Research On Tailings Steel Fiber Shotcrete In Iron Mine Roadways

In order to solve the problem of the application of tailing sand steel fiber shotcrete as the single layer lining of tunnel in the process of iron mine tunneling,the tailings were used as the fine aggregate to prepare steel fiber shotcrete instead of natural sand,and a series of mechanical properties tests with different steel fiber content were carried out on concrete to study the effect of steel fiber content on the basic mechanical properties of composites,and the optimum thickness of the tailings steel fiber shotcrete as single layer lining was obtained.In this paper,the experimental research on the tailings steel fiber shotcrete was carried out by means of compression tests,splitting tests and toughness tests.Then the mechanical parameters got from the study were applied to the numerical simulation.The optimum thickness of the spray was obtained by numerical simulation.Also stability analysis of tunnel with fluid solid coupling was carried out under optimum thickness.The main research done was as follows:(1)Mix design of tailings steel fiber shotcrete material.Tailings steel fiber concrete mix ratio was mixed under the guidance of the specification test via a large number of existing experimental studies,combined with the actual engineering concrete strength and work performance requirements.(2)Basic mechanical properties test and bending toughness test(measurement of the permeability coefficient under the optimal ratio),the influence of factors such as fly ash,silica fume,steel fiber content on the mechanical properties of concrete were analysised,and the lining of roadway control parameters of mechanical properties of tailings sand steel fiber shotcrete was puted forward.As the most important system of roadway support structure,concrete support needs sufficient toughness and crack strength.In the flexural toughness test,the influence of factors such as fly ash and steel fiber content on the bending toughness performance of concrete was analyzed.Under the optimum concrete mix ratio,the impermeability test specimens were made to obtain the permeability coefficient of the tailings sand steel fiber shotcrete.(3)Iron ore weak strata was analysised via ANSYS numerical simulation,and APDL parametric design language program was used to design and discuss the optimum thickness,also a reasonable thickness of 12 cm spray grouting of tailings sand steel fiber reinforced concrete was obtained.(4)In order to more realistically reveal the seepage problem during tunnel excavation,a fluid-structure coupled seepage model was established based on the Biot extened theory to study the long-term consolidation law of the roadway,the distribution and dissipation of pore water pressure,and the law of change of the displacement fields.