Research On The Technology Of Waiting Pressure When Passing Through Abandoned Roadway In Fully-Mechanized Face With Anual Coal Production Of 10 Million Tons

Distributed within the working face, a variety of roadway (abandoned roadway), which serviced for the early face, seriously restricted the safe production and rapid promotion of face. Through practical experience, Shendong had initially proposed waiting pressure technology that stopping coal mining to reserve a small pillar before passing through the abandoned roadway. This paper make a system research which focuses on the determination of relevant waiting pressure parameters.Using the numerical simulation, field measurement and theoretical research methods, the law of roof movement and strata behaviors when the working face passed through the abandoned roadway were analyzed and predicted. According to the simulation of numerical analysis software FLAC3D and field monitoring of surrounding-rock movement, we determined that the process of working face from 10 m away from abandoned roadway to 3m (stop mining isobar) is a stage that influence of mining is dramatic. In the constant pressure process of working face, the stress of Surrounding-rock movement for abandoned roadway moved forward and roof pressure was released in a form which the performance has changed. Through the field monitoring of support resistance, estimating the thickness of immediate roof and old roof with theoretical formula and predicting the position of fracture lines for old roof, we determined the roof structure of the top of abandoned roadway.The focus of Paper is the determination of the relevant waiting pressure parameters, namely, the determination of waiting pressure small pillar width W and waiting pressure time T. Through theoretical analysis and field measurement, we obtained the principles of the determination of waiting pressure small pillar width W:Pillar width should both be beneficial to the movement of top roof and prevent the harmful exercise of roof, besides, can achieve relief effect. Waiting pressure small pillar width W can be determined by the energy and numerical calculation method. The most effective way is that it was determined by making the law of strata behaviors as a measure. Generally, we make the numerical value of the waiting pressure small pillar width W is W=3～4m. The determination principle of the small pillar waiting pressure time T is that the elastic energy which decided by the amount of elastic deformation released completely. Specific method for determination is that when working face stopping mining and constant pressure, we send specialized personnel to notes and draw the curve of the roof movement. We can think isobaric process is over when the curve of the roof and floor closed to flatten and start to mine. We can also take surrounding-rock movement of abandoned roadway and the strata behaviors of waiting pressure small pillar A was significantly ease as a sign which means isobaric process is over. Usually, we make the waiting pressure time T within 4-8h.