3410 TERMINAL AVE 2018-03-09 - Laserfiche WebLink

i 1ANN IIWILSON,INC. axial loads that exceed 900 to 1,000 kips,the pile begins to experience plunging-type ' behavior. The spring constant should not be used for working loads that exceed the recommended allowable loads without further review by Shannon&Wilson. 6.3 Existing wharf piling The structural analysis being performed by MN also requires a soil spring constant to represent , axial pile tip response for the existing wharf piles. For the purposes of estimating this spring constant,we reviewed the as-built drawings provided to us for the existing wharf and piling. Pile driving records for the piles were not provided to us. Based on our review, our assumptions are as follows: ■ The existing piles were installed as indicated on the as-built drawings provided to us. This includes plan location,pile length, and allowable capacities. ■ Based on the assumed soil conditions, the existing piles were driven to the glacially 1 overridden or very dense beach deposits. Based on the experience of Shannon&Wilson, Inc. with construction practices during the time period that this wharf was constructed (late 1970's),pile driving in these soil conditions was typically performed until very hard or refusal-type driving conditions were experienced. For these conditions and assumptions,ultimate capacities were estimated using a factor-of-safety of 2.0 applied to the allowable capacities listed on the as-built drawings as was the standard of practice when the wharf was constructed. Based on these assumptions,we recommended that the soil spring constant to represent the pile I tip response for the existing piles is the same as that for the new piles: 2,200 kip/inch. We understand that the results of the structural analysis using these spring constant values indicate an increase in loading on the existing piling. The maximum of these loads, as provided by M&N, were 219, 274, 338, 389, 396,414, 420, and 375 kips for bents A to H,respectively. Based on these working load values and the assumptions stated above,we estimate that the axial response ' of the existing piles would remain in the elastic range as represented by the recommended soil spring constant. As previously discussed in Section 6.2.3, these loads are lower than the upper end of the estimated elastic range(approximately 500 kips)by a margin of about 15%to 55%. The recommended spring constant value should not be used for working loads that exceed those provided without re-evaluation by Shannon&Wilson. ' It is important to note that the spring constant is sensitive to the assumptions stated above. If the existing piles were not installed to very dense deposits,then the spring constant value would be I smaller than our recommended value. Because pile driving records and detailed subsurface information offshore is not available,there remains a risk that the existing piles were terminated 21-1-21962-003-R2.docx/wp/cp 21-1-21962-003 10 1