Abstract Aiming at the powered support jammed accidents are prone to take place in the working face with a raise of mining upper limit of Huainan mine area,the special overlying strata structure and its mechanism of powered support jammed are researched by using of theoretical analysis and field measurement. The corresponding mechanical models of support and surrounding-rock are established for different overlying strata structure,the loads of topsoil layer and overlying strata transfer into the key strata is deduced,the critical support working resistance is defined,and related preventive measures are put forward. The results show that: the structure type of overlying strata can be classified into six groups within four types according to filling coefficient of immediate roof,overburden key strata structure,and hydrogeology of topsoil layer on the bedrock surface. The risk of powered support jammed with single key strata structure is higher than that with multi-key strata in upper exploitation limitation-heightened working face. For the single key strata structure,when mining below the unconsolidated confined aquifer,the load on the key strata increases with the decrease of distance from the key strata to the aquifer and the increase of hydraulic pressure,so,the key stratum“voussoir beam”structure is more prone to sliding instability; while mining below the thick hardpan,the natural balance arch structure is formed in the hardpan,the sliding instability is not likely occur in the“voussoir beam”structure with the protection of arch structure.
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