On the word "Tension" when used in soil/rock mechanics

[slam00000]

Whenever I heard the word "TENSION" in the geotechnical business or read it in any text book I start to get confused.
-Sometime it implies the existence of cohesion which means that soil can bear a negative confining stress.
(Vertical cut which is subjected to tension: is sustained because of the cohesion).
-But in the vertical cut the confining stress is still positive and that drives me to think that tension means that the shear stress becomes negative (bottom part of the Mohr circle is considered)
-Some time the word tension is driven strictly by the horizontal and vertical directions. For example they refer to the extension triaxial shear to that test in which the lateral (confining) stress is larger than the vertical stress.

Please give me your insight on this matter.

 

[fattdad]

vertical cut the confining stress is still positive

The vertical confining stress is positive, but the horizontal confining stress is not. This makes for sigma 1 positive and sigma 3 negative, which is a Mohr's circle that straddles the "y" axis.

Hope this helps.

f-d

¡papá gordo ain’t no madre flaca!