Soil is a mixture of solid, liquid, gaseous, soil particles, mountain discrete water and air. In these components, small soil particles constitute the basic framework of continuous. So the soil is a typical discrete. In addition, the interaction between soilclods is much less than the internal force, in the external force when force, inter clodeasily destroyed and disappear, then the soil will be broken. Brittleness of the soil led to soil mechanics characteristics of a complex. Obviously, the complex mechanical properties of soil has shown, we must analyze the movement of soil particles from the microscopic view. In the dry traction power in soil than in wet soil is higher than two,and soil compaction than the soil compaction required power higher than 20%--100%.

In the design of agricultural machinery, soil mechanics in theory and experiment areused in a. However, the soil is mainly caused by shear broken hill, namely the cohesion mainly mountain soil shear stress to overcome. However, the soil is mainlycaused by shear broken hill, namely the cohesion mainly mountain soil shear stress to overcome. Mountain disc plough and Betula plow caused by soil deformationperformance of different. Changes in the larger pressure will produce shear stresswhen the stress and shear occurs, so that the soil deterioration and. Changes in the larger pressure will produce shear stress when the stress and shear occurs, so that the soil deterioration and. In addition to cohesion, shear stress can overcome most of the friction force.