Dependence of mechanical properties to the texture and water content of weak rock - A case of the Late Tertiary mudstone from the Mae Mo lignite mine, northern Thailand

The mudstones taken up here belong to the Miocene Mae Mo Group( Sithiprasana 1959). The Group is composed of mudstone beds interbedded with lignite beds. The beds have been designated alphabetically from bottom to top. The mudstones tested here belong to the beds on and under the upper most lignite bed 0. The mudstone under the lignite bed belongs to the bed 0 and mudstone on the lignite bed belongs to the bed P. The mudstone 0 contains seams, lenses and fragments of lignite and shows grayish appearance. Mudstone P is rather massive and is whitish colour containing less amount of carbonaceous shale and lignite. Sample blocks were collected from the same horizon within each of the beds.