| With the gradual entry of deep coal mining and the expansion of underground space,The surrounding rock control problem of soft rock engineering has been plagued by coal mine production and deep tunnel construction.At present,the soft rock roadway support technology is a key problem to be solved in the coal system,which has become one of the main tasks for the development of rock mechanics in China.In recent years,coupling support technology has been widely used in soft rock roadway support,especially the advantages of the anchor net cable coupling support technology has obvious.At present,it is a hot topic to study the technology of anchor cable-coupling support to better utilize its support effect in soft rock underground engineering.Therefore,for the support problem of soft rock mining roadway,through theoretical analysis,mathematical calculation and FLAC numerical simulation,study on optimization of anchor cable-coupling support parameters in soft rock roadway,The following research results were obtained:?1?Establishing a model of surrounding rock mechanics by classical support theory,it is deduced that the thickness of surrounding rock loose circle has a direct and important relationship with the deformation of soft rock roadway,and calculate the radius of the loose ring of the research roadway is 4.78m,and the thickness of the loose ring is 1.76m.?2?Using orthogonal method arrangement to rationalize the numerical simulation scheme,range analysis of the displacement of the top,the bottom and the two sides,determine the primary and secondary factors for controlling the parameters of roadway deformation.Selecting optimized support parameters through comprehensive analysis:anchor bolt?22mm×2000mm,row spacing of roof bolts 900mm×1000mm,row spacing of wall rock bolts 800mm×1000mm,bolt pretension 90KN,anchor cable length 6300mm,anchor cable pretension 150KN.?3?Combined with the actual engineering to determine the deformation mechanism of the roadway is?C?ABD?D,On the basis of the optimization parameters of support,According to the type of deformation mechanics,it is proposed to install two bottom anchors,adjust the top and wall rock bolts angles.To strengthen the coupling support of key parts,forming an optimization scheme of coupling support of bolt-net-anchor.?4?Using FLAC3D numerical simulation to calculate the optimization scheme of anchor cable-coupling support and original scheme under soft rock conditions.Comparative analysis of displacement deformation,stress distribution and plastic zone range,The bolt-net-anchor support scheme with optimized parameters has been improved in all aspects.Finally,through on-site experimental monitoring,the actual roadway deformation is almost the same as the numerical simulation results,which meets the roadway stability requirements of mine safety production,and verifies the scientific feasibility of optimization parameter research.It is determined that the optimal time period of secondary support is about 13 days before excavation,so as to achieve the ideal coupling support effect of the roadway by coupling the different supporting bodies while maximizing the bearing capacity of the surrounding rock. |
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