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

42Smith established four routines that act as the bases for his pile driving computerprogram. The condition in the routine No. 1, which is applied only to friction alongside thepile, is the ground displacement will remain unchanged unless either is less than D m –q or is greater than D m +q. Routine No. 2, which is applied only to the pile toe, sets thecondition that the ground displacement will remain unchanged unless is less than D p –q. Routine No. 3 takes into account the inelasticity of spring K1 for capblock and deliversthe ability to use Eq. (2.20) for compression and Eq. (2.21) for restitution alternatively.Similar to the routine No. 3, routine No. 4 is applied to spring K2 for cushion. Eqs. (2.20)and (2.21) are similarly applied to spring K2 by changing the subscript 1 to 2. The onlyexception is the force F 2 in routine No. 4 has an alternative of being zero, negative, orpositive value.(2.20)[ ( ) ] [ ( )] (2.21)where,F 1C 1= force exerted by spring 1 at time interval n, kN or kip,= spring 1 compression at time interval n, m or ft,C 1max = maximum value of C1, m or ft,K 1= spring 1 constant, kN/m or kip/ft, ande 1 = coefficient of restitution for spring K1.Svinkin and Woods (1998) highlighted that one of the limitations of Smith soil modelis the difficulty with determining the soil parameters, soil quakes (q) and damping factors (J),from any standard geotechnical tests. Robert Liang and Sheng (1993) realized that theaccuracy of dynamic analysis using the Smith’s model depends upon the proper input ofrepresentative Smith’s soil parameters. Robert Liang and Zhou (1997) used a probabilitymethod to determine a better representative of the Smith soil parameters and to establish analternative approach to estimate pile resistance. Although experimental investigations have