Engineering Rock Mechanics

20 Geological setting

possible that rock blocks could be formed and these might be unstable

because of the steepness of the slope. Also, the folding is variable along

the slope, meaning that some regions of the slope will be potentially

more unstable than other regions. Such limestone masses are likely to

contain shear zones, so the rock should be studied in order to anticipate

problems of major instabilities such as that illustrated in Fig. 2.4.

42.2 The picture below shows the surface of a fault in a hard rock

aggregate quarry on which a rock slide has occurred. Explain (a)

why the existence of this fault could indicate that other similar

features will be encountered as quarrying continues, and (b) why

encountering an adverse geological feature such as this is likely to

be less significant in a quarry than in a road cutting.

A2.2 (a) Faults and shear zones are caused by rock stresses: the presence
of one fault is an indicator that others may be present in the same region
where the mechanical conditions have been similar. (b) Unlike the rock