Issue 78

S. Majer et alii, Fracture and Structural Integrity, 78 (2026) 504-518; DOI: 10.3221/IGF-ESIS.78.29

  2 J



I k    

f

0

1

where:

 2sin 3 3 sin     6 cos 3 3 sin c  







 

 



k



 

A non-dilatant flow rule ( ψ = 0°) was used. The elastic and strength parameters, together with the corresponding Drucker– Prager constants, are summarized in Tab. 3.

γ [kN/m³]

γ sat [kN/m³]

E [MPa] 200.0

ν [–]

c ′ [kPa]

φ′ [°] 33 38 40 –

ψ [°]

α [–]

k [kPa] 4.098 3.775 1.457 5.648 7.797 7.797 2.459 2.382 –

Layer

Structural layer

21.0 16.5 17.5 17.5 12.0 14.0 21.0 16.5 20.0

21.0 18.0 18.0 18.0 13.0 15.0 21.5 18.0 21.0

0.30 0.30 0.30 0.30 0.27 0.27 0.27 0.30 0.30

– 5 5 2 5 7 7 3 3

– 0 0 0 0 0 0 0 0

–

0.1774 0.1966 0.2038 0.0230 0.0357 0.0357 0.1774 0.1853

N1 N2 N3

12.0 25.0 25.0

Peat (Pt)

2.2 4.5

3.5 5.5 5.5 33 35

Organic silt/gyttja

Clayey sand

18.5 30.0 40.0

Medium sand IVa Medium sand IVb

Table 3: Material parameters adopted in the FEM settlement model.

For consolidation, the saturated permeability coefficients k ₓ /k_z were respectively 2.5/4.5 m/day for N1, 3.0/5.5 m/day for N2 and N3, 2.5×10 ⁻⁵ /4.5×10 ⁻⁵ m/day for peat, 3.2×10 ⁻⁵ /4.5×10 ⁻⁵ m/day for organic silt/gyttja, 4.2×10 ⁻ ³/5.5×10 ⁻ ³ m/day for clayey sand, and 6.5/8.0 m/day for medium sands IVa and IVb. For the reference case, the maximum settlement was 51.4 cm and the average settlement within the loaded strip was 36.7 cm. Sensitivity checks were performed by varying the stiffness of the compressible organic layers, the effective strength parameters, groundwater level and load magnitude. The results are reported in Tab. 4. The response was governed mainly by the stiffness of the peat and organic silt/gyttja and by the applied pressure, whereas moderate changes in strength parameters and groundwater position had a smaller influence on the calculated settlement.

smax [cm] 51.4 60.8 44.3 55.2 48.3 53.1 49.7 42.2 61.0

savg [cm] 36.7 43.6 31.6 39.5 34.6 37.9 35.5 30.1 43.8

Δ smax [%] +18.3 − 13.8 +7.4 − 6.0 +3.3 − 3.3 − 17.9 +18.7 –

Variant

Modified input

Reference

–

Organic-layer E − 20% Organic-layer E +20% Reduced strength Increased strength Groundwater +1.0 m Groundwater − 1.0 m

E = 0.8Eref E = 1.2Eref

c ′ = 0.8c ′ ref; φ′ = φ′ ref − 2° c ′ = 1.2c ′ ref; φ′ = φ′ ref + 2° phreatic level raised phreatic level lowered

Load − 20% Load +20%

q = 120 kPa q = 180 kPa

Table 4: Sensitivity of the calculated settlements to the principal model assumptions

The numerical model was developed using geotechnical parameters obtained from site investigations and laboratory testing. During the construction stage, settlement monitoring was carried out in accordance with the requirements specified in the project documentation, and the observed settlements were found to be consistent with the design requirements. However, the detailed monitoring records and numerical measurement data are not currently available to the authors and therefore

516