Research And Application On Support Technology With Bolt-mesh-anchor For Large Section Roadway

With the increasing of mining intensity and scale, in order to satisfy the requirementof large mining equipment, transportation and ventlation, the roadway size expandingcontinuously, which reduce the stability of surrounding rock and poses new challenges forroadway support. large section roadway supporting has become an urgent problem.Take large section roadway of Nalinhe coal mine as background, through the methodof field research, theoretical analysis and simulation, failure mechnism of surrounding rockand support technology with bolt-mesh-anchor are studied, and aimed at geologicalcondition and support problem of Nalinhe coal mine, relevant support measure are putforward.(1) Deformation and failure mechanism of large section roadway is analyzed. afterroadway excavation, the original three dimensional stress imbalances turn to atwo-dimensional stress, stress concentration appear in roadway roof and two sides, result inreduction of rock strength, deformation and failure of surrounding rock.(2) Using FLAC3Dnumerical simulation software, effect of roadway size on itsstability is analyzed. research show that plastic area increase with the increase of roadwaysize, the roadway width has a great influence on roadway stability, if the roadway width isincreased from4m to5.6m the roof displacement is increased from65mm to85mm,resulting in the hardly support.(3) Mechanism of bolt-mesh-anchor support on large section roadway is analyzed.after roadway support, bolt and anchor preload can recover the three dimensional stress ofsurrounding rock, and control the deformation, so as to maintain the stability of thesurrounding rock. go deep into rock, the anchor play the role of hanging the loose andfracted rock, as the span is large, the anchor also play a role of decrease the span anddisplacement of the roof. the two sides bolts can reinforcement the broken coal, make theman entirety within the deep stability coal, restrain broke up of the deep coal, and control thedeformation of two sides. (4) Using FLAC3Dnumerical simulation software, the influence of bolt length,inter-row spacion, angle and preload on support result is studied. the results show that,increasing the length of anchor is conducive to the spreading of pretension into the deep,the primary zone of stress is in1/2of the bolt or less. decrease of the inter-row and angelcan make the pressure superimposed to a unitary compressed area, give a overallreinforcement of surrounding rock. Increased preload can increase the active support effectof anchor, the pressure intensity and range increased with the increase of preload, themaximum principal stress is0.02MPa when the preload is50KN, and the maximumprincipal stress is0.02MPa when the preload is50KN.(5) Aimed at deformation and fracture feature and existing support scheme in Nalinhecoal mine large section roadway, bolt-mesh-anchor support is put forward and applied.monitoring results show that this support scheme can effectively control the deformation ofsurrounding rock, and the support effect is satisfactory.