360 Underground excavation instability mechanisms
There are index tests which assist in characterizing aspects of weather-
ing, such as the slake durability test, although it is difficult to present the
information with the same impact as the purely mechanical concepts we
have dealt with above. Many aspects of the subject of weathering can be
raised, especially in connection with the interaction matrices introduced in
Chapter 14. At this juncture, we seek only to remind the reader that time-
dependent mechanisms do exist and need to be modelled.