Shearing resistance in soil refers to what principle?

Shearing resistance in soil is fundamentally related to the ability of soil to resist sliding or failure along a plane. It is primarily governed by the internal friction and cohesion between soil particles, which dictate how much shear stress the soil can withstand before it begins to fail.

When considering the principle of shearing resistance, it is important to understand that it involves the assessment of forces acting parallel to a surface. In the context of a wedge, the maximum shearing force is crucial since this represents the limit at which the soil can maintain stability and not slip or slide under applied forces. This principle applies particularly in the analysis of slopes, foundations, and retaining walls, where understanding the shearing resistance is critical for ensuring structural integrity and preventing failure.

The other choices do not accurately capture the concept of shearing resistance. For instance, the maximum tension force a soil layer can withstand refers to tensile strength, not shear. The amount of soil that can be excavated pertains to excavated volume or capacity, while the total pressure exerted on a retaining wall is more about lateral earth pressure rather than shearing resistance alone. Thus, the focus on the maximum shearing force a wedge can support aligns directly with the principles governing shearing resistance in soil mechanics.