The Comparison of Diverse Methods in California Bearing Ratio (CBR) Estimate of Soil in Forest Territory

The nomination of california bearing ratio estimate in the estimation of forest machines traffic is one of the most basic variables in the planning of forest harvesting. In a forest harvesting planning, accessing to these variables is important and we have diverse methods to estimate that. Accordingly, in this project we use three diverse methods in california bearing ratio estimate: results of CBR test, using penetrometer for CBR evaluation and CBR classification in USCS system as a testifier for selecting the best way for CBR estimate. We conducted this project in parcel 22 of series 7 in Haraz watershed (Amol, Mazandaran, Iran) according to 5 groups of soil in FAO classification with 15 samples in the randomized complete-block and LSD test with %99 confident level. The results show that there are no significant differences between testbased CBR and the testifier. However, the results from CBR estimate with penetrometer and testifier in soil groups including sand and coarse texture loam show that there is no significant difference between those too; but in silt, fine texture loam and clay group one can witness significant differences.