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

62for monotube piles. Furthermore, RSA cannot be performed together with two-pile analysis,two pile toe analysis, vibratory analysis, and on piles involving slacks. Likins et al. (1996)suggested that RSA is useful for piles with high blow count and not recommended for pileswith easy driving situations. Nevertheless, RSA provides better approximations than thetraditional Smith’s method on piles with residual forces.2.5.8. Soil profile input proceduresSoil type based method (ST) and SPT N-value based method (SA) are the two soilprofile input procedures customized in WEAP, which yield a rough estimate of static soilresistance. In addition, three other procedures: (1) Driven program developed by the FederalHighway Administration (FHWA) FHWA; (2) Iowa Blue Book (Iowa DOT steel pile DesignChart); and (3) the Iowa DOT current procedure are enumerated here. Table 2.6 summarizesthe five soil profile input procedures with respect to different soil types.The soil type based method (ST) simplifies the soil resistance calculation and aids inthe input process for both bearing graph and driveability analyses in WEAP. The soilparameters used in the analysis are based on the Bowles (1996) and Fellenius (1991)recommendations as shown in Table 2.7 and Table 2.8 for non-cohesive soils and cohesivesoils, respectively. This method uses the β-method, an effective stress method, to estimatethe unit shaft and toe resistances for non-cohesive soils. However, a modified α-method, atotal stress method, is used to predict the unit shaft and toe resistances for cohesive soils.The SPT N-value based method (SA) is based on soil types, soil unit weights, and SPTuncorrected N-values, which are limited to 60. The correlation between all these input soilparameters can be referred to Bowles (1988) as shown in Table 2.9 and Table 2.10 forgranular soils and cohesive soils respectively. Table 2.6 shows that the unit shaft resistancefor sands, gravels and clays can be calculated based on the basic theory of soil mechanicsgiven by Eq. (2.40). The toe unit resistances for sands, gravels and clays are calculated basedon SPT uncorrected N-value. In addition, Bjerrum-Borland β-method is used to calculate