Introduction

This example is about the rapid drawdown of a reservoir and the excess pore-water pressures that remain in the ground once the ponded water has been removed. The excess pore-water pressures can cause slope instability and, consequently, this is an important issue in the operation of water retention structures, such as embankment dams. There are many ways to approach rapid drawdown, as indicated by the significant number of papers in the research literature.

The purpose here is not to do a review of what has been done in the past, but to demonstrate how this issue can be addressed using GeoStudio. One way of computing the changes in pore-water pressures resulting from the drawdown is to do a water transfer analysis. Another way is to do a fully coupled stress/pore-water pressure analysis using SIGMA/W. The results from these two types of analyses are presented and compared here.