Geomechanics models

This

geos.geomechanics.model.MohrCircle module

MohrCircle module define the Mohr’s circle parameters.

Inputs are a 6 component stress vector, a circle id, and the mechanical convention used for compression. The class computes principal components from stress vector during initialization. Accessors get access to these 3 principal components as well as circle center and radius.

To use the object:

from processing.MohrCircle import MohrCircle

# create the object
stressVector :npt.NDArray[np.float64]
circleId :str
mohrCircle :MohrCircle = MohrCircle(circleId)

# either directly set principal components (p3 <= p2 <= p1)
mohrCircle.SetPrincipalComponents(p3, p2, p1)
# or compute them from stress vector
mohrCircle.computePrincipalComponents(stressVector)

# access to members
id :str = mohrCircle.getCircleId()
p1, p2, p3 :float = mohrCircle.getPrincipalComponents()
radius :float = mohrCircle.getCircleRadius()
center :float = mohrCircle.getCircleCenter()
class geos.geomechanics.model.MohrCircle.MohrCircle(circleId)[source]

Bases: object

Compute Mohr’s Circle from input stress.

Parameters:

circleId (str) – Mohr’s circle id.

computePrincipalComponents(stressVector)[source]

Calculate principal components.

Parameters:

stressVector (npt.NDArray[np.float64]) – 6 components stress vector Stress vector must follow GEOS convention (XX, YY, ZZ, YZ, XZ, XY)

getCircleCenter()[source]

Compute and return Mohr’s circle center from principal components.

getCircleId()[source]

Access the Id of the Mohr circle.

Returns:

Id of the Mohr circle

Return type:

str

getCircleRadius()[source]

Compute and return Mohr’s circle radius from principal components.

getPrincipalComponents()[source]

Get Moh’s circle principal components.

setCircleId(circleId)[source]

Set circle Id variable.

Parameters:

circleId (str) – circle Id.

setPrincipalComponents(p3, p2, p1)[source]

Set principal components.

Parameters:

  • p3 (float) – first component. Must be the lowest.

  • p2 (float) – second component.

  • p1 (float) – third component. Must be the greatest.

geos.geomechanics.model.MohrCoulomb module

MohrCoulomb module define the Mohr-Coulomb failure envelop class.

Inputs are the rock cohesion (Pa) and the friction angle (°). 2 methods allow to compute either shear stress values according to normal stress values, or the failure envelope including normal stress and corresponding shear stress values.

To use the object:

from processing.MohrCoulomb import MohrCoulomb

# create the object
rockCohesion :float = 1.5e9 # Pa
frictionAngle :float = 10 # degree
mohrCoulomb = MohrCoulomb(rockCohesion, frictionAngle)

# compute shear stress values according to normal stress values
normalStress :npt.NDArray[np.float64] = np.linspace(1e9, 1.5e9)
shearStress :npt.NDArray[np.float64] = mohrCoulomb.computeShearStress(normalStress)

# compute the failure envelope including normal stress and corresponding shear
# stress values
# ones may also define minimum normal stress and the number of points
normalStressMax :float = 1.5e9
normalStress, shearStress = mohrCoulomb.computeFailureEnvelop(normalStressMax)
class geos.geomechanics.model.MohrCoulomb.MohrCoulomb(rockCohesion, frictionAngle)[source]

Bases: object

Define Mohr-Coulomb failure envelop.

Parameters:

  • rockCohesion (float) – rock cohesion (Pa).

  • frictionAngle (float) – friction angle (rad).

computeFailureEnvelop(stressNormalMax, stressNormalMin=None, n=100)[source]

Compute the envelope failure between min and max normal stress.

Parameters:

  • stressNormalMax (float) – Maximum normal stress (Pa)

  • stressNormalMin (float | None, optional) –

    Minimum normal stress. If it is None, the envelop is computed from the its intersection with the abscissa axis.

    Defaults to None.

  • n (int, optional) – Number of points to define the envelop.

  • 100. (Defaults to)

Returns:

failure envelop coordinates where first element is the abscissa and second element is the ordinates.

Return type:

tuple[npt.NDArray[np.float64], npt.NDArray[np.float64]]

computeShearStress(stressNormal0)[source]

Compute shear stress from normal stress.

Parameters:

stressNormal0 (float | npt.NDArray[np.float64]) – normal stress value (Pa)

Returns:

shear stress value.

Return type:

float | npt.NDArray[np.float64])