Which foundation method combines both bearing capacity and settlement considerations in substation design?

The method that combines both bearing capacity and settlement considerations in substation design is grillage. Grillage foundations consist of a network of beams or girders that are placed in a grid pattern to distribute loads over a larger area. This design helps in effectively addressing both the bearing capacity of the underlying soil and the potential settlement that may occur due to the applied loads from the substation equipment.

With grillage foundations, the load is spread out, reducing the stress on the soil and minimizing differential settlement, which is critical in ensuring the structural integrity of substations. The design allows engineers to consider the soil’s bearing capacity while also planning for any anticipated settlement, making it a comprehensive solution for foundation needs.

In contrast, other foundation methods may focus primarily on one aspect over the other. For instance, slabs on grade are primarily concerned with load distribution at the surface but may not fully address settlement issues in deeper soil layers. Drilled shafts are excellent for bearing capacity in deep soil layers but may not inherently consider settlement over a wider area. Open pits might not be a suitable foundation method for substation designs as they deal more with excavation and may overlook comprehensive load distribution and settlement dynamics.