Load cell (jacks)

The load cell (jacks) is a specialized pressure cell that is attached to the reinforcement cage, and placed at the bottom or in the lower part of the drilled shaft. It has a hydraulic line extending from the cell to the top. After placement of the reinforcement cage, the hole is filled with concrete.

 

The cell is designed to expand both upward and downward when it is pressurized by way of the hydraulic line. The downward force from the bottom of the cell is resisted by the bearing stratum while the upward force from the top of the cell is resisted by the weight of the drilled shaft and by the skin friction along the shaft.

 

The test pile is instrumented with telltales to measure the upward and downward displacement of the cell.