Stability Of Large Height Supports In Fully Mechanized Face Mining Steeply Inclined Thick Coal Seam

Affected by the variation of seam dip angle, strata movement and gangue filling was complex in fully mechanized caving workingface in steeply dipping seam, resulting that it is difficult to achieve efficient production with conventional caving technology and difficult to achieve security management inthe fully mechanized working face with large mining height. In order to control thes tability of support in large mining height workingface in steeply dipping seam, it has high theoretical and practical value in the research of the lawof overlying strata and top coal deformation, destruction and migration.By using physical simulation experiment, numerical analysis and field monitoring methods to study the law of overlying strata and top coal deformation, destruction and migration,the time distribution of apparent stress and strata behaviors incaving workingface in steeply dipping seam in workingface 25221 of mine 2130, results show that:(1) In steeply dipping seam, compare with general mining height the stress of large mining hight releasing zone of roof is larger, and the movement of overlying strata is also larger than the normal working face. There are uneven stresses in the working face. Especially in the middle region and the upper region. Partial support is small or zero lead to “ support-surrounding rock” system element is missing. Roof displacement uneven distribution resulting supprot's beam in downward trend and support's base in upward trend. In the upper region of supportor than the lower region of the obvious characteristics of movement of the carriage, Support working properties can not function properly lead to "support- surrounding rock" system instability.(2) As larger overburden falling height, there is a symmetric filling zone appeared. The body of falling over burden was resemble “saddle” shape. There is a large space for filling in the middleregion. The periodical weighting is obvious, the working resistance is large. In the upper region of the roof caving working face supportor with impact, It is not conducive to support stability.(3) The large mining height support has the higher center, structural stability is poor. Important degree of the main factors of influence support stability are workingface angle, mining height, support working resistance. False-inclined mining, standardized move the supports, cutting height control, increase the setting load and other facilities can ensure the stability of the hydraulic support.(4) Field engineering practice and application shows that working resistance was bigger in the upper region than the lower region of working face, and the distribution of support load is reasonable and show normal distribution. Mostly, the support resistance was about 80% of rated resistance, and benefit to the stability of support.The paper related research results with the experiment, theoretical analysis' sesults are consistent. Field applicationeffect is good and well applied, can provide reference for the similar condition working face production safety.