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SM City, San Fernando, Pampanga
Unpredictable subsidence beneath the 34,000 sqm floor-slab at one of SM’s newest malls forced SFP to rethink the rule book and embark on a six month voyage of innovation into new methodologies, machinery and pile design.
Challenge 1 – Replace the entire floor-slab without interrupting business
Challenge 2 – Pollution free removal of the old slab and installation of screw piles and new suspended slab.
Challenge 3 – install piles up to 50 meters deep with only four meters of headroom
Challenge 4 – very soft, wet substrate with a hard crust
SM is the country’s largest developer and operator of shopping malls; their objective is to keep SM stores open for business 365 days of the year. SFP developed a methodology whereby only 4% of the mall would be closed at any one time, which allowed mall operations to continue with minimal disruption.
However, because the remainder of the mall needed to be open for business, it was also important that there be no noise or air pollution emanating from the ongoing works. SFP designed and built a hydraulic piling rig, powered by electricity – supplied from a super quiet diesel generator located outside the building – allowing for clean and virtually silent operation.SM think highly of their customers and spend millions turning a mall visit into an experience. A mix of low and high ceilings break the visual monotony that 30,000 square meters of space could otherwise impose (the lowest ceiling is around three meters). Screw Piles are normally installed in six meter section lengths, which obviously would not work with a four meter ceiling: SFP’s methodology and piling rig design centered around a two meter pile section length.
No matter what depth the piles eventually torqued-out at, they all have to penetrate the three to four meter compacted top layer and then churn their way through fifteen or more meters of sloppy clay and volcanic sand mixture. Finding a way through the crust required innovations to the leading edge of the helix and the installation of a whisker blade ahead of the helix itself.
Finding a way to continue penetration downwards through the “soup” while the hard crust was slowing this process by “gripping” the flange joins required innovations to the pile section joining method.
Notwithstanding these challenges, SFP completed the project on-time and within budget. Further proof that when it comes to screw pile foundations, SFP is a World leader.
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