As designers reach for the skies, they are more likely to specify piles to cope with the increasing loads of their buildings. Robin Abraham, director of Bachy Soletanche says the piling industry is helping designers to change the built environment with taller offices and highrise city living. “Yes the piling industry is able to cope,” he says. “You wouldn’t be getting the big towers if they couldn’t be properly founded. If you look across the world they seem to be managing and they’re putting buildings up at ever increasing heights. They keep breaking their own world records.”

Abraham says it’s not so much the height of the building but the loading that comes down onto the foundation and how that load is distributed that has a greater effect on the piles. “The loadings are obviously getting greater and we have to go deeper and put bigger diameter piles in the ground,” he says.

Bachy Soletanche has previously been involved with prestigious projects such as putting foundations in for towers at Canary Wharf. “We used deep piles founded in the sand and then base grouted,” says Abraham. “We are now looking at piles that are up to 2.4m in diameter and 50m deep, for carrying some of the major towers in London.”

James Apted, associate and team leader for Atkins geotecnic group agrees that piling technology is advancing to cope with increasing demands. “We are looking at advances in pile construction technology such as stronger concrete, the ability to dig deeper and techniques to enhance pile strength such as base grouting and side grouting,” he says. “In the Middle East we’ve been looking at the use of high-strength concrete to help up the structural capacity of piles.” He adds: “We are trying to make sure we get feedback from the performance of existing buildings, which is important when looking at the overall performance of foundations. You try and learn from what you’ve just built.”

Going underground

Apted claims there are no limitations with piling in terms of how high a building can go. He says it’s a case of choosing an appropriate site. “The important thing is to choose good locations, not forget the ground conditions and try and use sites where there is good founding stratum,” he says. But with the drive to build on brownfield land, and the fact that prime sites have already been built upon, engineers are trying cope with worsening ground conditions.

Because of this Apted says there needs to be a much more active involvement in the selection of appropriate pile types. “You need to make sure you engage with the appropriate regulators and the environment agency as soon as possible,” he says. “That can be difficult but you need to make sure you don’t just treat piling in isolation on brownfield sites. You make sure you definitely look at piling as well as looking at remediation so that the remediation is appropriate to the foundation and construction side.”

Apted says that some east London sites contain a lot more alluvium, which have soft ground near the surface, so piling is the appropriate form of foundation. “If you’re looking at large buildings, particularly high buildings, you’re likely to need piles if you have very strong ground materials close to the surface,” he says. But in general Apted says designers choose piling as the appropriate technology to cope with tall buildings, they look at piled rafts and raft foundations, placements and getting deeper with the main construction. “I don’t think we’ve got to a position where piling is limiting the height of buildings, he says. “That’s more down to structural considerations and planning issues.”

Abraham says that building on brownfield sites can sometimes have its advantages.

“When there are good records of existing foundations, sometimes those existing foundations can be incorporated into the new structure,” he says. “Where those records are not so good you haven’t got the certainty of the quality and they do cause a problem. In some cases we’ve had to core through existing piles or remove existing piles in order to put in the foundations for new structures.”

Trench warfare

In recent years fatalities and injuries caused by trenches collapsing have seen piles take a share from trenches. “I think piling generally is a safer option if you’ve got to go deep, unless you can use a trenching machine to do your trenching work,” says Abraham, “so you haven’t got to put people down there or have open trenches.” Abraham says putting in deep foundations often signifies poor ground. “If you start opening up deep trenches in poor ground then that’s got to be properly managed from a safety perspective,” he says. “One of the things in respect to safety is trying to eliminate risk, and a way of eliminating risk is to use piling.”

Future foundations

In the next few years the future for the piling industry looks positive says Abraham. “The building works that are going on, be it major buildings, housing and infrastructure, or work for the water, road and rail industries, they all seem to be moving forward, so for the next few years we should be busy,” he says. Atkins is talking to clients about three or four projects in London at the moment. “These projects have long lead-in periods,” he says.

“They’re not projects that you suddenly tender and go to site in two or three months time. We tend to sit down with engineers two or three years before the project is ever authorised and go through the cost plan to help the developer see if the scheme is cost effective. Foundations can be a significant part of the cost.”

Abraham also highlights the Olympics as a big potential source of work for the piling industry. “The Olympics are obviously going to take some resources, and Stratford City adjacent to the site will also take significant resources,” he says.

With the vast amount of construction work taking place throughout the UK and plans for even more in the future, this will be as a driving force in the piling industry, as Apted points out: “Given the current push on infrastructure, piling is a fundamental part of infrastructure and building provision. The future of the piling industry is tied intimately in with the future of construction.”

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