Deformation and failure characteristics and control technology of large-span open-off cut in soft and broken thick top coal
The large cross-section open-off cut of Anyang Zhujiao Coal Mine often uses passive supports arranged along the roof,resul-ting in large deformation of surrounding rock,easy leakage,and high labor intensity for workers.In response to the above issues,numeri-cal simulation methods were used to study the relationship between crack development,displacement and stress distribution,and the span of the open-off cut.Surrounding rock control strategy and support plan were proposed.The results showed that as the span of the open-off cut increased,the range of the plastic zone in the surrounding rock gradually increased.The roof was mainly subjected to shear slip or ten-sile shear failure,while the two sides were mainly subjected to Poisson effect expansion tensile and shear failure.The subsidence of the roof,the inward squeezing of the roadway,and the floor heave gradually increased.The top coal,direct roof,and main roof strata gradually moved layer by layer,with large cracks appearing in some areas of the roof,and overall movement of the deep roof above the falling arch.The range of harmful tensile stress areas in the roof and floor of the roadway presented an arched distribution and gradually increases.Based on the deformation and failure characteristics of the surrounding rock of the open-off cut,a combined active and passive supporting method of high-strength,high stiffness,and high preload strong supporting coupling passive single hydraulic prop reinforcement was pro-posed.Field investigations have shown that the surrounding rock of the open-off cut has been effectively controlled,providing reference for the control of large cross-section open-off cut surrounding rock similar to the development of fissures in supporting top coal.
crack developmentsupporting top coallarge cross-section open-off cutstrong anchoring
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