Study On FBG Monitoring Of Roof Based On Model Experiment And The Stability Analysis Of Tunnel

The stability of surrounding rock in mined-out area has become the most important issues inmine security, in which the roof falling has greatly affected the stability of surrounding rock andthe security of mining work. While because of the discontinuity, heterogeneity, anisotropy, andoccurrence difference of rock, it is difficult to predict and assess the instability of roof accurately,so it has significant economic and social benefits to study the instability rules of roofsurrounding rock and propose the warning standard.Through field investigation, theory analysis, similar simulation experiment, and numericalsimulation, the thesis has studied the dynamic regulation of roof instability based on the FiberBragg Grating (FBG) bolt monitoring technology and proposed the warning criterion based onthe Article Neural Network (ANN) and catastrophe theory, the main work is as follows:Firstly, the ground pressure distribution of tunnel surrounding rock and the effect of miningface forward to displacement, stress, failure field in drift and adjacent tunnel were studied usingFLAC numerical simulation technology, and based on the cusp catastrophe theory, the stabilityof surrounding rock in mining process was evaluated using the plastic volume strain as variable;Secondly, through the comparative study of indoor similar simulation experiment andnumerical simulation, the damage development of roof and signal characteristics of FBG undermining influence were revealed; the evaluation condition of roof instability using catastrophetheory was established, in which the strain of FBG bolt was using as the state variable, and thesensitivity of every parameter was analyzed.Finally, according to the result of the indoor experiment, the monitoring time series waspredicted using Radial Basis Function (RBF), and based on the view of energy band, thetransient signal evaluation system under different damage condition was established usingmathematics software Matlab, and a serial of continuous signal were analyzed.From the analysis above, the gound pressure distribution under mining influence was given inthis thesis, and based on the catastrophe analysis of palstic volumn strain, as the sudden releaseof plastic volumn strain, the roof was easily caused partial instability in the early mining process.And the result of indoor experiment and numerical simulation showed the signal characteristicsand change law of FBG monitoring, it is also shown that the ground pressure and vibration hadgreatly affected the stability of roof and the development of signal. Furthermore, the catastrophe theory analysis of monitoring data verified the great influence of ground pressure on roofinstability again, and the sensitivity of any other factor was given. At last, based on thenonlinear analysis technology such as ANN, Wavelet Analysis etc., making use of mathematicssoftware Matlab, the evaluation system of monitoring data was established, and the result wasproven to achieve high precision.