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In this article, we will discuss how to calculate pile load capacity static analysis.
1. How To Calculate Pile Load Capacity Static Analysis
The highest load-carrying capacity of a pile is the maximum load that it can bear without failure or extreme settlement of the ground.
The bearing capacity of a pile mostly relies on 3 factors as noted below,
a. Type of soil through which the pile is piled
b. Pile Installation Method
c. Pile Dimensions (Cross Section and Pile Length)
When estimating the pile load capacity for cast in situ concrete piles, utilizing static analysis, we need to utilize the soil shear strength parameter and the dimension of the pile.
2. Load Bearing Capacity Of Heap Using Static Analysis
The pile transfers the load to the soil in two ways. First, through tip-in compression, which is called “end bearing” or “point bearing“; secondly, shearing along the surface” is termed as skin friction.
3. Load Bearing Capacity of Cast In-situ Piles in Cohesive Soils
Final load-carrying capacity (Q.)You). The pile in the connective soil is given by the formula given below, where the first term denotes end bearing resistance (Whyb) and gives the second term skin abrasion resistance (Whys.
| Qu = Ap Nc Cp+ n∑i=1 αi Ci Ast |
Where,
WhyYou = final load capacity, kN
aP = area of cross-section of the top of the pile, m2.
nC = bearing capacity factor can be taken as 9.
αI = the adhesion factor for the ith layer depending on the consistency of the soil. It depends on the non-irrigated shear capacity of the soil and can be obtained from the figure given below.
CI = average cohesion for the ith layer, kN/m2
aSI = surface area of the pile shaft in the ith layer, m2
A minimum factor of 2.5 is used to arrive at a safe pile load capacity (Q.)Safe) from final load capacity (q.)You,
WhySafe = QYou/2.5
4. Load-bearing Capacity of Cast-in-situ Piles in Non-Cohesive Soils
The final load-carrying capacity of the pile, “QYou“. There are two parts. One part is caused by friction, which is called skin friction or shaft friction or side shear denoted as “Q”s“And the second reason is the end bearing at the base or tip of the pile toe, “Qb,
The equation given below is used to calculate the final load-carrying capacity of the pile.
| Qu = Ap( 0.5DyNy+ Pd Nq) + n∑i=1 Ki Pdi tanρA |
Where,
aP = area of cross-section of pile base, m2
D = diameter of pile shaft, m
ρ = effective unit weight of soil at the tip of the pile, kN/m3
nI= bearing capacity factor
nWhy = bearing capacity factor
A = angle of internal friction at the end of the pile
PD = effective overburden pressure at the pile tip, kN/m2
KI = coefficient of earth pressure applied to the ith layer
Pd = Effective overburden pressure for the ith layer kN/m2
II = angle of friction of the wall between the pile and the soil for the ith layer
aSI = surface area of the pile shaft in the ith layer, m2
The first term is the expression for the final bearing capacity of the pile (Whyb) and the second term is the expression for the skin friction capacity of the heap (Whys,
A minimum factor of 2.5 is used to arrive at the safe stack capacity (q.)Safe) from final load capacity (q.)You,
WhySafe = QYou / 2.5
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