Skip to content

Eurocode 7 module: ec7

Overview

The ec7 module provides tools for geotechnical design according to EN 1997-1: soil definitions, partial factors of the design approaches, bearing resistance of shallow foundations (static and seismic, EN 1998-5) and earth pressure coefficients.

Angles are in radians in the calculation functions (bearing_resistance, seismic_bearing_resistance, pressure_coefficients). Soil(friction_angle=30.0) takes degrees and stores radians.

Soil materials

Soil and SoilEnum

from eurocodepy.ec7 import Soil, SoilEnum

soil = Soil("Dense sand", unit_weight=19.0, friction_angle=34.0, cohesion=0.0)   # degrees, kN/m³, kPa
soil.unit_weight, soil.friction_angle, soil.cohesion          # friction_angle in radians
soil.is_drained, soil.is_coherent, soil.young, soil.poiss, soil.ks, soil.sig_adm

SoilEnum.Sand, SoilEnum.Clay, SoilEnum.Gravel, SoilEnum.Rock   # typical soils

SoilSafetyFactors and SoilSafetyFactorsEnum

Partial factors of the geotechnical design approaches (EN 1997-1).

from eurocodepy.ec7 import SoilSafetyFactorsEnum

sf = SoilSafetyFactorsEnum.STRGEO_A2
sf.phi, sf.c, sf.cu, sf.gamma                  # on tan φ', c', cu and γ
sf.perm_unfav, sf.var_unfav                    # on actions
sf.bearing, sf.slide                           # on resistances

Members (each is a SoilSafetyFactors): EQU, EQU_ACC, STRGEO_A1, STRGEO_A2, STRGEO_B, STRGEO_C, STRGEO_ACC, STRGEO_SLS.

Seismic parameters

from eurocodepy.ec7 import get_soil_seismic_parameters, soil_gamma_rd

params = get_soil_seismic_parameters("S1", "PT", "C", "ii", "PT1", "1_2")   # name, code, soil, class, spectrum, zone
params.alpha, params.smax, params.avg_ahg, params.r
params.kh, params.kv                             # horizontal and vertical seismic coefficients

soil_gamma_rd["compact sand"]                    # γRd by soil type: 1.0, 1.15, 1.5 …

SoilSurcharge

SoilSurcharge(q=10.0, psi0=0.6, psi1=0.4, psi2=0.2): a surcharge on the soil surface with its combination coefficients.

Bearing resistance — ec7.bearing_capacity

import numpy as np
from eurocodepy.ec7 import bearing_resistance, seismic_bearing_resistance

phi = np.radians(30.0)

# EN 1997-1: effective width Bx, length By, horizontal loads Hx, Hy and vertical load N
# [m, kN], effective friction angle, unit weight [kN/m³], surcharge beside the footing q [kPa], cohesion c
q = 0.8 * 18.0
r = bearing_resistance(Bx=1.5, By=2.0, Hx=20.0, Hy=0.0, N=200.0, phi=phi, gamma=18.0, q=q, c=0.0)

# EN 1998-5: True where the verification is satisfied (two vertical directions)
ok = seismic_bearing_resistance(ag=0.2, avg_ahg=0.5, S=1.4, B=1.5, H=20.0, N=200.0, M=10.0,
                                phi=phi, gamma_s=18.0)            # cu=..., soil_type="coherent" for clays

bearing_resistance also takes arrays (one value per combination).

Earth pressures — ec7.earth_pressures

import numpy as np
from eurocodepy.ec7 import pressure_coefficients, EarthPressureModels

phi, delta = np.radians(30.0), np.radians(15.0)      # soil and wall friction angles
theta, beta = 0.0, 0.0                                # backfill slope and wall inclination
Ka, Kp, Kaq, Kpq, dkas1, dkps1, dkas2, dkps2 = pressure_coefficients(
    phi, delta, theta, beta, method=EarthPressureModels.COULOMB)

Methods (EarthPressureModels): RANKINE, COULOMB, EC7 (the default) and INREST. Kaq and Kpq are the coefficients at rest; dkas* and dkps* the seismic increments of EN 1998-5 when seismic= (a SoilSeismicParameters) is given.

Compliance

Calculations follow EN 1997-1:2004. Seismic bearing resistance follows EN 1998-5.

Further reading