Clarendon Construction Update - mid-month, October 2010

A quick post on the construction projects going on around my office.  There is still a lot going on with the "north block" of Clarendon Center, of course, but I will save that for the end of the month.  In the meantime, thought I might post on what I like to call the "air space" building that is being built near Clarendon Church.

When I got to the office yesterday, I noticed a couple of things going on and decided I needed to get a picture of the site.  It looks like most of the piles and lagging are installed, and tiebacks are completed.  Still there were excavation machines working and I wanted to check it out further.

They've had a series of wells, pumps, and pipes installed to drian the site over the last two months.  Yesterday they installed a new sump deep in the hole - it's near the gravel in the center of the excavation, next to the galvanized pipe. 

But that wasn't the big thing yesterday.  I appreciate that readers of this series are as enthusiastic about the construction process as I am, so I know that you will like this:  the tieback drill has been brought up out of the hole, meaning that the excavation and shoring is completed!

Unlike the challenges of the Clarendon Center site (more on this to follow in a future post), the air space building used steel soldier beams with lagging plates, supplemented by tiebacks.  There are some technical aspects to the shoring near the existing buildings that will remain on the site as well, but I wanted to talk about the tie backs for now.

Don't get confused by the quality of this exposure.  The tieback drill is the blue machine at rest near the fence.  The back hoe, behind it, will stay at the site for now, taking care of any additional excavation related chores that are needed until the foundation is in.

The tieback process uses soil as an additional anchor to the lagging planks.  First, the drill bores a hole into stable soil, then steel prstressing tendons are inserted and grouted to anchor them.  Then, after the grout has hardened, the tendons are tensioned with a hydrolic jack.  There should be a waler here for additional anchoring, and I will keep an eye out for them.

The tieback drill is self-contained and takes care of most of the process, with the exception of installing the waler.

Glorious, eh?  Thanks for staying with me on this one.