Optional Capacity Considerations
Optional Capacity Considerations (only for Ultimate Capacity calculations) can be used for Driven and Bored pile analysis. The Driven analysis also has additional Groundwater options.
To access the Optional Capacity Considerations dialog:
- In the Project Settings dialog, ensure your Program Mode Selection is set to Capacity Calculations.
- Select Home > Optional Capacity Considerations
OPTIONAL CAPACITY CONSIDERATIONS
- Soft Compressible Soils
- Scourable Soil
These optional capacity considerations are mutually exclusive; both options cannot be selected at the same time.
SOFT COMPRESSIBLE SOIL
A depth of soft compressible soil at the top of the soil profile can be specified. For ultimate calculations, the shaft resistance from the soft soil layer can be considered as soft compressible soil or as negative skin friction.
If the shaft resistance is considered to be soft, the skin friction for the layer is not included in the ultimate skin friction. If negative skin friction is considered, the skin friction from the soft soil layer is considered to be negative and is subtracted from the total skin friction for ultimate capacity computations.
SCOURABLE SOIL
There are two types of scouring that can be considered: long-term and short-term (local) scour. For short-term scour, the shear stress is simply reduced to zero. This occurs due to erosion around the pile. The effective overburden pressure is not affected due to the presence of soil away from the local pile area. No end bearing can be placed above this level.
For long-term scour, the effective overburden stress is reduced to zero until the scour consideration depth. This is due to soil eroding over a large area, reducing the effective overburden stress. DRIVEN stacks the effects of both scour types, where long-term scour is first considered then local scour is applied below the long-term scour depth.