Nous vous avons envoyé un message électronique.

Nous sommes désolés mais nous n'avons pas pu vous envoyer le lien sur votre courriel. Veuillez vérifier votre adresse électronique.

Aide contextuelle

GEO5

Tree
Settings
Produit:
Program:
Langue:

Recommended Values of Parameters for Volume Loss Analysis

Data needed for the determination of subsidence trough using the volume loss method:

Coefficient to calculate inflection point k

Soil or rock

k

cohesionless soil

0.3

normaly consolidated clay

0.5

overconsolidated clay

0.6 - 0.7

clay slate

0.6 - 0.8

quartzite

0.8 - 0.9

Percentage of volume loss VL

Technology

VL

TBM

0.5 - 1

Sequential excavation method

0.8 - 1.5

Several relationships were also derived to determine the value of lost volume VL based on stability ratio N defined by Broms and Bennermarkem:

where:

σv

-

overall stress along excavation axis

σt

-

excavation lining resistance (if lining is installed)

Su

-

undrained stiffness of clay

For N < 2 the soil/rock in the vicinity of excavation is assumed elastic and stable. For local plastic zones begin to develop in the vicinity of excavation, for a large plastic zone develops around excavation and for N = 6  the loss of stability of tunnel face occurs. Figure shows the dependence of stability ration and lost volume VL.

Literature:

Broms, B.B., Bennemark, H., 1967. Stability of clay at vertical openings. ASCE, Journal of Soil Mechanics and Foundation Engineering Division, SMI 93, 71-94.