The Bertha TBM just received a shipment of spare parts to repair the giant tunneling machine. The manufacturer decided to redesign the seal system to make it easier to access from the inside, if necessary. That's probably a good idea considering the prospect of a repair like this one once the machine is moving beneath downtown Seattle. Other improvements and repairs to the TBM include:
A new main bearing
Enhanced monitoring systems
Added steel to strengthen the machine and accommodate the new seal system
Widened openings at the center of the cutterhead
Extended arms to mix excavated soil in the chamber behind the cutterhead
Fugro has completed one of the largest offshore geotechnical investigations in history according to Hydro-International.com. The investigation was performed by two vessels, MV Greatship Manisha and MV Bucentaur (pictured here), for DONG Energy's 1.2 gigawatt Hornsea Project One project which is located 120 km off the UK's Yorkshire coast. The investigation (contract valued at GBP13 million) consisted of 2,800 metres of seabed cone penetration testing and more than 5,000 metres of boreholes over a four month period. [Source: Hydro International. Image: Hydro International]
Advanced Construction Technology Services (ACTS) has contracts for geotechnical work for 3 lines of the proposed subway in Doha, Qatar. They have completed investigations for approximately 95 km of line and 51 stations and are currently working on the recommendations for track designers. The contract for the these services is worth approximately $1.37 million. [Source: Trade Arabia. Image: Trade Arabia]
WSDOT reported that Bertha has slowly began moving again. It must tunnel through 20 feet of unreinforced concrete with its broken seal to break through into the rescue shaft. Once that happens, the repairs to her cutterhead can commence. The Seattle Tunnel Partners predict Bertha will overheat, as she did before stopping for repairs. If that occurs, they will stop tunneling to wait for the machine to cool before continuing. STP crews also chipped away at a Bertha-sized cut-out in the access shaft to make for a cleaner breakthrough. See video below. [Source: WSDOT and WSDOT YouTube Channel. Image: YouTube]
The Alaskan Way Viaduct tunneling project was in the news late last year when settlement of the Viaduct was reported during the dewatering efforts for the Bertha TBM rescue shaft. A recent post by WSDOT makes it clear that the settlement of the viaduct has been a problem for many years before the start of construction. The most recent round of monitoring by WSDOT began in 2001 after the completion of repairs to the the Viaduct following the Nisqually Earthquake. By 2006, a total of 4 3/4 inches of settlement had been recorded at one location. It appears that the rate of settlement is on the order of about 1/8 inch to 1/4 inch per year. I am sure the dewatering around the access pit didn't help the problem, but it looks like it didn't create it by itself either. This information just underscores the importance of the tunnel project to replace this aging structure. [Source: WSDOT Alaskan Way Viaduct. Image: WSDOT and STP via KPLU]
The excavation has been completed for the access shaft or rescue shaft that was needed to be able to remove the damaged cutterhead of the Bertha TBM on the Alaskan Way Viaduct Replacement project in Seattle. The target depth of 120 feet was reached on January 30. WSDOT reports that settlement levels have remained stable in the pit area after an earlier settlement issue. In addition to the project update on the WSDOT project page, there is an excellent article on the work done by Malcom Drilling to construct the shafts used to form the excavation walls in the January issue of Foundation Drilling Magazine. I highly recommend that article. You can also see some neat raw video from WSDOT below.
Nicholson Construction Company, a GeoPrac sponsor, has been working on 68,000 square feet of shoring and permanent retaining walls for an indoor practice football field and running track, as well as two levels of underground parking at the University of Colorado Boulder. The wall types include soil nail walls, cantilevered drilled shaft and shotcrete wall, and cantilevered soldier pile with wood lagging. The project has been running since this summer and is projected to be complete in February. [Source: Read the full press release from Nicholson Construction Company. Image: Nicholson Construction via the Colorado Daily]
Areas surrounding the access pit being excavated to rescue the stalled Bertha TBM have experienced settlement as much as 1 to almost 1.5 inches according to a draft figure released by WSDOT on December 11, 2014. The aging and seismically deficient Viaduct itself has experienced 1 inch of settlement as well. Structural engineers have inspected it as well as numerous buildings in the area and have not found structural damage. The settlement is thought to be related to the dewatering associated with the access pit construction. The excavation was within 3 feet of the bottom when the settlement issues were first announced on December 5, and WSDOT has since allowed the contractor to complete the excavation. [Source: Read more information in the update provided by the WSDOT Alaskan Way Viaduct Replacement Project team. Image: WSDOT]
The latest issue of Pile Buck Magazine has a cover story on the Panama Canal Construction. Talk about a mega project! There are actually two articles, the first includes a very nice summary of the overall project. Both discuss the construction of a huge cofferdam to separate Miraflores Lake from the construction area for the new Pacific Access Channel. This channel will link the third set of locks to Culebra Cut. The cofferdam consisted of 58 circular cells comprised of 17,000 tons of straight and z-section sheet piling. [Source: Read the article for free in Pile Buck Magazine. Image: Pile Buck]
Hayward Baker will construct their Vibro Piers(TM) foundation system at the new stadium to house the Atlanta Falcons and a new MLS team. Their holes will be 2.5 feet in diameter and 27 feet deep and filled with vibro compacted No. 57 stone. The project is anticipated to take 5 weeks, operating 6 days a week to keep the project schedule on track. Hayward Baker is a sponsor of GeoPrac.net. [Source: Hayward Baker. Image: Hayward Baker]
The giant straddle cranes that load and unload cargo from the container ships at the Port of Oakland apply a fairly concentrated load along their wheel path. Over time, the wheel path area has settled, creating a hazard to crane operators, cargo, and all port workers. URETEK ICR and their affiliate EagleLIFT were called in to use their patented geopolymer technology to stabilize and lift the subgrade, restoring the wheel path to it's original elevation. Check out the video! URETEK ICR is a sponsor of GeoPrac.