Deformation Mechanism Of Surrounding Rock Of Roadway Driving Along Goaf In The Whole Process Of Driving And Fully Mechanized Caving Mining And Its Control Technology

As the supporting technology of full mechanized caving mining, gob side entrydriving already has a long-term promotion and extensive application in China with the widespread application of bolt support since the 90 s. But in mining roadway support design and construction, support form and parameter are often determined by experience and engineering analogy. This method causes many problems in roadway support, coefficient of mining, mining excavation relay and so on. The research on deformation mechanism of surrounding rock of roadway driving along goaf in the whole process of driving and fully mechanized caving mining and its control technology have great significance in improving coefficient of mining, maintaining railroad safety and promoting healthy and sustainable development of coal resource in our country. This paper has a systematic study on deformation mechanism of surrounding rock of roadway driving along goaf in the whole process of driving and fully mechanized caving mining and its law of stress evolution by the method of experimental test, theoretical analysis, numerical simulation and field measurement. Based on this research, we summarize the technology of surrounding rock controlling in gob-side entrydriving and the method of support design. Innovative results are as follows:(1) In order to learn the basic mechanical properties of the surrounding rocks, such as uniaxial compressive strength, uniaxial tensile strength, and triaxial compressive strength, a lot of related basic mechanical tests were conducted by DDL500 electronic universal testing system, MTS815.02 rock mechanics testing system. The triaxial creep properties of surrounding rock were obtained by MTS815.02 rock mechanics testing system. Through the test results, the creep curve under high stress and the accelerated creep curve under yield stress were recognized using classical Kelvin model and modified K-B model.(2) A new point was put forward that basic roof key blocks and narrow coal pillar were indirectly interacted by immediate roof structure, including roof coal. Through force analysis of mechanical model of immediate roof structure, analyzed the difference of mechanical features of immediate roof structure between before and after digging and obtained the formula of basic roof key blocks stability and established the evaluation system of surrounding rock structure stability.(3) According to the structure features of surrounding rock in gob-side entrydriving, built the mechanical model of roof coal deformation and based on Winkler elastic foundation model, got the analytic solution of roof coal subsidence curve. The relationships between roof coal deflection and roof coal stiffness under different supporting intensity were obtained by MATLAB.(4) The failure characteristics and deformation law of surrounding rock in full mechanized caving mining gob side entrydriving during stoping were researched. The pressure distribution law of basic roof stratum in full mechanized caving mining working face and gob side entrydriving was summarized. The inhomogeneous elastic cushion sheet mechanical model of basic roof was set up. Also, analytic solution of basic roof deformation was got by Ritz method and Galerkin method.Considering the strong rheological property and dilatancy property of coal mass under high stress, and based on linear Mohr-Coulomb criteria, set up the elastic-plastic plane strain mechanical model of integrated coal and narrow coal pillar. Then got the approximate solution of this plane strain problem by stress method and got displacement distribution function of integrated coal. According to these results, obtained the deformation distribution of integrated coal and narrow coal pillar.(5) In order to analyze the stress and deformation of different wide gateway protecting coal pillars during tunneling and stoping, the method of numerical simulation was used. From the perspective of economy, roadway maintenance and safety production, studied the effect of narrow coal pillar width on roadway stress and deformation during tunneling and stoping, and determined the rational width of narrow coal pillar in this mine.(6) During material roadway tunneling and stoping in Xin’an mine 3304 working face, surrounding rock stability and supporting effect were overall analyzed. Engineering practice showed that narrow coal pillar influenced surrounding rock stability in gob-side entrydriving, therefore, strengthening narrow coal pillar support could reduce triangular block rotation subsidence, guaranteed narrow coal pillar stability and reduced two sides relative displacement.