Theory 10/Geotechnical Engineering
Slope Failure Is a Rainfall Ratio
The claim
The timing of slope failure is set by the ratio of rainfall intensity to permeability rather than by rainfall total, so a short intense storm can trigger where a long gentle one does not.
01Mechanism
Failure requires pore pressure to rise, which happens when water arrives faster than it drains; the ratio determines whether pressure builds within the slope.
02Predictions
- P1Failure timing should track the ratio.
- P2Total rainfall alone should mispredict.
03Refutation
Failure timing tracking total rainfall would remove the permeability term.