Liquefaction mitigation for building clusters with drainage and densification
Journal
Acta Geotechnica
Series/Report No.
Acta Geotechnica
ISSN
1861-1125
1861-1133
Date Issued
2025-07-21
Author(s)
Dashti, Shideh
Abstract
Over the past years, ground densification and soil drains have been commonly used as countermeasures against the consequences of seismic soil liquefaction. However, the state-of-practice for designing such mitigation methods is typically for free-field conditions, without considering seismic soil–structure interaction (SSI) or structure–soil–structure interaction (SSSI). In this paper, three-dimensional (3D), fully-coupled, nonlinear finite element analyses are used to evaluate how the mitigation mechanism affects the seismic performance of adjacent, similar and dissimilar, inelastic, shallow-founded structures on liquefiable sites. A combination of densification with enhanced drainage under and around the entire footing is shown as the most effective strategy to notably reduce the mitigated foundation’s permanent settlement and tilt, regardless of building spacing. Enhanced drainage alone may reduce foundation’s average settlement, but it does not necessarily reduce tilt when near another structure. For the conditions evaluated, the presence of mitigation under one structure is shown to notably amplify the permanent tilt and possibly the flexural deflections of its unmitigated neighbor at shorter spacings, while having a minor impact on its settlement. On the other hand, this study utilizes a small suite of numerical simulations to examine the impact of ground motion characteristics on building engineering demands in both unmitigated and mitigated SSSI models at a spacing of 3 m, focusing on combined mitigation (i.e., densification and drainage). In general, increasing shaking intensity notably increases foundation settlements of both unmitigated and mitigated structures in SSSI models, whereas combined mitigation can effectively reduce the foundation tilts of mitigated structures, regardless of shaking intensity. Most importantly, the treated ground tends to amplify the neighboring unmitigated structure’s tilt. These results indicate that mitigation must be designed with extreme care in urban environments, with the goal of improving the overall performance at a systems level for the building as well as its neighbors.
Subjects
Centrifuge modeling
Finite element analysis
Ground densification
Liquefaction
Mitigation
Prefabricated vertical drains
Soil drains
Soil–structure interaction
Structure–soil–structure interaction
Urban mitigation
Publisher
Springer Science and Business Media LLC
Type
journal article