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Voids Open as a Result of Tunneling Under Seattle’s Beacon Hill

image The Seattle Times (hat tip to ASCE SmartBrief) has reported that seven voids have been discovered above the Beacon Hill Tunnel with one opening up at the ground surface. The tunnel is being constructed by Sound Transit, the area’s transportation agency as part of a roughly $2.6 billion (yep, billion) light-rail project connecting downtown Seattle with the University of Washington and SEA-TAC airport. The voids were a result of running sand pockets in the otherwise stable clay units that were encountered by the tunnel boring machine or TBM. These voids migrated up like a chimney with one reaching the surface, almost 160-ft above the tunnel. This void was apparently 21-ft deep and opened up in a resident’s front yard and could have easily swallowed her up as she noticed it while gardening. The other voids were discovered at a depth of 20- to 65-ft below the ground surface. More after the break. (Illustration from Seattle Times)

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kdICON bridge, center pylon
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kcICON Drilled Shafts Completed

The drilled shaft foundations for the kcICON bridge over the Missouri River have been completed according to Dan Brown and Associates, LLC, the geotechnical engineers on the job. The 1700-ft long bridge conveys the I-29/35 […]

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Niagara Tunnel – Crappy rock, Horizontal stress, SLOOOOOW progress

image[Updated November 17, 2009] A few new posts from Ontario-geofish [/Updated]

Those with interest in rock mechanics and tunneling might be interested in this project. The Ontario Power Generation (OPG) company is the owner of a $600M (Canadian) construction project to create a third hydro power tunnel under Niagara Falls.  Apparently the project is having all kinds of problems with overbreak in some very difficult tunneling conditions which means very slow progress and big $$ overruns. (Photo from niagarafrontier.com)

I’ve been meaning to post something on this project for some time. I admit that my perspective is biased by the viewpoint you can find on the Ontario-geofish blog. I’ve mentioned Harold Asmis before, he’s the owner of the OG blog, and a former OPG employee if I understand correctly. He left OPG for a career doing geophysics and earthquake engineering for the Nuclear Power industry in Canada.  I highly recommend his blog, he has great insight into tunneling, earthquakes, siting of nuclear power plants not to mention opinions on all kinds of other things.  His writing style is very colorful and entertaining as well.

So, Harold has written a whole series of blog posts on the Niagra Tunnel project, including a 5-part series entitled "The Disaster of the Niagara Tunnel" and a 4-part series called "Niagara Tunnel: doing it Right".  He is not directly involved with the project, but his long career with OPG and related disciplines gives him some great insights.  I’ve collected a list of some of his blog posts on the Niagara Tunnel project as well as a few other links about the project. Click through for the good stuff.

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Image of a sandhog inside the new water supply tunnel number 3 for the City of New York. Photo by History.com.
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New Water Supply Tunnels Underneath New York City

Image of a sandhog inside the new water supply tunnel number 3 for the City of New York. Photo by History.com. Urban miners have been busy constructing a new water supply tunnel underneath New York City to supply the megalopolis with the water it needs. The miners, or sandhogs as they are known, are about halfway complete with the new tunnel which is expected to be in service by the year 2020. Work on the 60-mile tunnel began in 1970 and the total projected cost is $6 billion and is widely regarded as one of the most complex public works projects in the western hemisphere. When complete, it will help deliver 1.2 billion gallons DAILY to 8 million New Yorkers. The city currently gets its drinking water from two water supply tunnels that were constructed in the early 20th century and have not been inspected or repaired since then. More after the break. (Image credit History.com)

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Katrina levee failure with Chinook Helicopter attmpting to fill the breach
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Possible Seepage at Newly Constructed New Orleans Levee

Katrina levee failure with Chinook Helicopter attmpting to fill the breachWet spots have been detected along a portion of a new levee being constructed by a US Army Corps of Engineers Contractor. The levee is approximately 95% complete, but the Levee Board wants to establish what is causing the apparent seepage before accepting the levee. More after the break. (Photo of Katrina levee failure from greenmannowar)

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Pine Hills Sinkhole, Pine Hills, Florida, 2002
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Video: The Pine Hills Sinkhole – Central Florida, 2002

Pine Hills Sinkhole, Pine Hills, Florida, 2002On June 11, 2002, a 150-foot wide and 60-foot deep sinkhole opened up in Pine Hills, Florida and came within a few feet of two 3-story appartment buildings. Geotechnical and Environmental Consultants (GEC) was contacted by the owner of the site to design emergency temporary and permanent stabilization measures to protect the buildings. The sinkhole mitigation began with a chemical stabilization of the soil using an injected sodium silicate chemical grout (incidentally, that work was performed by John N. Puder, Inc., recently acquired by Moretrench) to stabilize the sands underneath the buildings and adjacent to the sinkhole. After some GPR surveys, borings and other investigations, final sinkhole repair consisted of a 200-foot long wall omprised of interlocked 36-inch diameter steel tubular piles that extended to a depth of 50 feet. They were driven by Giken America Corp. using the press-in method which helped to avoid damage to the adjacent buildings. The entire stabilization was completed within 1-month of the initial sinkhole collapse! Click through for this fascinating video. (Photo credit Giken America Corp. by way of GEC)

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