Study Of Stability Of Pillars With Strip And Delayed Filling Mining Of Gently Inclined Deposits

Strip and delayed filling mining method could be used to gently inclined deposits,The stability of the strip pillars is a key to the success of mining under mining process.The V3 layer ore of Shanghengshan deposit is the object of study,The stability of pillars were analyzed by using theory of elastic strain energy,theory of rock fracture mechanics and numerical simulation.Based on the principle of elastic strain energy balance,energy stored in the strip ore layer was transformed into the energy of deformation and failure of the roof pillar.The energy was balanced before and after mining,the analytical expression of the width of fractured zone was deduced,and the calculation model of the width of the fractured zone was established.The influence factors of the rupture zone width were analyzed.According to the theory of rock fracture mechanics,the goaf zone was the collinear crack with a certain distance in the vertical section of infinite rock mass,and the distribution of stress field at crack tip was analyzed.Depend on the mining geological parameters,the stress intensity of the orebody buried at 150?400m was drawn.Based on the Mohr Coulomb criterion,the analytic expression of the destruction range of the surrounding rock was deduced,and the calculation model of the floor depth of the mine floor was established.In accordance with the principle of orthogonal test,six factors,such as depth,thickness,width of mine and the tensile strength,cohesion and internal friction angle of the ore body,were selected as the main factors of the fractured zone.All the orthogonal test tables L₉?3⁴?with 3 factors and 3 levels were used to design the program,and 18 kinds of simulation test schemes were obtained.FLAC³DD numerical simulation was used to calculate the width of the fractured zone of different schemes,which result show that the sensitivity of the two groups of factors are those which the depth of mining is more than width of the mining room which is more than the thickness,and the tensile strength is more than the internal friction angle which is more than cohesionThe numerical simulation method was used to simulate the width of the mine with different widths of 30m,25m,20m,15m and 10m respectively.The distribution law of the pillar support pressure in each scheme shows that the width of the pillar was 10m of the mining program,the other program mining pillar support pressure distribution for the‘dome'or‘saddle-shaped'distribution.At the same time,in addition to the mining chamber and pillar width all are 15m of the mining program,the other mining program recycling plastic zone through the entire pillar or developed to the adjacent ore body,the adjacent ore body was disturbed seriously.Combined the theoretical results of the pillar width estimated by the calculation model of the rupture zone width with numerical simulation results,which show stability of the pillars is better than others when the reasonable width of the rooms and pillars is 15m.The study could provide a reference for the design of the pillars and mining chambers parameters...