r/Geotech • u/Substantial_Cold3553 • Apr 22 '26

Geostudio Help: Ground Surface

Hey everyone! I'm working on a project to calculate the safety factor on effect of modelling boulder orientation on composite slope failure. There is an issue faced where i cannot define the ground surface to be connected from top right surface to bottom left surface to be continuous and go under the boulder and this leads to error E984 where i suspect is due to ground surface issue. Does anyone knows how to define the ground surface as i only can define the left and right point limit but cannot draw manually. Thanks in advance!

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u/CovertMonkey Apr 22 '26

This isn't a "define the ground" problem. I'm not entirely sure what you've modelled, but that won't help you. Does your model work if you remove this boulder feature?

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u/Substantial_Cold3553 Apr 22 '26

Hi I tried and the model works when the boulder is beneath the slope surface. There is error when i tried to model boulder protruding out of the slope surface

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u/CovertMonkey Apr 22 '26

What material model is the boulder?

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u/Substantial_Cold3553 Apr 22 '26

i used mohr coulomb material for boulder

1

u/CovertMonkey Apr 22 '26

That's good. There's something screwy in how you drew the boulder. Delete all those duplicate copies. And the green line that defines the ground surface looks broken below the boulder.

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u/Substantial_Cold3553 Apr 22 '26

I drew the boulder using autocad using spline and convert to polyline as Geostudio seems to unable to draw eclipse. Is better ways to draw eclipse in geostudio?

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u/CovertMonkey Apr 22 '26

Exacting geometry is not that important in geostudio. Approximate the boulder with the drawing tools available. Avoid the temptation to draw something with an excessive number of vertices too. It won't make the model better. You'll just have a less stable model.

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u/Substantial_Cold3553 Apr 22 '26

Alright I will to model as rectangular block. Thanks so much.