Research On Theory And Practice Of Mining Induced Overlying Strata Deformation And Surface Subsidence With Paste Backfilling

Paste backfilling mining is an effective approach to settle damage caused by coal mining to water resources, land resources, building resources. Compared with other approaches, such as fully caving mining, strip mining, separated bed grouting, water-gravel-mixed filling. it has some advantages, such as high security, high recovery ratio and environment friendly. The application of paste backfilling mining technology is an important solution to carry out scientific development concept and realize green coal mining, which is a revolution for coal mining technology and is also one of the important development directions in the coal mining technology in the 21st Century. It will surely promote the coal mine development of our country with security, high efficiency and sustainability. Based on the theoretical and practical points in this article, the problems were emphasizely studied which are related to strata deformation and surface subsidence control in paste backfilling.Strata control theory of paste backfilling is to study the relationship law between the deformation of the strata and surface deformation and paste backfilling mining under the condition that the filled body is in action. And it is different from strata control problem in caving mining. Compared with other backfilling mining methods, the greatest advantage of paste backfilling is that the mined-out area has been backfilled before roof stratum subsided, and the subsidence of roof stratum only happens in the front of working face and top control area. The subsidence of mined-out area was controlled by the support from the filling body. Therefore, in paste backfilling, the key point of strata control is to control the deformation of immediate roof and lower main roof which are the key layers for strata control.Based on combining with physical simulation and numerical simulation, the deformation procedure of the overlying strata and distribution characters of abutment pressures were analyzed in paste backfilling, and the strata deformation was classified. We define that the key point of strata control is to control the deformation of immediate roof and lower main roof. Based on the theoretical calculation and site measurement, the strata deformation zone in paste backfilling is studied. The result shows that the leakage zone of roof stratum can be predicted in the traditional calculating method. The support mechanism of the filled body was discussed.According to the coupling characters of the support composed of the coal on working face, the support and the filled body in paste backfilling, a combined roof stratum mechanical model and its deflection equation were established And the relationship equation between the co-activation of the filled body the support and coal body and the roof stratum deflection line was deduced. Through the roof stratum deflection equation, the calculating method of the abutment pressure was given and the relationship law among the key strata movement and the backfilled degree, and the mechanical characters was also systematically analyzed We analyse the requirement on initial strength of filled body and the support strength, and research the relationship between the primary and the secondary influence of key strata movement and the possible control degree, and clarify that the affecting factors from major to minor are the unmeet distance to the roof stratum of the filled body, the distance previously moved of the strata, the pressed ratio of the filled body. Finally, the parameters for judging the roof stratum stability were discussed and the subsidence control mechanism was clarified, in backfilling mining.According to numerical simulation, distribution characters of abutment pressures and the effect of the filling ratio on the deformation and abutment pressures were analyzed in Xiaotun mine. The demand on the filling ratio was indicated and the methods to enhance the filling ratio was stated. The predicting model of the surface subsidence was discussed. We predict that the subsidence coefficient can be controlled about 0.16 by the backfilling in Xiaotun mine. It can ensure the security of the buildings in Nanwang village.The main compositions of the paste backfilling background, the paste filling system,the technological process of filling and the evolution of backfilling mining about Xiaotun coal mine were introduced in the thesis.Combining the practical conditions of Xiaotun coal mine,the general characteristics requirements of the paste filling materials were put forward. Strata behaviors of filling work-face, filling body quality, the roof stratum management quality, and surface subsidence on the condition of filling mining were observed. The obtained achievements and existing problems were introduced in detail in the article, thus the advice for further improvement was presented on the basic of the experience by the author.