depth values .
Depths derived from
electromagnetic data are
usable for scaling due to
their similarity to borehole
peat depths .The main
difference of the
combination of
electromagnetic and
radiometric depths and the
peat depths about 100
boreholes is very small(-
0.08+_1.09m),but may
differ
significantly(>+_2m)at
some points.
The lateral extent of the bog is
derived from low radiometric
and elevated surface data .
The vertical extent results from
smooth resistivity models in
combination with a steepest
gradient approach as well as
from radiometric data
Table 4: Radiometric(Geophysical Investigation)
References:
1. Gatis,N.,Luscombe,D.J.,Carless,R.M.,Harrod[2019]mapping upland peat depth using airborne
radiometric and lidar survey data.Geoderma,335,78-87.

13. Vertical resistivity section along flight line (above)
derived from smooth inversion of HEM data and
peat elevations / thicknesses (below) derived from
HEM or/and HRD data in comparison with peat
ranges found in boreholes (brown columns).
Surface elevation and a peat indicator (derived
from airborne data) are also shown.

14. Table 5: Seismic Method(geophysical investigations)
Author Title Case study review Conclusion
V.Venkateswara
Rao
J.Srinivasa Raju
B.S.Prakasa
Rao
P.Koteswara
Rao
Bed Rock
Investigation by
Seismic Refraction
Method-A case
study
A high rise RCC bridge is under
construction across the river
Krishna on down stream side of
the Nagarjuna Sagar dam.
The data foe seismic gathered
during present survey along three
lines are line 1(110m),line 2
(115m),line 3(160m)
From the present results
,hard rock is found at 20 m
depth at pier location p-
6,27m at pier-7and 18m at
pier location p-
8.Accordingly the
recommended founding
levels for these piers are
50m,43m,and 53m
respectively.Appropriate
foundation design has to
evolved for such adeep
foundation.
References:
1.Donald p. Coduto,pearson Education(Singapore)Pte,Ltd., Indian Branch,Delhi,2001.
2. Ramachandra Rao, M.B., EBD Educational Pvt. Limited, Dehradun, India,1975, 1-403

15. Figure : Founding levels for various piers

17. THANK YOU