Drilled Shaft: Seismic Adaptation Measure


Installation of large drilled shafts to stabilize the shoreline
would require large equipment as shown here - San Francisco, CA ©Fugro

SHORELINE STABILIZATION:
TYPE: Geotechnical

SHORELINE LOCATION:
Landside


DESIGN LIFE
ADAPTABILITY
IMPACT ON THE WATERFRONT
CONSTRUCTION COST
100+ Years
Medium
Minor Intervention
High


SEISMIC HAZARDS MITIGATED:SEISMIC PERFORMANCE IMPROVED:
Lateral Spreading
Liquefaction
StructuresUtilities & Transportation


MEASURES COMPATIBILITY:
Flood
Seismic
Floodwalls
Raised Marine Structures


Liquefaction Mitigation

Bulkhead Wharf Retrofit

Utility Retrofit


DESCRIPTION:
Large diameter concrete-filled drilled shafts placed landside of and parallel to the shoreline. This would buttress the adjacent liquefiable fill and thus reduce lateral ground displacements that would otherwise damage the Embarcadero, the promendade, the light rail, utilites, and waterfront structures.


CONSIDERATIONS:
ADVANTAGES:
DISADVANTAGES:
  • The diameter of the shaft would be defined by the depth of Young Bay Mud which varies along the waterfront.
  • Measure less effective in areas of deep Young Bay Mud.


  • Construction duration likely less than landside buttress shoreline stabilization measure.
  • Shafts could provide a major component of a bulkhead wharf retrofit scheme.
  • Waterfront buildings can likely remain occupied during construction.
  • No in-water work
  • Higher construction impact to the Embarcadero and promenade compared to other shoreline stabilization measures.
  • Construction duration likely less than landside buttress shoreline stabilization measure.
  • Does not mitigate liquefaction-induced settlements. Requires some utility relocation work.


CONSTRUCTION IMPACTS TO THE PUBLIC:
SEA LEVEL RISE ADAPTATION OPPORTUNITIES:
  • Construction would require lengthy closure of northbound Embarcadero and the promenade.
  • Southbound Embarcadero would be changed to one lane in each direction.
  • Pedestrians would be diverted to the light rail guideway, thus interrupting Muni service during construction.
  • Drilled shafts could be employed to support a raised bulkhead wharf or a floodwall at the promenade.
  • Smaller diameter secant piles or soil-cement mixing could be placed between the shafts to provide a barrier that limits the influence of rising sea levels on groundwater elevations.



DESIGN CONSIDERATIONS:

  • The diameter of the shaft would be defined by the depth of Young Bay Mud which varies along the waterfront.
  • Measure is less effective in areas of deep Young Bay Mud.

SITE-SPECIFIC CONSIDERATIONS:

  • Special procedures would be required in the Fisherman’s Wharf area since contaminated soils below the water surface would be excavate by construction operations.
  • Diameter of shaft defined by depth of Young Bay Mud which varies along the waterfront.

URBAN DESIGN CONSIDERATIONS:

  • Construction work to demolish surface infrastructure and to relocate utilities may provide an opportunity to rebuild the Embarcadero and promenade following a new design.

HISTORICAL RESOURCE CONSIDERATIONS:

  • This measure would not impact any historical buildings.

INSTALLATION AND CONSTRUCTABILITY CONSIDERATIONS:

  • Requires significant utility relocation work. Requires demolition and restoration of promenade.
  • Large construction footprint required.



Download the Drilled Shaft Factsheet.

Learn about other types of measures from our Measures Explorer page.



Installation of large drilled shafts to stabilize the shoreline
would require large equipment as shown here - San Francisco, CA ©Fugro

SHORELINE STABILIZATION:
TYPE: Geotechnical

SHORELINE LOCATION:
Landside


DESIGN LIFE
ADAPTABILITY
IMPACT ON THE WATERFRONT
CONSTRUCTION COST
100+ Years
Medium
Minor Intervention
High


SEISMIC HAZARDS MITIGATED:SEISMIC PERFORMANCE IMPROVED:
Lateral Spreading
Liquefaction
StructuresUtilities & Transportation


MEASURES COMPATIBILITY:
Flood
Seismic
Floodwalls
Raised Marine Structures


Liquefaction Mitigation

Bulkhead Wharf Retrofit

Utility Retrofit


DESCRIPTION:
Large diameter concrete-filled drilled shafts placed landside of and parallel to the shoreline. This would buttress the adjacent liquefiable fill and thus reduce lateral ground displacements that would otherwise damage the Embarcadero, the promendade, the light rail, utilites, and waterfront structures.


CONSIDERATIONS:
ADVANTAGES:
DISADVANTAGES:
  • The diameter of the shaft would be defined by the depth of Young Bay Mud which varies along the waterfront.
  • Measure less effective in areas of deep Young Bay Mud.


  • Construction duration likely less than landside buttress shoreline stabilization measure.
  • Shafts could provide a major component of a bulkhead wharf retrofit scheme.
  • Waterfront buildings can likely remain occupied during construction.
  • No in-water work
  • Higher construction impact to the Embarcadero and promenade compared to other shoreline stabilization measures.
  • Construction duration likely less than landside buttress shoreline stabilization measure.
  • Does not mitigate liquefaction-induced settlements. Requires some utility relocation work.


CONSTRUCTION IMPACTS TO THE PUBLIC:
SEA LEVEL RISE ADAPTATION OPPORTUNITIES:
  • Construction would require lengthy closure of northbound Embarcadero and the promenade.
  • Southbound Embarcadero would be changed to one lane in each direction.
  • Pedestrians would be diverted to the light rail guideway, thus interrupting Muni service during construction.
  • Drilled shafts could be employed to support a raised bulkhead wharf or a floodwall at the promenade.
  • Smaller diameter secant piles or soil-cement mixing could be placed between the shafts to provide a barrier that limits the influence of rising sea levels on groundwater elevations.



DESIGN CONSIDERATIONS:

  • The diameter of the shaft would be defined by the depth of Young Bay Mud which varies along the waterfront.
  • Measure is less effective in areas of deep Young Bay Mud.

SITE-SPECIFIC CONSIDERATIONS:

  • Special procedures would be required in the Fisherman’s Wharf area since contaminated soils below the water surface would be excavate by construction operations.
  • Diameter of shaft defined by depth of Young Bay Mud which varies along the waterfront.

URBAN DESIGN CONSIDERATIONS:

  • Construction work to demolish surface infrastructure and to relocate utilities may provide an opportunity to rebuild the Embarcadero and promenade following a new design.

HISTORICAL RESOURCE CONSIDERATIONS:

  • This measure would not impact any historical buildings.

INSTALLATION AND CONSTRUCTABILITY CONSIDERATIONS:

  • Requires significant utility relocation work. Requires demolition and restoration of promenade.
  • Large construction footprint required.



Download the Drilled Shaft Factsheet.

Learn about other types of measures from our Measures Explorer page.