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# PLAXIS 2D for modelling Pile-Slope Stability (NEED HELP!!!)

## PLAXIS 2D for modelling Pile-Slope Stability (NEED HELP!!!)

(OP)
Hi guys,

I'm currently doing a research on pile-slope stability using PLAXIS 2D.

I'm not sure whether I have model it correctly. This is how I have done it:

1) 3 phases were used.
2) Initial phase: Activate the soil materials to proceed with Ko procedure.
3) Phase 1: Activate Slope and Pile using Plastic calculation as calculation type.
4) Phase 2: Calculate FoS using c-phi reduction.

I'm well aware that we shouldn't use the Ko procedure for non-horizontal soil layers. That's why I have created a soil polygon that's a rectangle for the initial phase and then deactivate half of the polygon to activate the slope. I will attach my PLAXIS file for you guys to have a look.

Any help from you guys will be appreciated. Thank you!

### RE: PLAXIS 2D for modelling Pile-Slope Stability (NEED HELP!!!)

Generating initial stress in a slope is tricky. K0 procedure, gravity loading, excavation or filling may be used, but you need to make sure the stresses and plastic points if any are realistic. You should generate initial stress first before activating piles. Noted pile contribution is overestimated in plane strain model. In Phi_c reduction you need to make sure pile shear capacity is not exceeded.

### RE: PLAXIS 2D for modelling Pile-Slope Stability (NEED HELP!!!)

Your work-around for using the Ko initial condition is not recommended. You initial conditions (after removing the soil block) will be different, which defeats the whole purpose of establishing the current stress state of the soil at all layers.
Why don't you just use Gravity to create the initial conditions? I have used this successfully for slope stability analysis.

I did not open your model, but you may want to experiment with the different pile options (embedded piles / beams) vs stiff soil elements (polygons with concrete properties). The latter act like continuous walls in a plane strain model. You will certainly get different results.

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