Stability Study On Surrounding Rock With Structural Rheology In High Stress Area

It has been greatly concerned to study the stability of underground caverns and theirs surrounding rocks under complex conditions. In highly stressed jointed rockmasses, because of strong effects of excavation and mining, galleries deformed and damaged very seriously and chronically. It is difficult to excavate, support, mine and maintain. This is the just problem feazed Jinchuan Nickel Mine all the while. Surrounding rocks mentioned as above have remarkable rheological property, but previous researchers consider that the rheology of rockmass resulted from rocks and that structure of rockmass is determinate and static and does not change in spite of any condition under which rockmass exists, so their researches had carried out by rheology theory of continua. Engineering practices show that these studies do not reveal the key of deformation and failure of surrounding rocks with above-mentioned properties and those supports adopted on the basis of their research results cannot be take effects.Take Jinchuan Nickel Mine as an example, on the basis of detail site investigation and lots of data tested, measured and monitored in laboratory and on site, referred also measured data of some other similar underground works domestic and oversea, it is found that rheology and other characteristics of jointed and firm surrounding rocks in high stress area resulted from not rocks but discontinuities. It is complicated time-dependent deformation of discontinuities that results in rheology of rockmass. Based on calculation and analysis by these data, the knowledge of structural rheology is put forward. Structural rheology is defined as the phenomena or process in which surrounding rocks put up rheology due to the complex time-dependent behaviors and response of discontinuities in the course of stress redistribution by excavation of firmly or semi-firmly jointed rockmass in high stress area. By spatial and temporal characteristics of secondary stress in surrounding rocks, displacements of surrounding rocks, ground pressures, deformation and failure of roadway and elastic wave velocity, the strong rheology and other correlate properties during structural rheology of surrounding rocks are discussed. The mechanism and its characteristics and pattern of structural rheology are also discussed. The analytical results and the numerical results about dynamical variation of surrounding rocks are given respectively from the viewpoint of structural rheology. Based on the knowledge and results gained from detail researches, select some a roadway as trial area to study further and validate the structural rheology and to search the sound countermeasure. The trial roadway, 50 m long, is portended that very large deformation and serious damage will happen, so its stability is very poor and its support very difficult. Success of support for the trial roadway shows that the knowledge of structural rheology is right, and also shows that the way to thoroughly solve the difficult problem of deformation and damage of roadway can be found on the basis of structuraltheology of surrounding rocks.From the viewpoint of structural rheology, rockmass and its characteristics are dynamically and constitutionally understood and studied, which modifies the classic knowledge completely. The research results obtained by the author of this dissertation can be used and referred for other similar underground works under complicated conditions.