An HP 13 × 87 pile is embedded 45 ft into a clay. The unit weight of this soil is 100 lb/f...

An HP 13 × 87 pile is embedded 45 ft into a clay. The unit weight of this soil is 100 lb/ft3 above the groundwater table (which is 12 ft below the ground surface) and 112 lb/ft3 below. The soil in the vicinity of the pile tip has an undrained shear strength of 2800 lb/ft2. According to a static load test, the ultimate downward load capacity is 143 k.

You wish to compute a site-specific β factor for HP 13 × 87 piles to be used in the design of other piles at this site. Based on these test results, what is that β factor? See Table for pile cross-section dimensions.

Hint: Compute β based on the average σ′z and the average measured fn.