TABLE OF CONTENTS The following notation is used in this chapter:
| Symbol | Definition |
|---|---|
| A ? | Initial area of soil specimen |
| c ? | Cohesion based on an effective stress analysis |
| D r | Relative density |
| e | Void ratio |
| P | Vertical load applied to soil specimen (direct shear test) |
| T | Horizontal force applied to upper half of direct shear box |
| u | Pore water pressure |
| u e | Excess pore water pressure |
| ? | Friction angle of nonplastic soil, such as tested in a dry state |
| ?? | Friction angle based on an effective stress analysis |
| ? u ? | Effective friction angle at ultimate shear strength state |
| ? d | Dry unit weight of soil |
| ? n ? | Effective normal stress |
| ? v | Vertical total stress |
| ? v ? | Vertical effective stress |
| ?? vo | Effective overburden pressure |
| ? | Shear stress |
| ? f | Shear strength of soil |
An understanding of the shear strength of soil is essential in geotechnical engineering. This is because most geotechnical failures involve a shear-type failure of the soil. This is due to the nature of soil, which is composed of individual soil particles that slide (i.e., shear past one another) when the soil is loaded. The shear strength of soil is required for many different types of engineering analyses, such as the bearing capacity of shallow and deep foundations, slope stability analyses, and the design of retaining walls.
The mechanisms that control the shear strength of soil are complex, but in simple terms the shear strength of soils can be divided into two broad...
