| Large deformation,rock burst and other dynamic disasters frequently happens in the roadway of deep and high intensity mining.High stress concentration is the core reason to leading high mining pressure phenomenon.However,failure mechanism and supporting method based on stress has obvious limitation for dynamic disasters.The nature of rock failure can be concluded that the energy storage capacity overwhelming energy input.Therefore,it is more reasonable to analysis roadway stability based on energy aspect.In this paper,energy evolution of roadway and energy absorbing supporting system with high strength have been studied by theoretical analysis,numerical modeling,laboratory and field experiments.The main conclusions are as followings:(1)The evolution model of energy input,concentration,dissipation and release density in excavation and extraction is established based on the law of elasticity,conservation of energy.The solution and calculated examples of energy distribution and evolution of roadway rocks with different cross-section shapes are provided using Gauss dispersion.In terms of the complex geological and stress conditions in the coal mine,the influence of the factors,such as tunnel depth,lateral pressure coefficient,rocks strength,length diameter ratio of tunnel,driving and mining speed,on the energy evolution of rocks are analyzed.(2)Based on the characteristics of energy evolution,the high-strength energy absorbing theory,which is defined as that not only consider the high-strength resistance to prevent the deformation of rocks,but also to reduce the internal energy accumulation and absorb the energy released from rocks has been put forward.The high-strength energy absorbing support materials,including high-strength energy absorbing rock bolt and high-strength energy absorbing prop,are developed to carry out the theory.(3)The mechanical properties of high strength energy absorbing rock bolts are obtained by the theoretical analysis and laboratory investigation.The expression of working resistance,supporting distance and energy absorbing capacity have been developed.The structure,principle and working mechanism of high-strength energy absorbing rock bolt are highlighted.The statically pull-out tests of new rock bolt show that the developed high-strength energy absorption support material has the characteristics of high strength,high rigidity,high energy absorbing performance and strong adaptability.(4)Based on the mechanical characteristic curve of high-strength energy absorbing rock bolt and prop,the numerical calculation model of support unit is established.Combined with the energy evolution model,the coordinated deformation mechanism between the high-strength energy absorption support system and the rock in the process of mining and driving is studied.The effects of deformation and energy evolution are analyzed,which helps acquire the characteristics of deformation and energy evolution.(5)Based on the high-strength energy absorbing support technology and the characteristics of large cross section open-off cut,the support concept,"equivalent roadway width" is put forward,and industrial test is carried out in a coal mine.The field results show that the high-strength energy absorbing support system can not only resist the deformation of the second excavation of rocks,but also reduce the energy accumulation and absorb the energy releases.The results prove that the high-strength energy absorbing support technology has a good effect on controlling the deformation of rocks and resisting the dynamic pressure.The design process of "equivalent roadway width" for large section roadway is suggested according to the research results.There are 95 figures,15 tables and 205 references in this thesis. |
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