I've a wall in tension that should be in compression.
As shown in the screenshot below I've a symmetric model where the excavation is conducted in 2 steps, removing half of the bench on the left & installing the wall then excavating the right half & constructing the right hand wall.
The wall on the left behaves as expected, with the wall going into axial compression however the wall on the right strangely goes into tension.
This is clearly as a result of the 2-step excavation as both walls go into axial compression when you clear the bench in one go & construct the walls at the same time.
Any idea as to why the model is behaving in this way?
Thanks
Hi Conor,
The big axial loads must be a result of the surcharge loads shown by the blue arrows, correct? So the surcharge load on the right are not getting into the pile. So here is my thought.
You're installing the pile on the right and removing the soil across the width of the excavation at the ground surface, so the surcharge loads are now redistributed into the remaining soil and pile on left. The stress distributions for the installation of the left pile are quite different from the conditions at which the right pile were installed. The surcharge has been removed across the width of the exaction an the majority of the soil has been removed. When the berm is removed there is no where near as much redistribution of surcharge loads as in the first step, and the heave causes the tension.
Try inserting a phase before excavation, where the surcharge is removed from the surface of just the excavation, prior to installing any walls. I bet this fixes the problem.
Martin
Opps I meant "You're installing the pile on the LEFT and removing the soil across the width of....