HOW TO CALCULATE PILE LOAD CAPACITY USING STATIC CONE PENETRATION TEST?

Pile Load Capacity Calculation Using Static Shank Penetration Test Data (SCPT)

Pile Load Capacity Calculation Using Static Cone Penetration (SCPT) Test Data

The safe load capacity of bore cast in situ piles can be calculated using test data obtained from Static Cone Penetration Test as described below.

We know that the final load capacity of a pile consists of two terms, namely

  • end bearing resistance
  • skin abrasion resistance

So we need to calculate the above two parameters, then by adding these two parameters we can get the final load capacity of the pile.

Step-1 (Calculate the end-bearing resistance of the pile)

The final end bearing resistance of the pile is calculated using the formula below.

Pile Capacity Calculation Formula Using SCPT Data

Where,

WhyYou = final end bearing resistance, kN/m . In2


Whyc0 = kN/m . Average static cone resistance at a depth of 2d below the pile tip in2

WhyC1 = kN/m . Minimum static cone resistance at the same 2D below the pile tip in2

Whyc2 = in kN/m, the average of the envelope of minimum constant cone resistance values ​​over a pile length of 8D above the pile tip2


d = diameter of the pile


Step-2 (Calculate Skin-Abrasion Resistance)

For a variety of soils, the ultimate skin abrasion resistance (f.)s), kN/m. In2, can be obtained using the table below.

soil type Skin abrasion resistance (fs), kN/m . In2
WhyC 1000 kN/m . less than2 WhyC/30 to QC/10
Soil WhyC/25 to 2qC/25
silty sand and silty clay WhyC/100 to QC/25
Sand WhyC/100 to QC/50
coarse sand and gravel WhyC/150 to QC/100

where, whyC kN/m . has cone resistance2,

Step-3 (Calculate Safe Heap Load Capacity)

Add end end bearing resistance (QYou) and ultimate skin abrasion resistance (f.)s) as calculated in step-1 and 2 respectively, and divide it by the appropriate factor of safety (minimum 2.5) to obtain the safe load capacity of the pile, i.e.

WhySafe = (QYou+fs) / FOS


Where,

WhySafe = safe load capacity of the pile

WhyYou = End end bearing resistance of pile


Fs = final skin abrasion resistance of the pile

FOS = heap protection factor (usually 2.5)

Reference

IS: 2911-Part-1-Sec-2


Er. Mukesh Kumar

Photo of author
Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.