Aren’t piles that don’t extend to bedrock common in many cities? They are ubiquitous in Dubai, and are even used in the Burj Khalifa. There’s a way to do it right. One confounding factor with this SF tower is the later construction of the Transbay Center nearby, which I read may have destabilized soils nearby through dewatering. Apparently their process reduced the water table by 20 feet (https://sf.curbed.com/2016/9/20/12991602/millennium-tower-si...), which would change the bearing capacity of soils and affect friction piles.
One oddity is that the city’s inspectors and departments approved all of this - their surveys, geological analyses, foundation design, building design, and so on. That work spanned many contractors. SF is a city with many controls to prevent this kind of situations, so it is unclear as yet where all the faults lies.
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Aren’t piles that don’t extend to bedrock common in many cities? They are ubiquitous in Dubai, and are even used in the Burj Khalifa. There’s a way to do it right. One confounding factor with this SF tower is the later construction of the Transbay Center nearby, which I read may have destabilized soils nearby through dewatering. Apparently their process reduced the water table by 20 feet (https://sf.curbed.com/2016/9/20/12991602/millennium-tower-si...), which would change the bearing capacity of soils and affect friction piles.
One oddity is that the city’s inspectors and departments approved all of this - their surveys, geological analyses, foundation design, building design, and so on. That work spanned many contractors. SF is a city with many controls to prevent this kind of situations, so it is unclear as yet where all the faults lies.