Internal Sliding
This limit state evaluates the possibility of structure to slide along the reinforcement. For the selected reinforcement the program searches for a critical slip surface in the range of 45 - 90o from the end of given reinforcement.
For each slip surfaces the program calculates the shear and resisting forces and performs verification.
The shear forces include:
- active pressure on a fictitious wall
- forces due to surcharge behind the wall
The resisting forces include:
- resistance of the wall structure against slip (it is calculated as for the wall dimensioning)
- friction between reinforcement and the sliding block
- forces due to other reinforcements
The resisting force due to friction between reinforcement and the sliding block is given by:
where: | N | - | normal force acting on reinforcement (due to self weight of soil and surcharge behind the fictitious wall) |
φ | - | angle of internal friction of soil surrounding the reinforcement | |
Cds | - | coefficient of reduction of friction on reinforcement |
The actual verification is then performed based on the input specified in the "Wall analysis" tab, according to the theory of limit states and factor of safety. It has to hold:
| resp. |
|
where: | Hres | - | resisting force |
Hact | - | active force | |
SFsr | - | safety factor for sliding along geo-reinforcement |