Liquefaction and Earthquakes

How Monolithic Domes stand up when all is falling down?

July 25, 2005

by David B. South

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fig. 1

fig. 2

Liquefaction: A condition during an earthquake where certain soils tend to act as a viscous liquid; the process of making or becoming liquid.

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 earthquake and liquefaction. Liquefaction has proven to be a huge problem for some of the California earthquakes. Even though the soil doesn't become as thin like water, its ability to support buildings is greatly compromised.

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 on a bowl of water, we have to make it float on a giant pad of shifting soil -- more like a bowl of jell-o.

By inverting a shallow dome underneath the main dome, it will act as a boat in the sand to prevent the dome home from sinking. A dome has plenty of structure to keep from being broken up by the earthquake. By tying the floors and walls to the dome -- everything is much safer.

The accompanying illustration shows what we are talking about. (fig. 2) Semi-liquid soil will handle 200 pounds per square foot. The inverted shallow dome and the sidewalks attached around the perimeter literally brings 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 in very similar to putting snow shoes on. By spreading the load out evenly across a large area the structure will tend not to sink into the soil as the 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 at least our customer will still have a home in place if such an earthquake occurs.

Liquefaction and Earthquakes

How Monolithic Domes stand up when all is falling down?

Click Images to Enlarge

What's the solution?

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