Study On Stability Mechanism And Control Of Compound Roof In Coal Roadway

It is difficult to control the deformation of composite roof in practical engineering.The mechanical state of composite roof under different conditions is analyzed theoretically,and the supporting theory of composite roof roadway is put forward.The composite roof is simplified as a rock beam model with both ends fixed,and the stress distribution and deformation in the rock girder are solved by means of elastic mechanics and material mechanics and other mechanical methods such as the vertical load of a homogeneous rock beam.The results show that the stress in the rock girder has a great relationship with its span and thickness,and the thickness of the rock beam can be improved to improve the bearing capacity of the rock beam.For the multilayer composite roof,it is considered that the superposition of multiple homogeneous beams,the uniform deformation of each layer and the load of each layer is equal to the total load of the composite roof,and the calculation formula of the stress of the composite roof is obtained by derivation of the theory.The results show that the stress of each rock stratum under the action of vertical load has a great relationship with its elastic modulus and thickness.Then the internal stress of the homogeneous rock beam under the action of vertical and horizontal loads is solved.By analyzing the stress state of composite roof,the paper gives the five aspects which should be paid attention to to control the surrounding rock of the compound roof roadway,and establishes the "arch-beam" supporting structure with the high position of self stabilized invisible arch as arch,and the anchor support as the composite beam.Based on the theory of the self-stable stealth arch of the homogeneous layer,the self stabilizing hidden arch equation of the composite roof roadway is solved,and the function of the bolt and the anchor cable in the whole supporting system is analyzed.According to the above mentioned "arch-beam" support structure,the calculation formula of supporting parameters of roadway with compound roof is given.In order to verify the rationality of "arch-beam" supporting structure,numerical simulation software is used to compare the effect of FLAC3D,top bolt support and anchor bolt support,and the results show that "arch-beam" supporting anchor bolt and cable combined support can control the deformation of roadway well.At last,the practical verification of the Dongdong mine has been carried out,through the analysis of monitoring data and on-site observation,the support method is very good control of the deformation of the roadway,achieved good support effect.