Geoscience Reference
In-Depth Information
Blasting 2
Blasting 1
P wave
Sequence 1
Sequence of principal stress loading:
Fig. 15.12. Orientationof principal stresses produced by sequence 1
Blasting 2
Blasting 1
P wave
Sequence 3
Sequence of principal stress loading :
Fig. 15.13. Orientationof principal stresses produced by sequence 3
seeFigure15.12;thesecondhalfofthefirstblastingandthefirsthalfofthesecondblast-
ing produce the same direction of major principal stress. This situation is not favorable
for efficient densification of sand. In contrast, the sequence 3 in Figure15.13 periodi-
cally changes the orientation of principal stresses and is expected to densify soil more
efficiently.
2.3. EXPERIMENTAL REPRODUCTION OFBLASTING STRESS
Undrained torsion shear tests were conducted to reproduce the stress history induced
by different blasting sequences. Test results obtained by stress sequences 1 and 3
