Table of Contents
Advertisement
Stake Face/
Stake Profile/
Check Profile/
Scan Profile,
page
47.3.2
Stake face
826
The
page displays the differences between the measured and design data.
The fields viewed on this page are configurable.
Refer to "43.3.10 Tunnel - Info Page - TS" for information on all available items
for the
page and how to select them.
Stake face
Overview
When excavating a tunnel, it is required to stake out the tunnel portal before
excavation can begin. For excavation methods other than those involving tun-
nel boring machines (TBMs), it is required to stake out the tunnel face at given
intervals during the excavation.
The tunnel face can be staked out at any time within the Tunnel app using
Stake face.
This function allows the staking out of a series of points perpendicular to the
horizontal alignment. The horizontal alignment indicates the position of the
design profile at the chainage of the tunnel face.
Cross section view
Tunnel_015
Given that it is likely that a degree of rock debris is present at the tunnel face
or that inexact excavation techniques such as blasting are used, it cannot be
assumed that the tunnel face at any stage of the excavation is perpendicular
to the horizontal alignment.
This situation in turn implies that we cannot stake out a point on the tunnel
face at a given chainage as the chainage of the tunnel face at any particular
point is unknown. Iterative techniques are necessary to enable any defined
point on the tunnel face to be staked out accurately.
The Stake face function involves setting out a point on the tunnel face at this
unknown chainage. First of all the point to stake out on the tunnel face is
staked out at an approximate chainage (e).
The point is defined by offsets regarding the centreline or by its position along
the design profile and its offset from the profile. Given that the excavated tun-
nel face does not intersect the defined chainage, another point (e') is meas-
ured.
a
a
Points to stake out
Roads - Tunnel
Advertisement
Table of Contents
