Pile Foundation Design and Testing

ParklandGEO personnel have undertaken or been involved in numerous static pile load test programs in the past twenty five years.  We have designed load frames for compressive load testing (ASTM ), tension load testing (ASTM   ) and lateral load testing (ATSM   ) for driven steel and CIP concrete piles.  We have also developed Osterberg Cell load test programs for CIP concrete piles in conjunction with the primary supplier of this proprietary test process in North America (LOADTEST Inc. of Spokane, WS, USA). ParklandGEO own a full pile load test (PLT) setup including: a 4450 kN load cell, a 69 MPa hydraulic pressure transducer, dedicated eight channel data logger (capable of monitoring 10 sensors, 40 strain gauges and 5 in-place inclinometers), eight linear variable displacement transducers (LVDT’s) and associated cabling for primary data acquisition; mechanical dial gauges for backup measurements, 40 m of sectional in-place inclinometers, along with other independent loggers and dial gauges.

 

 

There are four main non-destructive methods of pile integrity testing including the PDA test procedure discussed above.  The other three test methods include:

 

1. Crosshole Sonic Logging (CSL). CSL is an established method of determining the structural soundness of a drilled CIP concrete shaft in a prepared test pile.  Prior to pile installation, a number of CSL access tubes are attached to the reinforcing steel cage of the test pile prior to placement in the pile excavation.  The rebar cage is lowered into the shaft and the access tubes are filled with water and capped.  The concrete is placed and allowed to cure for about 7 days before testing.  During the test, an ultrasonic transmitter and receiver are lowered down two access tubes at constant elevations with the transmitter giving off a signal.  The relative energy, waveform and time lag of the sound is measured at regular intervals and graphed.  Comparing the graphs from combinations of paired tubes allows the shaft condition between the access tubes to be mapped.  The CSL method allows shaft measurements between the access tubes inside the rebar cage to detect necking when soil sloughs into the shaft or other non-uniformities.  After testing the access tubes are grouted.  CSL testing is undertaken in conformance with ASTM Standard D6760 and ACI 228.2R.

  

2. Thermal Integrity Profiling (TIP). TIP is a method of determining the structural soundness of a prepared CIP concrete test pile based on measuring the heat generated by concrete hydration of the shaft.  Wire strings fitted with temperature sensors are attached to the reinforcing steel cage of the test pile prior to placement in the pile excavation.  The sensor strings typically extend the full length of the pile and are attached to data loggers which collect temperature data versus depth in the pile shaft as the concrete cures over the initial 72 hour period.  Regions of the shaft with higher temperatures indicate hydrating concrete is present; and cooler regions around the pile shaft indicate the presence of soil.  If a cool region is detected within the pile shaft, it indicates a possible soil inclusion in the shaft.  TIP readings can be used to determine the final shaft shape and cage alignment with depth as shown pictorially in the figure above.  Unlike a CSL test, TIP measurements extend to the concrete/soil interface outside the rebar cage, so the TIP test method can detect the size and location of both necking and bulging.  The sensor strings are cut off after testing. TIP testing is undertaken in conformance with ASTM Standard D7949.  

 

3. Low-strain Pile Integrity Testing (PIT).  PIT is a non-destructive test method which involves producing a compressive stress wave by hitting the top of the pile with a small hand-held hammer.  The stress wave propagates down the shaft and is reflected back to top of the pile when it encounters either the pile toe or non-uniformity in the shaft. The reflection waves are measured by Pile Integrity Tester (PIT) equipment attached to the pile.  Structurally sound concrete shafts should have reflection wave from shaft toe with only minor variations of the record amplitudes between impact and toe reflection.  Major variations in the reflection wave could indicate pile damage.  Foundation evaluation with PIT test data requires careful interpretation along with installation observations such as concrete volumes and pile excavation logs, because results are not always conclusive.  If the shaft material has a high resistance; or the shaft is relatively long compared to the diameter; or if the shaft has numerous cross-sectional changes, it may be difficult to draw conclusions regarding the length or integrity of the entire shaft.  PIT testing is limited to assessment of major shaft defects or material changes, but the test can be performed on any concrete production pile so it is often undertaken as part of a basic QA/QC program for CIP concrete piles.  PIT testing is undertaken in conformance with ASTM Standard D5882.  

 

ParklandGEO’s CSL, TIP and PIT equipment is also manufactured by PDI Inc. who provide both training and support for their pile integrity equipment.  As of January 2019, ParklandGEO had 1 of five PDI supplied CSL units and 1 of only two PDI supplied TIP units in Canada.  

 

ParklandGEO has performed vibration and noise monitoring for construction projects dating back to 2002.  Vibration and noise are common issues for certain types of pile installation when construction is performed in developed areas or beside buildings with sensitivity issues (e.g. hospitals).  Vibration and noise testing is performed to control health impacts and limit possible damage to sensitive buildings, civil infrastructure, pipelines and other underground services/ utilities due to excess vibration and noise.  ParklandGEO have 15 seismographs with microphones.  Our units can monitor vibration and noise levels as required.  The seismographs are capable of continuous monitoring and real time display of results to facilitate control of vibration activities. All of our units are equipped with or are capable of remote monitoring which can trigger immediate responses when threshold limits are exceeded.