Unit end bearing¶

groundhog.deepfoundations.axialcapacity.endbearing.API_unit_end_bearing_clay(undrained_shear_strength, N_c=9.0, **kwargs)[source]¶

Calculates unit end bearing in clay according to API RP 2 GEO. For piles considered to be plugged, the bearing pressure may be assumed to act over the entire cross-section of the pile. For unplugged piles, the bearing pressure acts on the pile wall annulus only. That a pile is considered plugged or unplugged shall be based on static calculations. A pile can be driven in an unplugged condition but behave as plugged under static loads.

Use the string 'API RP2 GEO Clay' to define this method in a SoilProfile.

Parameters:

undrained_shear_strength – Undrained shear strenght at the pile tip (\(S_u\)) [\(kPa\)] - Suggested range: 0.0<=undrained_shear_strength<=400.0
N_c – Bearing capacity factor (\(N_c\)) [\(-\)] (optional, default=9.0) - Suggested range: 7.0<=N_c<=12.0

\[q = N_c \cdot S_u\]

Returns:: Unit end bearing (\(q\)) [\(kPa\)]
Return type:: Python dictionary with keys [‘q_b [kPa]’]

Reference - API RP 2GEO, API RP 2GEO Geotechnical and Foundation Design Considerations, 2011

groundhog.deepfoundations.axialcapacity.endbearing.API_unit_end_bearing_sand_rp2geo(api_relativedensity, api_soildescription, sigma_vo_eff, qb_limit=False, **kwargs)[source]¶

Calculates unit end bearing in sand according to API RP2 GEO.

Use the string 'API RP2 GEO Sand' to define this method in a SoilProfile.

Parameters:: api_relativedensity – Relative density of the sand (\(D_r\)) [\(-\)] Options: (“Very loose”,”Loose”,”Medium dense”,”Dense”,”Very dense”), regex: None

:param api_soildescription : Description of the soil type (\(-\)) [\(-\)] Options: (“Sand”,”Sand-silt”), regex: None :param sigma_vo_eff: In-situ vertical effective stress at the pile tip (\(p'_{o,tip}\)) [\(kPa\)] - Suggested range: 0.0<=vertical_effective_stress

\[q = N_q \cdot p'_{o,tip}\]

Returns:: Unit end bearing (\(q_b\)) [\(kPa\)], Unit end bearing (limited) (\(q_{b,limited}\)) [\(kPa\)], Unit end bearing limit (\(q_{b,lim}\)) [\(kPa\)]
Return type:: Python dictionary with keys [‘q_b [kPa]’,’q_b_with_lim [kPa]’,’q_b_lim [kPa]’]

../_images/API_unit_end_bearing_sand_1.PNG — API RP 2 GEO values (TODO: Add figure file in docs)¶

Reference - API RP 2GEO, API RP 2GEO Geotechnical and Foundation Design Considerations, 2011

groundhog.deepfoundations.axialcapacity.endbearing.unitendbearing_clay_almhamre(qt, multiplier=0.6, **kwargs)[source]¶

Calculates unit end bearing in clay according to Alm & Hamre.

Parameters:

qt – Total cone resistance (\(q_t\)) [\(MPa\)] - Suggested range: 0.0 <= qt <= 120.0
multiplier – Multipier for unit end bearing (:math:``) [\(-\)] (optional, default= 0.6)

\[q_{b,clay} = 0.6 \cdot q_t\]

Returns:

Dictionary with the following keys:

’q_b_coring [kPa]’: Unit end bearing for pile driving (\(q_{b,sand}\)) [\(kPa\)]
’q_b_plugged [kPa]’: Not applicable [\(kPa\)]
’plugged []’: Determines whether the pile is plugged (False for driving piles)
’internal_friction []’: Determines whether internal friction is taken into account (True by default for Alm & Hamre formula)

Reference - Alm, T., Hamre, L., 2001. Soil model for pile driveability predictions based on CPT interpretations. Presented at the International Conference On Soil Mechanics and Foundation Engineering. Alm, T., Hamre, L., 1998. Soil model for driveability predictions. Presented at the OTC 8835, Annual Offshore Technology Conference, Houston, Texas, p. 13.

groundhog.deepfoundations.axialcapacity.endbearing.unitendbearing_sand_almhamre(qt, sigma_vo_eff, multiplier=0.15, exponent=0.2, **kwargs)[source]¶

Calculates unit end bearing in sand according to Alm & Hamre.

Parameters:

qt – Total cone resistance (\(q_t\)) [\(MPa\)] - Suggested range: 0.0 <= qt <= 120.0
sigma_vo_eff – Vertical effective stress (\(\sigma_{vo}^{\prime}\)) [\(kPa\)] - Suggested range: sigma_vo_eff >= 0.0
multiplier – Multipier for unit end bearing (:math:``) [\(-\)] (optional, default= 0.15)
exponent – Exponent for unit end bearing (:math:``) [\(-\)] (optional, default= 0.2)

\[q_{b,sand} = 0.15 \cdot q_t \cdot \left( \frac{q_t}{\sigma_{vo}^{\prime}} \right)^{0.2}\]

Returns:

Dictionary with the following keys:

’q_b_coring [kPa]’: Unit end bearing for pile driving (\(q_{b,sand}\)) [\(kPa\)]
’q_b_plugged [kPa]’: Taken equal to the coring unit end bearing but tubular piles are not assumed to be driven in a plugged manner [\(kPa\)]
’plugged []’: Determines whether the pile is plugged (False for driving piles)
’internal_friction []’: Determines whether internal friction is taken into account (True by default for Alm & Hamre formula)

Reference - Alm, T., Hamre, L., 2001. Soil model for pile driveability predictions based on CPT interpretations. Presented at the International Conference On Soil Mechanics and Foundation Engineering. Alm, T., Hamre, L., 1998. Soil model for driveability predictions. Presented at the OTC 8835, Annual Offshore Technology Conference, Houston, Texas, p. 13.