伐木造材作業の特質について : 作業者の生理的変化を通しての考察

Abstract

足場が悪く, 作業条件が複雑で無理な作業姿勢を強いられることの多い森林で木の伐造材作業の特質を明らかにし, 森林で人間が機械を使用して作業する場合に考慮すべき要因を明らかにすることを目的とした。そこで無線テレメーターを使用して作業中の作業者の心電図と呼吸曲線をとらえ, これ等作業者の生理的変化を通して各種伐木造材作業の負担の大きさを定量的に推察した。実験結果は表-9等に示してあるが, それ等から次のことが結論として言えるであろう。即ち, 森林内での作業や歩行移動が平坦地でのそれ等に較べて著るしく負担が大であることが定量的に明らかにされ, 従って作業者が森林内で騒音が高く, 重い機器を持って無理な姿勢で作業したり歩行移動したりすることは出来るだけ避けなければならないし, 林業の現状にかんがみて言えば, 少なくともそれ等作業を林分内で行なうことを止めて, より足場の良い林道端ないし土場に集中することが, 作業者の負担を少なくする方策であると言える。

It is the purpose of this paper to point out that the properties of felling and bucking operation in the forest which conditions of the operations are severe and complicated, and that factors which will give the influence on the forest workers when with machines (a chain-saw etc.) the workers operate in the forest. For this purpose, using a wireless telemeter (Photo.-l ~ Photo.-4), the electrocardiogram and the respiration curve of workers in the operating were recorded (Photo.-5, Photo.-6). From these, the pulse and respiration frequency were calculated and the physiological responses for each operation were treated quantitatively. First, in order to clear up the factors which will strongly affect the bucking operation, the two experiments of bucking of square timbers or logs with chain-saws (using the orthogonal arrey L16 and L27) has performed on the even ground. The experimental results obtained are shown in Table 3 ~ 5 (for the arrey L16) and Table-7 ~ 8 (for the arrey L27) individually. Factor "Worker" and "Kinds of chain-saw" were significant. And it was clear up that of course the influence of weight of a chain-saw on the worker was remarkable but the influence of exhaust noise could not neglect. Next, in Table-9 the pules and respiration frequencies and their rate of increase of five workers for each condition of the operation in the felling, bucking, limbing and walking are summerized. As for A worker, in Fig.-4 the rate of increase of pulse for each poeration are shown in graphic form on the basis of the Table. And the examples of physiological response of workers during each operaiton are shown in Fig.-5 ~ 6 (by A worker) and in Fig.-7 ~ 8 (by B worker). The recovery time to the level of the pulse for before the operations was only about two minute regardless of times and kinds of the operations. We concluded from the experiment decribed above that in the forest the operations and walking with machines gave remarkable physiological load on the workers in comparison with these on the even ground, and accordingly such the operations and the walking so that the workers operated in the strained working posture with the heavy weight and high noise machine in the forest should avoid as much as possible. Properly speaking it is admirable that the workers move with driving a car from here to there in the forest and the felling or the bucking are performed through the button- or lever-operating of the machines indirectly, but speaking in view of the present situation of the forestry at least the operations should be concentrately performed on the side of the forest roads or on the wood yard of which the footholding are more favorable. If so, the workers will be able to perform their works more comfortably, safely and easily. We intend to perform the experiments with more various conditions of the operations by more various workers in order to obtain more universal results.