ABSTRACT
Relatively good engineering geological and hydrogeological conditions, e.g. rock mass structure of the surrounding rock is complete (no large-scale structural plane), ground water table is stable (no intensive groundwater migration) and seismicity is weak (no high-intensity earthquake occurs since 1513), form the basis of the long-term stability of Longyou Rock Caverns (Yang et al. 2000; Li et al. 2005; Zhu et al. 2008). In addition, the speciallydesigned structures of the caverns, e.g. roofs of these caverns are paralleled to the bedding layer of surrounding rock, the connection segments between roofs and rock pillars are in shape of fish tail (Li et al. 2007; Li et al. 2005), also make great contributions to their long-term stability. Another significant factor is the long-term immersion in
1 INTRODUCTION
Longyou Rock Caverns located at the north shore of Qu River, Zhejiang Province, China, are a group of shallow-embedded caverns buried in Cretaceous argillaceous siltstone layers. Their massive excavation volumes, well-designed structures and beautifully-carved patterns endow themselves important historical, scientific and artistic values. The first batch of caverns were excavated in the Western Han Dynasty (206 B.C.–A.D. 24) according to the researches of archaeologists. These caverns had been submerged for around 2000 years until 1992, they were brought to light again and immediately arouse the interests of engineering geologists. Former research interests concern the following topics: 1) how could these caverns stay stable in their 2000-year history considering their shallow cover depth, large span and limited amounts of rock pillars; 2) after their rediscovery
water which mechanically reduces the tensile stress in surrounding rock and chemically slows the weathering rate of it (Li et al. 2010; Li et al. 2005).
