Today’s projects require many different types of deep foundations. Hub Foundation provides all the services necessary for your design.
Well versed in drilled shafts, micropiles, and drilled-in-place support of excavation, Hub has broadened our expertise to include slurry walls, load-bearing elements, tiebacks, secant walls, soil nails, and shotcrete. Our newest capability, managed by our experienced crews, is ground improvement by means of stone columns and rigid inclusions.
Drilled shafts are high-capacity foundation elements often used for large bridges and high-rise buildings with diameters ranging from 18 inches to upwards of 12 feet. Hub has more than a dozen drill rigs of varying sizes and capabilities to service the requirements of the New England market. We drill massive shafts with specialized equipment, allowing for installation in marine, urban, and infrastructure job sites.
Micropiles can be installed in tight spaces yet hold high capacities. The market for micropile foundations has been growing nationally, especially in the Northeast. Hub has been at the forefront of design innovation, installation technique, and higher load capacities. We have more than two dozen micropile drill rigs with varying footprints and heights to allow for the maximum torque and the headroom any project demands. Many projects have daunting schedules requiring multiple foundation crews. Hub’s experience, fleet, and personnel are tailor made to meet these requirements.
Slurry Walls and LBEs (Load Bearing Elements)
In the past five years Hub has purchased new Bauer equipment to allow us to provide slurry wall excavation as an option to our clients. In addition we have added highly experienced people to our team to ensure a successful venture into this market. Diaphragm or slurry wall installation reduces the need for temporary support of excavation and has the benefit of providing efficient installation of underground levels to a structure.
LBEs are rectangular structural elements installed with slurry wall equipment used to support column loads, core, and sheer walls. They can be used in lieu of drilled shafts with the added benefit of mimicking the shape and structure of the building above, facilitating transfer of load from the structure into the foundation.
Financial limits on project development require the construction industry to provide cost savings in their products. Ground improvement technologies provide cost effective options to transfer building loads into the ground. Hub has the machinery and expertise to design and install stone columns and grout columns to shoulder the loads. A financially uncertain project can become viable with the implementation of a good ground improvement solution; a building with two hundred units can turn into four hundred units on the same footprint.
Support of Excavation
Dense urban environments, phased highway and railroad work, and efficient property utilization often require deep excavation without the space for sloping and setbacks. Hub can design and install any manner of earth retention system required on site. We can provide driven or drilled-in-place soldier beam and lagging walls; driven sheet walls; soil nail and shotcrete-faced walls in stable soil conditions; and tiebacks where cantilevered systems are not practical.
Soldier Beam and Lagging
This form of SOE is applicable in almost all scenarios. Usually beams are driven or drilled in place and wood timbers are lagged between them as the excavation proceeds. On sites with low headroom or difficult drilling conditions, micropiles can be used as the vertical structure. Whatever the scenario, Hub can design and install an effective earth retention system.
Steel sheet pile walls are a fast and effective way to provide earth retention. Material costs are typically higher but offset by the speed of installation. These walls are particularly effective for excavations that go below the water table, as they act as a water cut off. Hub has a Bauer RTG 18S and a fleet of ICE and APE vibratory hammers to drive sheets; we’ve recently added a HMC SP-50 Sonic side grip hammer to allow us to drive in low headroom conditions.
These horizontally loaded small diameter drilled holes prevent deformation in the wall as excavation deepens. They can be used in conjunction with any earth retention system whether it be slurry, secant, sheeting or lagging wall, but only if space permits outside the excavation footprint. Hub has installed temporary and permanent as well as hollow bar and strand tie back systems. We can design, install and test a system to support the excavation required.
Shotcrete and Soil Nails
This form of earth retention excels under the right conditions. It is economical and can help keep the owner’s budget in the black. We often use it in conjunction with other forms of SOE for cost savings. It consists of a rebar mesh laid against the excavated soil in a vertical or near vertical fashion and sprayed with concrete. Every five feet or so, a layer of soil nails are drilled and grouted to hold the concrete fascia to the soil. This knits the earth and concrete together to form a stable block of soil.
Cantilevered systems can’t work in all conditions, especially deep excavations or ones in soft soils. Sometimes it’s just a corner brace; other times it’s a multi level system with jacked cross lot braces and pin piles. Either way, Hub is at your service as our specialty crews will install whatever system the excavation requires. Bracing interferes with the excavation process and thus needs to be carefully planned to intersect with the structure being built after the hole is dug. The only braces we don’t do are the dental kind.
Secant and tangent walls are a rigid solution for an earth retention system that can also double as a permanent foundation structure. The upfront cost is elevated compared to a traditional SOE, however, when coupled with the added value as permanent foundation walls, their merit is evident.
Seismic events, flooding, and sea level rise can complicate foundation design. Heavy foundations can potentially become buoyant. Rock anchors can be used where significant uplift or overturning must be overcome. Hub installs rock anchors for underground parking facilities, monopole foundations, granite block abutment rehabilitations, observation towers, utility towers, and other projects where direct transfer to bedrock in a safe and predictable manner is required.
Helicals are a great solution for site conditions that do not allow for soil removal or have spatial constraints requiring equipment with very small footprints. Although helicals are typically lightly loaded, their capacities are increasing. Hub provides clients with helical pile foundation solutions for less accessible sites requiring expediency.
New construction directly adjacent to existing structures often requires the foundation of the existing structures to be supported during the excavation phase of the new building. The use of underpinning is a common support system for this purpose.