Mechanical Property Study On Separation Wall Of Gob-side Entry Retaining In Fully-mechanized Coal Mining

The elastic mechanics model of gob-side entry retaining s immediate roof is established based on critical layer theory, and the arithmetic expressions between subsidence and support resistance of separation wall is deduced by the displacement variational method, and their linear relations is discovered as well. Moreover, it is concluded that the subsidence of roadway roof of gob-side entry retaining is given deformed and calculation expression of deformation is available in this thesis. This thesis points out that the main function of gob-side entry retaining s separation wall is to maintain the stability of roadway roof, not to resist the subsidence of it. This thesis also points out that there will have no obvious effect to have a forcible control of roof s subsidence by increasing loading capacity of separation wall.The stress and deformation of the separation wall and roadway surrounding rock in different roof contact height is analyzed by numerical simulation software, and it is concluded that there exists a reasonable value for the roof contact height, which can improve the separation wall s lateral deformation and subsidence effectively. 200 mm to 300 mm of roof contact height is suggested if using filling concrete separation wall. A too low roof contact height will damage the separation wall for the reason that the forcible subsidence of roadway roof is difficult to support, while a too tall roof contact height will cause a larger deformation of roadway s surrounding rock and go against with roof s stability. Based on key points of yielding technology of separation wall, this thesis puts forward that pre-supporting concrete separation wall can improve the separation wall s mechanical property, which makes a smooth transition of roadway roof s supporting loading from pillar to wall, and avoids roof s damaging of the separation wall before the wall can support effectively.The traditional gob-side entry retaining technology is optimized based on the key points of separation wall s yielding technology. After carrying the optimized gob-side entry retaining technology out to Wulan coal mine 5868 s haulage roadway, it is discovered, by mine pressure monitoring data, that with the proceeding of stope face, the subsidence of separation wall and roadway-side support resistance can be divided into 3 phrases, which is the rapid subsidence phrase of the separation wall; the transitional phrase of separation wall s support resistance and the loading phrase of the separation wall. The thesis puts forward that the separation wall with yield pressure has a very obvious effect in maintaining roadway s surrounding rock s stability in gob-side entry retaining, which provides reliable theoretical foundation and technical index for gob-side entry retaining in coal mine.