Description |
FOSM Calculator uses first-order, second moment expressions to perform probabilistic or reliability-based analyses of several common geotechnical and hydrologic problems. Modules cover the stability of forested infinite slopes (including exceedance probability for specified Newmark critical acceleration), steady-state drawdown around a pumping well, Green-Ampt infiltration rate and wetting front travel time, and Manning's equation for open channel flow with either depth or discharge as the dependent variable. It uses analytical solutions rather than a numerical Monte Carlo approximation of the results for rapid calculations. Most input variables can be specified to follow uniform, normal, triangular, and beta distributions. Results are given as the mean and standard deviation of the dependent variable, lognormally distributed exceedance probabilities, and the distribution-independent reliability index. In most cases, the exceedance probabilities are calculated with regard to a user-specified threshold. It is written in JavaScript and runs within popular web browsers. |