Study On Subsidence Deformation Detecting Of Unconsolidated Strata By Fiber Grating Technology In No.3 Jining Coal Mine

The deep Cainozoic unconsolidated aquiferous strata is located widely in Huadong district of China. The water in the aquiferous strata is lost through the cranny of efflorescent rock, which results in the fall of water level and the augmentation of rock's impactful stress, and the aquiferous strata will be compressed. Hundreds of shafts distributed in Huaibei, Huainan, Xuzhou, Datun and Yanzhou are destroyed, which influences the safety production badly. Therefore, we should study an adaptive method to detect the subsidence deformation of unconsolidated aquiferous strata and realize the aim of detecting the function safety of the shaft, which is of great significance to achieve essential safety coal mine.In this paper, based on the theoretical analysis and the numerical analysis to the unconsolidated aquiferous strata, it believes that the vertical additional stress is the primary reason for the damage of shaft, which includes two processes—the water verus the unconsolidated strata and the unconsolidated strata verus the wall of shaft. We also have analysed the deformation theory and the damage mechanism of the shaft, provided the elementary explaination of additional stress for the shafts in the No.3 Jining coal mine, achieved the variety relationship between the depth and additional stress. Based on the numerical simulation, we get the conclusion that when the deformation reaches 500mm under the corresponding geological conditions the shaft will be damaged. According to the fiber Bragg grating sensor principle and the survey of engineering geology, we have designed the adaptive fiber Bragg grating detecting system , given a detailed analysis to the data which we have got from the detecting system. Besides, a contradistinctive analysis is conducted between the hydrology developments and strata deformation, thus to forecast the strata section which will damage the shaft easily. According to the compress property, we also carry out a fiber Bragg grating concrete sample experiment and performance experiment relatively, and conclude the relationship between wavelength excursion and the load under different compress conditions.It's has a good corresponding relation between the wavelength excursion and the strata deformation as well as the level of groundwater. When the unconsolidated strata compressed and the level of groundwater is fall, the wavelength will be short, when the compressed strata is relaxed and the level is upgrade, the wavelength will be on accretion. The fiber Bragg grating sensor detecting system can be used in the subsidence deformation of the unconsolidated strata. Accordingly, the safety of shaft's detecting will be realized, which will provide the feasibility to forecast the shaft damage for the similar diggings.