Comparative analyses of model tests and in-situ monitoring of zonal disintegration of rock mass in deep tunnels

With the development of national economy and the drying up of shallow resources, the embedded depth of rock mass engineering becomes more and more deep. The phenomenon of zonal disintegration appears and is monitored in surrounding rock mass of deep tunnels. The special geological engineering phenomenon has attracted scholars' great attention in the field rock mechanics. However, the knowledge on the fracture shape and forming mechanism of the zonal disintegration is not quite enough. There is doubt about whether or not the connection on the in-situ TV observation can represent the whole tunnel impersonally. There is argument that the fractured zones are the concentric circle of the cavity or the spirals and slip lines. The issue determines the essence of the zonal disintegration and whether or not it is an unexplained new phenomenon by using the theory in existence. In order to know about the phenomenon in substance, geo-mechanical model tests are carried out on the deep mine tunnel of Dingji Coal Mine in Huainan Mine area. Comparing the results of in-situ monitoring with those of model tests, the main characteristics and changing laws of the zonal disintegration are summarized. The zonal disintegration is the circular pull fracture which is concentric to the cavity. The research results are important for understanding the failure modes and revealing the deformation and failure mechanism of surrounding rock mass in deep tunnels.