Technology of micro-cement injection of destroyed and fractured massif at Orlovsky mine

Abstract

Purpose. Research into the method of strengthening destroyed and fractured rock massif by micro-cement injection during rock driving at Orlovsky mine of "Vostoktsvetmet" LLP. Methods.In situ researches of massif strengthening by cement slurry were performed. Monitoring of injection works implementation was carried out by control tests of reinforced rock cores. Phase composition of core samples (crushed probe) was defined on the X-ray diffractometer. Method of raster electron microscopy with energy dispersive microanalysis was used to determine the surface morphology and local elemental analysis of core samples. The material and labor costs related to works on strengthening of rock massif were calculated.Findings. Massif strengthening method was studied. MasterRoc MP 650 micro-cement produced by BASF Construction Chemicals Ltd with addition of 1 -2% of cement weight of Rheobuild 2000PF was used as cement slurry. The uniformity of the working contour in tunnel faces was observed after the third cycle of works on rocks injection. Unsafe working conditions for packer installation have been revealed. It was recommended to carry out pilot tests of tunneling technology in destroyed and fractured massif using the two-component organic-mineral resin "Blocksil" and long selfwedging packers with injection tubes.Originality. We established peculiarities of implementing technology of strengthening destroyed and fractured rock massif by micro-cement injection. Quantitative indicators of micro-cement content in the injected rock massif were identified.Practical implications. Technology of strengthening destroyed and fractured rock massif by micro-cement injection was developed and tested at Orlovsky mine.

Safety, health and hazards related to using of sprayed concrete in underground mining works

“…The particularity of the support made from mortar or spraying concrete consists in the participation of the rocks themselves to achieve the bearing strength [7,8]. Thus, the rocks, from the object of the support, became themselves a means of support, basically rocks are self-supporting.…”

“…To avoid this potential risk (hazard) a simple solution is to initially apply a thin layer of unreinforced sprayed concrete [1,7]. Special attention must to be given to safety requirements and operation instructions provided by the equipment manufacturer and the materials supplier [7,8,10]. Heavy and moving equipment through the high pressure may constitute high potential risks for underground personnel working in gallery face in which spraying is achieved.…”