Cause and Solution to Roadway Deformation in Vietnam Underground Coal Mines

The deformation and support method of roadways have always been important issues in safe mining and production. Vinacomin's statistics show that, by 2021, there will be 64.19 km of roadways that need to be repaired (accounting for 25% of the total new roadways). Thus, the problem of maintaining roadway stability is facing difficulties in underground coal mines in Vietnam. To find out the causes of roadway failures, a case study at roadways of the Khe Cham I and Khe Cham III coal mines, Vietnam, is presented in this paper. Based on the results of a detailed field survey, the deformation characteristics of roadways and the failure mode of support structures were investigated. The results show that the roadway deformation is severe and the main support cannot control surrounding rock mass. Also, the destruction of support structure is frequent on reused roadways, affecting production efficiency and work safety. Therefore, to reduce deformation and increase roadway stability, a new support method called "multistage anchor of rock bolt + cable bolt" has been developed and a new longwall mining system with critical coal pillar width has been proposed. The new findings of the research can provide references for scientific studies, and apply them in Vietnam's underground coal mine practices.