坚硬顶板控制放顶方式及合理悬顶长度的研究

 基于坚硬顶板长壁工作面初次跨落步距大、周期断裂悬顶长，对采场安全危害严重的特点，系统研究工作面顶板初次断裂的3种控制放顶方式和周期断裂的合理悬顶长度。通过建立两端固支岩梁力学模型，分析并比较采用循环浅孔拉槽、中部拉槽和端部拉槽等3种爆破控制放顶方式缩短坚硬顶板工作面初次断裂步距的拉槽深度与爆破工程量。结果表明，就爆破工程量而言，端部拉槽最小，中部拉槽次之，循环浅孔拉槽最大。通过顶板周期断裂悬臂岩梁力学模型的建立及其分析，基于工作面支架的设计工作阻力，推导顶板周期断裂的合理悬顶长度与工作面支架设计支护阻力，以及上覆岩层荷载和工作面控顶距之间的关系式。研究结果在晋城七岭煤矿15102工作面成功应用，可以为相应条件下坚硬顶板控制放顶提供理论依据与应用指导。

STUDY OF CONTROL CAVING METHODS AND REASONABLE HANGING ROOF LENGTH ON HARD ROOF

Based on the characteristic of large primary bestraddle distance,long periodic fracture hanging roof and serious threaten to mine safety in hard roof long working face,three control caving methods of the primary fracture and the reasonable hanging roof length of periodic fracture are studied systematically. Three caving methods controlled by blast such as cycle shallow kerve,middle kerve and tip kerve are used to shorten the primary fracture distance of hard roof working face,of which the kerve depth and blasting quantities are analyzed and contrasted by establishing mechanical model of rock embedded beam at both ends. The results show that side kerve is the least,middle kerve is followed and cycle shallow kerve is the largest on the part of blasting quantities. By establishing and analyzing the model of cantilever rock beam,the reasonable overhanging length and face support strength are ascertained on the basis of designed resistance of face support. Additionally,the relation between overlying strata load and the working face controlling roof distance is deduced. This study has a successful application to working face 15102 of Qiling mine in Jincheng;and it can provide theoretical support and application guidance to control caving in hard roof under the corresponding conditions.