Ultimate bearing capacity
The safe bearing capacity, also known as ultimate bearing capacity, is the maximum pressure that the soil can withstand without undergoing any shear failure. It is an important parameter in geotechnical engineering as it determines the stability and load-bearing capacity of a foundation or structure.

Definition
The ultimate bearing capacity is defined as the maximum pressure that can be applied to the soil without causing shear failure. Shear failure occurs when the soil loses its ability to resist further deformation and collapses under the applied load. The ultimate bearing capacity is typically expressed in units of force per unit area, such as kN/m² or kPa.

Determining factors
Several factors influence the ultimate bearing capacity of soil, including:
1. Soil type: Different types of soil have different bearing capacities. For example, cohesive soils like clay have higher bearing capacities compared to granular soils like sand.
2. Soil properties: The strength and stiffness of the soil also affect its bearing capacity. Soils with higher shear strength and lower compressibility generally have higher bearing capacities.
3. Groundwater conditions: The presence of groundwater can significantly affect the bearing capacity. In general, saturated soils have lower bearing capacities compared to unsaturated soils.
4. Depth of foundation: The depth at which the foundation is placed can affect the ultimate bearing capacity. Deeper foundations may have higher bearing capacities due to the increased confining pressure from the overlying soil layers.
5. Shape and size of the foundation: The shape and size of the foundation also influence the ultimate bearing capacity. Larger foundations generally have lower bearing capacities compared to smaller ones.

Importance
The ultimate bearing capacity is crucial in the design and construction of foundations and structures. Engineers need to ensure that the foundation can safely support the loads imposed by the structure and any external forces, such as wind or earthquakes. By considering the ultimate bearing capacity, engineers can determine the appropriate size, shape, and depth of the foundation to ensure stability and prevent failure.

In conclusion, the safe bearing capacity is synonymous with the ultimate bearing capacity. It represents the maximum pressure that the soil can bear without undergoing shear failure. Several factors influence the ultimate bearing capacity, including soil type, properties, groundwater conditions, depth of foundation, and shape/size of the foundation. By considering these factors, engineers can design and construct foundations that are safe and stable.