METHOD FOR PULLOUT TEST FOR PILES

Pile to be tested shall be chipped off and dressed to natural horizontal plane till sound concrete is met or till up to cut off level. Arrangement shall be made to fix the four dial gauges / LVDT set on periphery of the pile.

Reinforcement bars or special anchor bars shall be used for anchoring of girder with test pile as per design.

Supports shall be built as per design &requirement at both sides of test piles. The reaction to pull out will be generated from these supports (as per design), which shall be at least 3 D away from the test pile periphery, where D is the diameter of test pile.

Girder of sufficient length & section (as per design) shall be placed over test pile with center coinciding with center of test pile. Both ends of girder shall be temporarily supported to accommodate the hydraulic jacks & bearing plates kept over reaction supports.

Girder shall be anchored with reinforcement bars or anchor bars with test pile as per design.

Datum bars parallel to girder, rested on immovable support shall be fixed at a distance of 3D (subject to minimum 1.5 m) from the edge of the pile on both sides, where D is the diameter of pile. Datum bars should not be disturbed during Test period.

Four nos, of Dial Gauges of 0.01 mm sensitivity to measure the upward deflection of the pile shall be fixed with datum bars and needle of gauge shall be touched to the arrangement made on periphery of pile. Small glass piece shall be placed below needle of dial gauge to get smooth surface.

Hydraulic jack shall be placed over reaction supports at both sides of test pile. Bearing plate of sufficient size & thickness shall be placed at bottom & top of Hydraulic jacks. Hydraulic jack shall be connected to manifold which in turn shall be connection to Hydraulic pump fitted with calibrated pressure Gauge to read the applied pressure.

After completion of all above arrangement, load shall be applied in following manner;

The test shall be carried out by applying a load in stages, each increment being 20% of safe load on the pile (exact percentage of increment of load depends on ram diameter of jack & least count of Pressure Gauge).    

For each stage of loading, the load shall be maintained till rate of displacement is either 0.1mm in first 30 minutes or 0.2mm in first one hour or till 2 hours whichever occurs first. The settlement shall be noted at each stage of loading. 

The full test load shall be maintained for 24 hours and settlement shall be measure at every one-hour interval. 

Unloading of test load shall be started after 24 hours of observation. Unloading shall be done in same and rebound shall be measured at each stage of unloading.