Parallel Calculation Of Strata Movement By Roof Cutting And Pressure Releasing Considering Broken Expansion Of Rock And Interface Cohesion

Automatically formed the roadway technology with the roof cutting and pressure releasing has advantages of easy control the roof,low cost and safety.It has become a promising development direction in the coal mining field in our country.In order to more accurately simulate the strata movement with the roof cutting and pressure releasing,on the basis of the parallel computing system of strata motion(StrataKing),the broken expansion algorithm of rock and the interfacial cohesion algorithm between rock layers were considered,the support function of the equivalent hydraulic was enriched,two cutting seams in rock layers were realized,and related numerical simulation researches were carried out.For the double layer beams model under three-point bending condition,when the interface cohesion between layers is considered,the slope of the load-displacement curve is large,which is due to the fact that two single beams are approximated to a whole under the action of the interface cohesion.The smaller the discrete block size is,the better the broken expand effect is.For the simplified stope model and the stacking model of discrete blocks,the larger the broken expand coefficients is,the smaller the void between rock in the caving zone is,and the rotary subsidence of the roof is not easy to appear.For the 0908 fully mechanized working face of the Daqiang coal mine,compared with the no roof cutting model,the top of the roof cutting model is flat and there are no obvious cracks near it,and the subsidence of strata is small.In the roof cutting model,the dense crack zone is far away from the goaf,which is due to the fact that the stress can be transferred to the depth of the coal seam by roof cutting.For the 418 island working face of the Chenjiashan coal mine,under the condition of roof cutting and pressure releasing,there are fewer cracks in strata above coal pillars at both sides of the working face,which is due to the fact that the roof cutting can effectively cut off the relation between roof strata of the goaf and reduce the stress concentration.The peak abutment pressures of coal pillars at both sides of the working face of the model roof cutting are always smaller than of the model without roof cutting,which is due to the fact that the roof cutting has a better pressure relief effect.For the 8304 working face of the Tashan coal mine,the top of the model is relatively flat for the 110 mining method.The maximum subsidence of the top of the model for the 110 mining method is less than for the 121 mining method,which is due to the fact that the roof cutting promotes the broken expansion of falling rocks.For the 1105 working face of the Hecaogou No.2 coal mine,with the increase of the mining height,the downward movement distance of the roof increases,and the cracking range of strata increase.When the mining height is 1.2m,1.8m,2.4m,2.8m and 3.2m respectively,the maximum subsidence of the top of the model is about 1.11 m,1.61 m,2.07 m,2.32 m and 2.62 m respectively,which accounts for 92.5%,89.4%,86.25%,82.86% and 81.875% respectively of the mining height,indicating that the larger mining height leads to more sufficient the broken expansion of falling rocks.There are 46 figures,6 tables and 103 references in this thesis.