Squeezing rock conditions in tunnels are defined to occur due to shearing of the ground with an associated inward movement of the tunnel perimeter. The factors influencing squeezing conditions are complex. The initial state of stress is important, which is usually difficult to determine in poor quality rock. Ground strength and deformability are other important factors. They can practically only be estimated from correlation to a ground property index, of which the most suited is the Geological Strength Index (GSI). Orientations of the rock structure and groundwater conditions are also important factors.
Squeezing conditions are best identified by an estimate of the ground properties and an analytical estimate of convergence is the best estimate of bounclaiy conditions. Construction and lining procedures influence squeezing potential as well. Simple empirical rules are no substitute for analysing the complexity involved in squeezing rock conditions.
Squeezing rock c …
AUTORI: Steiner W. RIG ANNO: 1999 NUMERO: 1 Numero di pagina: 9