Experimental Study on Shear Strength of Alfalfa Grassland at High Soil Bulk Density

Grasslands are the important supplementary source of food. Shear strength at high soil bulk density grassland was studied to improve the traction performance and develop the crop yield. Shear force and shear displacement are tested at different vertical loads. Results indicated that with the increasing of shear displacement, shear force was found to show a parabolic trend of first increasing then decreasing. Moreover, larger vertical load would lead to steeper shear force curve against shear displacement. It also should be noted that, the maximum shear stress showed a parabolic increase trend following the increasing of the normal stress. This is the theoretical basis of matching appropriately tractor and implement system to maximize the traction performance and reduce tire slip.