132_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011

132_CEG 4012 Notes Fall 2011 CEG 4012 Notes Fall 2011 -...

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Unformatted text preview: DF18 Steel Pipe Piles: Pile Diameter S 36 inches End Bearing: Figure 5 is a plot of mobilized unit end bearing versus blowcount for the four soil types. The empirical equations for the four soil types are presented as follows: Soil Type 1 2 Description Plastic clay Clay-silt-sand mixtures, very silty sand, silts and marls Clean sands Soft limestone very shelly sand I Mobilized Unit End 8earing Capacity (TSF) Q = 0.7*N/3 q = 0.16*N/3 If N S 30, q = 3.2*N/3 If N > 30, Q = 32.0 + 4.0*(N-30.0ll30.0 If N S 30, q = 1.2*N If N > 30, q = 36.0 + 7.0*(N-30.0)/30.0 3 4 The methodology used to calculate the end bearing capacity for a given depth is the same as the concrete pile. This includes the critical depth correction, the end bearing contribution zone of 88 above and 3.58 below the pile tip and the bearing averaging technique remain the same as for concrete piles. Side Friction: Figure 6 is a plot of ultimate unit side friction versus blowcount for the four soil types. The empirical equations derived from the database are as follows; Soil Type 1 2 Description Plastic clay Clay-silt-sand mixtures, very silty sand, silts and marls Clean sands Soft limestone, very shelly sand Ultimate Unit Side Friction (TSF) f = -8.081 (10-4) +0.058*N - 1.202(1 03)*N 3 + 8.785(106 3 )*N f = 0.029 + 0.045*N - 8.98(1 0-4)*N 2 + 6.371 (1 06)*N 3 f = -0.026 + 0.023*N - 1.435(1 0-4)*N2 6.527(107)*N 3 f=O.Ol*N 3 4 Pile Capacity: Davisson's criteria is not used for this pile type because of the uncertainty of computing elastic settlement for a plugged pile. Instead the mobilized ultimate pile capacity is defined as an applied load at a settlement equal to three percent (3%) the diameter of the pile. The allowable pile capacity is equal to 1/2 the mobilized ultimate pile capacity. The ultimate pile capacity is determined as the ultimate side friction plus three (3) times the mobilized end bearing. ...
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