Founded on Rock or Sand?

You have heard the bible parable about the wise man who built his house on the rock and the rain came and the wind blew and the flood came but the house stood because it was built on rock and the foolish man’s house fell because it was built on sand.  The importance of building your house on a sound foundation is not a new topic.

Soil that makes up this planet earth is very complex.  The physical and chemical properties of soil affect how it reacts.  If you are new to soil mechanics you would find it interesting and fascinating to watch a few youtube videos of how soil interacts when disturbed.  The disturbances can come in the form of excavating the soil for building foundations.

I would highly recommend watching Prof. John Burland’s series of videos on this topic.  There are about 10 videos in this series.

Here is also another fascinating one that shows the soil water interaction.  This one is quite long (16 mins) and not directly related to civil engineering but it is fascinating to see how different types of soil retain water differently.  This will help you understand how and why some structures have to designed for buoyancy forces.

The above two cover general topics of the soil mechanics part of the geotechnical engineering.

Structural engineers rely on codes and geotechnical engineers for information about the soil on top of which the structure is to be built.

You have seen pictures of Leaning tower of Pisa and if you live in the San Francisco Bay are you have heard about the sinking Millennium tower.  Just google it to read the news.  It will highlight the importance of sound and adequate foundation design.  It is always better to do it right one time, the first time.  Fixing design mistakes in the field is a very expensive proposition.

There are two categories of foundations.

• Shallow Foundations ( spread footings, wall footings, matt foundation)
• Deep Foundations (CIDH: Cast in drilled hole, CISS: Cast in steel shell, etc)

Shallow Foundation

Deep Foundation

Spread Footings

Wall Footings

Retaining wall

Tieback walls

Piles