Efficient and active monitoring of stresses and strains in rock masses
The full-scale research has been undertaken in mines in Gornaya Shoria, Khakassia, Buryatia, Northern Kazakhstan and Western Australia to study geometrics of deformation of holes using special equipment-video endoscope, laser range finder, dip compass, hole treatment device, downhole operation device and guide rods. The new developed technology of live stress and strain monitoring in rocks allows basic characteristics of local areas in rocks to be determined within a short time: orientation and range of major principal stresses, relative deformation, location of damage rock zones (fractured rocks), zones of shearing and compression, sizes and dynamics of cracks, zone of influence of drivage and working excavation, mechanisms of failure and time of relaxation in rocks (maximum abutment pressure zones). The active monitoring technology is recommended for stress estimation in mining with caving with natural and manmade support. In the framework of the technology, the method is developed for downhole detection of damaged rock zones and the device is engineered for applying fast-drying coating on inner surface of holes for better examination of crack growth. Initiation and growth of cracks, as well as deformation and shearing in hole are clearly observed on negative images. To measure the length and width of cracks and for assessing dynamics of their growth, the measuring probes are designed and the downhole crack measurement technique is elaborated. After the full-scale mapping of holes, the data are processed, interpreted and presented in graphical form for analyzing geometry of deformation and jointing in holes.