Monday, August 24, 2015

Bolting Bertha Back Together!

Following a lengthy, costly delay, visible progress that the Earth Pressure Balance Tunnel Boring Machine (TBM) — Bertha — is approaching an important milestone.  Rigging was completed this weekend for the Mammoet Modular Lifting Device to lower the cutterhead assembly into the rescue pit, to be reconnected to the TBM.


The cutterhead will be lifted and moved over the rescue pit, where it will be rotated 90° and lowered to be rejoined with the rest of the TBM.


For articles I've previously submitted, from the arrival of the machine from Japan to final breakdown, type "Bertha" in the Blog Search Engine located in the right margin.


Out of the Pit!


Following Bertha's breakdown, a rescue pit was created in front of the TBM.  Bertha was then driven into the pit, where the front end cutterhead assembly was retrieved for repairs. In this nighttime photo taken in March 2015, Bertha's head end is suspended above the tunnel rescue  pit.


The rest of the machines will remain in the ground while repairs are conducted at the surface.

The lifting device tilted the drive motor and cutterhead assembly from the access pit, tilted it 90 degrees, and carried it to a repair platform just to the south of the pit.

 Mammoet Modular Lifting Device

This machine is so huge, it literally takes another massive crawler crane, traveling on a thick bed of "crane mats" to construct it! The Modular Lifting Device will pick up and move the 2,000 ton cutterhead assembly like it were a can of soup!

Wheels and pulleys are no match for excessive weights.  So the Lifting Device is moved horizontally on a skid bed, not on wheels.  Powerful hydraulic push-pull cylinders provide the motive power to move a load. 

The hydraulic push-pull cylinder extends to the specially designed skid bed, locks in, and pulls the device along, using massive amounts of lubricating grease!

And for lifting the ponderous weight of the cutterhead, instead of pulleys and winches, strandjacks grasp and pull the lifting cables, inches at a stroke, to lift and lower Bertha's components.


  Putting Bertha Back Together

In this June 2015 photo, crews working for Seattle Tunnel Partners watch as a crane carefully lowers the SR 99 tunneling machine’s new inner seal ring into position on top of the cutterhead. The inner seal ring is part of a seal system that is designed to protect the machine’s new main bearing.

In this June 2015 photo, crews working for Seattle Tunnel Partners inspect the installation of the new inner seal ring, which a crane had just lowered onto the cutterhead. The large white circle is Bertha’s new outer seal ring, which was installed the previous day. The outer and inner seal rings are part of a new seal system that is designed to protect the machine’s new main bearing.

Seattle Tunnel Partners crews install the SR 99 tunneling machine’s main bearing in July 2015. The red substance lubricates the rollers that help enable the cutterhead to rotate.

This July 2015 photo shows the tunneling machine’s main bearing encircled by the bull gear ring that facilitates rotation of the cutterhead.

This August 10, 2015, photo shows two of the big rotating pieces at the front end of the tunneling machine. The largest circle is Bertha’s main bearing and bull gear, which rotates the cutterhead. The smaller circle is the center pipe, part of the agitator that mixes excavated material in the chamber behind the cutterhead.

Crane crews lower the SR 99 tunneling machine’s inner cylinder into place in this August 13, 2015 photo. The inner cylinder houses the machine’s agitator, which mixes excavated material, and the inner seal ring, which protects the main bearing.

On Saturday, August 15, 2015, crane crews from Mammoet lifted the SR 99 tunneling machine’s bearing block by its trunnions into place atop the cutterhead and drive unit. The trunnions on the bearing block support the lift and lower of the front end assembly. And it is around these trunnions the cutterhead will pivot 90° to align the cutterhead with the rest of the TBM.


Back into the Pit!

Just after 9 a.m. Monday (24th) the impressive Mammoet Modular Lifting Device took up the slack in the lifting cables, and began the slow process of jacking the drive motor cutterhead assembly off the repair platform, advancing toward the rescue pit.

Photo captions tell the story ...


The lifting device will remain in place whilst the cutterhead assembly is reconnected to the main body of the TBM.


Progress Beyond the TBM

Significant progress has been made on preparation of north and south portals, and tunnel interior is beginning to look like a transportation tube.

Sunday August 24, 2015, Courtesy OxBlue & WSDOT



Seattle Tunnel Partners has issued this new timeline, to resume digging the Highway 99 tunnel:

•  August:  Lower front end into 120-foot-deep rescue pit.
•  September:  Connect front-end drive parts, hoses, pipes and cables to Bertha’s body.
•  October:  Open-air testing inside the vault.
•  November:  More testing, with dirt in the vault.
•  Restart boring November 23rd.
•  January 19, 2016:  Stop at a “safe haven” just before boring beneath the Alaskan Way Viaduct, for four weeks of inspection and adjustment.
•  February:  Drill under the viaduct, which may be closed to vehicular traffic, seven to 10 days.
•  November 29, 2016:  Bertha reaches the North Portal at Harrison Street.
•  June 2017:  Road decks, walls and ceilings done, followed by signals, ventilation and testing.
•  March 9, 2018:  Tunnel ready for traffic.

Not bad, considering the tunnel was originally scheduled to open for traffic next month ...

1 Comments - Click here:

l.hofley@yahoo.com said...

thanks for the comprehensive update-this is by far the most encouraging story we've seen or heard about and shows the project may turn out to be a success. Impressive, details- showing what a massive equipment undertaking this has been.

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