Considering stricter infrastructure standards and regulations – as well as digitalisation across the public sector and industry – geophysical techniques are set to play an even greater role in infrastructure planning, design and management.
A key contribution will be to address the current challenge of data sparsity in drilling, test pits and geotechnical data, according to Wesley Harrison, a Principal Geophysicist at SRK Consulting (South Africa). Harrison highlighted how the recent Engineering Geophysics Symposium, hosted by the South African Geophysical Association (SAGA) last month, showcased the immense potential that geophysical techniques could play in improving risk modelling.
"Through non-invasive subsurface imaging, we can efficiently and cost-effectively fill the gaps in traditional data sets", he said. "This helps us gain a holistic understanding of subsurface conditions and properties for project planning, infrastructure safety, and disaster mitigation preparedness".
He added that by combining geophysical techniques with geotechnical methods for site investigations, engineering firms were able to add further value by reducing the number of expensive boreholes and laboratory tests, resulting in cost and time savings.
Bruce Engelsman, a Partner and Principal Geotechnical Engineer at SRK Consulting (SA), said that the value that geophysics techniques provided had largely gone unnoticed due to the expertise needed to correctly interpret geophysical data for conclusive outcomes.
"However, our geophysical investigations have demonstrated the value of these techniques by providing a cost-effective and fast way of enhancing geotechnical studies," said Engelsman.
Harrison said that the growing interest in the potential of geophysical techniques for de-risking infrastructure projects was discussed at the symposium.
"The event was well-attended not only by geophysicists, but by civil, geotechnical and mining engineers from both the private and public sectors, as well as members of academia", he said.
Piecing together Data Assets
At the symposium, he presented how SRK had deployed Ground-Penetrating Radar (GPR) alongside geotechnical investigations to gain a holistic and detailed understanding of the health of rail foundations.
"GPR was deployed to investigate subsurface conditions between the 2m-deep test pits that were excavated every 5km to 10km along the railway line, enabling us to measure the foundations down to 2m at a 20mm horizontal interval", he explained. "The subsurface images that we obtained enabled us to accurately piece together the 1D datasets that were derived from the geotechnical investigations".
The survey was undertaken with a "rail ground-penetrating radar" which the company helped to develop with technology partners.
"High-frequency electromagnetic waves were emitted by a trailer-mounted ground-penetrating radar towed behind a vehicle", he said. He added that the technology could be easily adapted for various surveying applications by adjusting the programming and antennas.
"We foresee this technology playing an important role in transport infrastructure condition monitoring and maintenance planning moving forward", he said.
