Analysis of the mining failure regularity and safety mining of the weak and weathered composite roof

Firstly, the Shanxi formation coal seam sections and hydrogeological features were analysed in research coal field. Based on the engineering geological characteristics of the compositely structured overburden with weakness and weathering, the failure of the overburden and ground movement and deformation during coal mining were characterized by applying comprehensive research method combining engineering geological mechanical model test and finite element numerical simulation. The development height of caving zone and water flowing fractured zone of difference thickness of coal seam were calculated. The influence degree of coal layer safety mining was assessed. The appropriate measures on prevention and cure of water were submitted purposefully, which has been confirmed by the field tests and assured that no water-intrusion hazard or sand rush would occur.