Crucial strength validation tests — the first of their kind in the UK — have been carried out on the reinforcement piles for a project to stabilise the cliffs behind the Scarborough Spa complex in Yorkshire.

The University of Sheffield AMRC’s Advanced Structural Testing Centre (ASTC) (www.amrc.co.uk) conducted the tests for piling specialist Keller UK, which has been contracted to make 206 concrete-filled steel piles for the £13.4 million stabilisation scheme.

The project requires 15m-long piles to be driven deep into the ground, but restricted access means that Keller must use shorter piles and connect them together.

To ensure that the connected piles are strong enough to withstand soil movement, Keller turned to the ASTC.

A custom rig was designed and built to carry out four-point bending strength tests on four two-tonne concrete-filled steel piles with varying wall thicknesses and collar lengths, to measure deflection in the middle of the tube, where the two sections are connected by a threaded collar.

The first tube tested had a 17mm wall thickness with a short collar, as this was deemed to be the weakest of the four samples. Phil Spiers, head of the ASTC, said the result was ‘very positive’.

It withstood a load of 1500kN (150 tonnes) bearing down on it and surpassed Keller’s target for displacement.

“We continued to test the other tubes, and they all passed well, giving Keller the validation and confidence it needed to proceed.”