Stability analysis of roadway surrounding rock under the action of bolt bearing layer
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摘要: 针对现有巷道围岩稳定性控制方法是将锚杆支护阻力均匀作用于巷道表面,较少考虑锚杆与围岩耦合形成的锚固承载层的等效支护力问题,通过分析围岩力学模型得出锚固承载层等效支护力的解析表达式及巷道围岩在锚固承载层作用下的弹性区与塑性区应力、塑性区半径和巷道围岩表面位移的解析表达式。算例分析结果表明:① 锚杆长度增加时,锚固承载层厚度随之增大;锚杆长度一定时,随着锚杆排距的增加,锚固承载层厚度减小;锚固承载层等效支护力随着锚固承载层厚度的增大而增大。② 在塑性区中,相对于考虑锚固承载层的本文解下的围岩切向应力比不考虑锚固承载层的Fenner解下时大,应力峰值位置更接近巷道中心位置;在弹性区中,相对于Fenner解,本文解下的围岩切向应力较小,径向应力较大。③ 随着锚固承载层等效支护力的增大,塑性区半径呈下降趋势;随着锚固承载层等效支护力的增大,Fenner解与本文解下的巷道围岩表面位移减小,且Fenner解下的位移变化量比本文解下的大。利用Flac3D软件对锚固承载层作用下的巷道围岩应力、塑性区半径和巷道表面位移进行数值模拟,数值模拟结果与算例分析结果基本一致,锚固承载层作用下巷道围岩稳定性更为可靠。Abstract: The existing method of controlling the stability of roadway surrounding rock is to apply the bolt support resistance to the roadway surface uniformly. But there are few research on the equivalent support force of the bolt bearing layer formed by the coupling of the bolt and the surrounding rock. By analyzing the surrounding rock mechanical model, the analytical expression of the equivalent supporting force of the bolt bearing layer and the analytical expression of the stress in the elastic zone and the plastic zone of the roadway surrounding rock under the action of bolt bearing layer, the radius of the plastic zone and the surface displacement of roadway surrounding rock are obtained. The analysis results shows the following three points. ① The bolt bearing layer thickness increases when the bolt length increases. The bolt bearing layer thickness decreases with the increase of the bolt row spacing when the bolt length is fixed. The bolt bearing layer equivalent support force increases when the bolt bearing layer thickness increases. ② In the plastic zone, compared with the Fenner solution that without considering the bolt bearing layer, the tangential stress of the surrounding rock increases significantly with this solution that considering the bolt bearing layer, and the peak stress position is closer to the center of the roadway. In the elastic zone, compared with the Fenner solution, the tangential stress of the surrounding rock decreases and the radial stress increases with this solution. ③ With the increase of the equivalent support force of the bolt bearing layer, the radius of the plastic zone decreases. With the increase of the equivalent support force of the bolt bearing layer, the surface displacement of the roadway surrounding rock with the Fenner solution and this solution decreases, and the displacement change with the Fenner solution is larger than that of this solution. The Flac3D software is used to numerically simulate the stress of the roadway surrounding rock under the action of the bolt bearing layer, the radius of the plastic zone and the roadway surface displacement. The numerical simulation results are basically consistent with the analysis results of the calculation example, and the stability of the roadway surrounding rock under the action of the bolt bearing layer is more reliable.
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