Civil Engineering Reference
In-Depth Information
Appendix B
Analytical calculation of a
sprayed concrete lining using
the continuum method
B.1 Introduction
There are different analytical methods to estimate the internal forces in a
tunnel lining and give an indication on the type of support needed (see
section 3.5). In this section the focus is on tunnels which have a large
overburden (h
D). This allows the ground to be treated as a continuum,
i.e. a plate with deformations in one plane (Figure B.1). The plate has a
circular hole (the tunnel), which is stiffened by a circular ring (the lining).
It can be assumed that the area above the tunnel is not softened and can
carry some load. The primary stresses can be calculated without the associ-
ated deformations and the lateral coefficient of earth pressure is K
0
.
For the approach of a rigid interconnection between the ground and the
tunnel lining it is important to note whether the tangential component of
the stresses from the earth pressure can be transferred into the tunnel lining
for example through friction. In many cases it is better to assume tangential
slippage between the ground and the tunnel lining in order to be on the
≥
h
p
v
r
p
h
D
Figure B.1
a) Analytical model for deep tunnels and b) primary loads
(Ahrens
et al.
1982)
