Research On Numerical Simulation And Filling Material Performance Test Of Composite Support For Deep Roadway

Deep roadway is faced with geological conditions of high geothermal,high pore pressure and high buried depth,and the interaction between various physical fields makes it difficult for traditional support methods to cope with complex multi-physical field coupling.Therefore,the filling material layer with heat resistance,permeability resistance and pressure relief properties,the surrounding rock anchoring layer and support are used to form roadway composite support.It is of great significance to guarantee the stability and safety of roadway and surrounding rock.In addition,the rapid development of phosphate fertilizer and phosphoric acid industry led to a large amount of phosphogypsum accumulation,resulting in waste of land resources and environmental pollution,but its high temperature resistance,chemical corrosion resistance,high strength,good toughness,fit the deep roadway backfilling requirements.Taking huai hu ding coal company set the west three concentrations of belt conveyor in coal mine as engineering background,the indoor test to explore the physical and mechanical properties of phosphogypsum filling materials and the feasibility of numerical simulation to explore the deep roadway temperature,seepage,stress more physical field coupling interaction effects,and compound supporting phosphogypsum pack its heat resistance,permeability,pressure relief effect,macroscopic analysis of safety reserve of composite support in deep roadway.The main contents are as follows:(1)The filling material with phosphogypsum as aggregate was prepared.Single factor test and orthogonal test were used to explore the influence of various factors on compressive strength.From high to low,slag content,material concentration and calcium carbide slag content were successively studied.In order to find the best mixture ratio,the contents of phosphogypsum,slag and calcium carbide slag were 65%,30% and 5%,respectively,and the material concentration was 65%.The compressive strength was 5.831 MPa after 28 days.And through the fluidity test,the initial fluidity of the filling material of the ratio is up to 280 mm,which meets the pumping demand.The p H value of the filling slurry is 12,which can effectively prevent the corrosion of the steel support.Through the X-ray diffraction and electron scanning,the phosphogypsum and slag provide the filling material strength skeleton,the calcium silicate and calcium aluminate fill the skeleton,the calcium slag stimulates the slag activity and enhance the binding strength.(2)With the help of laser flash method,hydroscopicity test,water resistance test and digital speckle test,the feasibility of application of temperature,seepage and stress physical field parameters of filling materials in deep roadway is verified.The thermal conductivity,water absorption and softening coefficient of the filling material are 0.4W/(m ? K),25% and 0.931,respectively.The residual strength is 83.33% of the peak strength,and the Poisson’s ratio is 0.62.The filling material can play the role of heat resistance,permeability resistance and pressure relief in deep roadway.(3)Based on the small deformation theory,Fourier law and Darcy law,the THM multi-physical field coupling control equations of unsaturated porous continuum in deep roadway were constructed.COMSOL Multiphysics was used to simulate the evolution process of temperature field,seepage field and stress field under the condition of rock mass dynamic equilibrium in deep roadway.(4)The parameter changes of composite support under the coupling effect of multiple physical fields in deep roadway compared with traditional support are compared and analyzed.The composite support reduces the convection exchange of heat,reduces the pore pressure and seepage velocity in the support area,reduces the strain on the support layer and anchor layer,thus reducing the stress,and brings into play the effects of heat resistance,permeability resistance and pressure relief.(5)Explore the influence of different filling layer parameters on the heat resistance,permeability resistance and pressure relief effect of composite support: The results show that the lower the thermal conductivity and permeability of filling material,the more obvious the heat resistance and permeability resistance effect of composite support;When the elastic modulus is3～4GPa,the filling layer exerts pressure and active strain effect.The pressure relief effect of composite support is the best.The paper has 67 figures,18 tables,and 128 references.