Steeply dipping seam refers to the coal seam with dipping angle in the range of 35°~55°, which is well recognized to be very hard to mine by the mining industry all the world. Based on physical simulation test, some fundamental researches focused on the rock strata breaking and moving process, Rock structure stability mechanism and control provide a theoretical basis for mining safely and efficiently in steeply dipping seam. The results indicated that time sequence and unbalance are main caving traits of main roofs, In tendency direction, the bedding separation initially emerge at the upper position (two-thirds) of roof beams, which induces tensile failure and roof caving shifting towards the upper parts of working face, which results in the critical layer zone conversion and change along inclination, forming scalar structure. Mechanics model and stability criterion of scalar structure is established and destabilization model of critical layer rock is revealed.
Steeply dipping seam refers to coal seam dipping angle in the range of 35°~55°. The reserves of steeply coal seam account for approximately 15%-20% of the total coal reserves in China. The coal extraction ratio and production efficiency is low and accidents frequently occur in coal mine. The remarkable difficulty of mining steeply dipping seam is recognized by international mining industry (Wu 2006, Wu et al. 2013). Due to dip angle of steeply dipping seam is bigger, the gravity of rock along the stratification exists the horizontal component, and geological structure of steeply dipping seam is more complex than gently inclined coal seam and the overburden deformation and failure mechanism also has remarkable difference, mainly in strata movement, roof caving form and rock structural instability. Therefore, based on a large number of similar material physics simulation, movement of surrounding rock and instability mechanism of rock mass structure is researched systematically in steeply dipping seam mining and establishes the foundation for ground control and dynamic disaster prevention of overburden rock structure, which has great significance to safe and efficient mining.