Squeezing Rock - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 91

4 Squeezing Rock

4.1 Introduction

In squeezing rock the strength of the intact rock is exceeded during the excavation of
a tunnel or other underground opening because of the low strength of the intact rock
and the high overburden, respectively. As a consequence, radial displacements of the
opening's walls occur that are time-dependent and can be described by the elastic-visco-
plastic stress-strain law described in Chapter 3. Particularly in case of high overburden,
a stiff lining cannot carry the load which is required to stabilize the opening. This can
cause severe damages (Fig. 4.1) up to a complete failure of the lining (Fig. 4.2).

Figure 4.1 Squeezing
rock, cracks in the shotcrete
membrane, Kallidromo
Tunnel/Greece