Stratum Subsidence Of Dongtan Coal Mine In Water Injection Process From Upper Group To Middle Group Quaternary

Ground subsidence is one of the most common and main geological hazards in ourcountry. It has caused great losses and damages in the development of economic society andpublic life; At the same time, land subsidence has a strong impact on the sustainabledevelopment of our country’s ecological environment. The thick unconsolidated strata isgenerally located in East China,because of the groundwater recession, many mine shafts aredamaged. It has taken huge economic losses and safety risks to coal mines. Studies haveshown that roundwater recession will increase the effective stress of soil mass, thenconsolidation settlement will be occurred in mainly in stratum, which will cause shafts’damage. Deformation monitoring and replenishing water to unconsolidated layers are effectivemeasures. This research will study the monitoring technology of stratum settlement based onFBG sensing technique.Additionally, it will combine water injection project to analysis theinfluence of water injection to unconsolidated strata’s deformation.The analyses is performed on the settlement mechanism of unconsolidated strata andstudies subsidence of different lithology of strata after the unconsolidated strata lossing water;At the same time analyses the strain transfer of the embedded FBG strata subsidencemonitoring technology. Studies have shown that the strain transfer consists of transmission ofthe strain optical fiber core between packaging materials and fiber Bragg grating sensorbetween hole sealing materials, the formula of strain transfer was deduced by this dissertation.What’s more, The dissertation has further analysis of water level drop model and dependentvariable model.It calculates the compression deformation of sand and clay layerseparately,which makes calculation more accurate.In order to prevent the damage of west wind shaft in DongTan coal mine, long-term water injection to unconsolidated layers near west wind shaft is done. It uses a new way of waterinjection that putting water from upper Quaternary to middle Quaternary.Based on fiber Bragg grating strata subsidence monitoring system we get deformationrules of unconsolidated layers near west wind shaft, and obtain the subsidence deformationthough dependent variable model.Though hydrological monitoring system we get the changesof water injection and water level and cvomparethe water level with strain of layers. Theanalysis shows that Fiber Bragg grating strata subsidence monitoring system can effectivelydetect the deflection of the unconsolidated strata, it is sensitive to the water levelchange.Analysis obtains the mathematical formula of layer strain between water level change.The monitoring system of strata subsidence by Fiber Bragg grating and the new waterinjection style have played a positive and effective role in the administration of compressiondeformation of quaternary strata in Dongtan coal mine, and this method can be applied in theEastern China.