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Faculty of Civil and Geodetic EngineeringUniversity of Ljubljana
Axial compression behaviour of driven steel piles in soft marine soils of the Port of Koper
Sebastjan Kuder
18th European Young Geotechnical Engineers Conference, Ancona, Italy, 2007.
Introduction
Source: Google Earth
History
Source: www luka kp si
Geological conditions
γ = 20 – 21 kN/m3 ϕ’=35°, c’=0
γ = 17,0 – 18,5 kN/m3 cu = 10 kPa (at 0m) to 25 kPa (at -10 m) ϕ’=20°, c’=0
Eoed = 2,0 – 2,5 MPa pLM = 350 – 480 kPa (pressuremeter) EM = 1,3 – 2,0 MPa (pressuremeter)
AC class.: CL, CH, OH w = 33,2 – 47,2 % Ic = 0,15 – 0,55 γ = 15,8 – 18,1 kN/m3 cu = 20 – 55 kPa (DMT, CPT) ϕ’ = 15 – 20°, c’ = 0 – 7 kPa (laboratory)
Eoed = 1,4 – 2,5 MPa (at -10 m) Eoed = 2,5 – 3,5 MPa (at -30 m) k = 1 x 10-10 m/sec (CPT) pLM = 500 – 1000 kPa (pressuremeter) EM = 1,0 – 3,6 MPa (pressuremeter)
AC class.: GP, GM, GC, SM, SC, SU, ML γ = 20 – 22 kN/m3 ϕ’ = 28 – 40° (SPT)
Eoed = 25 – 60 MPa pLM = 1000 – 2500 kPa (pressuremeter) EM = 15 – 26 MPa (pressuremeter)
AC class.: CL w = 18,8 – 20,5 % Ic = 1,04 – 1,06 γ = 20,9 – 21,0 kN/m3
cu = 105 – 120 kPa (laboratory) Eoed = 13,6 – 16,2 MPa (400 – 800 kPa) Eoed = 42 – 56 MPa (800 – 1600 kPa) k = 1 x 10-11 – 2 x 10-11 m/s
Pile foundations
Pile foundations
Pile foundations
Objectives of the study
• To analyze existing data, • to design a model which would enable the
prediction of pile behaviour,• to compare the results of different
methods.
Analysis of existing data
• 17 static load tests• 2 dynamic load tests• Borehole logs• Pile driving logs• Pressuremeter test
results• Laboratory tests
results• Flat dilatometer test
results
Numerical model
Numerical model – cont.
• Shaft: rsi =rsi (s, Esi , qsi , B), for each segment
• Base rb =rb (b, Eb , qb , B),• Initial estimate based on
borehole logs, pile driving logs, laboratory tests.
Results
Soil layer
Average depth qs Es
m kPa MPaEMB 0-4 10 2S1 5 10 2CS1 8 15 3CS1 20 30 6CS2 29 45 9CS3 40 60 18GFc1 30 50 10GFc2 34 60-70 12-14GFc2 42 65-80 13-16GFc3 44 90 18
PilePile
lengthType of
base qb Eb
m kPa MPa13 42.4 cone 5500 5519 45.4 hollow 3000 30P3 41 hollow 4600 46vez7c 44 cone 7800 78
Shaft
Base
Results
Soil layer
Average depth qs Es
m kPa MPaEMB 0-4 10 2S1 5 10 2CS1 8 15 3CS1 20 30 6CS2 29 45 9CS3 40 60 18GFc1 30 50 10GFc2 34 60-70 12-14GFc2 42 65-80 13-16GFc3 44 90 18
PilePile
lengthType of
base qb Eb
m kPa MPa13 42.4 cone 5500 5519 45.4 hollow 3000 30P3 41 hollow 4600 46vez7c 44 cone 7800 78
Shaft
Base
Results
Soil layer
Average depth qs Es
m kPa MPaEMB 0-4 10 2S1 5 10 2CS1 8 15 3CS1 20 30 6CS2 29 45 9CS3 40 60 18GFc1 30 50 10GFc2 34 60-70 12-14GFc2 42 65-80 13-16GFc3 44 90 18
PilePile
lengthType of
base qb Eb
m kPa MPa13 42.4 cone 5500 5519 45.4 hollow 3000 30P3 41 hollow 4600 46vez7c 44 cone 7800 78
Shaft
Base
Results
Soil layer
Average depth qs Es
m kPa MPaEMB 0-4 10 2S1 5 10 2CS1 8 15 3CS1 20 30 6CS2 29 45 9CS3 40 60 18GFc1 30 50 10GFc2 34 60-70 12-14GFc2 42 65-80 13-16GFc3 44 90 18
PilePile
lengthType of
base qb Eb
m kPa MPa13 42.4 cone 5500 5519 45.4 hollow 3000 30P3 41 hollow 4600 46vez7c 44 cone 7800 78
Shaft
Base
Comparison of methods
• Location of pile vez7c• Static load test• Dynamic load test• Pressuremeter method• Numerical prediction
Comparison of methods – cont.
0
1000
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9000
10000
0 20 40 60 80 100 120 140s [mm]
Q [k
N]
staticdynamicnumericalpressurem.
Conclusions
• Very comparable results from dynamic load tests and static load tests,
• in such conditions pressuremeter method can moderately underestimate shaft bearing capacity,
• numerical method gives good results with some minor discrepancies,
• more advanced model of skin friction should be considered,
• for the future: some test piles should be instrumented along their shafts,
• the numerical model will be adapted to conditions in another locations.
