Dewatering, waterproofing and drainage - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 211

Table 5-14 Classification of the water-tightness of road tunnels according to ZTV-Ing. [263].

Waterprooing
class

Damp
characteristics

Waterproofing requirements

1 completely dry The sides of the lining must be so waterproof that no damp

patches are detectable on the inner face

2 largely dry The sides of the lining must be so waterproof that only a slight

dampness (e. g. noticeable through discoloration) is detectable
on the inner face in isolated locations. When the slightly damp
patches are touched with the hand, no trace of water should be
left on the hand. Blotting paper or absorbent newspaper laid
against the patch may not discolour due to moisture absorption.

3 capillary moisture

penetration

The sides of the lining must be so waterproof that only isolated
and localised patches, which are wet to touch, occur. Patches,
which are wet to touch, are defined in that moisture penetra-
tion of the tunnel sides is noticeable and blotting paper or
absorbent newspaper laid against the patch discolours due to
moisture absorption, but no water drips occur.

No explicit mention is made of the requirements of German Railways here because these
now almost correspond to the relevant content of the ZTV-Ing, and the relevant Ril 853
now actually refers to the ZTV-Ing concerning waterproofing questions.

The definite requirements on tunnel waterproofing used as the basis for this classification
derive from:
- The geological and hydrological conditions.
- Material requirements,
- Construction process,
- Design detailing,
- Balancing of the risks of production and the associated quality assurance,
- Maintenance,
- User requirements,
- Environmental and waterways protection requirements and
- Cost-effectiveness and maintenance.

5.3.1.2 Requirements resulting from geological and hydrological conditions
This demands the best possible detailed and binding statement of limit values by the em-
ployer regarding the following exposures:

- Type, quantity and aggressiveness of the water acting on the tunnel structure:
a) Groundwater.
b) Strata or joint water.
c) Dammed water.
- Maximum water pressure on the waterproofing and the structure.
- Maximum surface pressure in the construction and completed states.
- Possible deformations of the rock mass and tunnel.
- Highest and lowest temperatures in the construction and completed states.
- Tendency to sintering.