Experiments on the Instability of Loose Sandy Slopes Due to Rise in Water Level

In a soil mass, a rise in pore water pressure leads to a decrease in the mean effective normal stresses, while the vertical loads due to surcharge may experience small changes. Under such loading, very loose and loose sands may initially experience small volumetric expansion, and then start to contract significantly as failure is approached. These large contractions can lead to the increase in pore water pressure and, consequently, failure of the soil mass under poor drainage conditions. In this paper, an experimental model is used to examine slope instability resulting from rise in water level. It was noticed that the main factor controlling the mode of failure was initial density, but other factors such as method of increase in pore pressure, distribution of pore pressure, and geometry of the test tank also influenced failures.