Keller companies Hayward Baker and Bencor have completed the foundations for a 31-storey Marriott hotel in Austin, Texas.
In the first joint venture for the two firms, Bencor constructed a diaphragm wall and Hayward Baker installed the anchors.
The anchored diaphragm wall, which is 0.81m thick, 15.2m deep and 244m long, provided a temporary earth-retention system, and created structural foundational support for the building. The wall would be supported by temporary strand tieback anchors each with a design loading of 211 kips.
The 0.4ha site is bordered by three thoroughfares and is underlain by 7.62m of sandy clay, followed by 1.5m to 3m of poorly graded sand and finally limestone bedrock. After extensive site investigation, it was determined that it would be too costly to maintain a dewatering system that would allow for conventional earth retention.
Bencor and Hayward Baker also worked with the structural engineer, Magnusson Klemencic Associates (MKA), to modify the building design to replace the proposed typical cast-in-place basement wall with a diaphragm wall to support the building.
The site also had to be pre-excavated by nearly 2.1m to remove the contaminated soil. Once removed, new soil and rock was brought back to create a level working platform for the equipment.
A further Keller company McKinney Drilling was brought in for the drilling the shoring piles (2.4m to at 18.2m deep) for the wall.
Scheduled for completion in summer 2020, the 31-storey Austin Marriott Downtown will have more than 600 bedrooms and over 5574m² of conference space.