Pile testing specialist Testconsult is using a new dynamic load testing system on UK motorways.
Testconsult was recently contracted to verify the load bearing capacity of working piles for the foundations of a variable message sign on the M6 motorway.
Traffic management and safety considerations were of paramount importance for the piling contractor when deciding the most appropriate test method, given that the site is on one of the busiest motorways in the UK.
“The piling contractor had two options, static load testing or dynamic testing,” says Testconsult pile testing department head Iwan Jones.
A static load test would have required the construction of a load frame with 40t of kentledge placed on top, and a test duration of up to 24 hours for each pile.
Extended enclosures would also have been required for a mobile crane. But this option was considered too dangerous because of the amount of time the crane would have had to be in position and the risk that a vehicle could collide with it.
Instead, dynamic testing was chosen. Testconsult’s 1t Simbat midi-rig conducted each test in under half an hour, keeping traffic exposure time to a minimum. The midi-rig has been
specifically designed for difficult locations and to provide sufficient punch to test piles with loads up to 1,500kN and 600mm in diameter.
The rig is transported by trailer and can get into tight spots under its own power. Track width can be reduced for narrow access and hard lifting points means the rig can be craned into position where normal access is not available.
Two hour test
“Previously it would be almost impossible to test piles along a motorway network such as the M6 without severe disruption,” says Jones. “We can be in and out in a couple of hours and road closures are not necessary for us to get the rig into position.
“Proof testing of the foundations is the sensible option. Conventional load testing would be difficult, and would pose additional danger to motorway travellers.
While the midi-rig is designed for difficult access sites such as this, it can also be used to test piles on conventional sites, such as housing projects, retail developments or bridge structures.
“We are now able to carry out dynamic testing without the need for expensive free-fall cranes, transportation of drop weights or tying up client’s plant. We are totally self-contained,” says Jones.
Testconsult has also recently introduced a hand operated, portable SIMBAT micro-rig for testing micro piles up to 100KN dynamic test load.