Indian Journal of Geosynthetics and Ground Improvement
Year : 2022, Volume : 11, Issue : 1
First page : ( 22) Last page : ( 25)
Print ISSN : 2277-5625. Online ISSN : 2277-5633.

Strengthening masonry dams by means of downstream backfills

Lignier P.¹, Delmas S.¹

¹Tractebel Engineering S.A, France

Online published on 16 July, 2022.

Abstract

Many old masonry dams suffer from a lack of safety margin due to their ageing or the new criteria related to the latest regulations and standards. An easy way to strengthen a masonry dam is to put in place a backfill against its downstream face, which brings a beneficial force opposite to the water thrust. This article presents the 30 years’ experience of the strengthening of masonry dams in France by means of downstream backfills.

For the backfill material, it is recommended using a non-cohesive rocky material - 0/400 mm -with a friction angle comprised of approximately and 40°. It allows on the one hand to reduce the downstream slope of the backfill in comparison with soil material and on the other hand to obtain a higher beneficial force in comparison with blocky rock material. The main difficulty is to assess this beneficial force brought by the rocky backfill. A simple method to calculate this force is presented in this article. This method which can be applied for any geometry gives results close to FEM calculations, and is always on the safe side.

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