Helical pier installation of Pile Power LLC Piers should be completed by qualified installers only. Ultimate pier failure could occur if a proper installation criterion is not followed. (Installation of helical piers is to be completed using a torque head. Torque head should be well maintained and serviced on a regular basis. Information from the manufacture should be available to determine motor and gear efficiencies. Pressure gauges should be testing and or replaced on a regular basis. Gauge tolerances must be
accurate with 1%). Torque will be continuously monitored and recorded throughout the installation of each pier. Each pier section shall be recorded reflecting pier section length and any additional notes regarding installation conditions. Pier location and identification shall be documented as piers are installed. Such information should include; project name and location,
date, weather conditions, torque head used, a site map reflecting pier placement, starting psi and finishing psi and any notes regarding installation conditions.
For small shaft piers, there is a direct relationship between installation torque and pier capacity. Continuous monitoring or torque during installation will provide the installer with a profile of the underlying soil conditions.
Piers installed, for the purpose of compression, should be installed based on the hydraulic pressure curve of the torque head. During and ideal installation, the torque values should be constantly increasing, indicating that the pier is being inserted into more dense soil. If a drop in torque is recorded, it is most likely that a soft layer (such as soft clay) was found. The pier must continue to be inserted past the soft layer until a more dense soil (i.e. higher torque) is found. Refusal will be determined by no vertical movement of pier depth. Auguring of pier may be required in order to penetrate very hard layers of clay stone. Vertical drop, even of only 1/8″ per rotation, shall continue for either a depth into hard clay stones of 2’ min or until refusal.
An empirical method has been derived and used in the screw anchor industry for many years. Installation torque is used to calculate the ultimate capacity of the screw anchor. The average torque achieved during the last three (3) to five (5) feet of installation is directly proportional to the ultimate axial capacity of the pier. Colorado State University conducted a three-year study (1995-98) on the migration of water along helical piers shafts. The result indicates no more water penetration along the shafts of helical screw piles than along the sides of drilled concreted shafts. The starter section of the piers is cut to a 45 degree angle in order to assist the installer in targeting the pier during installation.
Design Installation limitations:
Piers should not be installed closer than 3 diameters of the helix apart, at any time. Piers installed in clusters, where load requirements exceed individual pier capacities, should be battered not greater than 5 degrees, in order to achieve the minimum 3 diameters apart.
Piers designed to be used in tension – use 70% of installed compression capacity.
For piers subjected to uplift (for frost depth) the embedment depth of the helix shall be at least five (5) helix diameters or deeper than the maximum frost penetration depth is in the area. Minimum pier depth is not to be less than 5’.
Pier Installation:
Installation of Pile Power LLC Piers should be completed by qualified installers only. Ultimate pier failure could occur if a proper installation criterion is not followed.
Installation of helical piles is to be completed using a torque head. Torque head should be well maintained and serviced on a regular basis. Information from the manufacture should be available to determine motor and gear efficiencies. Pressure gauges should be testing and or replaced on a regular basis. Gauge tolerances must be accurate with 1%.
Torque will be continuously monitored and recorded throughout the installation of each pier. Each pier section shall be recorded reflecting pier section length and any additional notes regarding installation conditions. Pier location and identification shall be documented as piers are installed. Such information should include; project name and location, date, weather conditions, torque head used, a site map reflecting pier placement, starting psi and finishing psi and any notes regarding installation conditions.
For small shaft piers, there is a direct relationship between installation torque and pier capacity. Continuous monitoring or torque during installation will provide the installer with a profile of the underlying soil conditions.
Piers installed, for the purpose of compression, should be installed based on the hydraulic pressure curve of the torque head. During and ideal installation, the torque values should be constantly increasing, indicating that the pier is being inserted into more dense soil. If a drop in torque is recorded, it is most likely that a soft layer (such as soft clay) was found. The pier must continue to be inserted past the soft layer until a more dense soil (i.e. higher torque) is found.
Refusal will be determined by no vertical movement of pier depth. Auguring of pier may be required in order to penetrate very hard layers of clay stone. Vertical drop, even of only 1/8” per rotation, shall continue for either a depth into hard clay stones of 2’ min or until refusal.
An empirical method has been derived and used in the screw anchor industry for many years. Installation torque is used to calculate the ultimate capacity of the screw anchor. The average torque achieved during the last three (3) to five (5) feet of installation is directly proportional to the ultimate axial capacity of the pier.
Colorado State University conducted a three-year study (1995-98) on the migration of water along helical piers shafts. The result indicates no more water penetration along the shafts of helical screw piles than along the sides of drilled concreted shafts.
The starter section of the piers is cut to a 45 degree angle in order to assist the installer in targeting the pier during installation.