CONTROL TECHNOLOGY FOR SOFT ROCK ROADWAY IN INCLINED COAL SEAM: A CASE STUDY IN NUI BEO MINE, QUANG NINH, VIETNAM
Keywords:Inclined seam, Soft rock, Asymmetric deformation, Prestressed bolt, RS2
The large deformation of soft rock roadway is still a main concern for a large number of coal
mines, particularly in terms of these located at the inclined seam with the large section. This paper presented
a successful case study conducted at Nui Beo coal mine in Vietnam. Borehole peep detector was first put into
the application to investigate the distribution of fractures to clarify the influenced range of surrounding rock.
Then, the finite element analysis software (i.e. RS2) program is adapted to establish the numerical model
aiming at exploring critical parameters for bolt support. Finally, a combined support technology including
primary support by using a high prestressed bolt and reinforced technology by cable have been proposed and
put into application. The results revealed that 1) the rheological strain is closely related to time, it is about
105 days from the firstly caving to be stable, 2) the maximum displacement of the ribs and roof-to-floor are
28mm and 47mmrespectively. The deformation of surrounding rock obtained from case study was used to
evaluate the effectiveness of proposed support technology. The use of high prestressed bolt can maintain the
stability of surrounding rock incline coal seam. Moreover, the experience can be used as a reference for other
mines in Vietnam.