Dear Bekir Firincioglu,

Static liquefaction is all related to critical hydraulic gradient. when the submerge unit weight of soil become equal to unit weight of water then their might be possibility of liquefaction. Its a critical analysis of fully saturated soil under a steady seepage. You could collect data regarding seepage and hydraulic gradient. However its a very important parameter to irrefutable the safety of earthen dams, earth embankment ect.

Interesting and important problem

Good initiative

Dear Bekir Firincioglu,

Static liquefaction is all related to critical hydraulic gradient. when the submerge unit weight of soil become equal to unit weight of water then their might be possibility of liquefaction. Its a critical analysis of fully saturated soil under a steady seepage. You could collect data regarding seepage and hydraulic gradient. However its a very important parameter to irrefutable the safety of earthen dams, earth embankment ect.

Nice Contribution

Thank you all for your responses. I am open to any kind of information related with static liquefaction and its measurement with triaxial apparatus.

Liquefaction is a phenomenon caused by the brittle failure of soils caused by the increase of pore water pressure. How you reach this state will provide the suffix. Initially liquefaction was defined after observing failures caused by seismic event, however, you can reach the liquefaction 'state' by means of static or quase static loading (i.e. static or flow liquefaction). By strict definition I guess you could liquefy any soil but we know that clayey soils are less susceptible to liquefaction due to van der waal forces among others. In short, it looks like you are looking for a experimental approach to liquefaction. My recommendation is to look in the literature for the characteristics of soils prone to liquefaction (fines content, grain size distribution, compacity etc) and then source locally a soil that meets as close those characteristics. Then you might want to measure the critical state line of your soil. It should take you a couple of months to get there, getting those Triaxials done are going to be an excellent learning exercise. Keep us updated on how you progress. Cheers

Static liquefaction is a kind of material instabilities. It is an example of the diffuse mode of failure. It may occur due to increase of pore water pressure but also it may occur as a drop of shear strength in dry loose sand. Due to liquefaction failure can occur spreading over large mass of soil deposits, commonly referred to as flow slides. Many researchers haave been dealing with this phenomenon, e.g. Felix Darve, Jerry Yamamuro and Poul Lade, Ronaldo Borja, Natalie Boukpeti together with Andrew Drescher and Zenon Mróz and others including myself.

You can check a part of numerous bibliography by referring to the papers below:

Article Technical Notoe: Prediction of Static Liquefaction by Nor Sa...

Article Constitutive models for predicting liquefaction of soils

Best regards

Krzysztof Sternik

Thank you all for your answers. How much time does it take on average to perform triaxial test for static liquefaction? I am assuming that I will be performing CU tests on sands?

Also, I am planning to build some physical scaled models to observe the mechanism of static liquefaction. Any thoughts?

Thanks again.

Liquefaction in quicksand is generated by applying upward gradient (excess pore pressure). During cyclic loading, the excess pore pressure is triggered by "two way loading", when the zero stress axis is crossed. Also, liquefaction can be generated by a monotonic load, if the foundation (or specimen) was disturbed (or "pre-loaded") to be more sensitive to liquefaction. Thus, "static liquefaction" could be caused by a "disturbed soil" state.

In our research, we observed the physical patterns governing liquefaction. We are able to reduce and increase soil stiffness. We can disturb and recover the "initial" stress path for both drained and undrained specimens. We can control the size, position and shape of individual stiffness hysteresis loops in both triaxial tests, and foundation prototypes. Surprisingly, sand stiffness hysteresis loops behave exclusively as functions of deformation history. Stiffness does not behave as a function of stress, it behaves as a function of strain (deformation history).

Fully automated triaxial controlling the stress path cannot fill the gap in the literature related to liquefaction. Stress paths are the output, not the input. Liquefaction is dependent exclusively on deformation history, and deformation amplitudes. The physical phenomenon is fundamentally governed by deformation history, and can be controlled only if deformatio (not stress) input is controlled. This is the big gap in contemporary litterature - a phenomenon behaving as a function of deformation, is treated as a function of stress.

If you'd like to control stiffness of specimens, you'll have to manipulate deformation history. Use deformation as input, measure stress as the output. Treat stress as a function of strain. This will provide real life control over real life specimens. This will resolve paradoxes and anomalies. Alas, it's not conventional. Nevertheless, convention fails to solve a lot of dynamic problems.

The gap in literature is mentioned by P.J.Yoder and R.Dobry (early work). Also, frictionless triaxial apparatus has unique testing options - liquefied specimen do not lose cylindrical shape (no shear rupture or bulging). Thus, frictionless triaxial allows to test "disturbed" specimens. To liquefy and drain after liquefaction many times, then test peak strength at many densities, pull the disturbed specimen back to initial length, etc... The mechanical properties of the frictionless triaxial apparatus provide access to a whole new paradigm of cyclic testing procedures. During which, conventional models collapse, and new data patterns can be observed.

Not quite answering the question, but the following paper could possibly lead to a better understanding:

"Undrained Monotonic Behaviour of Liquefied Pumiceous Sands" Orense. R. 2019 PCEE April 2019 Auckland

Static liquefaction of a soil deposit might occur even when the deposit is not fully saturated. You might want to investigate what are the thresholds in terms of soil grain size distribution and shape, slope gradient, hydrologic/hydraulic conditions that trigger such behaviour.