Ultimate bearing capacity

Definition

Ultimate bearing capacity is the maximum load per unit area that a soil can support without undergoing failure. This critical value determines how much weight a foundation can safely support before risking structural failure, which is essential for the design and safety of buildings and other structures.

5 Must Know Facts For Your Next Test

1. The ultimate bearing capacity is typically determined using several methods, including theoretical equations and empirical correlations based on field and laboratory tests.
2. Terzaghi's bearing capacity theory focuses on the concept of failure mechanisms, leading to the derivation of equations that account for factors like cohesion and friction angle.
3. Meyerhof expanded upon Terzaghi's work by considering additional factors such as depth of foundation and load inclination, providing a more comprehensive understanding of bearing capacity.
4. Vesic introduced the concept of the ultimate bearing capacity being influenced by factors like ground settlement and foundation shape, further refining the analysis of soil behavior under load.
5. Understanding ultimate bearing capacity is vital for preventing structural failures, as exceeding this limit can lead to significant settlement or even catastrophic collapse.

Review Questions

• Compare and contrast the methods used by Terzaghi, Meyerhof, and Vesic in calculating ultimate bearing capacity.
  • Terzaghi's method primarily focuses on failure mechanisms using basic parameters such as cohesion and internal friction angle to derive a fundamental equation for ultimate bearing capacity. Meyerhof built on this by introducing considerations for depth, load inclination, and foundation shape, which better reflects real-world conditions. Vesic further advanced these theories by incorporating additional factors such as settlement effects and other conditions impacting soil behavior, offering an even more nuanced approach to determining ultimate bearing capacity.
• Evaluate the importance of determining ultimate bearing capacity when designing foundations for structures.
  • Determining ultimate bearing capacity is crucial for foundation design because it directly influences how much load a structure can safely support. Without accurately assessing this value, engineers risk selecting inappropriate foundation sizes, leading to excessive settlement or structural failure. A thorough understanding ensures that foundations are designed with an adequate factor of safety to handle varying loads throughout the structure's lifespan, ultimately protecting both the structure and its occupants.
• Analyze how various factors can influence the ultimate bearing capacity of soil, and discuss the implications for civil engineering practice.
  • Factors such as soil type, moisture content, loading conditions, and depth significantly influence ultimate bearing capacity. For example, granular soils typically have higher bearing capacities than cohesive soils due to differences in shear strength characteristics. Moreover, factors like ground water levels and loading rates can alter soil behavior under stress. Understanding these influences allows civil engineers to tailor their designs to local conditions effectively, ensuring that foundations are not only safe but also efficient in material usage.

Related terms

allowable bearing capacity: The maximum load per unit area that a soil can support, considering a safety factor to account for uncertainties in soil properties and loading conditions.

factor of safety: A ratio used in engineering design to provide a margin of safety against failure, often calculated by dividing the ultimate bearing capacity by the allowable bearing capacity.

soil mechanics: The branch of civil engineering that studies the behavior of soil under various conditions, crucial for understanding bearing capacity and foundation design.