Measurement for monitoring, probing and recording evidence - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 181

- No damage up to 1/1000.
- Damage possible from 1/1000 to 1/600.
- Slight architectural damage predominant from 1/600 to 1/400.
- Medium architectural damage predominant from 1/400 to 1/300.
- Heavy architectural damage predominant from 1/300 to 1/200.
- Slight to medium structural damage predominant from 1/200 to 1/150.
- Heavy structural damage predominant from 1/150 to 1/120.
- Collapse or necessary demolition predominant from 1/120 to 1/90.
Fig. 4-50 shows the angular distortion with the damage limits depending on the degree of
damage in percent of the newbuild cost of the damaged building entered as a curve. The
curve shows that architectural damage can be repaired relatively cheaply, but that costs
increase in leaps and bounds for angular distortions of 1/250 to 1/200. Regarding the given
values, it should be considered that angular distortions of 1/400 to 1/500 are assumed as a
result of settlement during and after the building of a reinforced concrete framed building.
If a 1 cm settlement difference occurs at a spacing of 5 m, for example, then the critical
boundary between architectural and structural damage has already been reached. A fore-
cast or analysis of damage therefore also has to include consideration of loading that has
already occurred and possibly also that, which is to be expected. The following general
points apply to the behaviour of buildings subjected to settlement:
1. A free-standing single building reacts more favourably to a tunnel being driven beneath
it than a structure or wing of a building connected to adjacent buildings. The common
junction of two buildings can cause structural damage due to the different settlement
behaviour of the two buildings.
2. If the tunnel does not pass beneath the buildings at right angles, then this causes not
only a skew position but also a distortion, which worsens the risk of damage.
3. If two adjacent tunnels are driven one after the other, then the buildings on the surface
can be forced into a “swing movement”.
Figure 4-50 Damage to reinforced concrete framed buildings due to the effects of settlement [80].