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SLIQ2D is a 2D computer program which calculates whether in a submerged slope such metastability points as mentioned above may occur or not, based on the slope geometry, the relative density and the material properties of the sand or silt. In case the calculated metastable area is sufficiently large, this may lead to liquefaction flow slide. A clear approval criterion (e.g. the minimum size of the metastable area that will lead to a liquefaction flow slide) cannot be given. A possibility is to perform a slope stability analysis (a simple slip circle analysis or a more advanced Finite Element analysis), in which a reduced (liquefied) shear strength (e.g. a friction angle of 5 degrees) is assigned to the sand layers that are metastable according to SLIQ2D.
The first DOS-version of the program was developed by Grondmechanica Delft in 1994, commissioned by Rijkswaterstaat. In 2009 a Windows-version was released, in which it was possible to distinguish (horizontal) soil layers with different properties. That later version has been implemented in D-FlowSlide. The theoretical background of SLIQ2D can be found in the Handboek Zettingsvloeiingen. Background information on the Windows version of the model and guidance with respect to the determination of the input parameters can be found in the User Manual of SLIQ2D.
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