Unbalanced (out-of-balanced) force

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1

This picture below is from one the examples : “Assessment of Fault Slip Potential from Sill Pillar Mining.”

It was mentioned that: The figure plots the unbalanced forces depicting how the model comes to equilibrium after each mining step.

May I know how to identify the lower limit of the Y-Axis Unbal forces? How to define the value?

In this particular example, the unbalanced forces were dropping from a value of 1.810^10 to 0.210^10.
How was this lower limit (0.2*10^10) fixed ?

I believe it is very important to identify this lower limit value to choose number of cycles/steps for the model to reach equilibrium?

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Also, some times I get to see there is a spike in Unbal forces. Could it be due to joint slippage? If so then how to fix the number of steps required? And how to set the unbal ratio?

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Thanks,

V

2

The maximum unbalanced force is actually not that helpful. For small models you get small values, and for bigger models, you will get bigger values. A better measure is the unbalanced force ratio. You can take a history of this too. By default, the model is considered to be in equilibrium if the unbalanced force ratio is less than 1e-5.

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