Civil Engineering Reference
In-Depth Information
coefficients
f
SP
are entered as a group of hyperbolae and the performance ratio k (quotient
of
N
B
and the translational power
N
V
= F
v
ยท
v
n
) as a function of
v
n
and
p
(penetration) on
one side and as a variable of
F
v
on the other side. In this way, k can be used the decisive
characteristic value for classification.
Figure 2-27
Nomogram
for the evaluation of differ-
ent rock mass types using
rock mass-specific charac-
teristic curves, according to
Rauscher [185].
At this point, reference should also be made to the work of Beckmann, who investigated
influential factors and their effect on the advance rates of TBMs based on experience and
data from more than 40 km of tunnel driving [17]. Beckmann is able to prove that the rock
mass has an influence on the advance rate of a TBM both according to its cuttability and its
stability. The cuttability determined in in-situ tests is graded into six classes, as is the stabil-
ity. Both parameters can now be used as additional criteria for payment, with cuttability and
stability classes being combined in a price matrix, which is compared with a corresponding
performance matrix by the contractor.
The cuttability according to geological conditions (Fig. 2-28) was produced by Schmid in
1988 for the Swiss Master Builders Association.
Figure 2-28
Cuttability and geological conditions [206].
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