由于各种因素的作用和影响,工作面架前多次发生片帮、冒顶,严重影响正常生产和安全,直接影响综放技术发挥优势和效益。 Due to the influence and influence of various factors, there are many times such as sheet-metal caving and roof caving in front of working face, which seriously affect normal production and safety and directly affect the advantages and benefits of fully mechanized top-coal caving technology.