Settlement

groundhog.shallowfoundations.settlement.primaryconsolidationsettlement_nc(initial_height, initial_voidratio, initial_effective_stress, effective_stress_increase, compression_index, **kwargs)[source]

Calculates the primary consolidation settlement for normally consolidated fine grained soil.

Parameters
  • initial_height – Initial thickness of the layer (\(H_0\)) [\(m\)] - Suggested range: initial_height >= 0.0

  • initial_voidratio – Initial void ratio of the layer (\(e_0\)) [\(-\)] - Suggested range: 0.1 <= initial_voidratio <= 5.0

  • initial_effective_stress – Initial vertical effective stress in the center of the layer (\(\sigma_{v0}^{\prime}\)) [\(kPa\)] - Suggested range: initial_effective_stress >= 0.0

  • effective_stress_increase – Increase in vertical effective stress under the given load (\(\Delta sigma_{v}^{\prime}\)) [\(kPa\)] - Suggested range: effective_stress_increase >= 0.0

  • compression_index – Compression index derived from oedometer tests (\(C_c\)) [\(-\)] - Suggested range: 0.1 <= compression_index <= 0.8 (derived using logarithm with base 10)

\[\Delta z = \frac{H_0}{1 + e_0} C_c \log_{10} \frac{\sigma_{v0}^{\prime} + \Delta \sigma_v^{\prime}}{\sigma_{v0}^{\prime}}\]
Returns

Dictionary with the following keys:

  • ’delta z [m]’: Primary consolidation settlement for normally consolidated soil (\(\Delta z\)) [\(m\)]

Reference - Budhu (2011). Soil mechanics and foundation engineering

groundhog.shallowfoundations.settlement.primaryconsolidationsettlement_oc(initial_height, initial_voidratio, initial_effective_stress, preconsolidation_pressure, effective_stress_increase, compression_index, recompression_index, **kwargs)[source]

Calculates the primary consolidation settlement for an overconsolidated clay. This material is characterised using a compression index and a recompression index which can be derived from oedometer tests.

The settlement depends on whether the stress increase loads the layer beyond the preconsolidation pressure. If stresses remain below the preconsolidation pressure, the recompression index applies. If stresses go beyond the preconsolidation pressure, the compression index will apply for the increase beyond the preconsolidation pressure.

Parameters
  • initial_height – Initial thickness of the layer (\(H_0\)) [\(m\)] - Suggested range: initial_height >= 0.0

  • initial_voidratio – Initial void ratio of the layer (\(e_0\)) [\(-\)] - Suggested range: 0.1 <= initial_voidratio <= 5.0

  • initial_effective_stress – Initial vertical effective stress in the center of the layer (\(\sigma_{v0)^{\prime}\)) [\(kPa\)] - Suggested range: initial_effective_stress >= 0.0

  • preconsolidation_pressure – Preconsolidation pressure, maximum vertical stress to which the layer has been subjected (\(p_c^{\prime}\)) [\(kPa\)] - Suggested range: preconsolidation_pressure >= 0.0

  • effective_stress_increase – Increase in vertical effective stress under the given load (\(\Delta sigma_{v}^{\prime}\)) [\(kPa\)] - Suggested range: effective_stress_increase >= 0.0

  • compression_index – Compression index derived from oedometer tests (\(C_c\)) [\(-\)] - Suggested range: 0.1 <= compression_index <= 0.8

  • recompression_index – Recompression index derived from the unloading step in oedometer tests (\(C_r\)) [\(-\)] - Suggested range: 0.015 <= recompression_index <= 0.35

\[ \begin{align}\begin{aligned}\Delta z = \frac{H_0}{1 + e_0} C_r \log_{10} \frac{\sigma_{v0}^{\prime} + \Delta \sigma_v^{\prime}}{\sigma_{v0}^{\prime}}; \ \sigma_{v0}^{\prime} + \Delta \sigma_v^{\prime} < p_c^{\prime}\\\Delta z = \frac{H_0}{1 + e_0} \left( C_r \log_{10} \frac{p_c^{\prime}}{\sigma_{v0}^{\prime}} + C_c \log_{10} \frac{\sigma_{v0}^{\prime} + \Delta \sigma_v^{\prime}}{p_c^{\prime}} \right); \ \sigma_{v0}^{\prime} + \Delta \sigma_v^{\prime} > p_c^{\prime}\end{aligned}\end{align} \]
Returns

Dictionary with the following keys:

  • ’delta z [m]’: Primary consolidation settlement for the overconsolidated soil (\(\delta z\)) [\(m\)]

../_images/primaryconsolidation_settlement.png

Cases for calculating the primary consolidation settlement

Reference - Budhu (2011). Soil mechanics and foundation engineering