What are the key factors to consider when designing foundations and retaining structures?

1 Soil properties

One of the most important factors to consider is the soil properties at the site, such as the type, strength, compressibility, permeability, and variability of the soil. These properties determine the bearing capacity, settlement, and lateral pressure of the foundation and retaining structure, as well as the potential for liquefaction, slope instability, or erosion. Therefore, a thorough site investigation and characterization is essential to obtain reliable and representative soil data and samples for analysis and testing.

2 Loading conditions

Another factor to consider is the loading conditions that the foundation and retaining structure will be subjected to, such as the dead, live, wind, seismic, and hydrostatic loads. These loads affect the stability, deformation, and stress distribution of the foundation and retaining structure, as well as the interaction between them and the soil. Therefore, a realistic and accurate estimation of the loading conditions is necessary to design the appropriate size, shape, depth, and reinforcement of the foundation and retaining structure.

3 Environmental factors

A third factor to consider is the environmental factors that may influence the performance and durability of the foundation and retaining structure, such as the temperature, moisture, groundwater, chemical, and biological conditions. These factors may cause deterioration, corrosion, cracking, or swelling of the foundation and retaining structure materials, as well as changes in the soil properties over time. Therefore, a comprehensive assessment of the environmental factors is required to select the suitable materials, protection, and maintenance methods for the foundation and retaining structure.

4 Foundation type

A fourth factor to consider is the type of foundation that best suits the project requirements, such as the shallow or deep foundations. Shallow foundations are placed near the ground surface and transfer the load to the soil by bearing or shear. Deep foundations are embedded deeper into the soil or rock and transfer the load by end-bearing or friction. The choice of foundation type depends on the soil properties, loading conditions, environmental factors, and economic factors.

5 Retaining structure type

A fifth factor to consider is the type of retaining structure that best suits the project requirements, such as the gravity, cantilever, anchored, or reinforced soil retaining structures. Gravity retaining structures rely on their own weight to resist the lateral earth pressure. Cantilever retaining structures consist of a vertical stem and a base that act as a lever. Anchored retaining structures use anchors or tiebacks to provide additional support. Reinforced soil retaining structures use geosynthetics or steel strips to reinforce the soil mass. The choice of retaining structure type depends on the soil properties, loading conditions, environmental factors, and aesthetic factors.

6 Safety and serviceability

A sixth factor to consider is the safety and serviceability of the foundation and retaining structure, which are the main criteria for their design and evaluation. Safety refers to the ability of the foundation and retaining structure to resist failure or collapse under extreme or unexpected loads. Serviceability refers to the ability of the foundation and retaining structure to perform satisfactorily under normal or expected loads without excessive deformation or damage. Therefore, a proper analysis and verification of the safety and serviceability of the foundation and retaining structure is essential to ensure their reliability and functionality.