浅埋厚松散层薄基岩综采工作面开采覆岩切落体结构分析及应用

Analysis and application of sheared and fallen roof structure during shallowly buried fully mechanized mining under thick loose bed and thin base rock

浅埋厚松散层薄基岩综采工作面开采覆岩破断失稳诱发的强压显现问题日益凸显,已对矿井安全及高效生产带来严重威胁。为此,以神东矿区22614工作面为工程背景,采用现场监测、相似试验与力学建模相结合的研究方法,分析其强矿压显现特征,揭示采动覆岩破断失稳诱因,构建覆岩破断结构力学模型,核定工作面液压支架工作阻力,并开展现场实例应用。结果表明:现场监测的工作面开采顶板平均破断步距为11.2 m,液压支架平均工作阻力为8450.1 kN,最大工作阻力为11857 kN;相似试验中,工作面开采老顶呈短悬臂岩梁剪切破断,断裂面贯通地表,覆岩滞后煤壁整体切落,平均垮落步距为12.5 m;通过建立浅埋厚松散层薄基岩综采工作面覆岩切落体结构平面力学模型,提出了覆岩切落体结构失稳判据,指明不稳定系数与覆岩切落角和液压支架承载力间的正相关关系;并给定了工作面液压支架工作阻力计算公式,算出了液压支架平均承载力为8364.22kN,与现场监测结果具有较好的一致性。该结果可为我国浅埋厚松散层薄基岩综采工作面支架选型和顶板控制提供重要的理论依据。

Severe ground pressure problem during shallowly buried fully mechanized mining under thick loose bed and thin base rock is increasingly prominent,which has seriously threatened safety and efficient production in coal mine.This study took 22614 working face in Shendong mining field as engineering background,adopted the combination research method of field monitoring,similar experiment and mechanical modeling to analyze the characteristics of its strong ground pressure,to reveal cause of mining-induced roof broken and instability,to build mechanical model of roof broken structure,to determine working resistance of hydraulic support in working face,and finally to perform field example application.The study results showed that:based on field monitoring,the average roof broken length of 22614 working face was 11.2 m;the average working resistance of hydraulic support was 8450.1 kN,and the maximum working resistance was 11857 kN.In similar materials simulation experiment,the average caving length was 12.5 m,and roof sheared and broke as short suspension beams,crack extended to surface,which led to the whole sheared roof falling behind coal wall.As well plane mechanical model of sheared and fallen roof structure was established,then the structure instability criterion was put forward,the positive correlation between instability coefficient and roof sheared and fallen angle,bearing capacity of hydraulic support was pointed out.Certainly,working resistance calculation formula of hydraulic support in working face was given and calculated average bearing capacity of hydraulic support was 8364.22 kN,which is in good agreement with the field monitoring results.The results provided important theoretical basis for support selection and roof control of shallowly buried fully mechanized mining under thick loose bed and thin base rock in China.