煤柱应力应变分布的光纤监测试验研究

Research on Optical Fiber Sensing Monitoring Experiment of Stress-strain Distribution in Section Coal Pillar

为科学留设区段煤柱,基于光纤传感监测技术,从煤柱内部应力应变角度研究煤柱的合理尺寸及其稳定性。制作平面物理相似材料模型,通过3个工作面开挖形成2个区段煤柱,在煤柱内分别埋设5个光纤Bragg光栅传感器及分布式传感光纤,同时,在模型底板铺设60个压力传感器,监测煤柱内部应力应变变化。试验表明,煤柱内部垂直应变随工作面推进而增大,水平应变随工作面推进呈"马鞍形"分布;煤柱的破裂区宽度约为3~5 m,塑性区宽度约为5~8 m,弹性区宽度约为22~27 m;1~#区段煤柱和2~#区段煤柱一侧开采时,对应的应力集中系数分别为1.54和2.04;两侧均为采空区时,应力集中系数分别为1.99和2.18。光纤光栅监测结果揭示了煤柱内部应力应变规律,为煤柱稳定性实时监测提供了科学手段。

In order to design the section coal pillar of mining area scientifically,based on the optical fiber sensing technology,the reasonable size and the stability of pillar is studied from the view of distribution law of stressstrain in pillar. Similar material model was made,and two pillars were formed by excavation of three working faces. Five optical Bragg gratings and distributed sensor fibers were inbuilt in the two section coal pillars,besides,60 pressure sensors were layered in the floor of the model to monitor the strain change of pillar. The results show that the vertical strain in pillars becomes bigger with the increase of working face. However,distribution of the horizontal strain is ＂the shape of saddle＂. The breadth of fracture zone of pillar is about 3 m to 5 m,the breadth of plastic zone is about 5 m to 8 m,and the breadth of elastic zone is about 22 m to 27 m. When mining at the same side of 1^# section coal pillar and 2^# section coal pillar,the factor of stress concentration are 1.54 and 2.04. When it is goaf in both sides of pillar,the factor of stress concentration are 1.99 and 2.18. The monitoring results of optical reveal the law of stress-strain in pillar,and provide a scientific method to the real-time monitoring of stability of pillar.