Test Pile Program
New Haven, CT

Back to standard version

Blakeslee Arpaia Chapman (BAC) performed a contract to drive test piles for Parson Bickerhof Quade & Douglas (PBQ&D), coordinators for the new Quinnipiac River Bridge and I-91/I-95 interchange. The construction for both projects is scheduled to start in 2004. The piles supplied design and constructability information for the selection of the foundation piles for the new bridge and the I-91 and I-95 interchange at the West approach. The project required the installation of approximately 50 driven piles of various materials and lengths. Static load test were performed on half of the piles. The piles were primarily pipe piles and prestressed concrete piles; however, monotube piles and H-piles were also tested. The largest pile was a 180 foot-long, 24-inch diameter pipe pile, which was load tested to 675 tons.

The site was divided into four areas; two areas were on the south side of the existing Q Bridge along the west bank of the Quinnipiac River. The other two areas were adjacent to the existing highway. One area was between the Wooster Street Ramp and I-95. The other was in the grass median where I-95 joins Route 34.

The project had several challenges. The most significant was scheduling and coordination issues. The project had to be completed in three months in order to meet the engineers' aggressive design schedule. Further, the work had to be coordinated among:
• Connecticut DOT - the owner and overseers of both upcoming projects
• PBQ&D and Geodesign - the lead designers and geotechnical consultants respectively for the new Quinnipiac Bridge
• URS/Greiner and Haley and Aldrich - lead designers and geotechnical consultants respectively for the new I-95/I-91 interchange, and
• GZA Associates - the testing engineers responsible for data collection and monitoring the test pile installation and testing.

Another challenge was the size and variety of the piles. The pipe piles ranged in length from 120 to 180 feet with full length rebar cages and load testing instrumentation to be inserted prior to filling the piles with concrete. The precast piles were 14-inch and 16-inch square piles with driven lengths between 100 and 120 feet. These piles were cast and driven full length. Similar to the pipe piles, the load test instrumentation was cast into the prestressed concrete piles. Prior to driving the piles, the pile locations were either augured or augured and cased to approximately a depth of 20 feet.

Driving to depths up to 180 feet with the intent of determining how much capacity each pile type could generate provided another considerable challenge. BAC was charged with selection of a pile hammer which would be capable of driving the piles to the required depths without overstressing the piles and achieving the design capacity in fewer than 10 blows per inch. BAC utilized computer wave equation analysis and its considerable pile driving experience to select the proper equipment for the project. In the end, two hammers were chosen (an HMC 86H hydraulic impact hammer rated energy 64,000 ft-lbs, and an HPSI hydraulic impact hammer rated 80,000ft-lbs) to satisfy the stress limitations and capacity requirements of the various piles.

All piles were monitored by a Pile Driving Analyzer (PDA), during initial driving and 24-hour and 7-day re-strikes. The re-strikes were performed to determine any set-up or relaxation of the soils and pile capacities.

To complete the project within the allotted time, two BAC cranes were used to drive the piles. A Manitowoc M-80W 88 ton capacity crane was used to drive piles as well as a Liebherr LR 853 100 ton capacity crane. The cranes were fitted with 100 and 132 feet of fixed leads respectively. In addition, several sites were worked concurrently, performing initial driving on one site while performing re-strikes and/or static load testing on others.

Static pile load tests ranged in capacity from 250 tons up to 675 tons. The pile were extensively instrumented with tell tales and strain gauges. BAC designed and built the load test components to safely transfer the loads to piles, yet allow access to the testing hardware. The jacking loads were resisted by an innovative system using crane counterweights on a reaction frame. By carefully locating the test piles and scheduling the testing sequence, the weights were moved from a completed test to the next test without ever touching the ground. BAC provided enough material for three load test setups. This allowed a new pile to be tested everyday once load testing began in a particular area. The test weights were handled by our 150-ton Manitowoc 3950W Vicon crawler crane and our 75-ton Grove TMS870 hydraulic truck crane.

The project finished on time and on budget, allowing the engineers to complete the plans for the new bridge and intersection foundations. We also provided valuable information on the drivability and constructability of the system. The project needed to move quickly to allow the engineers to complete their designs, however the installation and testing work had to be done with sufficient care and attention to details to insure accurate and meaningful results from the testing data. BAC engineers and field supervisors worked closely with the client to improve project schedule and resolve unforeseen events as they arose. Because of this teamwork, as well as Blakeslee’s extensive field and engineering experience, this unusual project was completed quickly and provided the engineer with the information they needed.

Back to standard version

Top