Earthquake-induced large deformations and failure mechanisms of silty sands in sloped ground conditions

Assessment of undrained cyclic resistance of sand with non-plastic fines under sustained shear stress using a critical state interpretation

“…However, there are many geotechnical applications, such as beneath earth dams, embankments, slopes and nearbuilding structures, where soil elements are subjected to an initial static shear stress (τ stat ) on the horizontal plane, which can modify the CRR and the failure modes of silty sands. Case histories of liquefaction-induced failure in clean sands and silty sands in the presence of an initial static shear stress during several earthquakes were reported by Chiaro and Koseki (2013), Kokusho (2020), Diano (2016), andWei et al (2018) but only a limited number of studies concern laboratory investigation of undrained cyclic behaviour of silty sands with different f c considering an initial static shear effect (Kokusho 2020;Pan et al 2020Pan et al , 2021Porcino and Diano 2016;Porcino et al 2018b;Tomasello and Porcino 2023;Wei and Yang 2019b;Wei et al 2023;Zhou et al 2023).…”

“…Similarly to clean sands, a correction factor K α was introduced for silty sands to characterise the effect of α on cyclic resistance, based on undrained cyclic triaxial tests (Wei and Yang 2019b;Wei et al 2023) and undrained cyclic simple shear tests (Tomasello and Porcino 2023). Based on undrained cyclic simple shear tests performed on undisturbed low-plasticity silty sand (f c = 40%, 70%) recovered from a site where liquefaction phenomena occurred after the 2012 Emilia Romagna earthquake (Italy), Porcino and Diano (2016) discovered that static shear stress (α = 0.10) negatively affects the liquefaction potential and consequently results in a decrease in cyclic resistance.…”

Energy-Based Pore Pressure Generation Models in Silty Sands under Earthquake Loading

“…Mixtures of Ticino sand with non-plastic fines were tested, namely, 90% sand/10% fines (TS10), 80% sand/20% fines (TS20), 70% sand/30% fines (TS30), and 60% sand/40% fines (TS40). Since the f thre value for the Ticino-silt mixture was found to be 24.5% [22], the present study takes into account both cases of f c < f thre and f c > f thre . Emilia Romagna's silty sand (ES40) consists of 40% low-plasticity fines (with a plasticity index less than 8).…”

“…These controversial findings suggest that the influence of fines is still a challenging topic and more studies are needed. The different experimental evidences can be explained to some extent by considering the different state variables used in the analysis of test results and the complex types of intergrain contacts, which depend on the fines content, the plasticity of fines, the grading features of host sand and fines, and particle shape [19][20][21][22].…”

“…Thus, the necessary procedures are frequently complex and unreliable [43][44][45]. For this reason, the adopted methodology generally consists of relating earthquake magnitude to the equivalent number of loading cycles [22,[46][47][48] even if these correlations often result in inaccurate estimates of the number of equivalent loading cycles [44]. On the other hand, the energy-based models overcome this drawback, relating R u to the cumulative energy dissipated per unit volume of soil (W) without the need to convert ground motion into uniform cycles.…”