pyvstress package

Submodules

pyvstress.exceptions module

exception pyvstress.exceptions.ParamError

Bases: Exception

pyvstress.soil module

class pyvstress.soil.AbsPoint(z=0, total_stress=0.0, pore_pressure=0.0, effective_stress=0.0, layer_index=0)

Bases: object

Abstract point class

__init__(z=0, total_stress=0.0, pore_pressure=0.0, effective_stress=0.0, layer_index=0)

In most cases initilize with only the depth of the point and the rest are computed based on the location of the point in the soil layer.

Parameters:

• z (float) – distance below the ground surface.

• total_stress (float) – vertical total stress at the point

• pore_pressure (float) – porewater pressure at the point

• effective_stress (float) – vertical effective stress at the point

• layer_index (int) – index of the layer in which the point lies.

property z

Return the depth of the point from the ground surface.

property total_stress

Return the vertical total stress at the point.

property pore_pressure

Return the porewater pressure at the point.

property effective_stress

Return the vertical effective stress at the point.

property layer_index

Return the index of the layer in which the point lies

is_in(layer)

Check if the point is within a layer. Points lying at the top of the layer is not considered within the layer. A separate special case is required for point lying at the bottom of the soil layer. layer: instance of layer object

class pyvstress.soil.Point(z=0.0, layer_index=0)

Bases: AbsPoint

Class for Points

__init__(z=0.0, layer_index=0)

In most cases initilize with only the depth of the point and the rest are computed based on the location of the point in the soil layer.

Parameters:

• z (float) – distance below the ground surface.

• total_stress (float) – vertical total stress at the point

• pore_pressure (float) – porewater pressure at the point

• effective_stress (float) – vertical effective stress at the point

• layer_index (int) – index of the layer in which the point lies.

class pyvstress.soil.SoilLayer(layer_thickness, gamma_bulk, gamma_sat=None, **kwargs)

Bases: object

Class for soil layers, with layer properties.

__init__(layer_thickness, gamma_bulk, gamma_sat=None, **kwargs)

Parameters:

• layer_thickness (float) – thickness of the layer.

• gamma_bulk (float) – bulk unit weight of the layer.

• gamma_sat (float) – saturated unit weight of the layer.

• phi (float) – slope of the Mohr-Coulomb failure envelope, an effective stress strength parameter.

• c (float) – intercept of the Mohr-Coulomb, an effecitve stress strength parameter.

• su (float) – undrained shear strength, a total stress strength parameter.

• fc (float) – fines content, will be used for liquefaction triggering analysis.

• soiltype (str) – soil description, to be used in correlations.

Use bulk unit weights for soil layers above the water table and saturated unit weights for layers below the water table

property thickness

Depth to the top of the layer

property gamma_bulk

Bulk unit weight of the layer

property gamma_sat

Saturated unit weight of the layer

property ztop

Return the depth of the top of the layer from the ground surface.

property zbot

Return the depth of the bottom of the layer from the ground surface.

property sat

Return if the saturation status of the layer

property overburden

Return the total vertical stress at the top of the layer.

calc_inlayer_vertical_stress(depth)

Return total stress at a specified point within a layer depth: float, depth of the point below the top of the surface

class pyvstress.soil.SoilProfile(layers=[], zw=0, q=0.0, gammaw=62.4)

Bases: object

__init__(layers=[], zw=0, q=0.0, gammaw=62.4)

Parameters:

• layers ([]) – a list of :class: SoilLayer objects.

• zw (float) – depth to groundwater, positive depth below groundlevel, negative depths above groundlevel

• surcharge (float) – surface surchage load

• gammaw (float) – float, unit weight of water, use consistent units, the units of the the computations is the units of gammaw

index(layer)

add_layer(layer)

Add a :class: SoilLayer to the end of the :class: SoilProfile

Parameters:

layer –

class:

SoilLayer instance

insert(index, layer)

Insert a SoilLayer object into a list of SoilLayer objects in SoilProfile object.

property layers

property zw

property saturation_zone

property ztops

Return a list of depth to the top of the layers

property zbots

Return a list of depth to bottom of the layers

property surcharge

Return the surface surchage value

Returns:

external surcharge on the top of the soil profile

Return type:

float

property gammaw

Return the unit weight of water

Returns:

unit weight of water

Return type:

float

split_layer(z)

Split the layer into two layers if the depth z is not a layer boundary. i.e. ztop < z < zbot

set_saturation_flag()

Set a Boolean Flag, True if the layer is beneath the water table

update_profile()

Split the profile at the groundwater level and compute overburden stress at the top of each layer.

water_stress()

If there is standing water then compute the total stress from the water on the soil profile.

update_layer_depths()

Update the depths to top of the layers

vertical_stresses(pts)

Compute total vertical stress, pore pressure, and effective stress at the specified points, depth below the ground surface

Parameters:

pts – list of Point instances, depth below the surface at which stress is computed

calc_total_stress(pt)

Compute total stress at the specified point, depth below the ground surface

Parameters:

pt (Point) – Point instance

calc_pore_pressure(pt)

Compute pore pressure at the specified point, the water pressure with respect to the groundwater table

Parameters:

pt (Point) – Point instance

assign_layer_index(pts)

Assign layer index to the points.

Parameters:

pt (Point) – [] of Point object

get_params(pts, keylist)

Collect and return attribute values of layer object corresponding to point layer indices

Parameters:

• pts – [] of Point objects

• keylist – [] of class attributes as string class attributes for which the values are required

assign_params(pts)

Assign soil parameters of the layer in which the point falls to the point.

Return a dictionary of soil parameters that are in addition to regular class attributes attrs_list = [“_layer_thickness”, “_gamma_bulk”, “_gamma_sat”, “_sat”, “_ztop”, “_zbot”, “_overburden”]

The layers must be assigned indices using assign_layer_index before assigning soil parameters using this method.

Parameters:

pts (Point) – [] of Point objects

pyvstress.utility_functions module

pyvstress.utility_functions.check_required(obj, list_params)

Check if given parameters are supplied to an object, if all the required parameters are found return True else raise an error.

Parameters:

• obj – object of the class for which to check for the list of parameters

• list_params – list of strings, a list of required parameters

pyvstress.utility_functions.calc_rankine_ka(phi)

Compute Rankines active earth pressure coefficient

Parameters:

phi (float) – Mohr-Coulomb phi parameter

pyvstress.utility_functions.calc_rankine_kp(phi)

Compute Rankines passive earth pressure coefficient

Parameters:

c (float) – Mohr-Coulomb c parameter

pyvstress.utility_functions.calc_active_earth_pressure(sigma, phi, c)

Active earth pressure using both phi and c

Parameters:

• sigma (float) – effective stress

• phi (float) – Mohr-Coulomb phi parameter

• c (float) – Mohr-Coulomb c parameter

pyvstress.utility_functions.calc_passive_earth_pressure(sigma, phi, c)

Passive earth pressure using both phi and c

Parameters:

• sigma – float effective stress

• phi – Mohr-Coulomb phi parameter

• c – Mohr-Coulomb c parameter

pyvstress.utility_functions.stress_profile_points(soil_profile, analysis_type='vertical')

Returns points for computing vertical stresses / lateral earth pressures for the soil profile.

Parameters:

• :class – SoilProfile soil_profile: SoilProfile object

• analysis_type (str) – either “vertical” or “lateral” vertical: assigns a point at the soil profile top, one point each at the layer boundaries, at the groundwater table if it is not the same as one of the layer boundaries, and one at the bottom of the soil profile. lateral: assigns a pont at the soil profile top, two points at each of the layer boundaries, a point at the groundwater table if it is not one of the layer boundaries, and one point at the bottom of the soil profile. Two points at the interior layer boundaries are required because the top layer and the bottom layer have different values of phi and c, which will result in different lateral stresses.

pyvstress.utility_functions.profile_vertical_stresses(soilprofile)

Return vertical stress with depth.

Parameters:

soilprofile – SoilProfile instance

pyvstress.utility_functions.profile_lateral_earth_pressures(soilprofile, use_c=True)

Return lateral stresses with depth

Parameters:

• soilprofile (SoilProfile) – SoilProfile instance

• use_c (bool) – To indicate if Mohr-Coulomb c should be used in the calculation of lateral earth pressures. If False only phi parameter will be used.

pyvstress.utility_functions.generate_regular_points(soil_profile, analysis_type='vertical', dz=0.5)

Generate a list of points within the soil profile layer.

Generate points, when possible, at equal intervals of dz. Points may not be dz apart near layer boundaries. Either one or two points are generated at internal layer boundaries based on whether the type of analysis involves vertical stresses, 1 point per boundary, or lateral stresses 2 points per boundary, one point for the layer above the layer boundary and one point for the layer below the boundary.

Parameters:

• soilprofile (SoilProfile) – SoilProfile object

• dz (float) – maximum separation distance between points

• analysis_type (str) – type of analysis either ‘vertical’ or ‘lateral’

Returns:

a list of Point objects, almost equally spaced over the soil profile

Return type:

[Point]

Module contents