Rock mass variability and its effect on predicted performance

Before adding ‘complexity’ (i.e. fine-tuning), the term Q tbm and the gradient (-) m , an example application of this new TBM performance estimation will be given, in order to provide a ‘feel’ for the method. The following Q -value statistic for a 2 km long tunnel is assumed, based on pre-investigations (surface mapping, core logging, seismic refraction). 1.0 km https://www.w3.org/1998/Math/MathML" display="inline"> Q 1 = 100 6 × 2 1 × 0.66 1 = 22 σ c = 150 MPa Q c 1 = 33 γ = 2.7 tnf/m 3 0.5 km https://www.w3.org/1998/Math/MathML" display="inline"> Q 2 = 50 12 × 1 2 × 0.5 1 = 1.0 σ c = 100 MPa Q c 2 = 1.0 γ = 2.5 tnf/m 3 0.4 km https://www.w3.org/1998/Math/MathML" display="inline"> Q 3 = 25 15 × 1 4 × 0.66 1 = 0.27 σ c = 75 MPa Q c 3 = 0.2 γ = 2.4 tnf/m 3 0.1 km https://www.w3.org/1998/Math/MathML" display="inline"> Q 4 = 10 20 × 1 6 × 0.5 5 = 0.008 σ c = 10 MPa Q c 4 = 0.0008 γ = 2.1 tnf/m 3