Mine Pressure Manifestation Law of Dynamic Pressure Roadway with Multi-Layer Hard Roof and Roof Cutting Control Technology of Deep and Shallow Hole Combination Blasting
Aiming at the problem of difficult maintenance of roadway with multi-layer hard roof due to the influence of mining of adjacent working face,8104 transport channel of Nianyan Coal Mine was taken as the engineering background.Comprehensively adopting the laboratory test,theoretical analysis,numerical simulation and on-site industrial test,mine pressure manifestation law and mechanism of dynamic pressure roadway with multi-layer hard roof were studied,roof cutting and pressure relief technology of deep and shallow hole combination blasting was put forward,and the control effect was analyzed.The results are shown as follows.Firstly,the deformation of the surrounding rock with multi-layer hard roof is mainly divided into three stages of slow deformation,rapid deformation and deformation tends to stabilize.In the stage of rapid deformation,it shows the change law of step growth,and the number of steps is related to the number of layers of hard roof in the near field.Secondly,after the deep and shallow hole combination blasting,the lateral cantilever structure of the low key stratum is cut off,which reduces the number of dynamic loads caused by the fracture of the low key stratum.At the same time,the length of the cantilever beam of the high and low key strata is shortened,and the static load applied to the section coal pillar is reduced,so as to jointly reduce the pressure of the surrounding rock of the adjacent dynamic pressure roadway.Thirdly,Compared with no roof cutting,the average vertical stress on the side of the coal pillar is reduced by 14.8％,8.9％and 29.7％respectively after three different roof cutting methods,such as shallow hole blasting,deep hole blasting and deep and shallow hole combination blasting.After roof cutting by deep and shallow hole combination blasting,the roof collapses more fully in the caving zone,the fracture position of the rock layer in the fracture zone is closest to the coal pillar,and the cracks produced by the overburden in the middle of the goaf are more uniform.Finally,after roof cutting by deep and shallow hole combination blasting,the deformation of the surrounding rock is less than 400 mm after the two mining effects on the 8103 adjacent working face and the 8104 working face in the 8104 transport channel,which ensures the safe and efficient production of the mine.
Multi-layer hard roofMine pressure manifestation lawRoof cutting and pressure reliefDeep and shallow hole combination blastingRoof structure
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