Comparison of Driven Pile Capacities between Pile Load Testing Results and Dynamic Formula Method for Driven Pile

Abstract

This paper presents the comparison of driven pile capacities in sand layer between dynamic and static pile load testing results and dynamic formula methods for the construction of Central Festival Chiang Mai study project. All 28 tested piles were precast concrete square piles which were 14 to 19 meter long. End of the piles were installed in dense to very dense sand or gravel layer. Allowable pile capacity for 0.35x0.35m. and 0.40x0.40m. pile was 75 and 90 tons respectively. It was found that average safety factor from dynamic pile load tests was 2.99. The average pile capacity from the Pacific Coast Uniform Building Code (PCUBC) formula was closest capacity to the dynamic pile load testing results and the average safety factor from the formula was 2.96. The average pile capacities from Gate, Canadian National Building Code, and Hiley formula were lower than those from the dynamic pile load tests. The average safety factors from the formulas were 1.74, 2.46, and 2.73 respectively. The average pile capacities from Janbu, Danish, Modified ENR, Eytelwein, and Navy-McKay formula were higher than those from the dynamic pile load tests. The average safety factor from the formulas were 3.91, 5.27, 9.89, 13.31, and 24.79 respectively. The average safety factor from static pile load test was higher than 2.5 because of non-destructive testing. The tested piles were small settlements when loading reach to 250 percent of safe load. The settlement of 0.35x0.35m. and 0.40x0.40m. pile were 5.5 mm. and 8 mm. respectively.