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Determining the strength of logging roads for the safe operation of large forest machines


Article title

Required shear strength of logging roads’ embankment subjected to contact pressure of forest machines

Author (affiliation)

Hiroko Muneoka (a), Hidenori Suzuki (a), Satoshi Yamaguchi (a), Tatsuya Sasaki (a), Yuta Inomata (a), Hirokazu Yamaguchi (a)

(a) Department of Forest Engineering, FFPRI, Tsukuba, Ibaraki, Japan.

Publication Journal

Journal of the Japan Forest Engineering Society oc. 34(2)2019 :90-108

Content introduction

Crawler type excavator-based forest machines are operated at forestry sites. The size of such machinery has increased in the recent years, and there are increasing concerns as to whether logging roads, where forest machines work, can support the treading stress exerted by large machinery.

To address this concern, herein, the pressure exerted on the logging road surface when the machine takes several different boom-arm positions was measured. High pressure was measured at the front side of crawler tracks, particularly under the operation of track rollers, i.e., rollers inside the crawler tracks, when the arm was extended as its center of gravity shifts toward the front. Then, the required soil shear strength for logging road embankment to support the pressure acting near the road shoulder without failure was obtained by simulation. When the simulated soil shear strength was compared to that of an actual road, most logging roads satisfied the required soil shear strength. However, it was found that for some logging roads, the soil shear strength was not sufficient. For logging roads with sandy soil, i.e., soil with a sand-like smooth texture and extremely low cohesion, it was difficult to secure the required soil shear strength, and it was considered that reinforcement may be required on the road shoulder in some cases.

Herein, for the first time, we have presented the specific soil shear strength values for the logging road.

Figure1. Ground pressure exerted by a forest machine

Figure1. Ground pressure exerted by a forest machine. High pressure acts at the front side of the crawler tracks, particularly under track rollers when the arm is extended.

Figure2.The strength required to prevent the collapse

Figure2. The strength required to prevent the collapse of the logging road was determined by simulation.