Experimental Investigation for Water Flowing Fractured Zone Due to Coal Mining Under Sea Area

This paper presents an experimental investigation of development of water flowing fractured zone due to coal mining under sea area by scaled model test. Two models are designed to simulate coal mining along the strike and the dip. In model 1, the thickness of the overburden varies from 74 to 124 m and coal seam dips at an angle of 8 degrees, and model 2 with a overburden thickness of 90 m and a dip angle of 0 degrees. The results indicate that the height of overburden caving and water flowing fractured zones both increase at first then decrease to a comparatively stable values with the mining distance increasing; the height of overburden water flowing fractured zone increases significantly with the thickness of the overburden increasing and the height of overburden caving zone does not. When the coal mining thickness is 6 m, the maximum height of overburden water flowing fractured zones is 64.16 m (in model 1) and 48.20 m (in model 2), the maximum height of overburden caving zones is 12.76 m (model 1) and 12.00 m (model 2), respectively. The research results provide a helpful basis for upper mining limit decision-making and risk assessment.