This paper provides a method for designing anchor benches and trenches used
to secure geomembranes exposed to wind action. Only the cases where anchor
age is provided by gravity (i.e. by the weight of the material in the bench
or trench) are considered. Anchorage by tensile members is not considered.
Three potential failure mechanisms are identified for the case of anchor b
enches: (i) sliding of the anchor bench in the downslope direction; (ii) sl
iding of the anchor bench in the upslope direction; and (iii) uplifting of
the anchor bench. It is shown that the first mechanism is the most likely a
nd that the third mechanism is the least likely. Criteria are provided to d
etermine the governing potential failure mechanism as a function of the geo
metry of the slope on which the geomembrane is resting and the geomembrane
tensions induced by wind action. Equations are provided to calculate the re
quired size of anchor benches for each of the three identified potential fa
ilure mechanisms. It is shown that the usual method, which consists of only
checking the resistance of anchor benches against uplifting, is unconserva
tive because, in the case of anchor benches, lateral sliding is more likely
to occur than uplifting. The use of the proposed method as a conservative
approach for the design of anchor trenches is discussed. Practical recommen
dations are made and design examples are provided.