ABSTRACT
These elaborate a strength deteriorating of unloading rock mass, which is a breakthrough of providing suitable support form for roadway engineering. At present, numerous researches have studied unloading mechanics of rock mass. Taking ship lock engineering in three gorges as background, using the methods of rock mass acoustic tests and deformation tests in site, unloading disturbance and weakening degree of rock mass mechanical properties and value choice of mechanical parameters for rock mass were analyzed by Zhou et al. (2004). Through unloading experiments of granite and unloading physical model tests, Huang et al. (2008 & 2010) summarized that the mechanical properties of rock mass would be weaken to a certain proportion. Under the condition of unload. Changes of mechanical properties of rock mass in unloading process, such as slope or tunnel excavation, and underground mining, were studied by some researchers, such as Zhou (2008), Hu (2008), Wang (2012), Lei (2013), Hu (2012) et al.
