SPECS, GRLWEAPHow do I take the internal friction in consideration when analyzing unplugged open ended piles?
Plugging is a phenomenon that occurs during driving, when a soil column (or plug) is formed inside open ended piles or between flanges of H piles. If sufficient friction is developed between the soil column and the inside surface of the pile, and if the plug has become sufficiently stiff to no longer undergo significant compression, then the pile is said to be fully plugged, and it will tend to behave as if it were close ended. If these conditions are not met the pile is said to be unplugged. Partial plugging is also possible if these conditions are partially met. The total capacity of the pile is unit shaft resistance times shaft surface area plus unit end bearing times toe area. The shaft surface area is calculated based on the perimeter values that the user inputs. The perimeter used in the calculations is different for a plugged or unplugged pile. Normally for H-piles, the perimeter is computed using only 4 sides of the pile cross-section. An argument could be made for using all 6
