Transmission towers, utility poles, submerged pipelines, tunnels and offshore oil rigs could be made more stable by anchoring them in the soil with fractal-shaped root structures.
Taking direct inspiration from trees, Dr Pierre Rognon from the University of Sydney School of Civil Engineering’s particles and grains laboratory used granular models tests to assess the pull-out capacity of root-like anchors.
His team is working with industry partner, a local company called Anchoring Rope and Rigging to develop innovative anchors for geotechnical applications.
"The quality of anchoring is characterised by the pull-out capacity, F0, which is the maximum tensile force an anchor can sustain before moving upward," says Dr Rognon.
"We developed several models to predict the pull-out capacity of shallow anchors in granular soils."
The researchers found that anchors modelled on the fractal-shaped roots of trees required much less materials to build, making them more cost-effective compared to traditional shaped anchors.
The next step is to assess the effectiveness of different fractal geometries when used in various shallow depths in the soil.
"The pull-out capacity is governed by the weight of the soil that would be mobilised when the anchor moves upward," Dr Rognon explained.
This is why even small trees planted in shallow soil can be very difficult to uproot without the proper equipment.
According to Shivakumar Athani, a PhD geotechnical researcher in the School of Civil Engineering, part of this breakthrough in biomimicry comes with realising that soil is not concrete.
"Roots are not homogeneous like steel, sometimes soil can hold the trees very firmly and can offer enormous resistance for uplift," Athani said.
[Image credit: liz west (calliope) @ flickr]