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• RVC Homes <br /> Project BABX-01-0124 <br /> April 12, 2001 <br /> Page 6 <br /> We would like to note that there are numerous methods of predicting the static capacities of piles based <br /> on the results of borings, and that the results of the various methods often differ by a factor of two or <br /> more. In other words, predicting the static capacities of piles is not an exact science. We used the <br /> methods that appear to provide reasonable results based on our experience with pile length estimates <br /> and actual field results. <br /> It should also be kept in mind that measuring the ultimate capacity of a pile after it has been installed is <br /> also not an exact science. The measured capacity depends on the method used(dynamic formula, wave <br /> equation, Pile Dynamic Analyzer(PDA) or static load test)and the criteria used with each method. <br /> C.4.c. Estimated Pile Lengths. The estimated pile lengths given below in Table 2 are to provide pile <br /> suitable of providing up to 25-or 50-ton net working loads with a factor of safety of at least 2.25. The <br /> lengths assume the design cut-off elevation will be at an elevation of 929. Keep in mind the interior <br /> pile could be designed to have a pile cut-off elevation of about 931 or 932 thus increasing the required <br /> pile length by about 2 to 3 feet. <br /> Table 2. Estimated Pile Lengths <br /> Pile Assumed Estimated Estimated Estimated Net Working <br /> Size Cut-Off Downdrag Pile Length Pile Toe Capacity <br /> Boring (inches) Elevation (tons) (feet) Elevation (tons) <br /> ST-1 12.75 929 0 25 — 30 904— 899 25 <br /> ST-1 9.625 929 0 35 —40 894— 889 25 <br /> ST-2 12.75 929 17 45 — 50 884 — 879 25 <br /> ST-2 9.625 929 11 55 — 60 874— 869 25 <br /> ST-1 12.75 929 0 45 — 50 884— 879 50 <br /> ST-1 9.625 929 0 55 — 60 874— 869 50 <br /> ST-2 12.75 929 17 65 — 70 864 — 859 50 <br /> ST-2 9.625 929 11 75 — 80 854— 849 50 <br /> C.4.d. Pipe Pile Specifications. We recommend the pipe piles have a minimum wall thickness of <br /> 7/32 inches and the steel material meets specifications for ASTM A252 Grade 11. ASTM A252 Grade <br /> II requires the steel material to have a minimum steel yield strength of 36,000 pounds per square inch <br /> (psi). The piles should be driven closed end with plates welded to the toe of the piles. The end plates <br /> should have a minimum thickness of 1/2 inch. • <br />