林道の機械施工に関する研究 : その変遷と実態

Abstract

林道の機械施工の変遷を掘削機械でみると, 戦後のブルドーザにはじまり, 昭和30年代後半にショベルドーザ, 昭和40年代中頃にバックホウ, 昭和50年前後にブレーカが導入された。土工機械の発展発達に伴い, 林道開設現場の作場諸条件に見合った施工機械が利用されてきた。現在の開設現場では, バックホウ (0. 6m_3) とブルドーザ (11-21t) による組合せが主流で, ショベルドーザの使用頻度は低い。バックホウは掘削作業の設計に広くもちいられており, 設計担当者は施工難易度や土質区分の判定に関心が高く, 設計と実作業での作業能率の差をある程度認めており, ブレーカの使用問題とともに早急に解決しなければならない課題である。今後の施工機械としては多くの県でバックホウが伸ぴ, ブルドーザやショベルドーザが減少すると予想しており, バックホウをべースマシンとした各種アタッチメント (ブレーカ等) を取り入れた施工を期待している。

Tracing the historical change of forest road construction using a excavation machine, first bulldozer began to be use after Second world war, shovel-dozer began to be use at early 1960's, hydraulic excavator began to be use the late 1960's, and breaker began to be use at the 1970's. According the development of construction machine, some machines which adapt themselves to the condition of construction site-narrow and steep terrain began to be use. According to the questionnaires against each prefecture, now on many construction site, the combination of hydraulic excavator (0.6m3) and bulldozer (11-21t) is the mainly used, and shoveldozer is few. Hydraulic excavator is widely used for estimation of forest road construction. Many planners have interest in the judgment of the soil classification for machine and the difficulty of execution, and they recognize the difference of operational efficiency between actuality and plan. So, that is a very important problem which must be solved as early as possible. In addition, how to use breaker for cutting is the problem too. In the future, many people expect that hydraulic excavator and breaker will increase, but bulldozer and shovel-dozer will decrease for execution machine. And they hope that the execution will be done with many attachments for base-machine which is the hydraulic excavator.