25 and 26. The nature of the piling to be adopted will vary
according to the character of the beach. Figs. 27, 29, 30, and
31 show various types. With steel piling and bearers, as shown
in Fig. 29, it is generally difficult to drive the piles with
such accuracy that the bearers may be easily bolted up through
the holes provided in the piles, and, if the holes are not
drilled in the piles until after they are driven to their final
position, considerable time is occupied, and perhaps a tide
lost in the attempt to drill them below water. There is also
the difficulty of tightening up the bolts when the sewer is
partly below the surface of the shore, as shown. In both the
types shown in Figs. 29 and 30 it is essential that the piles
and the bearers should abut closely against the pipes;
otherwise the shock of the waves will cause the pipes to move
and hammer against the framing, and thus lead to failure of the
structure.
Piles similar to Fig. 31 can only be fixed in sand, as was the
case at Waterloo, because they must be absolutely true to line
and level, otherwise the pipes cannot be laid in the cradles.
The method of fixing these piles is described by Mr. Ben
Howarth (Minutes of Proceedings of Inst.C.E., Vol. CLXXV.) as
follows:--"The pile was slung vertically into position from a
four-legged derrick, two legs of which were on each side of the
trench; a small winch attached to one pair of the legs lifted
and lowered the pile, through a block and tackle.
Pages:
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112