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What Is Ground Penetrating Radar?

what-ground-penetrating-radar

Ground Penetrating Radar (GPR) is fast becoming one of the most popular techniques of inspecting buried structures non-destructively. 

The term refers to all techniques using radio frequencies (between 1-1,000 MHz), that engineers and GPR equipment operators use to generate a detailed profile of structures and features buried within manmade structures or underground. 

The data obtained using GPR techniques can be used to identify the depth, position and nature of underground objects. 

Additionally, the data can be used to identify different soil types and their structure.  

Read on to learn more about:

  • How GPR Works
  • Depth of Penetration
  • GPR Data Collection
  • GPR Data Analysis
  • Potential GPR Limitations

How It Works 

GPR uses a high-frequency radio signal to map out subsurface objects and structures, hence eliminating the need to disturb the ground, or surface in question. 

The high-frequency radio signal is transmitted into the ground by a transmitting antenna, while a receiver picks up reflected signals which are then stored on digital media. 

A computer calculates the time it takes a signal to travel from the transmitter into the ground and back into the receiver to come up with the positioning and depth of buried objects. 

The processed data is then displayed on the GPR unit’s display screen for interpretation by the device operator. 

How Deep Can It Penetrate?

GPR units can be used to map out objects and structures at varying depths. 

The frequency of the transmitting antenna plays a huge role in determining the range of depth that can be reached. 

Basically, high-frequency signals, around 1000MHz, narrowly penetrate the ground. 

However, they produce high-resolution images of any buried objects. 

They are usually preferred in applications that involve inspection of concrete structures for buried objects such as conduits and rebar among others.  

Low-frequency signals, 500MHz or lower, on the other hand, penetrate deep into the ground, thousands of feet in some cases. 

However, the resulting image has a low resolution. Such signals are used in establishing soil structures and identifying sinkholes among other things.  

Data Collection 

To collect the data needed to map structures and objects buried underground, different types of GPR systems are used – depending on the nature and size of the objects as described above i.e. low frequency and high-frequency systems. 

The GPR equipment repeatedly emits radio signals, up to a thousand times per second. 

The data displayed on the unit is translated by the operator in the field, immediately after it is received, and/or further analysed later using a computer – in case more information is needed. 

Data Analysis 

The GPR unit operator should have some field experience to be able to accurately interpret the data displayed on the unit. 

The main reason for this is that the GPR waves emitted and received by the equipment in use are affected by the conductive and dielectric properties of the soil.

This includes any objects, concrete and water lying beneath the surface of the area being scanned. 

The above is an outline of the entire GPR scanning process. 

It is, however, important to mention that this non-destructive technique does actually have a number of limitations.

GPR Limitations 

  • Conductivity – this term simply refers to how well the radio signal can pass through a given material. 

The signal can penetrate deeper in highly conductive materials. The opposite is also true, in low conductivity hinders signal penetration. 

  • Diameter Of Buried Pipes Or Cables – GPR signals may also fail to detect objects that are buried too deep or those, such as cables or pipes, which have a diameter of less than four inches. 

Summary

From the above, you can see how, as one of the most accurate and reliable non-destructive testing techniques, GPR has made the mapping of buried structures and objects a much easier, faster and cheaper undertaking.  

If you have any construction or excavation projects on the go, it is vitally important to hire a concrete scanning company to scan the location first. 

High Resolution Concrete Scanning is a company you can trust to provide you with the most accurate and detailed information when it comes to scanning your concrete structures. 

They have years of experience and use the most advanced tools and equipment in the business.

At High Resolution Concrete Scanning, our specialisation in concrete scanning services has made us industry leaders. If you need to perform any type of concrete scanning, then look no further than us at High Resolution Concrete Scanning.

Please call us today on 0437 365 830 or contact us through our website www.high-res.com.au/contact-us/

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