基于BOFDA的覆岩采动“两带”变形表征研究

Fiber optic strain characterization of“two zones”deformation of overburden mining based on BOFDA

为研究荫营矿150313工作面两带高度的光纤应变表征方法,分析了BOFDA的应变监测原理,建立了光纤应变表征冒落带和裂隙带岩层变形的力学分析模型,详细分析和讨论了两带范围内岩块位移变形时水平光纤、垂直光纤的应变变化特征,得出光纤应变变化和岩层破断垮落强度、垂直位移量成正相关关系;光纤应变突变点表征了岩块的破断垮落位置,光纤应变突变点之间的范围表征了岩层变形的范围。并进行了基于BOFDA技术的平面模型相似模拟试验,试验结果表明,两带发育规律和BOFDA光纤应变曲线有明显的对应关系:垂直光纤应变不仅表征了采动两带在采场横三区横向演化过程的变形特征,还表征了岩层垮落的高度和垮落强度;水平光纤应变曲线不仅表征了两带范围内岩层的垮落范围和垮落强度,其多级凸台曲线同样表征了采场横三区岩层破断垮落的不均衡性。相似模拟试验得到该工作面的实际冒落带高度和裂隙带高度,与理论计算数值吻合,符合该矿实际情况。研究结果为BOFDA技术在上覆岩层变形的物理模型试验中应用提供了可靠依据。

In order to study the fiber optic strain characterization of the height of two belts in working face 150313 in Yinying coal mine,the principle of BOFDA strain monitoring has been analyzed,and the mechanical analysis models of fiber optic strain characterization of rock deformation in caving zone and fracture zone have been established.The strain characteristics of horizontal fiber and vertical fiber have been analyzed and discussed in detail.It is concluded that the strain value of optical fiber is positively correlated with the strength and vertical displacement of rock failure.The fracture of rock mass is characterized by the optical fiber strain mutation point,and the range of rock deformation is characterized by the range between the optical fiber strain mutation points.In addition,the plane model simulation experiment based on BOFDA technology has been carried out.The experiment results have shown that there is obvious correspondence between the development law of the two zones and the BOFDA fiber strain curves:the vertical fiber strain represents not only the horizontal evolution process of the deformation of the two zones in the third horizontal area of the stope,but also the height and strength of the rock collapse;the horizontal fiber strain curve represents the collapse range and strength of the strata of the two zones and its multi-stage convex curves represent the imbalance of the strata in the three areas of the stope.The actual height of caving zone and fracture zone are obtained through similar simulation experiments,which is consistent with the theoretical calculation and the actual situation.The results provide a reliable basis for the application of BOFDA technology in the physical model test of overburden deformation.