Automating the analysis of 160 ground improvement designs with PLAXIS Featured

WSP, using the automation capability of PLAXIS together with Python, found the right ground improvement solution, from more than 160 different design combinations, for the Stephenson Avenue phase 2 exntension in Perth, Western Australia. 

The Stephenson Avenue phase 2 extension is a $165 million complex road infrastructure project where site conditions showed varying ground settlement rates were a major roadblock. The extension includes a traffic bridge that crosses the busy Mitchell Freeway (built in the early 1980s) with site ground improvement due for completion in 2024. Data collected by InSAR over a six-year period up to 2020 revealed that although the freeway was built 40 years ago, the site at the proposed road extension is still settling at varying rates of up to a few millimetres a year. “If the approach embankments and bridge ramps were built without ground improvement, the peat would continue to settle significantly,” says Shan Tom Wong, Principal Geotechnical Engineer at WSP Australia.

The WSP team selected the ground improvement method of installing concrete columns through to the competent stratum below the peat layer. Three crucial design variables – peat thickness, embankment height, and concrete column spacing – resulted in a whopping 160 design combinations to be analysed, a huge task to build this many models one by one.

WSP decided to use PLAXIS 2D and 3D modelling software together with Python, which enabled them to (1) design and perform and automate advanced finite element soil and rock deformation analysis and (2) efficiently automate the modelling of all 160 different design combinations.

Initially, 160 2D axisymmetric numerical models in PLAXIS were created and the Python wrapper for the PLAXIS API (Application Programming Interface) was used along with the Linear Search or Brute Force Algorithm. Together with forty-year estimated settlements data files for graph plotting enabled the team to automate visualization and inteprete easily the results, as a preliminary decision before more detailed analyses using PLAXIS 3D were conducted, including additional elements such as a retaining wall, to simulate lateral movements of the ground and wall over time.  The automation contributed to saving time and cost throughout the project.

The WSP geotechnical team agreed that using PLAXIS together with Python could have many other potential applications, especially in the repetitive design tasks space, to help save time and cost across infrastructure projects.

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