3410 TERMINAL AVE 2018-03-09 - Laserfiche WebLink

SHANNON EIM OR(N( A discussion of our studies, analyses, conclusions, and recommendations is presented in the ' following sections. It should be noted that at the direction of the Port and MN, we were not contracted to provide 1 seismic design(including liquefaction evaluations, seismically induced settlement, and lateral spreading) and general static slope stability analyses for this wharf upgrade. 6.2 Pile Foundation Design for New Piles The current project plans specify the use of 18- and 24-inch closed-end, steel pipe piles as the I foundations being added to provide additional capacity to the northern portion of the wharf. Specifically, 24-inch steel pipe piles are planned on rows F and G while 18-inch steel pipe piles are planned on rows B through E. The use of this pile configuration was determined based on the recommendations presented in I this section and results of structural analyses performed by MN. Closed-end, steel pipe piles provide both skin friction and end bearing to support axial loads and allow for shorter pile lengths in comparison to open-ended pipe piles. It is possible, depending on the nature of the dense bearing soils encountered during driving,that the piles may encounter refusal prior to reaching the planned tip elevation requiring pile cut-off Based on discussions with the design ' team, this scenario is acceptable and preferable to the scenario of driving open-ended steel pipe piles which would possibly require splicing and longer lengths to achieve the desired bearing capacity during driving. ' 6.2.1 Axial Resistance of New Piles We evaluated axial compressive(downward) resistance of both 18- and 24-inch closed- end steel pipe. We used an in-house spreadsheet developed based on our experience in the region to perform calculations and estimate the axial resistance. The analyses were based on the two design profiles described previously and our experience with similar subsurface and project conditions. We estimated the allowable capacity of these piles and have presented these I capacities in Figure 3. A factor of safety of 1.55 was used to determine the allowable capacity which assumes that PDA testing will be used for at least two of the planned 42 piles. Ultimate capacity is defined as the maximum axial pile load the site soils can support without undergoing large undesirable settlements. For the subsurface conditions assumed for this site and project requirements, an undesirable settlement is assumed to be one quarter to one-half inch under the allowable design loads. 21-1-21962-003-R2.docx/wp/cp 21-1-21962-003 8 I