The Continuous Mining Cement Strength Model And Its Application After Filling In The Open Field

Filling mining method will be widely used with the development of the green mining technology and implementation of the "three rates" evaluation standard of solid non-energy mineral.Panel mechanized continuous mining,safe,efficient,low cost and low dilution and loss are the core research topics of the filling mining technology.Two-step open stoping with subsequent filling mining is the main method to stope moderately-stable and medium thickness and above orebody.It is a two-step mining method,filling the ore pillar with the cementing paste and the ore room with tailings.To enhance farthest ore recovery rate it has developed to no pillar continuous mining mode.The framework forms with the stable cementing filling body provides security assurance for the ore room.It is the key to confirm scientifically and reasonably the required strength of the cementing filling body of two-step open stoping with subsequent filling mining method,it also relates the realistic requirement of reduce filling cost.At present,lacking system research on the required strength of the cementing filling body,the experience analogies is often applied to design the strength of the cementing filling body which often result in high cost of filling or strength can’t meet engineering requirement.Filling body occurred collapse due to insufficient strength,the high filling cost caused by high strength,which affect the benefit,It affect directly the safe,efficient mining and ore mining rate.Therefore,it is necessary to establish strength model of the cementing filling body according to the technological characteristics and the stress state of cementing filling body.It is important for further theoretical research of filling mining and guiding the mine production practice.The mechanical functions of cemented filling body was confirm by analyzing its stress state change with the stoping steps of the two-step open stoping with subsequent filling mining method and the its research status of the mechanical mechanism.Including improving the stress state of roof rock and supporting the broken roof rock,providing lateral pressure for the unloading rock that has sliding trend,resisting the stope closed and limiting the flow of tailings.The point that cementing filling body is a self-supporting artificial pillar was selected to establish the strength model.The main research methods and contents included the following aspects:(1)The function relationship between the height of arch and the stope sizes and the stability of surrounding rock was established according to analyzing the measured results of goaf of collapse form in Dahonshan copper mine and the research results of rock mechanics.Taking the contact part roof rock between roof and cementing filling body as the roof pressure act on the cemented filling body,and its computing method was established.(2)The wall caving scope of stope was confirmed by using the slip angle,the three dimensional wedge with a sliding trend under the action of the sliding resistance on the sliding surface and the force of cementing filling body keeps stability.The calculation method of the force of stope wall acts on the cementing filling body was inferred by using the wedge sliding theory to establish limit equilibrium state equation of the sliding part of stope wall.(3)According to the results of high pressure consolidation tests of tailings,the power relationship between density of tailings and pressure was established.The power function between density of tailings and height was established by analyzing the equilibrium conditions of talings’ infinitesimal body in gravity environment.Using the Fluent software to simulate the density distribution under the action of its weight in the stope.The result showed that,under the condition of the same height,the maximum differential value of talings’ density is 0.062 t/m3,minimum differential value is 0.001 t/m3,average differential value is 0.011 t/m3,the calculation of fuction relationship between talings’ density and height highly consistent with the results of numerical simulation.(4)Respectively using the mohr-coulomb criterion analysis the equilibrium state of stress of the tailings unit on the contact surface between the cementing filling body and tailings filling body,and using wedge sliding theory analysis the limit equilibrium state of three dimensional sliding wedge of tailings,combining with the research result between tailings’ density and the height,the integration method to calculate the lateral pressure of the tailings filling body acts on the cementing filling body was got.Although the two analysis method is different,but they can deduce the same result.(5)Combining the above research contents with each other,the strength model of the cementing filling body that one side is exposed and the other side is affected by the lateral pressure of tailings was established,concluding cohesion model,compressive strength model and shear strength model.Structure sizes of cementing filling body,roof pressure,the contact condition between cementing filling body and surrounding rock and the lateral pressure of the tailings filling body acts on the cementing filling body were fully considered in the model,which more correspond to actual fact of the stope.(6)The FLAG 3D numerical simulation software was applied to build the model of ore between 48 and 54 exploration line of 385 level in Dahongshan copper mine,the strength parameters of layer of cementing filling pillars were designed according to the computation of the strength model.The deformation parameters were selected according to the results of compression and stress-strain test.Model morh was applied to simulate and analyze the stability of the cementing filling pillar.The numerical simulation results showed that,cementing filling pillar keeps stability with the designed parameters and layered filling during the recovery process of the stope.(7)The research results were applied to the production practice of the zone between 48 and 54 exploration line of 385 level in Dahongshan copper mine.The mine statistics showed that,2238919t ore was stoped,the average grade is 0.45%,dilution ratio is 10.03%,recovery rate is 87.5%,stope production capacity is 2487 t/d.The cementing filling body doesn’t occur massive collapse during the recovery process of the zone.The practical industrial application demonstrate,the strength and mix proportion of the cementing filling body were designed by the strength model which was established in this paper conforms to the requirements of the production practice of Dahongshan copper mine.The research results of paper has significance to deepen the theoretical research of filling mining,and it also has comparatively high application and spread value for the similar mine.