A layered liquefiable soil column on an elastic half-space, shaken from below. The OpenSees model uses SSPquadUP elements for coupled soil and pore water and the PM4Sand constitutive model for the liquefiable layers, and the notebooks run it as a DesignSafe job and plot accelerations, response spectra, peak-response profiles, and the excess pore pressures that signal liquefaction. The model and plotting scripts come from the University of Washington’s freeFieldJupyterPM4Sand example by the Arduino group; the dapi version runs from any machine through the opensees-s3 app on Stampede3, one core of one node on skx-dev, and the solution also shows the no-allocation opensees-express variant.
The example ships as a pair. The exercise poses the run as four TODOs with hints, translate the inputs, submit and monitor, collect the recorders, plot, and the solution is the executed answer.
Exercise: 
Solution:
Files¶
| File | Role |
|---|---|
DS_PM4Sand_FreeField_Exercise.ipynb | The run as four TODOs with hints |
DS_PM4Sand_FreeField_Solution.ipynb | The executed answer |
N10_T3.tcl | The soil column model, gravity stages then dynamic analysis |
velocity.input | The input motion |
plotAcc.py, plotProfile.py, plotPorepressure.py, respSpectra.py | Plotting, each taking the results folder as its argument |
interactiveplot.py | Time-slider widgets for pore pressure and the deforming profile, on a live kernel |
The tcl declares its input motion with the modern explicit timeSeries form; the legacy inline form in the original is rejected by current OpenSees, which left recorders empty.