Research On Large Section Ingate Support Theory And Technology In Deep Shaft

With the increasing demand of coal resources in our country,shallow resources can't meet our demand of national production.Especially in some areas of Shanxi province,shallow resources are nearly exhausted.While newly developed energy still can't satisfy the needs of resources in economic development.Therefore,exploration of deep coal resources become the main developmental direction of future mining industry in order to realize coal resources sustainable development.As the joint of shaft bottom and laneways,the stress state of ingate is very complicated.Especially for the mines with increasing mining depth,there are many urgent problems during construction and supporting at ingate area including great ground stress,large laneway section,disturbance effect during construction,serious stress concentration,ect.Foreign countries focus a lot on ingate support design in deep mines and have taken a series of special measures in many aspects such as design and construction. In deep mine with high ground pressure and soft strata,intensive I-beam steel structure has been adopted and special treatment has been used at the both higher and lower sections of shaft in order to ensure the safety of ingate and shaft. With support of secondary shaft ingate in Xingyue coalmine in Xiaoyi city of Lvliang as the object of study and with the combined methods of field investigation,mechanical experiment,theoretical analysis and numerical simulation,the paper made a detailed analysis of stress state at secondary shaft ingate,damage pattern and support method optimization.The main contents include the following aspects.1,Mechanical parameters of surrounding rocks at secondary shaft ingate in Xingyue coalmine had been obtained through on-site sampling practice and experimental test of rock mechanical characteristics,wich provides a solid foundation for theoretical analysis and numerical simulation.2,Theoretical analysis indicated that the location of high ground pressure concentration area of secondary shaft ingate is at the joint of ingate and shaft bottom and the stress concentration isoline distribution state was summarized.Hign ground pressure concentration area is at the joint of ingate and shaft bottom.Plastic damage occurs at the bottom of rocks at the beginning when concentrated stress exceeds supporting capability of surrounding rocks.Decrease of the supporting capability of surrounding rocks in fracture zone leads to the movement of stress concentration area towards deep rocks,meanwhile,the fracture zone begins to expand and deepen.With repeated cycles in the above way,damage deepens until the internal stress of surrounding rocks reaches a state of equilibrium.3,Through numerical simulation,stress concentration area and failure and damage range were analysized qualitatively. Stress concentration factor and damage depth were determined quantitively.In this paper,stability of surrounding rocks at ingate area in deep mine andhigh ground pressure ingate support in Xingyue coalmine were studied.Firstly,active support capability(surrounding rock strengh)should be enhanced;secondly,supporting parameters should be optimized;thirdly,pretightening force of bolt and anchor cable should meet the requirement of design during construction and construction quality in other sessions should be valued.The optimum supporting method at ingate area wes determined finally.