无煤柱自成巷采空区顶板碎胀系数测定方法
Method for Determination of Mined-out Roof Expansion Coefficient of Self-formed Roadway Without Pillar
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摘要: 以宝山煤矿6302工作面垮落细砂岩顶板碎石帮为研究对象,对岩石碎胀系数的现场实测方法及其对巷道顶板变形的影响展开研究;通过分析碎胀系数的机理,结合工程实际,建立了自然标定准线法测量碎胀系数模型,确定了碎胀系数现场实测的方法。现场实测结果表明:采空区顶板垮落后至压实稳定经历3个阶段,快速压实阶段碎胀系数由1.83~1.88迅速降至1.37~1.42,初步稳定阶段碎胀系数变化速度减缓,为1.35~1.39,在缓慢压实阶段,碎胀系数变化值≤0.01;巷道围岩变形规律与采空区矸石碎胀系数变化规律呈现一定相关性,同样存在3个区段,最终巷道顶底板的移近量为296 mm,两帮移近量为135 mm;根据采空区矸石碎胀系数和巷道围岩变形规律,切顶卸压自动成巷期间需要进行巷内临时补强支护,且支护距离≥120 m。Abstract: With the background of gangue rib formed by fine sandstone roof of 6302 working face in Baoshan Coal Mine, the field measurement method of bulking coefficient and its influence on roof deformation of roadway are studied. By analyzing the mechanism of bulking coefficient and combining with engineering practice, the model of measuring bulking coefficient by natural calibration alignment method is established and the method of measuring broken expand coefficient in field is confirmed. And the field measurement shows that there are three stages of roof from collapse to compaction in goaf: the bulking coefficient decreases from 1.83-1.88 to 1.37-1.42 in rapid compaction stage; and in the initial stable stage, which slows down to 1.35 to 1.39. Then in the stage of slow compaction, and the change value of coefficient of fragmentation and expansion is less than or equal to 0.01. Furthermore, there is a certain correlation between the deformation law of roadway surrounding rock and the variation law of gangue bulking coefficient in goaf, which also has three sections, and the final movement amount of roadway roof and floor is 296 mm and 135 mm respectively. According to the gangue bulking coefficient in goaf and the surrounding rock deformation law of roadway, temporary reinforcement support is needed in the roadway during the gob-side entry retaining, and the supporting distance shall be at least 120 m.