Tabish Ali

Erosion of cohesive sediment is a complex phenomena and involves various factors comprising effective gravity, dry unit weight, sediment microstructure, particle size distribution, mineralogy, organic content and water chemical condition. The response of cohesive sediment to flow of water has received little attention. In light of this, a study is conducted in the hydraulics laboratory of National Institute of Technology, Kurukshetra. The objective of the study, besides filling up gaps in information, is to make an attempt to establish the effect of certain parameters of cohesive sediment on the erosion process in general and on the incipient motion in particular. The present paper, which is a part of the bigger study, compiles a review of the works by various researchers on the basis of parameters such as shear strength, consolidation pressure, plasticity index, clay content, salinity, compaction water content etc

In this paper, the results of experimental work that has been conducted to study the incipient motion of cohesive sediments are reported. A layer of clay having 15 cm thickness and 2m length was laid down in a flume. A number of experiments were performed on this layer observing the behaviour of clay under the action of fluid forces. Time ts (time for which clay was being saturated before experiment), velocity of fluid and time for the flowing fluid were taken as different parameters for observing the behaviour. The experimental results demonstrate that clay behaves differently for different periods of time for which it is kept saturated. It also shows that there is development of sticky layer which further resists the erosion.