Dynamic evolution of overlying strata stress induced by mining and mine water disaster identification based on information entropy

The evolution of roof fracture in coal seam mining is important for the formation of roof water passage in coal mine.The first mining face of No.2 coal seam in the research area is taken as geological background,and the dynamic evolution process of overburden stress under different mining distances was studied by using similar material model.Based on the information entropy of information theory,the moni toring results of stress in the model were calculated to obtain the stress information entropy under different mining distances,so as to conduct a quantitative dynamic analysis of overburden strata stress induced by mining.The results show that the evolution of stress information entropy can be divided into three stages:occurrence period,expansion period and stable period.With the increase of mining distance,the stress information entropy is fluctuating and rising,which is caused by the development of separation and the wa ter conducting fracture zone in the overlying strata system.The stress information entropy increases when the separation is formed and the water conducting fracture zone is developed,and decreases when the fracture is closed.In different spaces,there are great differences in stress information entropy.From the vertical moni toring line,the stress information entropy near the open off cut position decreases with the advance of the working face,and the stress information entropy near the stop line position increases with the advance of the working face.The stress information entropy at the middle position is basically the same before and after mining.From the horizontal monitoring line,the fracture develops most strongly in the expansion period of stress information entropy.By identifying the hazard sources of mine water disaster,the formation stage of water passage is revealed.During a similar material model excavation from 45 cm to 105 cm,this is the expansion period of stress information entropy,and the water passage is formed in this stage.The engineering example shows that the extension period of stress information entropy is consistent with the dangerous period of mine water disaster.At this stage,some preventive measures should be taken in time to prevent the occur rence of mine water disasters.