Metla Project 3259
Trafficability of Forested Peatland
Duration: 1999-2002
Keywords: Trafficability, modeling, timber harvesting on peatland
Research Program: Ecologically and economically sustainable forestry on drained peatlands
Objectives
The project aims at developing an estimation procedure for the trafficability of peatland. The procedure is to assist in the selection of appropriate harvesting machinery in order to minimize ground damage.
Results
Plate load tests were performed on peatlands with varying properties in order to determine the modulus of elasticity, chosen to describe mechanical strength and trafficability. Maximum strength and the strength of underlying decomposed peat was predicted on the basis of modulus of elasticity. Amongst the measured variables describing the test sites, the basal area of the stand and the relative surface wetness class of the peatland had the strongest correlation with modulus of elasticity.
In the mobility model constructed, mechanical strength of peatland was described by modulus of elasticity, also used for predicting maximum strength and strength of decomposed peat. The model output is the sinkage of a rigid wheel with known dimensions and loading on the number wheel pass in question. Judgement on trafficability is based on wheel sinkage and vehicle ground clearance. In the light of full-scale vehicle tests the model results were realistic.
Greatest hindrances in applying the method into practice are the large spatial variation in peatland strength, resulting in a large number of measurements needed, and the tedious operation of the model in its present form. The measurement device for practical needs should be lightweight, low-cost, easy to use and provided with adequate processing capability.
Project leader:
Ala-Ilomäki, Jari
The Finnish Forest Research Institute,
Vantaa Unit,
PL 18, 01301 Vantaa
Phone: +358 10 211 2337 Telefax: +358 10 211 2203
E-mail: jari.ala-ilomaki@metla.fi
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Updated 31.12.2005
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