Comparison of two approaches to soil strength classifications

The paper presents a comparison of two approaches to describing vehicle trafficability of cohesive soils. The first approach is based on soil consistency and Atterberg index indicators. The second approach is based on the cone penetrometer measurement and on the vane shear test, as well as on the EcoWood classification of soil strength. The research was carried out in the lowland region of pedunculate oak forests in the Sava River basin. Three cut-blocks of different moisture and forest soil strength were selected, in which timber was extracted by a forwarder. Measurements and sampling were carried out on undisturbed soil. Research results have shown that both approaches to describing vehicle trafficability of cohesive soils describe the soil strength of forest wilderness in a similar way and provide a good basis for developing a trafficability evaluation system, as a future task of forest engineering. The soil cone index and shear strength values calculated in this research do not concur with the classes of EcoWood soil strength classification and indicate that the limits and ranges of these parameters are questionable. The problem of defining the threshold values of soil strength parameters covered by this research will be the subject of future investigations