Determination of steel arch support distance for roadways under the open-pit mine: a case study at the Mong Duong Coal Mine (Vietnam)

Abstract

Purpose. Nowadays, in Quang Ninh coalfield, the mining activity in quarries is increasing. For this purpose, mine roadways are dug and supported. After the mine roadways are dug, they are mainly supported by steel arches. Statistics in fact show that about 85 % of the roadway support structure at the underground coal mines in Quang Ninh are supported by the steel arch support made of SVP profile. The purpose of the study is to calculate and determine a reasonable steel support distance for the roadways located under the open-pit mine to ensure their stability and the safety of exploitation. Methodology. In this study, the numerical simulation method was used. On the basis of Phase2 software and geological conditions of the mine, the authors established a simulation model to determine the pressure acting on the roadway and select a reasonable support distance. Findings. The study considered different steel arch support structure distance following the structure of the rock mass under the 790 open-pit area at the Mong Duong Coal Mine, the internal forces in SVP steel arch support structure distance were also studied for one-lane railway and two-lane railways roadway. From the results of internal forces in the steel support structure, a reasonable SVP-22 steel arch distance was selected, which is 0.7 m for the one-lane railway roadway, as well as SVP-27, which is 0.7 m for the two-lane railway roadway. Originality. Using Phase2 software, the authors created a simulation model of the roadways in Seam L7 located on the West side of Mong Duong Coal Mine, which allowed analyzing and describing the condition of the surrounding rock mass. This study utilized a numerical modeling approach to simulate and establish the bending moment and axial force of both single and double lane railway roadways, across a range of support distances. Based on the results of pressure calculation for the roadways, the authors have selected a reasonable support distance for each corresponding roadway. Practical value. The findings of the study serve as the foundation for the practical application of production methods at the Mong Duong Coal Mine. On the basis of calculating the pressure acting on the roadways at the Seam L7 in the West Side under the 790 open-pit area, the distance of steel arch support was determined, from which the roadway support plan has been developed. This research result will also serve as a basis for other mines with similar geological conditions in Quang Ninh coalfield to consider and apply.