Foundation Engineering

Thermal Integrity Profiling

Clifton offers Thermal Integrity Profiling (TIP), in accordance with ASTM D7949 (Standard Test Methods for Thermal Integrity Profiling of Concrete Deep Foundations) as a method of quality control for the construction of cast-in-place (CIP) concrete piles. TIP uses a series of thermal wire cables secured to the pile reinforcing cage and embedded in the concrete with the cage. The thermal wire cables monitor the temperature of the concrete while it cures. The heat generated by cement hydration can be related to concrete cover thickness to assess the:

  • Thickness of concrete cover between the reinforcing cage and surrounding soils;

  • Integrity of the concrete;

  • Orientation of the reinforcing cage; and

  • Location (depth) and orientation of anomalies

TIP is commonly coupled with Crosshole Sonic Logging to provide a record of the complete cross section of concrete piles.

Crosshole Sonic Logging

Crosshole Sonic Logging (CSL) is another method of quality control for CIP concrete piles (ASTM D6760, Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing). PVC or steel tubes are secured to the pile rebar cage, and cast in place. Once the concrete is cured, a set of transmitters and receivers are lowered and raised in the tubes along the length of the pile. The strength of the received signals is analyzed to assess the quality and integrity of concrete within the rebar cage. The location (depth) of poor quality concrete, segregation, or voids is determined, and further investigation can be completed to confirm acceptability of the pile.

High Strain Dynamic Load Testing with the Pile Driving Analyzer (PDA Testing)

Efficient pile design relies on confirmation of the geotechnical resistance of piles at the site. Clifton employs state-of-the-art PDA equipment, supplied by Pile Dynamics Inc., to conduct high-strain dynamic load testing on steel, concrete, and timber driven piles to measure geotechnical resistance for efficient pile design and reliable quality control.

PDA testing involves the securing of a set of sensors to the pile that measure strain and velocity during the pile driving. During driving, the tensile and compressive stresses in the pile, pile bending, and pile integrity are monitored. If the known acceptable limits for these parameters are approached, the pile driving contractor is notified to adjust their equipment or approach to avoid pile damage.

Strain and velocity records are converted to force and displacement; this data is analyzed using the Case Pile Wave Analysis Program (CAPWAP®) to calculate the static geotechnical resistance and the distribution of shaft and toe resistance. Piles may be retested to assess setup or relaxation effects.

Wave Equation Analysis of Pile Driving (WEAP)

To compliment PDA testing, Clifton offers Wave Equation Analysis of Pile Driving (WEAP) to assess the suitability of available driving hammers for a project, estimate geotechnical capacity, and establish preliminary termination criteria. Driving energy, pile stresses, and blow counts are considered to select the appropriate pile driving hammer for sites, and capacity estimation is used to select preliminary pile dimensions. Termination criteria can be confirmed and adjusted once PDA testing is underway.

Clifton can create and manage project-specific PDA testing programs, from initial WEAP to help select hammers and pile dimensions, to measurement of static pile resistance as part of quality control during construction.