Developing Law Of Water-flowing Fracture With Wongawilli Backfill In Coal Mines

Based on the mining geological condition of coal mine, wongawilli backfilling mining method is proposed. On the basis of that, by means of numerical simulation, physical simulation and laboratory test, water-flowing fracture developing law with wongawilli backfill is studied and analyzed, in order to provide the research basis for water preserved mining with wongawilli backfill in coal mines. The main research results are as follows:(1) Equivalent mining height model of wongawilli backfilling mining and the main factors of water-flowing fracture developing height are proposed, and the developing height of water-flowing fracture is expected. To provide the basic reference for numerical simulation and physical simulation, compressive strength of high-water swelling backfilling materials are carried out.(2) Using physical simulation method, the change rules of overburden movement with wongawilli backfilling mining in different stages are studied. Focus on the dynamic evolution law of overlyburden water-flowing fracture, quantitatively derived the height of water-flowing fracture. The simulation results show that: wongawilli backfilling mining can effectively control the rock movement; Overlyburden water-flowing fracture basically undeveloped and roof subsidence small in first and second stage, when the backfilling rate is 80%. Overlyburden water-flowing fracture increases rapidly, which largest height is 9.8m and maximum subsidence is 9mm.(3) Backfilling mining model and Equivalent mining height model(under long wall mining)are established. Developing law of overlyburden water-flowing fracture in different equivalent mining height and backfilling rates are studied. Overlying strata displacement, stress and water- flowing fracture of equivalent mining height model and backfilling mining model are the comparative analysis. The simulation results show that: developing law of overburden water-flowing fracture with wongawilli backfill in coal mines is different from the long wall mining. Waterflowing fracture of backfilling mining model in different backfilling rate is lower than corresponding equivalent mining height model. with the backfilling rate is reduced, the water-flowing fracture development height gradually increased. When the backfilling rate is 90% and 0, respectively 4m and 43 m water-flowing fracture height. With equivalent mining height is increased, the water-flowing fracture development height gradually increased; When the equivalent mining height is 2.5m and 0.25 m, respectively 58 m and 8m water-flowing fracture height.