Need Help Recognizing an Equation for Slot Cuts

[sdgeotech]

I have been given an excel file to use as a calculation tool for slot-cut stability. I've gone through the equations to make sure I understand how to use the tool, and there is an equation that I don't understand that is for the resistance generated along the sides of the assumed failure wedge.

The equation is: Area of the side of the failure wedge * 1/3 * gamma * Height of slot * Ko * tan phi + C

I cannot recognize the equation to be able to verify it / look it up in a textbook. Am I dealing with a typo, or does anyone recognize the equation and can provide a reference it?

 

[killswitchengage]

Hello
First of all i never heard of a slot cut excavation , its probably a language issue here since i am not American .
Anyway, your equation seems to say that the resistance to instability is function of the degree of consolidation as well as shear strength ; but i am also puzzeled that the its proportional to the height which is not consistent with reality .