Effect of lattice-shaped ground improvement geometry on seismic response of liquefiable soil deposits via 3-D seismic effective stress analysis

This manuscript presents the results of an investigation into the effect of various configurations of lattice-shaped soil improvement on the seismic response of liquefiable soil deposits using 3-dimensional seismic effective stress analysis with an advanced constitutive model for sandy soils. The particular problem considered is based on the soil stratigraphy of the down-hole seismic array site at Port Island, Kobe, and the input ground motion recorded at this location in the 1995 Kobe earthquake. Nine different soil improvement geometries are considered by changing the number and wall thickness of improved soil cells for the site. For each of the different improvement geometries, the salient features of the ground response are presented, including: (i) peak surface acceleration, displacement and response spectra; (ii) excess pore pressure, stress path, and stress–strain response of the enclosed unimproved soil; and (iii) peak deformations of the improved soil, among others. Finally, the obtained results for all considered improvement geometries are summarised based on improved area ratio (RIA); improvement length-to-height ratio (RLH); and normalised construction cost (RCC). The results demonstrate the complexity of the seismic response and interaction between improved and enclosed liquefaction-susceptible native soils when subjected to strong ground shaking; the dependence on both the improved area and length-to-height ratios; as well as the wealth of insightful information that advanced effective stress analyses can provide for assessing the seismic response of such soil deposits.

► Effect of various geometries on 3-D seismic response of liquefiable soils examined.
► Advanced constitutive model for sandy soils employed based on state index.
► Insight into the complex response and interaction of improved and unimproved soils.
► Results summarised as a function of improved area ratio and improved length-to-height ratio.