long axis. Model studies conducted by the Waterways Experiment Station for
the Portland District developed the appropriate stability coefficients (See
Kibdy, Powell and Roberts 1964; Markle and Davidson 1979). Large scale tests
of placed stone were conducted at Oregon State University (Debok, Sollitt
1974). For special placement, the longest axial dimension of the stone should
be at least twice as long as either of the other two dimensions, as shown in
Figure 1. The special placement method and the associated stability coeffi-
cient should not be used unless quarrystone meets these dimensional specifica-
tions and prospective contractors for the project can assure obtaining this
type of quarrystone and placing it with the long axis normal to the face of
the structure slope. Figure 2 illustrates the quarrystone used in applying
the special placement stability coefficient. Additional factors are listed
below.
1. The special placement method can be used only where it is possible to
observe and place stones accurately. Even then special care must be taken to
assure proper orientation and seating at the interface of the change-in-
placement and at the slope-crown interface.
2. The special placement method will require close inspection and clear
instruction to the contractor to assure proper placement procedures.
3 . Special placement requires more time than random placement and would,
therefore, increase the selection, handling, and placement costs of the
quarrystone.
A similar method of placement was used many years ago on structures built
in the Great Lakes and Delaware Bay where hewed-masonry blocks were fitted
into the structure. Although these structures have been stable, it is not
practical to publish a general stability coefficient for this particular
placement method since each application depends upon the individual hewed
shape and the special care used to place the blocks in a fitted structure.
Random (formerly pell-mell) placement is a term used in the SPM to
describe a variety of placement techniques ranging from dumping the underwater
armor stone from a scow to careful, individual placement of the angular
quarrystone in the above water section. Quarrystone placement by a contractor
can vary not only above and below the water level and along the axis of the
rubble structure but also from one job to the next. Placement can also vary
from one contractor to another. The variables and difficulties in placing
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