Bugfix/wrong stress stuff

[EleniSmyrniou]

Added the following for the norm calc:
Tests for n_method=True and n_method=False:
In the first test, we set n_method=True so that the stress exponent is forced to 0.5. We then compute the expected normalized tip resistance (Qtn) and friction ratio (Fr) using the same formulas and verify that the output arrays match our expectations (taking into account the clamping).

In the second test, we let the iterative procedure compute n (which for these inputs converges to 1.0). The expected values for Qtn and Fr are then computed using the resulting n.

Added the following unit tests for the effective stresses:

test_stress_calc_no_pwp_effect

• Scenario: The computed pore water pressure (pwp) is zero.
• Expected Outcome: Effective stress equals total stress.

test_stress_calc_positive_pwp

• Scenario: A positive pwp is computed that subtracts from the total stress.
• Expected Outcome: Effective stress is reduced by the pwp amount.

test_stress_calc_negative_pwp_clipped

• Scenario: The calculated pwp would be negative (indicating suction).
• Expected Outcome: Negative pwp values are clipped to zero, so effective stress remains equal to total stress.

test_stress_calc_negative_effective_clipped

• Scenario: The pore water pressure is so high that it would make the effective stress negative.
• Expected Outcome: Negative effective stress values are clipped to zero.

[sonarqubecloud]

Quality Gate passed

Issues
5 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[bramvandeneijnden]

correct changes to pore water pressure and calculation of Qtn and Fr