Validity of the method of fragments for seepage analysis in circular cofferdams

Madanayaka, Thushara Asela, and Sivakugan, Nagaratnam (2020) Validity of the method of fragments for seepage analysis in circular cofferdams. Geotechnical and Geological Engineering, 38. pp. 1547-1565.

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Abstract

The method of fragments (MoF) is a simple solution method for confined seepage problems. MoF based seepage solutions have been proposed and validated in the literature on cofferdams analyzed in the 2D Cartesian plane (i.e., double-walled cofferdams). More recently, this method has been extended by the authors for determining the flow rate and exit hydraulic gradient for axisymmetric cases (circular cofferdams). The accuracy of the MoF solutions for circular cofferdams relies on the assumption that the equipotential surface along the cofferdam perimeter at the tip of the cut-off wall is vertical. Therefore, in the first part of the paper, the validity of this assumption and the effect of any deviation on the seepage solutions for circular cofferdams were studied. For that, series of circular cofferdam geometries were studied using numerical simulations, and then the seepage solutions (flow rate and exit hydraulic gradient values) obtained were compared with corresponding MoF solutions. It shows that the MoF solutions are conservative in all the cases and also the error is limited to 10% for most of the cases. In the second part of the paper, an attempt is made to simplify the MoF solutions, further developing expressions for the form factors of the two fragments and the exit hydraulic gradient without relying on the graphical solutions proposed by the authors. The equations presented herein enable the MoF to be implemented in spreadsheet and hence be used as an effective tool for parametric studies.

Item ID: 62519
Item Type: Article (Research - C1)
ISSN: 1573-1529
Keywords: Method of fragments, Circular cofferdams, Flow rate, Exit hydraulic gradient
Copyright Information: (C) Springer Nature Switzerland AG 2019
Date Deposited: 12 Mar 2020 01:17
FoR Codes: 40 ENGINEERING > 4005 Civil engineering > 400502 Civil geotechnical engineering @ 100%
SEO Codes: 87 CONSTRUCTION > 8702 Construction Design > 870201 Civil Construction Design @ 100%
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