AbstractThe interaction effects in multi-seam mining depends on many factors such as local geological and geotechnical conditions, mining depth, seam sequencing, and mining method employed, etc. The paper discusses preliminary study on the interaction effects in underground mining of double extra-thick coal seams in Mae Moh coalfield in Thailand. The Mae Moh mine is currently operated as open pit mine by EGAT (Electricity Generating Authority of Thailand) and it is the largest open -pit lignite mine in Thailand. In the near future, the final pit limit of the mine will be reached and underground mining will be commence d from the final highwall in the depth of 400-600 m from the surface. However, due to the challenges such as poor geological and geotechnical conditions, extra-thickness (20-30 m) of the coal seams and huge final pit slope, success probability for underground mining are being evaluated at the present. This paper discusses the ground response and possible interaction effects in the double extra-thick seams mining by means of numerical analyses using three dimensional finite difference code FLAC3D.