is 13% less than for
. If the value,
, for fresh earth slightly damp and lightly rammed, given by Leygue above, is even approximately correct, it is seen that, for such a filling, the effect of cohesion must be included to get results at all agreeable with experience or experiment.
Recurring to the experimental retaining walls proper, [Figs. 4] to [9], it is evident from the foregoing, that cohesion will affect the results inappreciably, except perhaps in the case of [Figs. 6] and 7, where the height was about 0.6 ft. Assuming
, it seems to be probable, from the results of [Table 4], that the thrust should be decreased in the ratio of 93:111. Effecting the construction for the new thrust, it is found that the point, I, falls within the base, 0.03 of its width for [Fig. 6] (Trautwine’s wall), and 0.02 of its width for [Fig. 7] (Curie’s wall).
The theory advocated is thus practically sustained by all the experiments given above, either on retaining boards or retaining walls proper, when a coefficient of cohesion of about