WSDOT held a press conference on Friday to discuss findings regarding the obstruction that had stalled the Bertha Tunnel Boring Machine since December 6. It is an 8 inch well casing, 119 feet deep from a 2002 groundwater investigation associated with the tunnel project. Crews were finally able to dewater the TBM face enough to get a look last week.
The interesting part is that the TBM struck the casing on December 3, three days before it stopped. The rotation of the cutterhead lifted the casing 5 to 7 feet out of the ground. Crews removed the upper 55 feet of casing and thought that was the end of it. There were fragments of boulder on the conveyor belt, and crews felt they were dealing with a large boulder problem. So what now? The WSDOT officials were not specific, but likely Seattle Tunnel Partners crews will need to perform an intervention outside of the cutter face to remove the pipe and inspect for any damage to the cutterhead. The cost of the issue will count against a $40 million risk allowance for repairs and inspections near the front of the rotary cutting face â€” plus a $105 million general contingency fund. The overall tunnel project budget is $2 billion.
Anderson Drilling has a unique tradition dating back to the founders of the compnay where they name most items in their fleet of foundation drilling equipment. They recently purchases a 48-inch Atlas Copco cluster drill for a bridge project in California, and appropriately named it 'Thor' after the Norse God of thunder (and the Marvel comic book hero by the same name that wields a magical hammer). The project is a bridge project near San Diego that required drilled shafts with 20 foot long rock sockets from 48 to 96 inches in diameter in 25,000 psi granite. [Source: Read more at the National Driller. Image: National Driller]
Access into the Bingham Canyon Mine pit has been restored for the first time since the mega landslide moved 165 million tons of material. Rio Tinto has moved 14 million tons of that material to restore access into the pit so that they can continue their efforts to stabilize, clean up and recover buried equipment. [Source: UPR Utah Public Radio. Image: Utah Public Radio]
Last week I attended the AEG 2013 conference in Seattle, Washington. The conference was excellent, with many great presentations and networking opportunities. I have been playing catch-up since I returned, but I have some very interesting things to blog about once I sit down and start writing. Keep watching!
One interesting thing was the view right outside my hotel window. I could see the construction site for a new high-rise building which is currently being excavated by DBM Contractors, a specialty geotechnical contractor based in Federal Way, Washington (Seattle Metro area). I didn’t see mention of this project on DBM’s website, but they did work on a similar project just a few blocks away. It looks like there are soldier pile lagging retaining walls with multiple levels of anchors. I imagine that once they finish the excavation, they will also construct the drilled shaft foundations for the structure as well. I'm guessing they performed some de-watering as well.
Maybe I got a little over-excited, but I don’t see these types of excavations too often in my geotechnical practice!
The Burj Khalifa is founded on pile supported raft foundation consisting of 194 bored-in-situ piles or drilled shafts as we commonly call them in the US with a 12 foot thick mat. The piles were 1.5 meters (5 feet) in diameter and extended 140 feet below the mat. The piles had an allowable axial load of 3,000 tonnes (6,614 kips) and load tests were performed on piles up to 6,000 tonnes. This article by the foundationconcretes.com discusses the foundation system of the world's tallest skyscraper, and discusses some of the issues and design features of a pile supported raft foundation. [Source: Read more at Structural, Concrete and Foundation Engineering. Image: Foundation Concretes.com]
Washington's Governor, Jay Inslee and WSDOT had a celebration over the weekend to allow the public the chance to see the world's largest tunnel boring machine, Big Bertha, before she begins her drive for the creating the Highway 99 tunnel underneath downtown Seattle. This is the tunnel that will replace the aging Alaskan Way Viaduct. Check out the great video below from Seattle's King 5.
Geotechnical contractor Bauer performed work to upgrade the foundations of a historic building on an island in the middle of the River Neckar in Esslingen, Germany. The historic carpenter's workshop will become a restaurant and market hall thanks to the 70 m long, 5 m deep anchored secant pile cutoff wall around the outside of the building and a soldier pile retaining wall carefully constructed within the building. [Source: Check out more on the project at The New Civil Engineer. Image: NCE]
Soletanche Bachy's Hungarian company, HBM was successful in winning a design-build contract for a new factory for the world famous toy company, LEGO. The foundation work, which was undertaken in 2012, included 50 km of HBM's reinforced concrete Screwsol piles installed with up to four piling rigs. Soletanche Bachy is the parent company of GeoPrac sponsor Nicholson Construction. [Source: Read more at Soletanche Bachy . Image: Soletanche Bachy]
Geogrid reinforced soil slopes, gabion retaining walls, erosion control blankets and other geosynthetics are being used to construct the world's largest human form sculpted into the landscape on a project known as Northcumberlandia. The woman sculpture is the centerpiece of a public park near Cramlington, in the north of England. The site is located adjacent to a surface coal mine, and the byproducts of the coal mining were used to construct the landform. A cover story in Geosynthetics Magazine a few months back featured the project, and the design aspects of the RSS and gabion walls that were use to form some of the woman's more challenging features such as the chin, nose, and eyebrows. [Source: Read more about Northcumberlandia at GeosyntheticsMagazine.com. Image: Geosynthetics Ltd. via Geosynthetics Magazine]
This is a great piece that covers a lot of ground about the project. The author included information on the background of the original highway, and a nice discussion of the political aspects that drove the selection of a tunnel option over the inland bypass option that Caltrans initially favored. But of course, being a geoengineer, the best part was a discussion of the geology and the tunneling activities.
The author interviewed Doug Hamilton, a local consulting geologist who worked on several phases of the project. The description of Mr. Hamilton tying a rope to the bumper of his pickup truck to repel down the side of the cliff at Devil's slide with his rock hammer is classic (his permit said he needed three other climbers with him). There are also interviews from tunnel contractor Kiewit and the head miner from Laborer International Union of North America. The Devil's Slide Tunnel project has been a pet project of mine for years, and if you have been interested in it like I have, don't miss this article. Great photos too! [Source: Read the full article at CE News. Image: Michal Cialowicz/michalography.com via CE News]
It seems like every time I turn around these days there is another amazing tunnel project in the news. The level of engineering brought to bear on these challenges is phenomenal, whether it's in the tunnel alignment or the TBM design and fabrication, or shoring and ground improvement in advance of the tunneling. This article highlights 7 record-breaking tunnels from around the world. Check back in another year or two and I'm sure there will be some new accomplishments to add to this list! [Source: Check out the Record Breaking Tunnels on Fox News! via ASCE SmartBrief. Image: Fox News]