This week, guest contributor and geotechnical engineer, Michael Diez de Aux, will be taking over our 'Explainer'. This is the first part of a series that will look at shoring, or the supporting of walls in an excavation site. While there are other methods that work in less confined environments, shoring is virtually always used when construction sites are tight. Our sister site, SkyriseCities.com, looks at shoring in greater depth: 

The Massey Tower excavation extended below the foundations of Canon Theatre and Massey Hall, image by Jack Landau

Why dig a deep hole in the first place? Why are there so many of these deep holes downtown, where it’s hardest to dig? The answer is that the underground space is necessary. The depth could be driven by a requirement for a certain number of parking spaces from the City or prospective tenants. Sometimes, foundation systems also impose restrictions. More on that in a future Explainer. 

You can find the rest of the story on our sister site, SkyriseCities.com.