Environmental Engineering Reference
In-Depth Information
Fig. 10.13
Spray construction (
left
) and greening of the face after growth of vegetation (
right
):
National Highway 13
10.3.2
Construction Case Studies
10.3.2.1
Rokuro Sayama Road Improvement Project (Tohoku Regional
Development Bureau of MLIT Yamagata River National Highway
Office)
The construction was the planting (greening) of the slopes resulting from the con-
struction of a cutting to remove a bottleneck in Highway 13 between northern Ya-
magata Prefecture and southern Akita prefecture. The project had a total area of
9.9 km of earthworks between Kanayamacho/Tobinomori and Mamurogawa. The
cutting produced much soil mixed with roots, branches and leaves, making recy-
cling on site difficult. The tree residues were thus chipped to provide an alternative
to the usual shredded paper in the fiber-solidification process. The resulting mate-
rial was sprayed onto the slope as a base for replanting and provided significant cost
savings relative to the standard slope spray methods, as well as making effective use
of the waste materials (Fig.
10.13
).
10.3.2.2
Fiscal Year 2004-2007 Akasa 8th Dam Embankment Construction
(Tohoku Regional Bureau of MLIT Shinjo River Office)
Road construction and construction of an erosion-control dam in Ookura-village
Mogami-county Yamagata Prefecture produced large quantities of soil with residues
of trees (roots, small-diameter trees and branches). To make effective use of this ma-
terial, the wooden material was chipped and mixed in the fiber-solidification method
and applied to the slopes as a base material. The area included cracks in the rock and
springs and a steep slope of 1:0.3, so there was concern whether the coating might
erode and slip. However even after the winter snows had melted, there was no slip-
page and the new vegetation was growing steadily. Three months after the coating
