Liquefaction and Earthquakes

How do Monolithic Domes stay up when all is falling down?

Liquefaction: A condition during an earthquake where certain soils tend to act as a viscous liquid; the process of making or becoming liquid. Liquefaction has proven to be a huge problem in some California earthquakes. Even though the soil doesn’t become as thin as water, its ability to support buildings is greatly compromised.

The challenge

We have a customer who wants to build a retirement home on one of the San Juan Islands in northwest Washington state. His land is subject to liquefaction during an earthquake. He asked us to help him design a building that would survive both earthquakes and liquefaction.

What’s the solution?

The solution is to construct an uninsulated, concrete, thin-shell dome upside down, underneath the main dome. The inverted dome can be filled with dirt or concrete.

The goal is to make the building float. We don’t have to worry about making it float as if on a bowl of water; we have to make it float on a giant pad of shifting soil, that’s more like a bowl of Jell-o.

An inverted, shallow dome underneath the main dome will act as a boat in the sand and prevent the dome-home from sinking. A dome has plenty of structure to keep from being broken by the earthquake. By tying the floors and walls of the dome-home to the dome-bowl during the construction process, everything becomes much safer.

The accompanying illustration shows what we are talking about. Figure 2: Semi-liquid soil will handle 200 pounds per square foot. The inverted, shallow dome-bowl and the sidewalks, attached around the perimeter, literally bring the soil-bearing need down to about 200 pounds per square foot. That’s a significant decrease of the average soil-bearing load of a house, which is 3,000 pounds per square foot.

The condition created by the dome-bowl is similar to putting on snowshoes, that keep you from sinking deeply into snow and becoming immobile. By spreading the load out evenly across a large area, the structure tends not to sink into the soil as liquefaction takes place.

Will it work?

Yes, it will work. Will it be the answer to everything? No one knows. We hope that they never get the chance to find out.

Earthquakes are terrible disasters that disrupt lives and destroy property, but our solution provides one way to safeguard against such destruction.

^{Originally published July 25, 2005}