Key Technologies and Application Test of an Innovative Noncoal Pillar Mining Approach: A Case Study

TLDR

Longwall mining is hindered by coal waste, complex processes, and slow speeds. The study introduces the Gob‑side Entry Retaining by Roof Cutting (GERRC) approach to enable effective pillarless mining. GERRC combines roof support, directional presplit cumulative blasting, and surrounding rock control, validated through theory, simulation, lab, and field tests on medium‑thick seams with compound roofs. Tests confirm that the combined technologies control roof damage, preserve entry integrity, and meet safety requirements, demonstrating the feasibility of GERRC for pillarless mining.

Abstract

The waste of coal resources, a complicated production process and slow mining speed seriously restrict the rapid development of longwall mining. To achieve effective mining, an innovative noncoal pillar mining approach (i.e., Gob-side Entry Retaining by Roof Cutting (GERRC)) was introduced. The mechanism of the GERRC approach and its three key technologies (i.e., roof support technology, directional presplit cumulative blasting technology and surrounding rock control technology) were studied by theoretical analysis, numerical simulation, laboratory and field experiments. The new approach was finally tested under medium-thick coal seam and compound roof conditions. The results show that the directional presplit cumulative blasting technology can effectively control the damage evolution in the roof rock, maintain the integrity of the entry roof and contribute the gob roof to the cave in time. The support technologies in different roof movement stages can control the entry surroundings, and the final section of the retained entry met the safety production requirements. The test results suggested that the proposed approach for coal effective mining is feasible, and the introduced key technologies and design methods potentially produce reasonable values for applications of pillarless mining in similar projects.