standing block stability

[John Twilley <jtwilley@zzzzzzzzzzz>]

I'm not an engineer either, but consider the following:

The analogy with an inflated car tire for calculating the weight-load
per square inch breaks down when you consider these points:  The tire is
flexible and conforms itself to the ground somewhat.  The flat bottom of
the stone can be considered to apply a uniform load to the ground only
so long as it remains perfectly level.  As soon as it inclines ever so
slightly the load is no longer being applied uniformly or exclusively in
a vertical direction - the flat bottom is now exerting a slight lateral
push to the soil.  As the inclination increases, the flat bottom begins
to act more and more like a wedge, with the lateral component of the
weight becoming larger and the propensity for the sculpture to deform
the soil becoming greater.  This is what might be called a positive
feed-back loop: any slight instability is magnified to create a larger
one.

Ancient sculptures that were installed without a solid base often made
use of a base "tang", a narrow extension that acted like a rudder to
oppose toppling.  In this way the flat bottom of the sculpture
transferred the weight load to the ground and the tang extending below
resisted any tendency to lean by pushing laterally against soil that was
constrained beneath the sculpture.

This wouldn't meet the safety concerns that exist today and in a seismic
zone (or even one with heavy vibrations from traffic) where "live" loads
are involved, it could be fatally ineffective.

John Twilley