According to Brent Cock, engineering geologist at SRK Consulting, the risk of ground failure should be taken very seriously – engaging the right geotechnical expertise from the start of a project is extremely important.
There is significant focus on what takes place above ground – and rightly so.
However, more focus needs to be directed to what takes place below the surface at the start of a construction project.
While deep excavations – for high-rise buildings, for instance – require specialised geotechnical assessment and design to offset the risk of failure, there are also
risks attached to relatively shallow excavations of just a few metres.
“A cubic metre of soil might look innocuous, but it typically weighs more than a small car and can weigh almost two tons, so any scale of ground failure can cause considerable harm to anyone nearby. We know of fatalities in excavations as shallow as 1m,” says Cock. “Even if people aren’t harmed, such failures can lead to costly delays in the project timeline.”
Not only does an excavation wall collapse require immediate attention to allow construction to proceed, it may also hinder a range of activities by the subcontractor – all of whom need to be paid, even if their equipment and personnel are standing idle. Often projects are conducted close to other structures, which
may be damaged or threatened by a nearby ground failure.
A fundamental starting point is a thorough technical analysis of ground conditions in the early stages of project planning. The Geotechnical Division of the SA Institute of Civil Engineering (SAICE) Code of Practice for Geotechnical Investigations provides excellent, industry-relevant guidelines on how to proceed with a geotechnical investigation for a wide range of infrastructure development projects.
