Drilled shafts, also known as caissons, are high-capacity reinforced concrete foundation elements, ranging in size from approximately 18″ in diameter to more than 10 feet. Shafts can be constructed in many types of soil and rock and are often used when high axial and/or lateral loads need to be resisted.

Drilled shafts require an array of specialized tooling and support equipment. H.B. Fleming owns what’s needed, including soil and rock augers, core barrels, boulder extractors, drilling and cleanout buckets, and casing twisters. If we’re drilling in particularly hard rock formations, we use a rotary pneumatic drill (aka a cluster drill) to maintain productivity. 

H.B. Fleming has experience with the following types of drilling:

  • Drilled shafts and rock-socketed piles for building and bridge foundations
  • Drilled shafts for sound wall foundations
  • Drilled-in-place and rock-socketed soldier piles
  • Drilled shaft foundations for tower and pole foundations (CCTV poles, cell towers, etc.)
  • Drilled shaft foundations for roadway overhead sign structures

We can provide design-build foundations in accordance with AASHTO/FHWA specifications.

We generally include any testing that is required in our scope of work and have experience with a variety of testing methods, including CSL and the Sonic Echo Method.

The same methods and equipment we use to construct drilled shafts can be used to pre-drill for piles. Pre-drilling for H-piles, pipe piles, etc., can be advantageous when working in areas that are particularly sensitive to noise, vibration, or lateral clearances.

H.B. Fleming constructed a soldier pile and lagging excavation support system within a few feet of the historic Hopkinton Public Library in Hopkinton, Massachusetts. Pre-drilling for the piles allowed for installation to a strict tolerance requirement, mitigated the potential for vibration transfer to the sensitive foundation, and allowed for removal of cobbles and boulders that would otherwise have impeded the piles from reaching their required embedment depths.

Projects Including Drilled Shafts

York Toll Plaza

Owner: Maine Turnpike Authority Partner: Reed & Reed Type: Highway Construction Location: York, Maine Project Description: H.B. Fleming is constructing 28 rock-socketed, drilled-shaft foundations to support the new toll gantries and overhead signage. Challenge: The project requires drilling hard rock at multiple locations in multiple phases.  Solution: To minimize drilling durations at each location and…