Insight into the Seismic Liquefaction Performance of Shallow Foundations

Equivalent-Linear Dynamic Stiffness of Surface Footings on Liquefiable Soil

“…Unless otherwise specified, the material properties of the surface layer employed in the following analyses are shear wave propagation velocity V s1 = 100, 250 m/s, Poisson's ratio v 1 The total thickness of the soil profile equals H/B 15, thus, the presence of bedrock does not affect the dynamic response of the footing. Accordingly, the parametric investigation is focused upon the effect of the thickness of the liquefied stratum, as well as the thickness and stiffness of the non-liquefiable surface crust (which should meet the bearing capacity and settlement requirements under gravity loading).…”

“…If this non-liquefiable surface "crust" exhibits adequate thickness and shear strength, it can prevent the seismic settlement accumulation and post-shaking bearing capacity failure. Recently, Karamitros et al [1][2][3] have developed a design approach for the performance-based design of shallow foundations on liquefiable soils. The design is based on the idea of a natural or artificial crust, which needs not extend over the whole depth of the liquefiable sand, in order to take advantage of the observed benefits of settlement reduction [4][5], as well as the seismic motion attenuation ("natural seismic isolation") due to the liquefiable soil below the crust.…”

Numerical Evaluation of Earthquake Settlements of Road Embankments and Mitigation by Preloading

“…In addition, the liquefaction induces settlements at the crest due to the combined action of the migration of the underneath foundation soil and the deformation of the road embankment itself. However, as expected, the development of excess pore pressure during the earthquake loading induces a shear strength degradation of the foundation soil which results in an accumulation of seismic settlements (Bouckovalas et al 1991;Liu and Dobry 1997;Elgamal et al 2002;Dashti et al 2010a;Dashti et al 2010b;Karamitros et al 2013). Furthermore, co-seismic displacements are almost identical to permanent displacements.…”

Shaking Table Studies on the Conditions of Sand Liquefaction

“…The maximum pore water pressure ratio under a building foundation can be calculated from equation (1) given by Karamitros et al (2013) ' , , v o ff σ Δ is the effective vertical stress in free field conditions. The maximum pore water ratio for the sand bed with a surcharge of 1.1 kPa as per equation (1) is 0.72.…”

“…Niigata earthquake of 1964 demonstrated the importance of liquefaction studies near to the existing buildings. The influence of building load on liquefaction potential was studied by many researchers (Karamitros et al, 2013;Liu and Dobry, 1997;Vaid et al, 2001;Yoshimi and Oh-Oka, 1975;Yoshimi and Tokimatsu, 1977). Rollins and Seed (1990) addressed the effect of soil structure interaction on liquefaction during earthquakes through shaking table and centrifuge model tests and suggested to include natural period of the building in analyzing the liquefaction resistance of the soil.…”