Engineering Rock Mechanics

364 Design and analysis OF underground excavations

1

When the strata thin upwards, replace y in these equations with yo:

When a uniform pressure, p, acts in the zone of separation:

Figure 20.4 Deflection of roof strata assumed to act as elastic beams.

Voussoiv arch model. The analysis in Fig. 20.4 is only valid for a CHILE
material. However, it is possible to have a stable roof in a discontinuous
medium. This is the reason why many of the ancient constructions using
rock blocks have been possible. Figure 20.5 shows a photograph of an
ancient bridge over a river in northern Turkey. The span of the bridge is
comprised of a single set of rock blocks with no binding agent; this type of
arch is called a voussoir arch-and examples are common in masonry
structures.

Figure 20.5 Masonry bridge demonstrating a voussoir arch comprised of a single

set of rock blocks (northern Turkey).