Theoretical Solution Of Deep Beam Section And Its Application In Coal Mine Water Control Project

The problem of mine water inrush affects the safety production of coal mine for a long time.In the theoretical analysis of water inrush prediction,the model is generalized into beams in many cases,such as the risk analysis of water inrush from water-resistant floor of coal mining in high confined water and the retention of fault waterproof coal pillars,etc.At present,many scholars generally use the shallow beam theory for research.As we all know,shallow beam refers to the beam with a height span ratio of less than 0.2.In fact,water-resistant floor and fault coal pillar can not meet the requirements of shallow beam in many cases,and the calculated stress and deformation have large errors.Therefore,in view of the deep beam theory to solve the problem,based on predecessors' research results,on the basis of deep beam article points to solve the technology and the deep beam under gravity bending stress solution,and the calculated results with conventional solutions of material mechanics,elastic mechanics and FLAC3D numerical solutions is compared,analysis of deep Liang Yingli precision as well as the changing rule of the neutral axis,Finally,the deep beam division method is applied to the risk of water inrush from bottom floor of key water-isolation layer of coal seam and the width of fault waterproof coal pillar,which provides theoretical basis for water prevention and control in coal mine engineering.The results achieved are as follows:(1)Compared with conventional material mechanics and elasticity mechanics,the solution of deep beam bending stress bar splitting technique is more accurate.With the increase of height-span ratio,the neutral axis of deep beam solved by bar splitting method has different degrees of deviation,which is in good agreement with the numerical simulation.With the same height-span ratio,with the increase of the number of layers,that is,with the decrease of the thickness of layers,the solution accuracy of the middle stress of deep beam span gradually improves,but the range of improvement decreases with the increase of the number of layers.In addition,for deep beams with the same fraction,the solution error of mid-span stress increases gradually with the increase of height-span ratio,that is,the increase of delamination thickness,indicating that the delamination thickness of deep beams should not be too large,otherwise the accuracy will be greatly affected.(2)according to the characteristics of the deep beam gravity can not be ignored,the article points of each layer of beam surface gravity loads on the points of beam,precision increase with the increase of the layers,can satisfy engineering demand,but due to gravity processing brought about by the approximation error,the same conditions the solution and not considering gravity solution error increase.(3)the floor water inrush risk of key stratum water determination showed that when the key layer water across more hours,is a typical problem of deep beam,the conventional material mechanics and mechanics of elasticity of the maximum tensile stress results and FLAC3D numerical solution than smaller obviously,to correctly determine the key layer of water inrush risk of an adverse impact,this article adopts deep beam points method to solve stress accuracy is higher,The judgment result is reliable.(4)According to the characteristics of fault waterproof coal pillar,the coal thickness is generally less than the wide band of coal pillar,which is a typical deep beam problem.By using deep beam decomposition,the reasonable width of coal pillar is given,and the calculated results are compared with the conventional formula.It is concluded that when calculating the deep beam by conventional material mechanics solution,the calculation result of maximum tensile stress is smaller than the FLAC3D numerical solution because the interlayer compressive stress is not taken into account,resulting in a smaller reserved width of the calculated coal pillar.However,when multiplied by the safety factor,the obtained result is consistent with the theoretical solution of deep beam section.It reflects that the reasonable application of safety factor in conventional theoretical solution can not be missing in the installation of fault waterproof coal pillar.Figure[59]tabLe[5]reference[116]...