Victory Village- DSM Ground Improvement to Mitigate Lateral Spreading of Liquefiable Soils on Sloping Topography-PPT Presentation

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Victory Village is a 54-unit, 51,000-square-foot residential development in Fairfax, California, consisting of two- to three-story buildings. The site occupies a slopewash-filled valley surrounded by mountain bedrock, which dips beneath the property. Subsurface conditions included very loose to loose clayey sands with silts and gravels, a shallow water table, and a thin, approximately five-foot non-liquefiable crust. The project’s seismic design considered a peak ground acceleration of 0.55g and a magnitude 7.4 earthquake.<br /><br />The primary geotechnical challenges were supporting building foundations with limited settlement, mitigating soil liquefaction and surface ejecta, and resisting lateral spreading. Deep foundations were considered but rejected as uneconomical: piles would need to transfer loads and seismic effects to bedrock, while lateral spreading could impose large forces on battered piles.<br /><br />The selected solution was deep-soil-mixing (DSM) ground improvement. Cementitious materials were mixed with native soil to form non-liquefiable blocks arranged in a grid beneath the buildings. The DSM grid was designed to transfer building loads toward bedrock, constrain and redistribute seismic effects within the soil, and engage the improved soil mass to resist lateral spreading.<br /><br />Design evaluations included pseudo-static analysis, PLAXIS finite-element modeling for global stability under seismic thrust, and fully nonlinear OpenSees dynamic modeling. Construction involved triple-auger mixing, sequenced grid installation, and verification activities including load testing and core sampling.<br /><br />The project demonstrates the use of DSM ground improvement as an integrated alternative to deep foundations for supporting buildings and addressing liquefaction and lateral-spreading hazards on sloping, seismically active sites.

Keywords

Victory Village

deep-soil-mixing

ground improvement

liquefaction mitigation

lateral spreading

seismic design

Fairfax California

geotechnical engineering

building foundations

earthquake hazard