FEM or LEM? A false choice in geotechnical engineering.
Computers and computerized analyses are genuinely great tools that can sometimes lead us astray from delivering a true engineering solution. Many engineers are carried away by beautiful colors from finite element analyses to represent a true analysis. Others question whether a finite element analysis or a limit-equilibrium analysis is the right way to go in geotechnical problems.
The surprising answer is both and none.
Each method has advantages and disadvantages, but the fundamental question is different. We forget that we need engineering judgement to solve engineering problems. Rather than approaching geotechnical problems from an analytical perspective we need to encourage engineers to use an engineering mindset.
Before you walk you need to crawl, before you run you need to walk… The same principle should apply into how we approach geotechnical problems. Start with the basics, frame the problem, get the right data, understand the uncertainties, run basic analyses. Once the problem is framed in a proper initial way then go towards finite elements.
Too often you see younger engineers jump directly into a 3D FEM analysis before even the basic understanding of site conditions. Not every problem needs a brain surgery approach tool. Start simpler and build up towards more complex.
I am currently reviewing an excavation that failed spectacularly two times where FEM was only used. FEM can lie to you beautifully.
On our next deep excavation workshop, we will be talking about theory, methods, concepts, finite elements, and limit-equilibrium, but most importantly we will be focusing on how you can approach deep excavations as an engineer, not an analyst.
Be an engineer not an analyst
Solutions for Geotechnical Engineering Professionals:
DeepEX: Deep Excavations Design Software
DeepFND: Pile Foundations Design Software
HelixPile Helical Piles Design Software
SnailPlus: Soil Nail Walls Design Software
