Engineering Rock Mechanics

86 lntod rock: deformabili?., strength and failure

Whole specimen

volume is

critically stressed

Only a small part of

the specimen volume

is critically stressed

Indentation

I

Hydraulic

fracturing

I

Compression

of

irregular

specimen

The sketch above shows the direct tension test followed by eight indirect tensile

strength test methods.

These are the trends which are observed in the testing of all rock

strengths. Thus, rock strengths, as determined by these engineering

tests, are not material properties because they depend on the specimen

geometry and the loading conditions of the test: a material property does

not depend on these factors.

Q6. IO The two marble panels illustrated below are from the Greek

Parthenon frieze which depicts the four-yearly procession of the

'Great Panathenaia'. They were sculpted in light relief under the

direction of Pheidias and placed in position around 450 BC. One

panel is from the north side of the Parthenon and one panel is from

the south side. Which is which?

A6.10 The Parthenon is situated in Athens in Greece, at a latitude of

38W. At such a latitude, the southern side of a building is subjected

to more intense light, temperature gradients, wind and rain than the

northern side. After about 2450 years of such exposure, we would expect

rock facing south to be more severely weathered than rock facing north.

Thus, Panel A is from the south frieze and Panel B is from the north

frieze.

Howard Staunton used these sculptures as the source for his 19th century design of

the knight in the classic Staunton chess pieces.