According to the definition of soil shear strength, soils with higher shear strengths ________.

• A. Slide easily down an embankment
• B. Cause more erosion
• C. Require less moisture
• D. Do not slide easily down an embankment

Answer: (D)

Soil shear strength is the soil’s resistance to sliding along a potential plane inside the material when a shear force is applied. This resistance comes from two main sources: internal friction between soil grains and any cohesive bonds holding particles together. When a soil has higher shear strength, it can withstand larger sliding stresses without failure, which means it’s more stable on a slope or embankment.

That’s why soils with higher shear strengths do not slide easily down an embankment. They resist the forces trying to make a slip surface.

The other options don’t fit this concept. Sliding easily would indicate low shear strength, not high. Erosion involves factors beyond shear strength, like water flow and surface protection. Requiring less moisture isn’t a direct consequence of higher shear strength, since moisture can affect shear strength in different ways depending on the soil.