Experimental Study On The Separation Evolution Of Overlying Strata Above The Stope By Distributed Optical Fiber Sensing

After mining will cause the overlying strata movement and breaking, so as to form a layer of mining in the overburden. Is closely related to the study on the principle of separation process of the movements in overlying strata and grouting minus sink, the prevention and the control of separation water disasters and pressure relief gas drainage engineering problems and need monitoring overburden bed separation development and state, master of goaf on overlying strata absciss layer evolution. The traditional detection methods of bed-separation mostly used the technologies such as geological radar detection, borehole camera and seismic technology and so on. In view of the fiber optic sensor can be embedded in the structure which can detect internal stress and deformation of materials effectively, proposing a new testing method that a distributed fiber optic strain gauges for researching laws of bed-separation development in mining.In this paper, the mechanism of bed-separation of overburden strata, bed-separation of the mechanical structure, fiber grating sensing mechanism and the distributed deformation detecting mechanism of the optical fiber are introduced. A similar material physical model was been made, its dimensions is 2000(L)×200(W)×1150(H) mm,and dial indicator,FBG and φ0.9mm sleeve single-mode fiber as the monitoring means are mounted in the model for detecting the bed-separation of Overburdens development.By targeting experiments to determine the relationships between corresponded position to the distributed optical fiber in the model. Articles about the laws of overburden strata movement and breaking, rock subsidence and distributed optical fiber test results are analyzed. The results of the distributed optical fiber testing are compared with FBG test results and dial indicators results. The study shows that(BOTDA) Brillouin distributed optical fiber sensing technology can be a good method for testing the bed-separation of overburden strata in the model. Besides, it can reflect the position and the laws of development of overburden strata bed-separation well. With different advancing distance, distribution curve of the center frequency shift occurs frequency hopping nodes, where are dubious positions of bed-separation. In the process of advancing, the point on the fiber pull force increases where the rock below this point may have separation.