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Abstract A key issue in underground mining is to understand and master the evolving patterns of mining-induced stress，especially abutment pressure，and to control and utilize the action of rock pressure. Based on the mechanical characteristics analyses of macro stress shell(MSS)，in-situ observation，numerical and physical modeling tests have been carried out to investigate the redistribution patterns，mechanical characteristics and geometrical parameters of the MSS developing and those correlations in the rock surrounding a fully mechanized top-coal caving (FMTC) face with unsymmetrical disposal. The results show that，with the face advancing，the MSS evolution is bundled of mined-induced high stress developing and recurrently equilibrating process until one new balance forming and the MSS development shape is an approximate half-space ellipsoid shell in overburden strata. The mechanical characteristics of MSS evolution are opened out and the MSS development could be divided into three stages in unsymmetrical disposal with small wide coal pillar，namely the old MSS expanding stage，the new MSS forming stage，and the gradually-correspondingly stabilizing stage. Drastic rock pressure in mine may occur when the balance of the stress shell is destruction or the forces system of the stress shell transfers. This study will pay an active role in theoretic references to rocks stability control，gateway layout，efficiency and safety mining.
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Received: 26 December 2008
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