Deep Foundation Testing, Analysis, and Consulting Services. 

Challenge: The Corvallis Van Buren Bridge, originally constructed in 1913, underwent a replacement initiative to create an earthquake-ready bridge over the Willamette River on eastbound OR-34. Although the area near the bridge was used as a community dump site in the early 20^th century, today this stretch of the Willamette River is a critical habitat for fish and other wildlife. It’s also an environmentally attractive area with local recreational activities such as rowing and golf. To prepare for the new bridge, a comprehensive understanding of the soil and foundation was pertinent. GRL Engineers were hired to analyze the foundation’s capacity, along with the construction quality of the project’s drilled shafts. Method: Two 98.4-inch diameter test shafts were constructed, and Bi-Directional Static Load Testing was utilized to assess end bearing and side shear data of the drilled shafts. The Load Test Assembly (LTA) consisted of three hydraulic jacks positioned between a top and bottom 2-inch-thick steel bearing plate. The LTAs were incorporated at predetermined locations (approximately 70-80 feet above the base) in the shafts with total lengths of approximately 220 and 235 feet. GRL conducted the tests in two cycles as per the loading schedule. Thermal Wire® cables were installed on the reinforcing cage of the test shafts to help locate potential anomalies along the shaft length. The thermal data was analyzed approximately 2-3 days after concrete placement with Thermal Integrity Profiling (TIP). Crosshole Sonic Logging (CSL) was implemented on the project’s 8 drilled shafts. The CSL testing was performed more than 3 or 4 days after concrete placement. Each tested shaft was approximately 8-feet in diameter with 8 steel access tubes of 1.5-inch diameter. A total of 28 CSL profiles were collected for each shaft. Shaft verticality was assessed with a SHAPE® device lowered into the shaft while eight ultra-sonic signals scanned the shaft’s sidewalls simultaneously as the unit ascended and descended the length of the excavation. The device used sonic pulse arrival time to estimate verticality, depth vs diameter, and volume. Results: During the Bi-Directional Static Load Test in Bent 3, the LTA applied an average maximum downward gross load of 2,805 kips and simultaneously an upward net load of 1,983 kips (less the shaft self-weight of 822 kips). At this loading, the top of LTA displaced 0.29 inches, and the base of LTA displaced 0.19 inches (see Figure 1 and Figure 2). Based on the TIP results, the Effective Radius was generally consistent with the reported as-built shaft radii. The reported volume of concrete was 102 percent of the theoretical volume. Some of the wires in the cage did not function at all temperature nodes for the full duration of curing which made a complete interpretation of data difficult (Figure 3), thus the complementary value of the CSL testing was proven. The areas that were able to be assessed were rated as “Satisfactory”. CSL results for the assessment of the relative concrete and shaft construction quality were considered within an acceptable range. (Figure 4) It was noted in the report that the Engineer of Record and Design Team would consider further assessment of an anomaly localized near one of the access tubes. Following drilled shaft verticality testing with the SHAPE device, the offset verticality was reported as 0.25 feet over a vertical height of 232.9 feet, or a verticality percentage of 0.11%. (Figure 5)

Challenge: The Saint Francis Hospital in Hartford, Connecticut is one of the largest hospital facilities in New England, housing a Level 1 trauma center with 617 beds and is a major teaching hospital. The original facility was constructed in 1885, and a four-level parking garage was constructed in 1983. The project at hand was to completely replace the existing parking garage structure requiring innovative construction due to the age of the foundation and minimal installation records available. GRL Engineers were hired to conduct foundation testing to assess the reuse of viable caissons in the new design. Method: The original caissons consisted of 40, 3-ft diameter and 26, 4.5-ft diameter piles that extended 3.5 ft into bedrock. To determine if the existing caissons were viable, GRL Engineers performed High Strain Dynamic Load Testing with the GRL APPLE 8 utilizing a 64-kip (32-ton) ram weight. The purpose of the dynamic pile testing was to evaluate mobilized soil resistance and resistance distribution along the embedded shaft lengths. A Pile Driving Analyzer^® (PDA) acquired and processed the dynamic test data to meet these objectives. GRL conducted CAPWAP^® analyses to further assess static soil resistance including an estimate of the soil resistance distribution along the shaft and at the shaft base. Results: The axial compressive resistances from the high strain dynamic load tests were verified as 2,000 to 4,500 kips. Once the existing caisson capacities were reported, the designer was able to create a design implementing the existing caissons and supplemental composite piles. Calculated findings of at least $3 Million was saved, as well as weeks of construction schedule with the composite piles.

Challenge: The Ashbridges Bay plant is one of Toronto’s four wastewater treatment plants which services the metropolitan area. According to an annual report, it was determined that the plant was ready for several upgrades. The proposed foundation consisted of large diameter pipe piles with conical tips. GRL Engineers provided static load testing onsite and high strain dynamic testing both onsite and remotely from Ohio. Method: GRL conducted testing and collected data for large static compressive and lateral load tests. GRL’s reaction frame, rated for 1000 tons, was used for the compression load test. (Figure 1) A Pile Driving Analyzer^® (PDA) was used to acquire field process measurements taken on the dynamically tested piles. 100% of the approximately 150 production piles were monitored during initial driving and several piles were chosen for restriking or redriving. The piles tested were 762 mm (30 inch) O.D. pipe piles with a wall thickness of 19 mm (0.75 inches).(Figure 2) Pile top force and velocity traces were evaluated for data quality, pile integrity, and aspects of soil resistance. CAPWAP analyses were performed using the collected data to evaluate the resistance distribution and refine the overall pile capacity estimates. Results: According to the project documents, the required pile capacity was 8,000 kN (1800 kips) in compression. The piles were to be installed at minimum of 5 meters (16 feet) into dense sand and to practical refusal criteria established in the project documents. As requested, pre-production static load testing and dynamic testing were performed. All production piles were dynamically tested during initial driving and during selected restrike events. The flexibility to monitor pile driving remotely saved significant costs and travel related time delays.