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

126to 201 kPa (29 psi), respectively. The average S u value of the top low plasticity clay layerwas 92 kPa (13 psi) underlain by sandy low plasticity clay having an average S u of 142 kPa(21 psi). The OCR values ranged from 1.3 to 4.5, and the C v values ranged from 0.051 to0.107 cm 2 /min (0.008 to 0.017 in 2 /min).For ISU6, which was situated in the loamy glacial region subjecting to a historicaloutwash, the soil profile was divided into four layers consisting of 4 m (13 ft) of a mixed fillof clayey sand and low plasticity clay (SC and CL) overlaying a 2.1 m (7 ft) of silty sand(SM), 9.05 m (30 ft) of sandy low plasticity clay (CL) with 0.35 m (1 ft) of silty sand (SM)and approximately 3.55 m (11.6 ft) of low plasticity silt (ML). The ground water table(GWT) was located approximately 4.6 m (15 ft) below the ground surface. The SPT N-values ranged from 8 to 23 with a softest layer of sandy low plasticity clay at the depthbetween 6.1 and 8.95 m (20 and 29 ft). The q c and f s values ranged from 488 kPa (71 psi) to12,353 kPa (1,792 psi) and from 10 kPa (1.5 psi) to 645 kPa (93.5 psi), respectively. Theaverage S u values ranged from 71 kPa (10.3 psi) for the sandy low plasticity clay layerbetween 6.1 to 9.0 m (20 to 30 ft) underlain by sandy low plasticity clay having an average S uof 348 kPa (50.5 psi). The horizontal coefficient of consolidation at the depth of 15.2 m (50ft) was 0.008 cm 2 /min (0.0013 in 2 /min). The OCR values ranged from 1.1 to 1.2, and the C vvalues ranged from 0.033 to 0.057 cm 2 /min (0.005 to 0.009 in 2 /min).Since the CPT dissipation test was not conducted for all soil layers at each site and itrequires excessively long time to achieve 50% pore water pressure dissipation during a CPTfor a C h estimation, a relationship between C h and SPT N-values was established as shown inFigure 3.4. Using this relationship, the C h values were estimated for cohesive layers wherethe dissipation test was not performed. Table 3.2 lists the weighted average SPT N, C h , andC v, values along each pile shaft. The weighted average N-value was calculated by weightingthe measured soil property for the cohesive soil layer by its thickness divided by the totallength for all cohesive layers located along the embedded pile length.