Bearing Capacity
Bearing capacity refers to the maximum load that a soil or rock can support without experiencing a failure or excessive settlement. It is a critical consideration in construction and engineering projects to ensure that the foundation of a structure can safely support the anticipated loads. Factors such as soil type, moisture content, and depth play a significant role in determining the bearing capacity of a site.
3 Key excerpts on "Bearing Capacity"
eBook - ePubGeotechnical Problems and Solutions
A Practical Perspective
- Buddhima Indraratna, Ana Heitor, Jayan Vinod(Authors)
- 2020(Publication Date)
- CRC Press(Publisher)
...Chapter 9 Bearing Capacity of foundations Foundations are part of civil infrastructure that facilitate transfer of both static and dynamic loads from the superstructure safely to the underlying ground. Shallow foundations are considered when geological material at the ground surface has ample strength to withstand this applied load. Deep foundations are usually required when the soil below the structure has a relatively poor load-Bearing Capacity; thus, the loads must then be carried to deeper soil layers using piles (driven or bored), granular columns or caissons. In general, the Bearing Capacity can be defined as the largest intensity of applied pressure by a structural member to the soil, which supports it without causing excessive settlement or shear failure. In view of design, the ultimate and allowable bearing capacities play an important role. Ultimate Bearing Capacity (q ult): the maximum pressure a foundation soil can withstand without causing shear failure in soil. Allowable bearing pressure (q a): the maximum allowable net loading pressure at which the soil neither fails in shear nor exhibit excessive settlement. 9.1 Bearing Capacity equations A foundation can be considered shallow when the depth of the foundation is less than its width (D < B). The theory proposed by Terzaghi (1943) is commonly used for determining the Bearing Capacity of a foundation. It was originally developed for a strip footing considering the roughness of the foundation and its self-weight below the base, hence: q u l t = c N c + γ D N q + 0.5 B γ N γ (9.1) Where N c, N q and N γ are non-dimensionless Bearing Capacity factors that depend only on the angle of internal friction (ϕ). γ is the unit-weight of the soil, c is the cohesion of the soil, D is the depth of the foundation and B is the width of the foundation. Terzaghi (1943) bearing-capacity factors are given...
- Rodrigo Salgado(Author)
- 2022(Publication Date)
- CRC Press(Publisher)
...Leonard (the epigraph contains an extract from the corresponding court opinion) twice brought the building foundations to their limit Bearing Capacity. The magnitude of the load causing a foundation element to fail in this manner (referred to as the limit Bearing Capacity, limit resistance, or limit load capacity of the footing) depends on a variety of factors, including the plan dimensions of the element, the depth at which it is placed in the ground, and the shear strength of the soil. Bearing Capacity checks are an essential part of foundation design: a foundation element must not give under the application of the structural loads. While some questions remain unsolved, there is now a solid theoretical basis for the calculation of shallow foundation limit Bearing Capacity. In this chapter, we will examine this theory: the mechanics of Bearing Capacity failures and the analyses available for calculating the limit Bearing Capacity of a shallow foundation. 10.1 The Bearing Capacity equation for strip footings 10.1.1 Bearing Capacity failure and the Bearing Capacity equation Figure 10.1a shows the force equilibrium for a vertically loaded shallow foundation element. The water table is assumed to be deep. Any side resistance is neglected, and the weight W ftg of the footing, the weight W fill of the backfill, and the applied load Q are carried only by the mobilized base resistance Q b. In Figure 10.1b, the water table is located above the footing base, and the pore pressure at the footing base also helps support the applied load and weight of footing and backfill. As Q increases, the mobilized gross base resistance Q b also increases. The increase in Q b will be capped at the limit load Q bL, the value of the gross resistance at which the footing will plunge into the ground. This is referred to as the limit Bearing Capacity failure...
eBook - ePubFoundation Design
Theory and Practice
- N. S. V. Kamesware Rao(Author)
- 2010(Publication Date)
- Wiley(Publisher)
...Chapter 3 Bearing Capacity, Settlement, Stresses and Lateral Pressures in Soils 3.1 Introduction The soil which is supporting the loads transmitted by the foundation should be capable enough so that the structure–foundation–soil system is safe and stable besides being serviceable without excessive settlements. Thus, stability and settlement aspects of soil have to be analyzed to arrive at the design pressure that can be safely carried by the soil so that the foundation type, shape, size and other parameters can be selected and designed accordingly. The limiting shear resistance beyond which the soil collapses or becomes unstable is called the ultimate Bearing Capacity (UBC). This is also referred to as soil shear failure and results in distortions in the superstructure leading to collapse. The foundation sinks into the ground as if there is no resistance from the soil below. This type of failure is also called Bearing Capacity failure. 3.1.1 General and Local Shear Failure of Soils If the soil is generally dense, the settlement of the footing that precedes the ultimate shear failure is relatively small. It is called general shear failure (GSF) as shown in Figure 3.1(a) and curve 1 of the load settlement curves. If the soil is loose, then a large settlement precedes the shear failure as shown in Figure 3.1(b) and curve 2, of the load settlement curve...
