Study on overburden structure and mechanism of rock pressure in large space stope

The thick coal seam mining causes the formation of large space stope,the wide range of overlying disturb- ance and the roof pressure of stope has obvious periodic pressure and characteristics of strong pressure. There are many overlying disturbance strata in large space stope,the mechanism of interlayer interaction is complex,and the force and direction among roof fault blocks are varied,which makes the theoretical analysis of overlying structure in large space stope more difficult. In order to reveal the over-burden structure characteristics and the mechanism of rock pressure ac- tion,on the basis of the characteristics of overlying rock structure in large space stope which are obtained by the meas- ured analysis,the mechanical model of overlying structure in large space stope is established based on energy variation principle,reveals the mechanism of mine pressure of overlying structure in large space stope. A coal-support coopera- tive bearing model in large space stope is established,and the interaction relationship between surrounding rock and support is obtained. Studies show that overlying strata of large space stope caused by thick coal seam mining have significant “low-medium-high” layer structure characteristics which are the direct cause of the complex strata behaviors, the roof structure instability in “medium-low” layers is related to the large and small stope periodic weighting and the high roof structure instability of linkage is a main factor which induces the strong strata behaviors of large space stope. The instability movement of overlying structure is also restricted by the support of gangue in goaf,the effective potential energy of roof and the suspension length of high roof,and it is an important factor affecting the pressure of stope. Coop- erative bearing of coal-support under large space stope condition,the corresponding theoretical research results are in good agreement with the research conclusions of relationship between surrounding rock and stope support based on measured inversion analysis,which verifies the validity of the theory of overlying rock structure in large space stope.