Pregledni rad
Challenges in Road Construction and Timber Harvesting in Japan
Hideo Sakai
; The University of Tokyo Graduate School of Agricultural and Life Sciences Department of Forest Sciences Bunkyo-ku Yayoi 1-1-1 113-8657 Tokyo JAPAN
Sažetak
Japan Islands fundamentally consisted of the accretionary wedges. The stratum of accretionary wedges inclined, and it made dip slope and opposite slope. Granite magma intruded among accretionary wedges, and later granite itself became decomposed soil. Much annual precipitation of nearly 2000 mm, caused by monsoons, attacks forest roads, so innovative technologies for road construction are required. From ancient days, numerous circular slips and deepseated landslides occurred. For the inclined stratum at Shimanto belt composed of sedimentary rocks, deep excavation for preparing structural road foundation was invented. After deep excavation until the depth that ensured the road width, about 30 cm thick blocks of compacted subsoil were piled up. It is difficult to make high cutting slope on smooth soil area, and the retaining wall with log structure is effective both for cutting and fill slopes at spur roads. Underground water that comes out through crushing zones is often troublesome. When crashing zone and dip slope overlap, the valley head is unstable causing landslide. This makes this area inadequate for road construction. Some forest road retaining technologies have been introduced recently in Japan. When crossing the crushing zone by simple structures, cage or L-shaped steel retaining wall is effective because the weight of stones and rocks in the structure presses down the road foundation with high water permeability. It is important to adopt the most appropriate road construction method in accordance with the soil, geology and terrain conditions to provide sustainable forestry.
Ključne riječi
accretionary wedge; crashing zone; dip slope; reinforced soil wall; rolled grade drainage
Hrčak ID:
190901
URI
Datum izdavanja:
1.7.2017.
Posjeta: 1.038 *