671017.pdf

(a) Normal deformation of original joints (b) Tangential deformation of joints (c) Deformation of surrounding

rocks

Figure 7: Numerical simulation results of the surrounding rock deformations.

Slip possible

No slip

(a) Original joints

CurrentFailure stshearate

Shear Tensiand le faitlensiurele

ElElastastic ic prev prev sheartens

Elastic strs om itted

(b) Aphanitic joints

(m)

(m)

755

750

745

740

Nonrelaxed Slighlty relaxed W eekly relaxed Stron gly relaxed

5000 4000 3000 2000

− 15 − 10 −50 5 101520

(c) Relaxation zone of columnar joints

Figure 8: Relaxation zones of joints after excavation of the first layer.

wave velocity and by modeling on the rock mass integrity
evaluation system, a relaxation coefficient of rock mass푘is
established:

푘=

V^0 푝−V푝

V^0 푝

, (6)

wherekis the coefficient of relaxation,V푝is the velocity of

longitudinal wave of rock mass at the testing position, andV^0 푝

is the eigen wave velocity of nonrelaxed rock mass.

In order to distinguish the relaxation degree of rock mass

in a more detailed manner, the relaxation degree of columnar