There hasn’t been much to report recently for the Alaskan Way Viaduct Tunnel Project in Seattle. As you probably know, Bertha has not advanced since about December of 2013 after drilling through an abandoned steel well casing left over from engineering studies. Whether it was the casing or boulders, or something else that damaged the seals around the giant TBM’s cutterhead, they have some major repair planned. If you like, feel free to read more about what happened with Bertha.
WSDOT and Seattle Tunnel Partners JV (STP) announced a conceptual repair plan back in April. It involves creating a vertical access shaft approximately 80 feet in diameter, and 120 feet deep. STP member Malcolm Drilling is currently working on constructing I believe 5-ft diameter secant shafts to form the perimeter of the access shaft. The work is progressing a little slower than expected. The initial schedule issued by STP had the secant shaft wall complete at the end of July. It is now supposed to be the end of August, although they have said this won’t affect the overall repair schedule. You can watch a time lapse video of the access pit construction…pretty cool.
Another interesting item I found recently is a discussion of the cranes that will be needed to repair the bertha cutterhead. If you read my post on the tour I took of Bertha at her launch pit, you might have noticed a huge gantry crane in my photos that lifted components of the TBM into the launch pit for assembly. They will be constructing something similar at the repair site. However, first they need to assemble a 300-ton crawler crane beginning in September. The 300-ton crane will help assemble a 600-ton crawler crane. The 600-ton crawler crane will then help assemble the 2,000-ton modular lift tower (what looks like a gantry crane to my untrained eye). Talk about a heavy equipment ballet!
Professor Petley, the author of the Landslide Blog, has an interesting discussion about a controversy in the geoengineering / geology community regarding the Oso landslide in Washington State. The Geotechnical Engineering Extreme Events Reconaissance (or GEER) report was recently issued for the OSO landslide. But USGS scientists have a different theory about the event. Both the GEER committee and the USGS agree that the Oso landslide was a two-fold failure event. But the difference in interpretation is the relative sizes of the two events and the mechanism they took. I won't try and explain the controversy here as the post at the Landslide Blog does a great job of that. [Source: The Landslide Blog. Image: Landslide Blog]
According to the Landslide Blog, this rockfall video was taken in Maoxian County in Sichuan Province of China on or around July 17, 2014. It shows a very dangerous rockfall event with people running from their cars. In one scene you can even see someone being struck by a rock and knocked over. The person is later able to walk away with assistance. Towards the end of the video, even the windshield of the videographer is struck by a smaller rock and cracked. Very dramatic and very scary video!
Equipment manufacturer Liebherr has created a new simulator to allow operators to train on foundation drilling equipment virtually. The simulator is based on other simulators created by Liebherr, and includes things like a real construction site with neighboring buildings and structures, uneven ground, varying soil conditions, etc. [Source: Read more at GE Innovation News | New Civil Engineer via @GE_magazine. Image: NCE / GE Innovation News]
Hayward Baker was among the contractors called in for emergency repairs to a failed retaining wall in Baltimore that destabilized a slope, causing a landslide that enveloped cars and threatened a railroad track below. The final episode of the slope failure was caught on video and showed several cars being swallowed. GeoPrac sponsor, Hayward Baker is currently on-site installing a temporary soldier pile lagging wall with tiebacks to facilitate the construction of a permanent wall. They are anticipating to have the temporary wall complete in August. [Source: Read more about the project at Haywardbaker.com. Image: Hayward Baker]
Congratulations to Crux Subsurface, Inc. on winning the Deep Foundation Institute's (DFI) 2014 Outstanding Project Award (OPA) and the 2014 C. William Bermingham Innovation Award for their Sunrise Powerlink Project in California. The project involved the installation of over 3,700 micropiles for the foundations of new steel lattice towers for a 117 mile transmission line running from Imperial Valley to San Diego. All of the micopiles were installed using rigs and equipment mobilized by helicopter in the difficult terrain. The project was the first to use Crux' patented steel micropile cap, which is what they were awarded the Bermingham Innovation Award for. Crux credits the steel cap design for reducing the on-site construction time by 64%. [Source: Read more about the awards from the Deep Foundations Institute (DFI). Image: Crux Subsurface, Inc.]
Geotechnical work has commenced for a project involving reconstructing the Historic Columbia River Highway in Hood River County as a segment of Oregon's Historic Highway State Trail. The geotechnical scope consists of 48 test pits, 58 boreholes, and constructing 4,000 linear feet of temporary access roads. [Source: Hood River News. Image: Hood River News]
Torrential rain in the World Cup city of Natal caused a landslide right around the time that the USA defeated Ghana. According to the Landslide Blog, the landslide destroyed 50 homes but there were no lives lost. A You-Tube Video showing the landslide as seen from a small UAV shows the devestation, and interestingly shows a storm drain that could have played a role in the failure, perhaps becoming overwhelmed after the 50 hours of rain that fell on Natal. [Source: The Landslide Blog. Image: NBC News]