Study on the structural stability of the blistering of the Vajrasana pagoda in Miaozhan Temple, Kunming, Yunnan, China

Abstract

AbstractThe Vajrasana pagoda is the only stone overturned-bowl pagoda among the 12 existing Vajrasana pagodas built during the Ming Dynasty in the Guandu District, Kunming City, Yunnan Province, China. The location of the Vajrasana pagoda is in an earthquake-active zone with high rainfall. The small towers on the upper side were damaged by an earthquake in 1696 AD. All the stone statues representing religious figures have blistered and may peel further due to external factors, such as sunshine and rainfall. To assess the structural stability of the blistering, we employed 3D laser scanning to record the building’s geometry over time. Subsequently, X-ray diffraction, thin section identification, and uniaxial compressive strength tests were conducted on the pagoda stone to reveal physical–mechanical properties. Finally, a finite element model was constructed to analyze stress and displacement in various scenarios. The results revealed: (1) Blistering on the pagoda stone is secure under self-gravity and heavy rainfall. (2) In an earthquake, the upper blistering near the junction of two sides may break. (3) A 3D color deviation model of blistering over 8 months showed peeling and bursting within the finite element simulation's predicted range. This research offers a fresh approach to stone tower preservation, shifting from reactive measures to proactive prevention and prediction. These methods and concepts hold relevance for stone towers in similar high-rainfall and earthquake-prone regions.