Comparison between the in situ and laboratory water retention curves for a silty sand

After an extreme rainfall event in May 2002 a series of landslides occurred in Ruedlingen in Canton Schaffhausen, North Switzerland. A 38° steep slope has been chosen in this area beside the river Rhine to carry out an artificial rainfall experiment to investigate the dependence between rainfall, suction, saturation and shear resistance. Two sprinkling experiments were conducted to represent an extreme rainfall event, the second of which resulted in failure of 130 m 3 of the slope. Several cycles of wetting and drying were applied to the soil and suction and volumetric water content were measured at different depths in three locations of the slope, by which in-situ Water Retention Curves (WRC) can be derived. The WRC of an undisturbed sample was also determined from laboratory test. The in situ and laboratory WRCs are compared in this paper and the differences will be discussed.