自走式搬器による集材作業システムの検討

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静岡県天竜地域を対象地として自走式搬器を用いた集材作業システムについて検討した。重回帰分析の結果，短材集材作業に必要な人工数を求める回帰式を出材材積，間伐率，最大斜面傾斜を説明変数として有意水準1％で得た。さらに，架設撤去に必要な人工数の回帰式を架設距離を説明変数として有意水準1％で得た。これらを基に作成したシミュレーションモデルを標準伐区（伐区長：伐区幅＝1：0.4）に適用した結果によれば，斜面に対して平行に索を架設できる場合には，傾斜が25度，30度では主索を伐区の中心に架設して，人力木寄せ作業を行なわずに短材集材または全幹集材を行なうのが最も能率的であった。傾斜が35度では，主索を伐区の中心よりも下部に架設して，架線よりも山側の材は人力木寄せ作業を併用し，架線よりも谷側にある材はそのまま集材を行なうのが最も能率的であった。なお，傾斜が35度で伐区の中心に索を架設する場合には，標準伐区では人力木寄せ作業を行なわずに集材するのが能率的であるが，伐区長：伐区幅を1：0.8にすると，人力木寄せ作業を行なってから集材するほうが能率的になる。伐区最上部から最下部方向に斜めに索を架設する場合には，傾斜25度，30度では，伐区の中心に架設して短材および全幹集材を行なうのが能率が良いが，斜面傾斜35度では，人力木寄せ作業を行なってから集材を行なうのが能率的であった。このシミュレーションモデルを既知の現場へ適用することにより，モデルの精度と最適な作業システムの検討を行なった。自走式搬器集材作業および人力木寄せ作業の実測値11.0人工，4.5人工に対して予測値は，それぞれ12.0人工，4.6人工となり，本シミュレーションの精度を確認した。さらに，同一条件下で人力木寄せ作業を行なわずに短材集材を行なうものとすると21.7人工必要と予測され，同様に全幹集材システムは18.5人工，全木集材システムは19.6人工と予測された。全木集材の場合，土場で造材が能率的に行なわれるのであれば最も能率的となることが予測された。This study was undertaken to establish an efficient yarding operation system by field investigation of the yarding system assisted by self-propelled hoist-carriers which is currently employed in the Tenryu District of Shizuoka Prefecture. In multiple regression analysis, such variables as the cut volume, the thinning intensity and the maximum incline slope emerged with a significance level of 1% using the amount of manpower required for short-wood logging as the dependent variable. The rigging distance showed a significance level of 1% when the amount of manpower required for rigging and dismantling was the dependent variable. The following findings were obtained in a simulation study with a standard model of cutting ground (length: width=1:0.4). Simulation was at first attempted for grounds where wire-ropes could be set up parallel to the incline slope. On a ground with a slope of 25 or 30 degrees, it is most efficient to pitch wire-ropes through the center of the ground and carry out short-wood or tree-length logging without manual prehauling. On a ground with a slope of 35 degrees, it is most efficient to pitch wire-ropes on the lower side of the center and gather timbers on the lower side of the rig after timbers on the upper side of the rig are manually prehauled. When wire-ropes are pitched through the center on a ground with a slope of 35 degrees, yarding without manual prehauling was efficient on the standard cutting ground. However, if the length/width ratio of the cutting ground is altered to 1:0.8, yarding preceded by manual prehauling becomes more effcient. When wire-ropes are set up obliquely from the highest to the lowest level, it is efficient to pitch wire-ropes through the center and gather short and tree-length logs, if the incline slope does not exceed 30 degrees. On a ground with an incline slope of 35 degrees, yarding preceded by manual prehauling is efficient. The simulation model was applied to actual cutting fields to assess the appropriateness of the simulation study and to define an optimum yarding operation system. In yarding operations with a self-propelled hoist-carrier system, the amount of manpower required was predicted to increase (12.0 man-days) compared to the amount actually expended (11.0 man-days). The amount of manpower required for prehauling was predicted to increase to 4.6 man-days which was larger than the amount actually expended (4.5 man-days). If short-wood logging is to be carried out without manual prehauling under the same conditions, the amount of manpower required is estimated to be 21.7 man-days, which means that the yarding efficiency is reduced. Similarly, tree-length logging requires 18.5 man-days and full-tree logging 19.6 man-days. If bucking is efficiently managed at timber yards, full-tree logging assisted by a self-propelled hoist-carrier system would increase its efficiency and would attain the highest efficiency.

自走式搬器による集材作業システムの検討

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