Thursday, June 9, 2016

Ottawa Sinkhole - Another badly done geotechnical job


I am familiar with certain companies that may or may not have been involved, and they couldn't geotech themselves out of a paper bag.  Of course, they are all wonderful companies, and big institutions should always hire them (a legal thing).

It's my contention that all the good geotechs are retired.  All contractors pooh-pooh them and go on without.  We'll never know if this was a good job, or a foolish risk, since everything is so secret these days.  We can only see the results.

This section had a displacement sensitivity beyond the norm because of the water main.  The only way to get zero displacement is with a positive-pressure full shield tunnel machine, but you can't really go with that for 30 foot section.  I assume that all the buildings are on deep piles for this section, otherwise it is a horrible seismic risk.  I would have bypassed the water main, and frozen everything.

It has been said that if you don't anything about it then keep your mouth shut.  However, when faced with deliberate secrecy, I have always assumed the worst.  It's much more entertaining that way.  

I predict many more of these failures in the future.

No comments: