def test_negative_friction(self):
layer_table = pd.read_csv("files/d_foundation_layer_table.csv")
self.gef.groundwater_level = 1
df = soil.join_cpt_with_classification(self.gef, layer_table)
tipping_point = nap_to_depth(self.gef.zid, -2.1)
idx_tp = np.argmin(np.abs(self.gef.df.depth.values - tipping_point))
s = slice(0, idx_tp - 1)
if SHOW_PLOTS:
# show chamfer line
fig = self.gef.plot(show=False)
fig.axes[0].plot(df.qc.values[s], df.depth.values[s], color="red")
fig.axes[0].hlines(tipping_point, 0, df.qc.values[s].max())
plt.show()
f = bearing.negative_friction(df.depth.values[s],
df.grain_pressure.values[s], 0.25 * 4,
df.phi.values[s])
deviation = abs(1 - 19.355 / (f.sum() * 1000))
self.assertTrue(deviation < 1e-2)
def negative_friction(self, negative_friction_range=None, agg=True):
"""
Determine negative friction.
Parameters
----------
negative_friction_range : np.array[float]
Length == 2.
Start and end depth of negative friction.
agg : bool
Influences return type.
True: aggregates the friction values in total friction.
False: Return friction values per cpt layer.
Returns
-------
out : Union[float, np.array[float]]
unit [MPa]
See agg parameter
"""
if negative_friction_range:
self.negative_friction_slice = det_slice(
self.merged_soil_properties.depth.values, negative_friction_range
)
negative_friction = bearing.negative_friction(
depth=self.merged_soil_properties.depth.values[
self.negative_friction_slice
],
grain_pressure=self.merged_soil_properties.grain_pressure.values[
self.negative_friction_slice
],
circum=self.circum,
phi=self.merged_soil_properties.phi[self.negative_friction_slice],
gamma_m=self.gamma_m,
)
self.nk = negative_friction.sum()
if agg:
return self.nk
return negative_friction
# find the index of the pile tip
idx_ptl = np.argmin(np.abs(gef.df.depth.values - ptl))
ptl_slice = slice(0, idx_ptl)
# assume the tipping point is on top of the sand layers.
tipping_point = soil.find_last_negative_friction_tipping_point(
df.depth.values[ptl_slice], df.soil_code[ptl_slice])
idx_tp = np.argmin(np.abs(df.depth.values - tipping_point))
negative_friction_slice = slice(0, idx_tp)
negative_friction = (bearing.negative_friction(
depth=df.depth.values[negative_friction_slice],
grain_pressure=df.grain_pressure.values[negative_friction_slice],
circum=circum,
phi=df.phi[negative_friction_slice],
gamma_m=1,
)).sum() * 1000
positive_friction_slice = slice(idx_tp, idx_ptl)
chamfered_qc = bearing.chamfer_positive_friction(
df.qc.values, gef.df.depth.values)[positive_friction_slice]
rs = (bearing.positive_friction(
depth=df.depth.values[positive_friction_slice],
chamfered_qc=chamfered_qc,
circum=circum,
alpha_s=0.01,
)).sum() * 1000