Applications of Cement Stabilization for Mitigating Earthquake Disaster-Paper

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The paper reviews three cement-based soil stabilization methods used in Japan to reduce earthquake damage, particularly from soil liquefaction. This is important because loose, saturated sands can liquefy during earthquakes, while soft clay soils are vulnerable to settlement and instability. Historical port damage data indicate that damage associated with liquefaction can be many times greater than damage without it.

The <strong>Deep Mixing Method (DMM)</strong> stabilizes soil in place by mixing it with binder. Columns can be arranged as grids or blocks to strengthen foundations and limit liquefaction. Grid-type DMM protected a building foundation in Urayasu during the 2011 Tohoku earthquake, while nearby unimproved ground liquefied. A treated road embankment in Chiba also remained undamaged, unlike an adjacent untreated road. High-pressure injection DMM has likewise been used beneath an existing historic building where conventional mixing equipment could not operate.

The <strong>Premixing Method</strong> blends sand with a small amount of binder and additives before placing it as reclaimed ground or backfill. It prevents liquefaction and can reduce earth pressure on retaining structures. After the 1995 Kobe earthquake, treated backfill was installed behind a damaged quay wall.

The <strong>Lightweight Treated Soil Method</strong> mixes dredged soil with binder and foam or lightweight beads. Its low density and strength reduce settlement and earth pressure. At Kobe Port, it was used as replacement backfill behind a displaced quay wall.

The examples demonstrate that these methods can protect buildings, roads, and port facilities by improving soil strength, preventing liquefaction, and reducing loads on structures. The paper concludes that cement stabilization is broadly effective for earthquake disaster mitigation and has potential for further applications.

Keywords

soil stabilization

cement-based methods

deep mixing method

premixing method

lightweight treated soil

earthquake mitigation

soil liquefaction

port infrastructure

retaining structures

earthquake damage reduction