ABC Slot Cutting Calculation 1

[140lbHammer]

Dear Professional, City requires following if ABC Slot Cutting is recommended,

(1) analysis will be required to demonstrate the stability of excavated slots.
(2) The resistance on the sides of the wedge shall be taken in a direction parallel to the critical failure plane (not in a horizontal direction).
(3) The factor of safety for slot-cut calculations decreases and then increases with increasing excavation height.
(4) Therefore, the calculations shall demonstrate that a shallower excavation does not have a lower safety factor than the plan excavation height.

p.36

http://www01.smgov.net/planning/buildingsafety/PDF/smgeotechguidelines - may 2008.pdf

I still have hard time find out what City is looking for. I will:

(1) <5 feet, vertical cut
(2) >5 feet sloped as OSHA
(3) >5 feet and cant slope, then NO slotcut but to use shoring or soil nail

Can anyone give me a hint what calculations the City is exactly looking at before I call them.

Much appreciated!!

 

[FixedEarth]

They can sure drive any consultant nuts!

On your option (2), draw a 4 point slope and do a simple circular slope stability analysis. Ayyach the diagram with the computer results and show that Static F.S. > 1.5 and Pseudo-Static F.S. > 1.10. Good luck.