SPECS, GRLWEAPHow do I model the end bearing for unplugged open ended piles?
During driving 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. In the case of unplugged open ended piles, the annulus area should be used instead of the full toe area. Note also that the recommended toe quake for non-displacement (unplugged) piles is 2.54 mm (0.1 inch), instead of D/60 or D/120 for displacement (close ended or plugged piles). Since the default values of GRLWEAP for the pile toe area and for the t
