ABSTRACT
Although there are numbers of ancient caves in the world, such as several world cultural heritage sites in China, Dunhuang Grottos, Yungang Grottos, Longmen Grottos and Maijishan Grottos, none of them has the momentum of amazement brought by the Longyou ancient caves, in scale, style or carving craft. In the view of engineering geology and rock mechanics the Longyou caves have many interesting characteristics, such as large scale, shallow burial depth, weak rock masses, inclined roof, peculiar sculpted pillars. Moreover, a part of the caves are very close to each other but not connected, caves at different levels are overlapped at top and bottom, and some caves are different very much in time-dependent deformations of their surrounding rocks. In fact the Longyou Caves provide a series of valuable full-scale field tests for scientific studies, for instance the different existing environments (under water, half under water, dry), different entrance types (vertical, horizontally flat), different deformation failure states (complete collapse, partial collapse, cracking in roof, cracking in pillars, no cracking in the cave), which are of great values in rock mechanics and engineering geology. Studies about the long term effects of water on rock deformation, rock mass quality and cave stability (Canacki 2007, Erguler & Ulusay 2009, Hawkins & McConnell 1992, Li 2006, Okubo et al. 2010, Vásárhelyi & Ván 2006) are still scarce. Moreover, our knowledge about long-term strength and stability of rock mass for hundreds of years is very poor and even less is known for thousands of years (Aubertin et al. 2000, Berest et al. 2005, Damjanac & Fairhurst 2010, Kemeny 2005, Tesarik et al. 2009, Zhang et al. 2011, Zhang et al. 2012). According to these two points only, the great value of academic and practical significance of the Longyou Caves becomes obvious.
