Civil & Environmental
Slope Stability Lab
Slope stability is decided by a tug-of-war on a curved slip surface: the weight of the soil mass drives it downhill, while cohesion and friction along the surface resist. Drag the slope angle, the cohesion c and the friction angle φ and the trial slip circle is sliced (the ordinary, or Fellenius, method of slices), each slice's weight split into a driving and a resisting part. The factor of safety is the resisting sum over the driving sum — above 1.5 the slope is stable, below 1.0 it fails. You'll see directly why steepening the face tips a slope into failure, and why a little cohesion goes a long way.
1.26
Factor of safety
374 kN
Driving Σ
471 kN
Resisting Σ
The failure mass is sliced and each slice's weight is split into a part that drives the slide (down the arc) and a part friction + cohesion resist. The factor of safety is resisting ÷ driving — below 1.0 the slope fails. Cohesion and friction hold it up; steepening the face piles on driving weight. Soil unit weight fixed at 18 kN/m³, slope height 12 m; solved by the ordinary (Fellenius) method of slices.
How to use this simulation
Slope stability is decided by a tug-of-war on a curved slip surface: the weight of the soil mass drives it downhill, while cohesion and friction along the surface resist. Drag the slope angle, the cohesion c and the friction angle φ and the trial slip circle is sliced (the ordinary, or Fellenius, method of slices), each slice's weight split into a driving and a resisting part. The factor of safety is the resisting sum over the driving sum — above 1.5 the slope is stable, below 1.0 it fails. You'll see directly why steepening the face tips a slope into failure, and why a little cohesion goes a long way.
Everything runs in your browser — no sign-up, no download. Change a value and the result updates instantly, so you can build a feel for how each input shapes the outcome. It pairs with Crameleon's practice exams and step sheets when you want to go from intuition to working the problems.