Pile Capacity
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Description
Pile Geotechnical and Structural Capacity Check
1.0 Input
1.1 Design Soil Parameters
1.2 Pile Details
Existing ground level
Pile Diameter, D
Pile Cut-off level
Dredge level
Scour level
Pile Founding level
Depth from G.L.corresponding to F.L.
Pile Embedment length
Total Pile Length, L
Pile Density
Factor of Safety
Pile Fixity condition at top
Grade of Concrete
Modulus of subgrade reaction at fixity zone
Type of soil in fixity zone
Unsupported Length of Pile, L1
Allowable displacement of pile at head
(For Horizontal capacity)
1.3 Sketch
2.0 Calculation of Vertical Capacity
Ultimate Capacity of Pile , Qult = Qb + Qs - Wp
Whetre, Qb = Ultimate End Bearing
Qsafe = Qult / FOS
Where, FOS = Factor of Safety
2.1 Calculation of Skin Resistances
2.1.1 Layer-1:
Layer thickness, L1
Pile embedment in the layer, h1
Ultimate Skin Resistance, Qs1 =
Where, Reduction factor, a
Ultimate Skin Resistance, Qs1 =
2.1.2 Layer-2:
Layer thickness, L2
Pile embedment in the layer, h1
Ultimate Skin Resistance, Qs2 =
Where, Reduction factor, a
Ultimate Skin Resistance, Qs2 =
2.1.3 Layer-3:
Layer thickness, L3
Pile embedment in the layer, h3
Ultimate Skin Resistance, Qs3 =
Where, Reduction factor, a
Ultimate Skin Resistance, Qs3 =
2.1.4 Layer-4:
Layer thickness, L4
Pile embedment in the layer, h4
Ultimate Skin Resistance, Qs4 =
Where, Reduction factor, a
Ultimate Skin Resistance, Qs4 =
Total Ultimate Skin resistance, Qs = Qs1 +Qs2 +Qs3 +….. +Qsn
2.2 Ultimate End Bearing Resistance
Ultimate End bearing Resistance, Qb = (c Nc + Pd Nq ) * Ap
Where,
Ultimate End bearing Resistance, Qb = (c Nc + Pd Nq ) * Ap
2.3 Self Weight of the Pile, Wp
Self weight of the Pile , Wp = Ap L gp
Where, Area of pile, Ap
Self weight of the Pile , Wp = Ap L gp
2.4 Ultimate Capacity of the Pile , Qult = Qb + Qs - Wp
Where, Ultimate End Bearing, Qb
Ultimate Capacity of the Pile , Qult = Qb + Qs - Wp
2.5 Safe Capacity of Pile, Qsafe = Qult / FOS
Where, Ultimate Capacity of Pile, Qult
Safe Capacity of Pile, Qsafe = Qult / FOS
3.0 Tension Capacity of Pile
Ultimate Tension Capacity of the Pile , Qult(T) = 2/3 x Qs + Wp
Where, Ultimate Skin Resistance, Qs
Ultimate Tension Capacity of the Pile , Qult(T) = 2/3 x Qs + Wp
Safe Tension Capacity of the Pile , Qsafe(T) = Qult(T) / FoS
Where, FoS = Factor of Safety
Safe Tension Capacity of the Pile , Qsafe(T) = Qult(T) / FoS
4.0 Fixity Depth Calculation
Pile fixity condition at top
Type of Soil in fixity zone
Modulus of subgrade reaction at fixity zone, K
Elastic modulus of concrete, Ec = 5000 * SQRT(fck)
Where, fck = Characteristic strength of concrete
Elastic modulus of concrete, Ec = 5000 * SQRT(fck)
Moment of inertia of Pile, I = 3.14 /64 *D^4
where, D = Diameter of the pile
Moment of inertia of Pile, I = 3.14 /64 *D^4
Relative Stiffness factor, T = (EI/K)^(1/5)
Unsupported length of pile, L1
Ratio of L1/T or L1/R
Lf/T or Lf /R =
Therefore, Fixity Depth , Lf =
Fixity depth, in terms of diameter of pile
5.0 Minimum Pile Length for lateral Capacity
Minimum Pile Length for flexible pile, Lmin
Where, T = Relative stiffness factor
Let us consider a minimum length of pile , Lmin =
6.0 Horizontal Capacity of the Pile
Pile fixity condition at top
The horizontal capacity, H
Where, y = Diaplacement of pile at head
The horizontal capacity, H =
7.0 Summary of Calculations
Pile Diameter
Pile Cut-off level
Pile Founding Level
Safe Vertical Capacity
Safe Tension Capacity
Pile head Condition
Grade of Concrete
Horizontal capacity for a Displacement of
Minimum Pile length for Lateral Capacity
Fixity Depth, Lf
Calculation Reference
Pile Capacity
Geotechnic Calculations
Soil Mechanics
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