2D FEM Analysis of Slippage Phenomenon in Earth and Rockfill Dams

Nishtha Saraswat

Dams are gaining more attention in recent years due to the rise of the environmental awareness and ‘renewable energy’ and ‘sustainability’ concepts. Earth embankment dams are preferred over gravity dams for the ease of construction and economical advantage. Despite considerable advances in the field of geotechnical engineering, the occurrence of frequent destructive earthquakes during the past decade and the trend towards construction of structures of unprecedented size and of novel designs has enhanced the importance of earthquake resistant structural design. Rock-fill dam is a type of earth dam where a compacted central clay core is supported from the rock shells by a series of transition zones built of properly graded material. In recent years, rock-fill dams, especially the impervious-faced rock-fill dams (IFRD), are built all around the world using asphalt or concrete as the impervious material in the upstream face of the dam. This paper analyses the slippage phenomenon in the core-shell interface of earth and rock-fill dams with the aid of ANSYS16.2 package. The software was first validated then used to examine the slippage in Tehri Dam, which is located in the seismically active region of Himalayas. A 2D fem analysis is done by modelling the dam as a linear, elastic, non-homogenous material. The slippage phenomenon is modelled using contact element feature of ANSYS. Among the variables, the non-homogeneity of the core and shell material and coefficient of friction is considered in the analysis. On evaluation it is found that core settlement increases where core-shell influence has been considered.