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Foundation Repair

Resistance Piers

Resistance are hydraulically driven high strength steel tubular piles end-bearing piles. The pile sizes vary in diameter from 2 2/8” to 41/2”, vary in steel thickness and transfer brackets to accommodate a wide range of load and support conditions.

The steel piles (piers) are driven in connected sections, using the weight and structural integrity of the structure to advance the piles to a stabile load bearing stratum. There is a direct correlation between drive force and pile capacity, drive force is continuously measured during installation to a pre-determined ultimate capacity with a factor of safety from 1.5-2X. The drive force measures the end bearing capacity of the soil, rock and pile. The stiffer the soil the more drive force that is required. The predetermined capacity is derived from analyzing and estimating the buildings weight (live loads, dead loads and soil loads) and structural strength of the building support components. Pier spacing is determined by a number of influences: weight of structure, capacity of selected pile, soil type and structural strength of the foundation, to determine span limits. By measuring drive force the capacity of the soil is measured and the pier is continuously tested.

Drawings “art 3 pier “ “21 2pc Res pier”

 

 

Helical Piers

A helical pier is constructed of a steel central shaft with and end bent plates (helixes) at the bottom of the pile. The piles sizes differ by various shaft and combination of shafts from high strength solid steel bar from 1 ½” to 2 ½” to tubular with diameters from 2 7/8” to 12” diameters with various steel thicknesses.

The piles are advance into the soils by screwing them in with hydraulic gear motors and the piles are bolted and connected in shaft lengths from 3 to 20 ft. (3-10 ft. most common) to extend the depth of the pile. Just like the above resistance pier capacity can be measure during installation, there is a direct relationship between torque (force required to cause rotation) and capacity. The stiffer the soil the more drive force by way of torque is required, measuring the end bearing capacity of the soil and the pile. Loads are transfer from the foundation to the pier shaft to end bearing strata the same as the above resistance piers.

 

 

 

          

 

 

 

 

  

 

Micro Piles

Helical Pull Down Piles are helical piles with the benefit of a surrounding grout column of various diameters. The grout column increases the strength of the pile by adding skin friction to the pile and increasing the shaft diameter. The pier then has the benefit of end bearing and friction combined. The grout column is a more economical method to increase pile capacity with less depth and without increasing the shaft size (more steel equals more money). Thus, pier depths can be better controlled and high pier capacities achieved. Pier capacities can be as much as doubled without upsizing to a much larger pier shaft. It does however take some depth, usually over 15 ft. to be of benefit. A typical install may reduce the same pier capacity the pier cost by 1/3 to ½.