Gpr data simulation for engineering investigations in shallow regions

Dissertant

al-Dami, Haidar Abbas Neam

Thesis advisor

Karim, Husayn Hamid

University

University of Technology

Faculty

-

Department

Department of Building and Construction Engineering

University Country

Iraq

Degree

Master

Degree Date

2011

English Abstract

-Ground-penetrating radar (GPR) technique was used at University of Technology-Baghdad, as a non destructive, quick, low cost and powerful technique in detecting any change in the constituents of subsurface materials which can be consequently applied in urban and constructed areas.

The main objectives of this study are: to simulate GPR data for shallow engineering investigation obtained by 250 and 500 MHz antennas by detecting different buried bodies; investigating the foundations and inspection the condition of reinforced concrete.

This work is carried out in three different sites with different applications, Turning Unit, Old Plumping and Building Department sites.

In the first site , a simulation is used for GPR data with different geometric buried bodies, located at different depth and tested them in different conditions (dry and wet conditions).

In the second site, a survey of unknown areas is achieved by using GPR, which is mainly concentrated on investigating the foundations of old Plumping.

While the third site is represented by inspecting the conditions of reinforced concrete using medium frequencies to detect bars and their quantity and configurations.

Most of the raw data (before processing) of radargram do not appear clearly the presence of buried bodies or other subsurface structures.

But after processing (by using suitable filters and other interpretation tool parameters), many of the investigated subsurface structures appeared clearly.

This leads to extract information about the dielectric constant and velocity and suggest the buried structures that are responsible for such reflection signals with the assistance of RadExplorer and ObjectMapper softwares.

It is found from this study that the degree of clarity of the buried bodies don’t depend on the higher value of dielectric constant of the body, but it depends on the contrast between the body and the host medium.

Thus the body with low dielectric constant appears more clearly than that with higher dielectric constant when they are at the same depth.

The best detecting depths are 1.5 and 1 m for antenna frequencies 250 and 500 MHz respectively.

The accuracy which indicates the type of the buried bodies depends on the dielectric constant and velocity of reflected wave from these bodies.

It is noticed that wet condition (moisture content) affects the depth of penetration radar waves.

The near surface bodies appeared more clearly than the deeper ones.

The best results have been obtained when the transmitter and receiver antenna is perpendicular to the axis of the buried bodies.

But when the transmitter and receiver antenna is rotated to be perpendicular to the profiles (and at the same time the antenna is parallel to the axis of the buried bodies), the results are good but with some confusion concerning the location and depth of the buried bodies.

Regarding the parallel survey, none of the buried objects appears except the appearance the buried sewage pipe at 80 cm depth.

Processing of radargrams of the old plumping site reflects clearly the foundation of some devices such as; sand hammer, sieves vibration, treatment oven, fusion ovens and sand mixer.

The study suggests the ability of using the 500 MHz antenna for investigating and identifying the subsurface reinforced concrete in the foundation of this site.

Also it suggests the ability of using the 250 MHz antenna to investigate the reinforced steel bars and their configuration and network that are used in hidden mensurations of Building Dep.

site.

Main Subjects

Civil Engineering

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305303