Long-Distance and High-Efficiency Temporary Support Technology in Dynamic Pressure Bearing Area of Gob-Side Entry Retaining

The stability of surrounding rock in dynamic pressure bearing area of gob-side entry retaining is important to the safety of working face. However, the problems of long-distance and high-efficiency temporary support in DPBA of GER are not fully resolved. In the present study, a GER of Shuguang Mine in Shanxi Province, north China, has been taken as the research background, and the temporary support technology was studied systematically through theoretical analysis and field practice. The overlying rock structure and the interaction between support devices and surrounding rock of GER were analyzed, and the main function of temporary support of GER was proposed. The temporary support mechanics model based on the synergy of “support device–bolt (cable) support system” was established, and the calculation formula of the synergistic support strength was derived. This way, a new type of alternate circulation support technology (ACST) was put forward, and a complete set of support and transportation equipment composed of large-span portal support devices and multifunctional transportation equipment was developed. Combined with the actual conditions of No. 1228 GRE, the temporary support strength was calculated to be not less than 500.00 kPa, ZLQ2826/22.5/38 type of large-span portal support device was determined, the temporary support mechanism of “pre-active supporting, onetime loading, synergistic supporting, overall supporting” was proposed, and the long-distance support scheme was put forward. Engineering application results showed that the temporary support parameter was reasonable, and the surrounding rock was well maintained, which has achieved the safe, efficient and long-distance temporary support in the DPBA of GER. Finally, according to the actual application, the existing problems of temporary support technology were summarized, the improvement measures were given, and the follow-up research work of alternating cycle temporary support technology was prospected.