| The Houhemushan mining area of Masteel Gushan Mining Company Hemushan Iron Mine is a sloping medium-thick to thick ore body.The ore body and the surrounding rock near the bottom wall are broken and unstable to extremely unstable.The surrounding rock of the hanging wall is stable to moderately stable.Induced caving method mining,when the working face enters the-200 m section,large-scale ground pressure activity occurs,a large number of caves in the upper wall side mining approach,large deformation and sliding of the lower wall joint road,seriously affecting the normal mining production get on.In this paper,theoretical analysis and experimental research have investigated the main reasons for large-scale ground pressure activities,and accordingly improved stope structure parameters and mining technology,and effectively controlled the pressure hazards of the stope.The thesis mainly carries out the following research work:First,the on-site investigation of the ground pressure manifestation process and damage scope of the mining project,analyzed the influence of the rock mass structure of the mined ore deposit and the fault structure of the footwall,revealed the characteristics of ground pressure activity,and revealed that the destructive ground pressure originated from The wedge-shaped body formed by the collapse and cracking of the overlying rock mass in the mined-out area belongs to the wedge-shaped ground pressure.Secondly,a mechanical model of wedge-shaped ground pressure was established.The calculation and analysis showed that in the-200 section of Houhemushan mining area,the ground pressure of the wedge-shaped body on the hanging wall side is greater than the compressive strength of some magnetites.Therefore,the roadway in this part is very difficult after excavation.Collapse is about to occur;and after the hanging wall approach collapses,the compressive stress is transferred to the footwall,which causes the sliding of the footwall fractured structural surface,resulting in the destruction of the roadway along the vein that the structural surface passes through and adjacent to it.In order to control the ground pressure activity in the roadway,a method of dispersing the wedge-shaped ground pressure is proposed,that is,setting up an induced caving project,by releasing the caving and induced caving side of the hanging wall to crush the ore,so that the caving develops upward along the surface of the hanging wall,and then forms The loose body that develops upward along the surface of the upper plate uses the loose body in the loose body to alleviate the concentrated stress at the tip of the wedge-shaped body,thereby achieving the purpose of reasonable pressure relief and inconvenient pressure to the lower plate for a large amount of transfer.Third,using the test results of similar materials to analyze the sensitive relationship between the goaf span,sidewall width and ground pressure activity,as well as the allowable deformation conditions of the goaf surrounding rock and the pressure relief disturbance conditions of the adjacent goaf,which aggravate the ground pressure.The degree of pressure activity.Based on this analysis,it is proposed that the interval between-200m sectioned roads is too small and 8m is too small.Combined with the conditions of the ore and rock,three different stope structures in the middle section of-250m are proposed:the lower wall combined road stoping program,the upper wall combined road mining program,and the upper and lower side.The combined mining plan of the combined roadway,from the economic and reliability analysis,finally selects the main mining from the bottom wall to the upper wall,the combination of pressure relief and the anti-skid structure of the structural surface,the two-step recovery of the primary ore with large structural parameters and the two-step recovery of small structural parameters.A combined mining plan that combines the amount of residual ore in the footwall.Fourth,the intensity of the-200m sectioned ground pressure activity indicates that the wedge-shaped ground pressure has entered an active period.At this time,in order to enhance the stability of the roadway,it is necessary to increase the support strength while increasing the distance between the access roads.According to the failure characteristics of the mining access road and the analysis of the surrounding forces of the roadway,a support system is proposed to strengthen the wall support of the roadway,increase the length of the bolts,and take the primary bolt mesh shotcrete and the secondary prestressed bolts as the main body.Production practice shows that the proposed combination of large structural parameter hanging wall combined road mining and small structural parameter lower wall two-step recovery combined pressure relief mining plan,as well as the corresponding roadway support plan,are highly adapted to the characteristics of ground pressure activity in the Houmushan mining area.,Effectively controlling the ground pressure activity in the middle section of250m,so that the ore in each section can be better recovered,and the goal of safe and efficient mining is achieved. |
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