Engineering geology aspects for design and classification - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 37

Stress relief tests in
excavation
17. Doorstopper

u σ 1 , σ 2 , θ 1 , θ 2 Recording of the biaxial stress state at

right angles to the borehole axis

18. Triaxial cell σ 1 , σ 2 , σ 3

θ 1 , θ 2 , θ 3

Recording of the triaxial stress state

19. Borehole expansion
test

See also 1

Compensation measu-
rements
20. pressure cushion test

See also 2

Stress measurement in
the support
21. Mechanical, hydraulic
and electrical measu-
rement systems

See also Chapter IV

Water permeability of the rock mass (measured in the borehole)
22. Wished-in-place, per-
colation and pumping
tests (Lugeon test)

p, Q k f Time-consuming. expensive: various

evaluation criteria

Water permeability of the rock mass (in a larger zone)
23. Dye, salting and
isotope tests

Q k f

Key to symbols
u Deflection F Force E Modulus of elasticity c Cohesion Q Water quantity

v L Propagation velocity, longitudinal N Normal force E v Modulus of deformation ϕ Friction angle k f Water permeability

v T Propagation velocity, transverse θ Principal stress direction ν Poisson's ratio τ Shear stress

σ Normal stress P Line load λ Lateral stress coefficient p Grouting pressure