Study on optimization of support parameters for roof caving prevention and control in fully mechanized mining face

Aiming at the phenomenon of roof caving at the end face of fully mechanized mining face with large mining height, the stress distribution characteristics and instability mechanism of roof strata under three working conditions of pitch, upward pitch and horizontal advance are compared and analyzed based on numerical simulation method. By establishing the mechanical response model of hydraulic support, the load transfer law of support system under different advancing angles is studied, and the mechanism of adjusting the position parameter configuration of support system on roof control is revealed. The research confirms that optimizing the parameter configuration of the action point position of the support system can improve the distribution pattern of the surrounding rock stress field, effectively inhibit the development of roof separation, reduce the expansion probability of the tensile stress concentration area, and realize the prevention and control of roof caving risk. Taking ZY20000 / 34 / 70 D two-column shield support as the research object, the optimal support parameters under different propulsion conditions are determined by adjusting the pressure distribution scheme of the column: the vertical support component should be controlled in the range of 600 ～ 1600 kN during horizontal propulsion; it is suggested to maintain 400 ～ 1000 kN vertical support force under inclined mining condition. The vertical support force should be maintained in the range of 300 ～ 600 kN in the inclined mining mode.