Study On The Influence Of Open Pit Backfilling On Underground Rock Mass Stress And Strain

For the mines from open pit to underground, how to deal with open gob is a majorproblem. In order to reduce the affection of underground mining engineering, most ofmines owner have chosen to abandon the open gob, but the method is neither economic norpractical.The subject with the Fengshan Copper Mine is the research of the unreasonableprocessing the open gob. During the study, access to lots of field investigation and read theliterature data, using the method of numerical simulation and analyzing the impact of theopen-air pit piled dry residue tailings underground rock, so as to explore the open-air goafconverted into dry slag tailings is feasible to provide a theoretical basis. First, selecting tworepresentative geological structure profiles of the Copper mine(NO.17＆NO.19),andbuilding the three-dimensional finite element model with ANSYS finite element program.Second, leading the model into the finite difference software FLAC3D, which test theunderground rock stress and strain fields with the open gob discharged the dry slag tailings.Last, we can educes the following conclusions:(1) During the under orebody was excavating, discharging the dry slag tailings intothe open gob, which would cause the roof and floor of underground stope sink and rebounddeformation,but generally small amount of deformation in every parts. Its affection for thestability of open-air slope is also small. (2) After Underground Orebody have been excavated, surrounding rock stress haveredistribution, Stress concentration mainly appears in both ends of the goaf, the maximumtensile stress appears in Goaf roof and floor, Plastic zone is mainly distributed in the top ofthe open-air pit bottom and goaf backplane, the stope of the maximum compressive stressand the maximum tensile stress have a little increase after stacked the tailings. Tailingsloaded that lead in the confining pressure of overlying rock mass stress were increasing.(3) Eventually, we can be drawn that Fengshan Copper open pit was piled dry residuetailings with less affection of additional stress on the lower part of the mining and oremining under cover, thus the open-air pit piled dry slag tailings program is feasible.At present, in the case of Chinese land resources become tension, Studying of thistopic, for Chinese mining industry in exploring is a new development on the road andsignificance, especially on the construction of the tailings.