2025 Volume 90 Issue 830 Pages 679-690
This paper examines the trend of underground extensions of existing buildings in Japan using case studies from Shinkenchiku magazine (1983-2019). It proposes a conceptual framework for integrating new underground spaces with both old and modern structures, emphasizing engineering advances and disaster prevention. The findings reveal a shift towards less conservative designs that enhance visual presence and urban connectivity. The framework categorizes diverse approaches for analyzing spatial continuity and visual impact, identifying hybrid strategies for complex sites. This research offers a flexible guide for architects, planners, and policymakers, highlighting the significance of underground extensions in contemporary design.
