Have you read this book?

gistfile1.txt

I'm trying to figure out what sci-fi book I read in junior high, about 25 years ago.

The book is post-apocalyptic although I don't know the nature of the apolcalypse: either 
nuclear and/or environmental.  The story centers around a young man who lives with his 
father. They live in some sort of oppressive society and have to keep things (or 
people?) hidden beneath their house. I think they grow their own food down there, which 
is against the law. They use the dirt they've dug up as sound insulation in their walls. 
Something is wrong with the air and they can't always be outside, or they need special 
breathing gear. I don't remember anything about the story arc, but at the end they go 
out to the desert and find a hatch that takes them to a passenger jet that is buried 
underground. The jet isn't functional, but serves as a hidden suspended-animation 
chamber which many "escapees" are using to travel to the future to escape the troubles 
they are having in the present.

I don't remember anything about the title or author, but the cover of the book had a 
ring on it with a figure-8 in the jewel. It was an older book and if I had to guess I would 
say it was published sometime between the late 50s and early 70s.