冲击煤层煤柱变形与地面建筑物保护关系研究

保护煤柱合理宽度(或停采位置)是确保地面重要设施长期稳定的关键。以山东某矿地面引水渠("南水北调"工程组成部分)下不规则下山保护煤柱宽度设计为工程背景,首先,通过分析煤柱变形可能引起地面建(构)筑物的破坏方式,提出了控制长期高应力作用下冲击煤层煤柱变形的原则:1走向方向煤柱不发生冲击失稳破坏;2走向方向煤柱不发生煤体长时强度降低而导致的失稳破坏;3倾斜方向煤柱保持均匀变形,从而使地面不发生明显拉伸破坏。其次,依据煤柱上方覆岩空间结构形式,建立了煤柱应力估算模型,提出了保持煤柱长期稳定及地面建筑安全的煤柱设计方法。最后,应用研究成果,分析了工程案例的煤柱应力、围岩稳定性和变形特征,并对该引水渠工程和井下开采设计进行了安全评估。该研究成果对类似开采条件下的保护煤柱宽度确定具有指导意义。

Relationship between deformation of coal pillars in coal seam with rockburst hazards and protection of surface buildings

It is essential to ensure the long-term stability of surface infrastructures by designing a reasonable protective width (or stopping line) of coal pillars. The design of the irregular downhill protective pillars under a surface diversion canal (part of South-to-North Water Transfer Project) in a mine is regarded as the engineering background. First, the govering principles for deformation of coal pillars under the function of long-term high stress in the coal seam with rockburst hazards are proposed by analyzing the damage modes of surface buildings induced by pillar deformation as follows: (1) No rockburst instability damage occurs in strike coal pillars; (2) No instability damage due to strength decrease over time takes place in strike coal pillars; (3) The deformation of dip coal pillars is uniform so that tensile damage does not take place on surface. Second, an evaluation model for pillar stress is established, and the design method for keeping pillars to be stable and surface buildings to be safe in a long-term period is proposed according to the spatial structure in the overlying strata. Finally, the stresses of coal pillars, stability of surrounding rock and deformation stability of the engineering case are analyzed, and the safety evaluation for diversion canal project and undermine mining design is carried out. The results are of great guiding significance for the width design of protective coal pillars in similar mines.