Effect of fines on liquefaction resistance of sand
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Effect of fines on liquefaction resistance of sand Asskar Janalizadeh Choobbasti1 · Hediyeh Selatahneh2 · Mehrdad Karimi Petanlar1 Received: 20 February 2020 / Accepted: 10 July 2020 © Springer Nature Switzerland AG 2020
Abstract To evaluate the effect of non-plastic fines on liquefaction resistance of Babolsar sand, a series of undrained static and cyclic triaxial tests alongside a series of numerical analysis were carried out. The cyclic triaxial tests were conducted in stresscontrolled conditions with 1 Hz frequency at 0.35 constant cyclic stress ratio for 50 kPa and 0.25 for 100 and 200 kPa confining pressures. The samples contained 0%, 10%, 20%, 30% and 40% of fine grains. The numerical analysis was performed by a finite difference method, and Finn’s constitutive model was applied to investigate the liquefaction resistance of the mixtures. The tests’ results showed that the number of cycles leading to liquefaction of a sand–silt mixture decreases after increasing fine-grained percentage. Poorer performance in compression and better performance in tension was observed in this situation. The test outcomes also showed that dominant behavior of the mixtures changes from sand to silt at 20% fines content. It was observed from the test results and the numerical analysis that in low percentages of silt, the behavior of the sand–silt mixture is similar to those of the clean sand sample. But by increasing silt, the mixture’s behavior becomes more dependent on contacts between fine and granular particles. The concept presented by Thevanayagam was used to check the contacts between fine and coarse particles. It was also observed that the Finn constitutive model is in good consistency with the test results as long as the behavior of the sand is dominant in the mixture. Keywords Liquefaction · Babolsar sand · Firoozkooh silt · Cyclic triaxial test · Static triaxial test · FLAC software List of symbols emin Minimum index void ratio emax Maximum index void ratio B Pore pressure parameter N Number of cycles to cause liquefaction 𝜎3′ Consolidation stress VT Total volume of soil sample Gs Specific gravity of soil fc Fines content Rd Size disparity Dr Relative density CSR Cyclic stress ratio
eskeleton Sand skeleton void ratio e∗ Intergranular contact index void ratio e∗f Equivalent interfine void ratio 𝜌W Density of water M Mass of soil Mf Mass of fines e Void ratio ϒmin Maximum index unit weight ϒmax Minimum index unit weight D50 Mean grain size
* Mehrdad Karimi Petanlar [email protected]
One of the most complex topics in geotechnical engineering is liquefaction phenomenon [1]. Since the notable damage caused by liquefaction during the 1964 Niigata earthquake and Alaska earthquake, many researchers have begun investigating different aspects of liquefaction [2, 3]. Many modern structures built by humans were collapsed during this earthquake without any damage inflicted onto the structure. The matter highlighted the importance of focusing on the problem of liquef
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