Socotec said that its bidirectional pile testing method was developed to more clearly distinguish between shaft and end resistances and the true capacity of the element, particularly when dealing with long piles and high loads.
Socotec’s solution has been developed using Supercell embedded elements, a cast-in-place loading system which produces the bidirectional axial loading forces during the testing process. The Supercell creates an extendable element within the structure that allows for separate movement in both the shaft and the base, providing individual data on the end bearing and shaft resistance and fully mobilising the base.
Initial installations and tests have been performed in conjunction with Franki Pile, whose low-headroom high capacity piles are well suited to the bidirectional test method, Socotec said.
Alistair MacDonald, pre-construction director at Franki Foundations UK, said: “Franki installed the first test within our new plant facility at Markham Moor and the process was seamless. We can see real benefits of using the product, especially when testing our specialist high capacity Martello piles, which are usually installed in restricted site conditions where the use of standard testing frames is not possible.
“Franki Foundations will be collaborating with Socotec in the future on the back of the successful trials and already have opportunities for use in upcoming projects.”
With Socotec’s bidirectional test, the load cell is incorporated within the steel reinforcement cage off site; when used in conjunction with thermal integrity profiling (TIP), it can be loaded as soon as the concrete has reached the required strength. In addition, all loading takes place underground, eliminating the need for energy to be stored in loaded beams and thread bars, which takes time and space on site.
Bidirectional pile load testing can also be applied to a variety of foundation elements, including barrettes, bored piles, preformed steel and precast concrete. By making use of these different elements, the new approach can simplify design consistency across the entire foundation monitoring project by load testing each pile type with the same method, Socotec says.