With the characteristic of less roadway excavation and high resource recovery, gob-side entry retaining (GER) technology is a safe and efficient green mining technology. Many experts and scholars have done extensive research on its principle and application. However, GERs are rarely used in thick soft coal seams. In this paper, based on the geological conditions of a coal mine in China, we propose a novelty approach of GER in thick three-soft coal seam (it means a single seam with a soft roof and a soft floor). The engineering scheme includes roadway expansion, large section roadway support, cutting roof to relieve pressure, and road-inside backfill body construction. The established mechanical and numerical calculation models effectively guide the engineering practice. Field observations showed that all the processes met the requirements of field production. The research results could provide theoretical guidance for the application of GER under similar geological conditions.

With the advantages of large anchoring force and fast anchoring speed, resin cartridge has become the main anchoring means of geotechnical engineering and underground space engineering support. Based on the theoretical analysis, it is clear that adding aggregate can improve the mechanical properties of grout and the bolt-grout interface stress state; the mechanical properties of aggregate are positively correlated with its improvement effect on anchorage performance. By using the numerical simulation method, it is concluded that the addition of steel segments into the resin grout can improve the stiffness of the anchorage system and enhance the energy absorption and antifailure ability of the anchorage system. Relying on the self-developed anchorage mixing device, the effects of steel segment diameter and addition amount on the anchoring force were studied experimentally, and the optimal addition amount of different types of steel segment to improve the maximum anchoring force was determined.