S - Kam Ng PhD Dissertation Final.pdf - Digital Repository of CCEE ...

22over the conventional static load test, and the most important benefit in pile testing is that itcan be performed quickly and economically (Fellenius and Altaee 2001).With more thantwenty years of experience in using the PDA, Fellenius (1999) notes that he has numerousexamples of good agreement between resistances determined from PDA and static load testson various piles. A similar conclusion has been drawn by Wei et al. (1991) and Abe et al.(1990) through testing of steel H-piles. However, in some cases, the pile resistanceprediction from the PDA method does not correlate well with that found from a static loadtest. The main reason for such discrepancy is attributed to time dependent issues such as thetime between the compared tests, the changes in pile resistance with time, and the variationof soil properties with time are not considered in the comparison process (Svinkin & Woods1998, and Long et al. 2002).800kipsForce (F) FIOWA DOTMahaska CountyPDA OP: Frame2L/C= 4.00 mst* t*+2L/C800t*+L/CkipsWD0T1 = Time of hammer impact;T2 = Time after a complete wave propagation;t* = Time when first velocity peak occurs, ms;L = Pile length below gauges, ft; andC = Wave speed, ft/s.T1Figure 2.2: Typical PDA graphical and numeric summary outputs2.3.2. Wave propagation conceptT2t mt m +2L/CTime (T)PILE DRIVING ANALYZER ®Version 2001.086steel H test10x57Hammer blow number (BN) = 175OUTPUT 12/18/2007 9:58:26 AM26.7 Velocity at Time T1 (VT1) = 12.4 f/sf/s Velocity at Time T2 (VT2) = 9.5 f/sVelocity(V) VForce at Time T1 (FT1) FT1 = 410 kipsForce at Time T2 (FT2) FT2 = -20 kipsTotal Soil Resistance (RTL) = 239 kipsMax. Static Resistance RMX (RMX)= 138 kipsMax. Comp. Stress (CSX) = 24.5 ksiMax. Tensile Stress (TSX) TSN = 2.8 ksiIntegrity Factor (BTA) BTA = 100.0 (%)INPUTPile Length (L) LE = 33.00 ftPile Area (A) AR = 16.80 in^251.2ms Pile Modulus (E) EM = 30000 ksi51.2 msPile Specific Weight SP(SP)=0.492 k/ft3Pile Wave Speed (C) WS = 16807.9 f/s800 Pile Impedance (EA/C) = 30.0 ksec/ftkipsLP 1.00 ftF12 A12F1: [2355] 86 (1)F2: [2356] 89 (1)A1: [42695] 1060 g's/v (1)A2: [41315] 1105 g's/v (1)As described by Hannigan et al. (1998), when a pile is impacted by a hammer, it isonly compressed at the ram pile interface and a compressive force pulse is generated. ThisWU51.2ms