Total stress

Definition

Total stress is the overall stress exerted on a soil element, comprising both the weight of the soil above it and any external loads applied. Understanding total stress is crucial because it lays the foundation for assessing how soil behaves under various conditions, particularly when considering the interplay of effective stress, the distribution of stress in layered soils, and how earth pressures are calculated according to established theories.

5 Must Know Facts For Your Next Test

1. Total stress can be represented mathematically as $$ ext{Total Stress} = ext{Weight of Soil} + ext{Applied Loads}$$.
2. In a saturated soil, total stress affects pore water pressure, which subsequently influences effective stress and stability.
3. The concept of total stress is essential for understanding how loads are transmitted through soil layers in geotechnical engineering.
4. Total stress can vary within layered soils due to differences in material properties, layering thickness, and external loads.
5. Rankine's and Coulomb's theories for earth pressure calculations rely on accurate assessment of total stress to determine lateral forces on structures.

Review Questions

• How does total stress relate to effective stress and why is this relationship important in geotechnical engineering?
  • Total stress is the sum of the vertical loads acting on a soil mass, including both the weight of overlying soil and any additional loads. Effective stress is derived from total stress by subtracting pore water pressure, and this relationship is fundamental in geotechnical engineering because it governs the soil's strength and deformation behavior. Recognizing how total stress influences effective stress helps engineers design stable foundations and structures that can withstand varying loads and conditions.
• What role does total stress play in understanding stress distribution within layered soils?
  • Total stress plays a pivotal role in understanding how loads are distributed across different layers of soil. In layered systems, each layer may have distinct properties that affect how total stress is transmitted through them. By analyzing total stress, engineers can predict how stresses will vary between layers, which is critical for assessing stability and ensuring that structures are appropriately supported across heterogeneous soil profiles.
• Evaluate how total stress impacts the application of Rankine's and Coulomb's theories in calculating earth pressures.
  • Total stress is a key factor in both Rankine's and Coulomb's theories for calculating earth pressures because these theories are predicated on understanding how stresses are distributed within a soil mass. Total stress determines the lateral pressures exerted on retaining walls or other structures. If total stresses change due to factors like added loads or changes in groundwater levels, then the predictions made by these theories must be re-evaluated to ensure that they still apply correctly. An accurate grasp of total stress enables better predictions and designs that account for changing conditions in real-world scenarios.

Related terms

Effective stress: The stress carried by the soil skeleton, which governs strength and deformation characteristics, calculated as total stress minus pore water pressure.

Pore water pressure: The pressure exerted by water within the soil pores, which influences the overall effective stress and stability of soil structures.

Earth pressure: The lateral force exerted by soil on retaining structures, influenced by total stress and how it is distributed within the soil mass.