Study on rib spalling control of shortwall drilling mining technology with a large mining height

The drilling shearer and drilling mining technology has been developed in order to effectively control the rib spalling of a shortwall with a large mining height face in a soft thick coal seam. Working face no. 1305 of the Zhaozhuang Coal Mine was taken as the research subject. The rationality and superiority of shortwall drilling mining technology with a large mining height (SDMTLMH) were explained by combining the theoretical analysis with a numerical simulation. First, based on the occurrence characteristics of the immediate roof, the mechanical model of a simple supported beam was established to calculate the maximum unsupported roof distance. The advance of the working cycle was determined. Then, based on the spatial mobilization plane (SMP) theory, the abutment pressure distribution in the reserved coal was deduced by establishing the unit mechanical model. The appropriate range of the width of the reserved coal (WRC) was determined according to the principle of conservation of energy. Finally, six drilling mining schemes were proposed according to the range of the WRC. In addition, we redeveloped the constitutive model of supports and compacted rock mass in the gob using FLAC3D software. The distribution of the abutment pressure in the drilling mining face and the control effect of the rib spalling were obtained. It was proved that the SDMTLMH can effectively suppress rib spalling and roof fall. The distribution of the strain energy and the external potential energy in reserved coal in six schemes was plotted by Surfer software. The rationality of the theoretical analysis was verified. Considering the caving effect of the reserved coal, the control effect of rib spalling, and the appropriate advancing speed of the working face, the appropriate WRC was determined to be 0.4 m. A field investigation showed that the control effect of rib spalling for working face No. 1305 was much better than that of other large mining height faces in this coal mine.