Study On Strata Movement Controlling By Raw Waste Backfilling With Fully-Mechanized Coal Winning Technology And Its Engineering Applications

Many coal reserves are trapped under building structure, railway and water body in Chinese coal mines. During the procedure of coal mining environmental pollution has been simultaneously deteriorated due to the large amount of raw waste discharge. A new mining technology raw waste backfilling with fully-mechanized coal mining technology is therefore developed independently which has lots of advantages, such as high mechanization, simple mining system layout, and low mining cost as well. Key issues for the raw waste backfilling with fully-mechanized coal mining technology are how to control strata movement by backfilling waste to make sure that ground deformation within the allowable range. According to the dominant stratum theory for controlling of strata movement, physical mechanics of backfilling raw waste and the structure characteristics of the overlying strata, comprehensive studies on the strata behaviors of waste filling stope with fully-mechanized coal mining, the movement features of key stratum and the ground deformation characteristics are conducted by applying experiments, theoretical analysis and numerical simulation. The results indicate that bending subsidence of key stratum and ground deformation are effectively restrained because of the waste backfilling. The innovations of this thesis are as follows.(1) Based on the compressibility of backfilling waste and the corresponding rheological mechanical theories, the model of equivalent mining thickness for the raw waste backfilling with fully-mechanized coal mining technology is built, the difference of supporting intensity between the raw waste backfilling with fully-mechanized coal mining technology and the conventional one is analyzed and relationship and correction factor for them is given as well. The mechanics principle for the reduce of ground pressure in fully-mechanized coal mining technology working face is obtained in the end.(2) The ground subsidence controlling principle to limit the sinkage of key stratum is proposed by using the dominant stratum theory for controlling of strata movement. Using the theory of beam on elastic foundation and PTH rheological model, the deformation of stratum, the foundation coefficient on elastic foundations and rheological characteristics of underside strata are researched, the time-relationship regularity of key stratum deformation is got.(3) The movement features and stress distribution characteristics of the strata in the waste backfilling strata with fully-mechanized coal mining technology working face are researched by numerical simulation method, the dynamic change regularity of the overlying strata is revealed and the influences of the elastic modules of backfilling material on the bending subsidence of the key stratum and the ground deformation is analyzed as well.(4) Based on the theory of rock pressure under waste backfilling condition and the ground subsidence regulations, the new methods and techniques for the raw waste backfilling with fully-mechanized coal mining technology are designed, some facilities, such as the hydraulic pressure shield support, raw waste backfilling transportation facilities are designed as well. This technology has been applied in the Zhaizhen Coal Mine successfully, and the economical and social benefits are pretty good.