Abstract
Based on the overburdened structure of shallow coal seams in the West of China, the traditional support resistance method may not apply in such regions due to many roof shear and support crushing accidents. Four support working resistance indexes—rated working resistance, average working resistance, average-partial working resistance, and average-upper working resistance are counted as the candidate working resistance. The method of optimizing and inverting working resistance was put forward based on the roof control effect and working resistance overrun percentage. The simulation of a fully-mechanized top coal caving working face was built by using the UDEC software to analyze the top coal cavability and roof subsidence under different supporting strengths to determine the final working resistance. The project practice of 1322 working face in Jindi coal mine shows that the working resistance is 80–90% of calculated rated working resistance. The hydraulic support is worked under good condition. There is no pillar shrinkage and support crushing during coal mining.
Highlights
Half of the world’s coal reserve is thick coal seam [1,2,3]
The fully-mechanized top coal caving method is used with top-cave hydraulic support model ZF8000/23/35
The end working resistance of No 60 support shows that overruns for about 10 times and the longest overrun was obtained to continue for 8.7 m of the pressure overruns for about 10 times and the longest overrun was obtained to continue for 8.7 m of advancing distance
Summary
Half of the world’s coal reserve is thick coal seam [1,2,3]. Mining methods in Poland, Hungary, former Yugoslavia, France, India, and China are generally similar. Zhang [27] and He [28] analyzed the overburden movement character in the top caving working face, which is an important factor to calculate the hydraulic support working resistance. Kong [35] studied the reasonable working resistance of hydraulic support by using microseismic monitoring technology, similar material simulation test. Those working resistance calculation methods did not consider shallow depth coal seams where the support resistance may not be applicable. A design flow to calculate the support resistance in the fully-mechanized top coal caving working face is proposed by considering the overburden movement characteristic, using statistics and verifying with field practice. The top coal caving property and roof subsidence in different supporting intensities are analyzed by using numerical simulation method to justify reasonable working resistance
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