| In the technical system of comprehensive mechanized filling mining, important content should be studies not only on mechanical properties of gangue filling body, but also on mechanical relationships among backfilling-coal mining hydraulic support, surrounding rock and gangue filling body. In the thesis, by utilizing methods of experimental tests, theoretical analysis, numerical simulation and physical simulation of similar materials, macro-mesoscopic mechanical properties of gangue filling body has been studied. Furthermore, relationships of the “support-surrounding rock-filling body” during comprehensive mechanized filling mining have also been systematically studied. The main innovations and research results include the following aspects:(1) Based on confined compression tests, characteristics of slag mixture with different water and lime content including stress-strain, compaction degree and deformation modulus have been studied. It is found that stress-strain meet the logarithmic relationship. Moreover, with the content of fine particle suitably increases, or with appropriate addition of water and lime, the anti-compression properties of the whole system will be better. Combining with Singh-Mitchell creep model, the creep process has been analyzed, and the compaction creep function which can apply to five kinds of broken gangue being obtained.(2) The slag mixture particle flow models and the gangue backfills particle flow models with different gangue contents and bond strength have been set up to study the behaviors of confined compression and biaxial compression. It is found that the stress-strain curve which obtained by cluster model is more close to reality. When bond strength or contents of gangue are high, the peak strength is high and the phenomena of post-peak softening and fluctuation are obvious. When the gangue contents are higher than 50%, the interconnectivity of strong force chains decreases gradually, at the same time, the strong force chains become inclined, and the shape of the force chain changes in the loading process.(3) The particle flow interaction model of gangue filling body and hydraulic support have been set up, and the study found that the introduction of vibration mechanism in the pushing and pressing procedure of self-ramming backfilling hydraulic support can slow down the rate of stress-increasing of ramming structure effectivity. Under the same stress, the distance that ramming structure with vibration travelling is greater than that without vibration. By increasing the frequency or amplitude of ramming structure, ramming effect can be improved.(4) The mechanical model of “backfilling mining support-surrounding rock-filling body” has been set up, and roof beam subsidence and distribution of advance stress in working face have been calculated respectively. The results show that the initial filling height being found as not only the decisive factor to control the stability in each part of roof beam during its subsiding and migration, but also have great influence in the distribution of advance stress in working face. Additionally, the pushing force of backfilling-coal mining hydraulic support show a significant control effect mainly within the range of 2.0MPa, and the pressure yielding height of the support has some influence on the working face advance stress.(5) The backfilling-coal mining hydraulic support and stope model have been built to analyze the processes of filling mining, which verified the controlling rules to the roof and influencing rules to the advance stress in working face. Stress distribution in the top beam of hydraulic support generally present the rules of small to big from front to back, which will change during the process of backfilling-coal mining. Additionally, pressure yielding height of the support has notable influence in both numerical value and stress distribution of the top beam.(6) After a reasonable determination of the similar models of filling body and support, the filling mining process has been studied by similar simulation tests. The results show that the influence law from initial filling height and the support pressure yielding height to roof subsidence is identical to the theoretical part, and the measured values through experiments are also coincide well with those obtained through theoretical calculations.(7) The mechanical model of “support-surrounding rock-filling body” is applied to the working face of a mine, the roof subsidence and stress distribution are calculated and compared with the field measurement results, the rationality of the model is verified. |
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