(The influence of climatic conditions on the bearing capacity of forest road surfaces in the region of Carpatian flysch)

1990

S. 341-348

2 Abb., 3 Tab., 10 Lit. Ang.

Unselbständiges Werk

200061829

The region of Carpathian flysch in Slovakia occupies 38 % of forest land area, i.e. 430 138 ha and can be divided into a western part with the area of 174 668 ha and an eastern part with the area of 255 470 ha. In the flysch zone prevailing soils are loamy ones - 63 %, followed by sand loamy soils 18,8 %, clay-loamy soils 6,2 %; on 10,4 % of the area there are soils with a gravel content of 20 to 40 %. With respect to a large extent of the flysch zone the conditions for road construction are diversified and in a prevailing part of the flysch zone there are unfavourable water and aeration regimes; the soils are susceptible to muddiness, there occur land slides and overall reduction in the subsoil bearing capacity; all this leads to changes in the bearing capacity of forest road surfaces. The bearing capacity of road surface and its changes are influenced to a large extent by climatic conditions. Changes in the bearing capacity were evaluated according to changes in road surface deflection which was measured four times a year by means of a lever deflectometer. The results of investigation have indicated that there was observed the largest deflection and in this way the lowest bearing capacity in the spring season, then followed a slow decrease in road surface deflection until late summer and early autumn when the road surface had the highest bearing capacity, and then followed another increase in road surface deflection diminishing the boaring capacity until the onset of winter. Comparing the influence of climatic conditions in the region of Carpathian flysch and those outside this region, there were not found any larger differences: flexible road surfaces in the region of Carpathian flysch can be characterized by the same regularities and it is not therefore necessary to specify them when calculating seasonal coefficients which belong to the method of road surface reinforcement.