Voids & Soft Ground

Subsurface voids (whether naturally occurring or manmade) and associated areas of soft ground present a significant risk to future, and existing, infrastructure and buildings. Unknown voids can be discovered during construction and can cause hazards and expensive delays to a construction project.

Geophysical techniques provide a suite of site reconnaissance tools that enable site characterisation and provide total site coverage. Relatively simple geophysical surveys can be applied to a site in order to plan and design a targeted intrusive investigation and subsequent remedial works to problem areas of ground. The use of geophysics reduces the associated risks and can save the developer time and money during the project.

The use of GPR can be effective in identifying small or shallow voids in structures or ground up to 5m depth. Detailed analysis of microgravity readings can identify the size and shape of voids and is the primary method of void detection, in particular for locating deeper voids. A series of case studies are provided here to illustrate the power of the technique.

Voiding Investigation Techniques