Deep foundation support systems are constructed to transfer structural loads through soils of inadequate strength to stronger soils or rock at greater depths below the surface. Foundation support systems are designed and constructed with consideration of axial and lateral load support, uplift force resistance, and settlement control.
Drill Tech Drilling & Shoring, Inc. designs and builds foundation support systems for various applications
including new foundation construction, existing foundation retrofitting, and underpinning of existing structures. We routinely employ drilled shafts, micropiles, tiedown anchors, torque down piles, augercast piles, helical piles and stone columns for these applications.
Drill Tech and our staff of professional engineers have been involved in some of the biggest, deepest, and most high profile tiedown anchor projects in the United States, including the retrofit of the Golden Gate Bridge.
Tiedown anchors are pre-stressed structural elements installed at a near vertical orientation in soil or rock that are used to transmit an applied load into the ground.
Tiedown anchors provide resistance to vertical forces generated by earthquakes, overturning, and hydrostatic forces. They consist of a high strength steel tendon (bar or strand) grouted into drilled holes and tensioned against a structural anchorage.
The steel tendons have a bonded length and a free stressing (unbonded) length.
The bonded portion of a tiedown is the length of the tendon that is bonded to the anchor grout and transmits the applied tensile load into the ground. The unbonded length is the portion of the tendon that is free to elongate elastically and transfer the resisting force from the bond length to the anchorage. Tiedown anchors are corrosion protected with epoxy coating or corrugated plastic sheathing to provide a permanent service life.
The steel tendons have a free stressing (unbonded) length and a bonded length. The bonded portion of a tiedown is the length of the tendon bonded to the anchor grout and transmits the applied tensile load into the ground. The unbonded length is the portion of the tendon that is free to elongate and transfer the resisting force from the bond length to the anchorage.
Tiedown anchors are corrosion protected with epoxy coating or corrugated plastic sheathing to provide a permanent service life.
New bridge and building foundations
Seismic retrofits of existing structures
Existing dam and spillway stabilization
Uplift resistance for foundation slabs below the water table
Micropiles are small diameter (typically less than 12 inches) drilled and grouted steel-reinforced piles used to transmit foundation loads through relatively weak soil strata to deeper, more competent soil or rock.
Micropiles derive their capacity primarily through grout to soil skin friction and the capacity of the reinforcing steel member.
Micropiles can be designed to resist compression, uplift, and lateral loads and are often used as a substitute for conventional deep foundation piles.
Micropiles are especially advantageous because they can be installed in limited access and low overhead environments and in all soil and rock conditions. The equipment used to install micropiles can be relatively small, and thus micropiles can be installed where access may only be a few feet wide, with overhead restrictions as low as 8 feet. Drill Tech is an experienced micropile contractor providing micropile drilling and micropile installation.
Seismic retrofitting of existing foundation
New foundation construction
Slope and landslide Stabilization
With over 25 years of experience in the design and construction of drilled shafts foundations, Drill Tech is an industry leader in the Western United States.
Drill Tech’s fleet of vertical drilling equipment is capable of drilling holes up to 15 feet in diameter and 215 feet deep in almost any ground conditions.
Drilled shafts (also called caissons) and drilled piers are deep foundation members commonly referred to as CIDH piles (cast-in-drilled-hole). Drilled shafts derive their load-carrying capacity through both end-bearing (in competent material) and skin friction. Drilled shafts can also be used to resist heavy uplift forces, or in poor soil conditions to resist lateral loads. Drilled shafts are formed by drilling a hole into the soil or rock, placing steel reinforcements (typically rebar cages or steel piles), and filling the hole with concrete. Drill Tech constructs drilled shafts for new foundation construction including bridges, highway overpasses, and buildings. For difficult drilling conditions, Drill Tech can utilize casing and/or drilling, and place concrete under slurry.
Augercast piles are slender foundation support members (typically 16 to 36 inches in diameter) used to transmit loads to the ground, primarily through skin friction between the pile surface and the surrounding ground, and occasionally end-bearing.
Augercast piles are constructed by drilling into the ground with a hollow-stem, continuous-flight auger to a specified depth.
High-strength cement grout is pumped under pressure through the hollow stem as the auger is withdrawn. Steel reinforcement, if required, in the form of a rebar cage and/or high strength bar can be installed while the cement grout is still fluid. Augercast piles cause minimal disturbance compared to driven piles, and are often used on noise- and environmentally sensitive sites.
Drill Tech is an experienced augercast pile contractor providing augercast pile installation in the Western United States.
Torque Down Piles
Torque Down® Piles (TDPs) are full-displacement, concrete-filled, steel pipe piles with a proprietary closed-end conical tip. Using the right proportions of torque and crowd (downward pressure), TDPs are driven by literally screwing them into the ground with a large drill rig. As a result, the screw-driven method of the TDP presents several unique benefits when compared to other conventional driven-pile systems which use heavy impact or vibration.
Torque Down® Piles are used for enhanced load capacity to size ratio, cost-effectiveness, rapid installation rate, overall operation safety, the lack of noise and vibration, and the ability to unobtrusively install in close proximity to existing, inhabited structures.
The steel pipe portion is typically 12.75-inch or larger outside-diameter. TDP tips typically include a single steel-helix plate and a site-specific configuration of cutting teeth designed for maximum installation efficiency. These patented elements, combined with unique installation procedures, make it possible for TDPs to penetrate very dense clays, sands, and weathered bedrock, providing exceptional deep-foundation support for any project.
TDP's are typically used for densely populated urban areas as well as business districts, environmentally sensitive regions, high water tables, contaminated soil, loose fill and highly compressible marine deposits. They are also ideal when piles must be installed in close proximity to occupied and/or sensitive structures, high-tech high-cost equipment, aircraft, railroad and medical facilities, as well as utilities and other infrastructure.