Design and development of an in-flight simulator for flooding and drawdown in a geotechnical centrifuge

Geotechnical structures such as levees, dikes, canals and tailing dams, when subjected to extreme climatic conditions, such as flooding and drawdown, are prone to failure on the upstream and downstream sides due to transient seepage conditions. Therefore, it is imperative to physically replicate such conditions in the actual stress state to understand the performance of these geotechnical structures. Hence, the objective of this paper is to present the performance of an in-flight simulator developed to simulate flooding and drawdown (ISFD) events at enhanced gravities. The working principle, design details, various components of the developed simulator, and calibration at normal (1g) and high gravities are discussed. In the present study, the calibration and performance of the ISFD setup were demonstrated on a model levee section in a 4.5 m radius large beam geotechnical centrifuge facility available at the Indian Institute of Technology Bombay, India. The rate of flooding and drawdown varied from 2.2 m/day to 7 m/day and 1.65 m/day to 4.4 m/day (in prototype dimensions), respectively, obtained with the help of pore-water pressure transducers placed on the upstream and downstream sides of the levee section. A total of three centrifuge model tests were conducted on a scaled-down levee section (with and without internal drainage layers) constructed with silty sand type material to validate the ISFD capabilities. In addition, seepage and slope stability analysis for the centrifuge models was carried out using Plaxis-2D geotechnical software which compared favourably with physically observed tests results.