This morning, a photograph from the Expo Association captured a memorable moment that I recently had the privilege of experiencing. I met with representatives from various countries responsible for their respective Expo participation.

The impression they left was indelible: each one of them was exceptionally talented, earnest, and an exemplary figure of youth. Their collective brilliance left a lasting mark on me. Despite any potential gaps in our preparations on the Japanese side, I am wholeheartedly convinced that when such outstanding individuals from across the globe come together, pooling their diverse wisdom and insights, we can surely surmount even the most challenging of obstacles.

It’s a powerful reminder of the extraordinary potential that collaborative efforts hold on an international scale. Together, united in our diversity and shared goals, we can pave the way for meaningful progress and solutions.

#ExpoInnovation #GlobalLeadership #InternationalCollaboration #Expo2025 #CulturalDiversity #YoungTalent #GlobalSolutions #Teamwork #WorldExpo #InspirationalYouth #DiverseWisdom #UnityInAction

Recent reports indicate that Mexico 🇲🇽 has communicated its decision to withdraw from the Osaka Expo, stepping back from their planned construction of a TYPE-A pavilion. This development raises questions about the support and response of the Japanese Organizing Committee to participating countries.

If I were a member of the Japanese Organizing Committee, this would be my approach to engage and support our international participants:

1. “What challenges are you currently facing?”
2. “Is it a matter of interpretation, budget constraints, technical issues, or design?”
3. “If there are difficulties, let’s collaboratively work towards solving them as Japan, the host nation.”
4. “We, as the host, are fully committed to supporting the construction and participation of your pavilion.”

I firmly believe that a host country, armed with a warm and compassionate approach, can pave the way towards resolving such issues. Embracing our guests from abroad with understanding and support is essential to foster strong international relationships and successful global events.

#Expo2025 #GlobalPartnerships #JapanHost #InternationalCollaboration #CulturalExchange #MexicoWithdrawal #PavilionConstruction #ProblemSolving #GlobalEvents #InternationalSupport #CompassionateHosting

The URL for the original Japanese version of the paper:https://www.osaka-shisei.jp/cms/wp-content/uploads/2020/10/208-2tainosho.pdf

I am compelled to share profound insights from Emeritus Professor Yoshiaki Tainoshou of Kobe University regarding the geotechnical risks associated with the development of Yumeshima, the proposed site for Expo 2025.

6. Subsidence due to Consolidation of Alluvial and Diluvial Clay Layers

The professor articulates that clay, inherently soft and high in water content, tends to flatten and shrink due to the expulsion of interstitial water under the load of thick landfill layers, resulting in consolidation subsidence. Once subsided, these clay layers do not revert to their original state.

Consequently, only lightweight structures can be erected atop these layers. The City of Osaka (2017) anticipates a subsidence of over 10 cm, proposing elevated landfill as a countermeasure. However, as time progresses, further subsidence is anticipated to become a significant issue.

The Kansai International Airport has faced considerable challenges, not only with the alluvial clay layers but also with older diluvial clay layers that were not initially anticipated, resulting in subsidence exceeding predictions.

The City of Osaka’s “Osaka Port Landfill Project” (2014) acknowledges the issue of landfill layer consolidation subsidence. Still, the underlying alluvial and diluvial clay layers present a more substantial concern due to their extensive consolidation subsidence.

Located immediately below the landfill layers (see Figure 3), alluvial clay exhibits standard penetration test N-values between 2 to 5 (with values below 10 indicating softness), indicating a soft layer similar to paddy fields, prone to consolidation subsidence under the weight of the landfill.

Furthermore, with the alluvial clay layer being over 20 meters thick, there is a grave concern for subsidence beyond initial projections.

While the sand drain method has been considered to expedite consolidation subsidence (City of Osaka, 2017), Kansai International Airport experienced greater-than-expected subsidence despite this method.

Beneath the alluvial clay layer lies an older diluvial clay layer (Ma12) (see Figure 3), exceeding 10 meters in thickness with N-values of about 4 to 5, denoting softness. The lack of anticipation for the consolidation subsidence of this layer was contributory to the predicament.

For the Yumeshima Expo and IR project site, unmitigated consolidation subsidence could result in residual ground subsidence exceeding 50 cm (City of Osaka, 2014), far surpassing the allowable residual subsidence.

Moreover, as the landfill layer also undergoes consolidation subsidence, many areas are expected to exceed the 50 cm threshold, jeopardizing the maintenance of the planned ground level.

This consolidation subsidence could lead to a disconnect between buildings and ground, and coastal areas may see dikes subside, potentially failing to serve their intended purpose, arguably making it the most significant concern for the Expo and IR project development.

Additionally, landfill operations are slated to conclude a year before the Expo (City of Osaka 2017), potentially hindering adequate compaction of landfill materials.

Potential countermeasures such as sand compaction piles, piling, ground improvement (solidification, etc.), and deep mixing methods are under consideration, but no concrete plans have been presented.

Moreover, the assumption that consolidation subsidence occurs uniformly is not guaranteed, and long-term predictions over a decade are extremely challenging to ascertain through laboratory experiments due to parameter limitations.

In essence, the extent of actual subsidence remains uncertain until the landfill is completed, illustrating that the issue of consolidation subsidence remains unresolved to this day.

#GeotechnicalEngineering #YumeshimaDevelopment #Expo2025 #InfrastructureRisk #LandfillSubsidence #SoilConsolidation #CivilEngineering #UrbanDevelopment #EnvironmentalRisk #SustainableConstruction #EngineeringResearch #KobeUniversity