Calculation Sheet Bored Pile [PDF]

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1.0



GENERAL



1.1



General This calculation is prepared to check the Bored Pile Capacity for Cinyemeh River, Cilacap



1.2



Design Code and references - ACI-318 2014: Building Code Requirement for Reinforec Concrete - Principles of Foundation Engineering, 6th Edition, Braja M. Das, Thomson Learning, 2007 - FHWA-IF-99-025: Drilled Shafts: Construction Procedures and Design Methods



1.3



Design Data 1) Pile - Type - Dimension, - Modulus of Elasticity, - Pile Section,



D Ec Ap



= Bored Pile = 600 mm = 25000 Mpa 2 = 0.28 m



fc' γc Ec



= = =



2) Concrete - Compressive strength of concrete, - Specific gravity of RC concrete, - Modulus of Elasticity,



35 Mpa 3 25 kN/m 25000 Mpa



3) Reinforcing Steel Bar - Use deformed rebar conform to SNI 07-2052-2002 BJTD 40 - Yield strength, fy = 460 Mpa - Modulus of Elasticity, Es = 2.E+05 Mpa - Cover for concrete protection, C = 60 mm 1.4



Design Criteria - Factor of Safety for End Bearing, Fsbearing - Factor of Safety for Skin Friction, Fsfriction - Factor of Safety for Lateral Load, Fslateral



= = =



3.0 3.0 3.0



2.0



GEOTECHNICAL PILE CAPACITY



2.1



BH-08A (Refer to Soilens' Report)



2.1.1 Subsoil Condition BH-8A



Pile Length =



30



m



G.W.T (m) =



γ2) Depth of Layer (m) Soil Type1) (kN/m3) from to center -4.15 -2.08 Cohesionless 16.70 0.00 -4.15 -8.15 -6.15 Cohesionless 19.20 -18.15 -13.15 -8.15 Cohesive 15.80 -18.15 -22.15 -20.15 Cohesive 16.20 -28.15 -25.15 -22.15 Cohesive 15.80 -32.15 -30.15 -28.15 Cohesive 15.20 -32.15 -36.15 -34.15 Cohesive 16.20 -46.15 -41.15 -36.15 Cohesive 16.20 -46.15 -50.15 -48.15 Cohesive 16.20 0.00 -50.15



Cohesive



N3) (blow) 11 14 5 20 34 52 43 44 62



N604) (blow) 11 14 5 20 34 52 43 44 62



16.20



-3.3 Su5) (kPa) 48.40 61.60 22.00 88.00 149.60 228.80 189.20 193.60 272.80



1254.00



Note: 1)



"Cohesive" = clay or plastic sily, "Cohesionless" = sand, gravel or non-plastic silt



2)



SPT N-value obtained from the field test



3)



Corrected for hammer energy without overburden pressure correction N60 = (ER/60) x N where, ER = SPT energy ratio = 60%



4)



Cohesion of sc(take minimum value from following two equations) K x N, where K = kPa (Stroud, 1974) 4.4 29 x N0.7 (Hara et al, 1971)



2.1.2 Allowable Compression Capacity (Reese and O'Neill, 1999) 1) Base Resistance for Compression Loading a) Cohesive soil qmax = Nc* x su



= 1722.6 kpa



where, Nc* = bearing capacity factor = 6.50 at su = 24 kPa 8.00 at su = 48 kPa 9.00 at su > 25 kPa



9



su = average undrained shear strength between the base of the pile and an elevation 2B below the base = 191.40 kPa b) Cohesionless soil qmax = 57.5 N60



=



0 kPa



where, N60 = average SPT blow count between the base of the pile and an elevation 2B below the base for condition which approximately 60 percent of the potential energy of hammer is transferred 2) Side Resistance for Compression Loading a) Cohesive soil fmax = α x su where, α = a dimensionless correction coefficient defined as follows: α= 0 between the ground surface and a depth of 1.5 m or to the depth of seasonal moisture change, whichever is deeper α= 0 for a distance of B (the diameter of the base) above the base α = 0.55 for su / pa < 1.5 (Mpa) α = 0.55 - 0.1 (su/ Pa - 1.5) for 1.5 < su / pa < 2.5 (Mpa) Pa =the atmospheric pressure in the units being used (e.g., 101 kPa in the SI system). b) Cohesionless soil fmax = ϐ x σ'v where, σ'v = vertical effective stress at the middle of layer ϐ = dimensionless correction factor defined as follows: in sands ϐ = 1.5 - 0.245 z0.5 for N60 > 15B / 0.3 m 0.5 ϐ = (N60/15) x (1.5 - 0.245 z ) for N60 < 15B / 0.3 m in gravelly sands or gravels ϐ = 2.0 - 0.15 z0.75 for N60 > 15B / 0.3 m 0.5 ϐ = (N60/15) x (1.5 - 0.245 z ) for N60 < 15B / 0.3 m where, z = vertical distance from the ground surface to the middle



Layer No. 1 2 3 4 5 6 7 8 9



N60 (blow) 11 14 5 20 34 52 43 44 62



Su (kPa) 48.40 61.60 22.00 88.00 149.60 228.80 189.20 193.60 272.80



ϐ 0.84 0.83 0.20 0.53 0.27 0.15 0.07 -0.07 -0.20



σ'v (kPa) 34.7 90.1 111.1 161.1 183.0 194.9 250.6 295.3 340.1



α 0.55 0.55 0.55 0.55 0.55 0.47 0.51 0.51 0.43



fmax (kPa) 29.1 75.1 12.1 48.4 82.3 108.3 97.0 98.4 117.3



SUM Note:



Thick 1) (m) 3.00 4.00 10.00 4.00 6.00 4.00 3.00



As (m2) 5.7 7.5 18.8 7.5 11.3 7.5 5.7



Qs (kN) 164.8 566.0 228.1 364.9 930.6 816.8 548.5



3619.7 1)



Thickness of layer



3) Allowable compression capacity Qall = (qmax x Ap)/ Fsbearing + Qs/ Fsfriction



=



1368.9 kN



2.1.3 Allowable Tension Capacity (Reese and O'Neill, 1999) 1) Base Resistance for Uplift Loading a) Cohesive soil qmax uplift 1) Note: 1)



=



0



kpa



qmax should be taken as zero for uplift loading unless experience or load testing at the construction site can show that suction between the bottom of the drilled shaft and the soil can be predicted reliably or the drilled shaft has a bell.



2) Side Resistance for Uplift Loading fmax uplift 1)



= ψ x fmax compression



where, ψ = ψ =



1.00 for Cohesive soil 0.75 for Cohesionless soil



Soil Type



Qs



Cohesionless Cohesionless Cohesive Cohesive Cohesive Cohesive Cohesive



(kN) 164.8 566.0 228.1 364.9 930.6 816.8 548.5



ψ



Ts



0.75 0.75 1.00 1.00 1.00 1.00 1.00



(kN) 123.6 424.5 228.1 364.9 930.6 816.8 548.5



sum =



3437.0



3) Allowable Tension Capacity Tall = (Tp + Ts)/ Fsfriction



=



1145.7 kN



2.1.4 Allowable Lateral Load Capacity (Broms' Method) 1) Coefficient of horizontal subgrade reaction 1) a) General soil type



Note:



:



Cohesionless



1) Determine the general soil type within the critical depth below the ground surface (about 4 or 5 pile diameters).



b) Average soil parameter with the critical depth su



=



48.40



kPa for Cohesive soil



φ



=



29.8



deg for Cohesionless soil



1) where, φ = Internal friction angle correleted by Ozaki's equation



Note:



1) φ = (20 N)0.5 + 15



c) Coefficient of horizontal subgrade reaction, Kh Kh = n1 x n2 x 80 x qu / b where,



=



5343.4 kN/m3



qu = Unconfined compressive strength = 2 su b = Width or diameter of pile



Kh =



for Cohesive oil =



96.8 kPa



=



0.6 m



n1 = Empirical coefficients dependent on qu = 0.32 for less than 48 kPa = 0.36 for 48 to 191 kPa = 0.40 for more than 191 kPa



=



0.36



n2 = Empirical coefficient dependent on pile material = 1.00 for steel = 1.15 for concrete = 1.30 for wood



=



1.15



1900



kN/m3



for Cohesionless oil



where, above ground water Kh = 1900 kN/m3 = 8143 kN/m3 = 17644 kN/m3 below ground water Kh = 1086 kN/m3 = 5429 kN/m3 = 10857 kN/m3



for loose density for medium density for dense density



for loose density for medium density for dense density



2) Pile Parameters a) Modulus of elasticity,



E



=



25000



Mpa



b) Moment of inertia,



I



=



0.0064



m4



c) Section modulus,



S



=



0.0212



m3



d) Embedded pile length,



D



=



30



m



e) Diameter or width,



b



=



0.6



m



f) Ultimate compression strength for concrete,



f'c



=



35



g) Eccentricity of applied load for free-headed piles,



ec



=



0



h) Resisting moment of pile for concrete piles,



My = f'c S = 742.2 kN-m



3) Dimensionless length factor a) Stiffness factor m-1



βh = ( Kh b / 4EI )0.25



=



η = (Kh / EI)0.20



-1 = 0.4125 m



0.27



for Cohesive oil for Cohesionless oil



b) Length factor βh D



=



7.99



ηD



=



12.38



for Cohesive oil for Cohesionless oil



4) Determine if the pile is long or short a) Cohesive soil: where,



long pile βh D > 2.25 (long pile) βh D < 2.25 (short pile)



b) Cohesionless soil: where,



→ Soil type: → Pile type:



long pile



η D > 4.0 (long pile) η D < 2.0 (short pile) 2.0 < η D < 4.0 (intermediate pile) Cohesionless long pile



Mpa



5) Soil parameters cu



=



where,



48.40 kPa



for cohesive soil



cu = cohesion for cohesive soil



Kp



=



2.9798



for cohesionless soil



Kp = Rankine passive earth pressure coefficient = tan2(45+φ/2)



where,



6) Ultimate lateral load (Cohesionless, long pile) a) For Cohesive soil = 70.994 My/cub3 ec/b Qu/cub2 Qu



= = =



0 0



from the chart kN



b) For Cohesionless soil My/Kpγb4



=



where, γ



= =



ec/b 4



Qu/Kpγb Qu



= =



100.1 3 19.20 kN/m 0 76.2 from the chart 565 kN



Broms's solution for ultimate lateral resistance of long piles (a) in sand (b) in clay Reference: Braja M. Das (page 465) 7) Allowable lateral load capacity Hu



=



565.0 kN



Hall = Hu / FSlateral



=



188.3 kN



2.1.5 Result for pile capacity 1) Pile Capacity for Axial Compression,



Pall =



1300 kN



2) Pile Capacity for Axial Tension,



Tall =



1100 kN



3) Pile Capacity for Lateral Force,



Hall =



180 kN