in [Equations (5)] and [(6)] from which the
and
for the top of the tunnel are found. To these values, add
, for the water pressure, where the surface of the water extends a height,
, above the top of the tunnel. Similarly, in the case of the retaining wall, add 0.4 of the full water thrust on the wall to that given by the earth, weighing only 75 lb. per cu. ft.