Measurement for monitoring, probing and recording evidence - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 147

Figure 4-10 Example of a
data logging system [254].

4.3 Measurement processes, instruments

The next section describes measurement processes and instrumentation that are currently
in use. Table 4-2 gives an initial overview of the purpose and example applications of the
instrumentation used.

Table 4-2 Overview of the purpose of measurements, applications and instruments [25].

No. Measuring instrument (e. g.) Purpose Example

1

Convergence (KV) - measuring
tape
Geodesy

Demonstration of a new
equilibrium after the driving
of the tunnel

- Convergence measure-
ments
- Location surveying

2 Extensometer and inclinometer Comparison with calculations - Measurement of deforma-

tion in surrounding ground

Pressure cells --> for improved tunnel

design

- Stress measurement in the
shotcrete layer

3

Tunnel scanner DIBIT
deflectometer

Quality assurance
of individual construction
projects

- Excavation profile
- Directional precision of
boring

4 Electronic hose levelling

instrument
Electrolevel measuring chain
Motorised digital level

Control measurements
of entire construction
sequences

Soilfrac ® process in inner-
city tunnelling
(heave/settlement)