Development characteristics of water conducted fracture zone based on overburden structural effect

In order to study the roof water disaster caused by coal mining in Huanglong coalfield, taking mining failure of layered overburden as research object, four typical composite structural models for coal-soft rock-hard rock-soft rock-hard rock(combination I), coal-soft rock-soft rock-hard rock-hard rock(combination Ⅱ), coal-hard rock-soft rock-hard rock-soft rock(combination Ⅲ) and coal-hard rock-hard rock-soft rock-soft rock(combination IV) were generalized. Numerical simulation and theoretical calculation were used to analyze the mining failure characteristics of different overburden combinations and correlation between water conducting fissures and lithologic combination structure of overburden. The law of the effect of overburden structure on the development height of water conducting fracture was studied. The research results show that under the same mining height, the coal-soft rock-hard rock-soft rock-hard rock overburden structure has the minimum conducting height and the coal- hard rock-hard rock-soft rock-soft rock overburden structure has the maximum conducting height.The engineering examples show that the conducting height of the coal seam mining in Huanglong coalfield is not a simple linear relationship with the mining height, and the guiding height predicted by the overburden structure effect is closer to the measured value.